Omicron Bode 100 User Manual

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Bode 100

User Manual

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Bode 100 User Manual

Article Number VESD0661 - Manual Version: Bode100.AE.3

© OMICRON Lab 2008. All rights reserved. This User Manual is a publication of OMICRON electronics GmbH. This User Manual represents the technical status at the time of printing. The product information,

specifications, and all technic al data contai ned within this User Manual a re not contractu ally bindin g. OMICRON electronics reserves the right to make changes at any time to the technology and/or configuration without announcement. OMICRON electronics is not to be held liable for statements and declarations given in this User Ma nual. T he user is respon sible for ev ery appli cati on descr ibed in this User Manual and its results. OMICRON electronics explicitly exonerates itself from all liability for mistakes in this manual.

Please feel free to copy this manual for your needs. Windows is a registered trademark of Microsoft Corporation. Excel is a registered trademark of

Microsoft Corporation. Visual C++ is a registered trademark of Microsoft Corporation. MATLAB is a registered trademark of The MathWorks, Inc. LabVIEW is a registered trademark of National Instruments.

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Contents

Using This Manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Conventions and Symbols Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Related Documents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

1.2 Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

1.3 Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

1.4 Standard Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

1.5 Normative Conformity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

1.6 Test Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

1.7 Delivery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

2 Getting Started. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

2.1 Installing the Bode Analyzer Suite. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

2.2 Powering the Bode 100. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

2.3 Connecting the Bode 100 to the Computer. . . . . . . . . . . . . . . . . . . . . . .15

2.4 How to Proceed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

3 Gain/Phase Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

3.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

3.1.1 Internal Reference Connection. . . . . . . . . . . . . . . . . . . . . . . . . .21

3.1.2 External Reference Connection . . . . . . . . . . . . . . . . . . . . . . . . . 21

3.2 Choosing the Reference Connection. . . . . . . . . . . . . . . . . . . . . . . . . . . .22

3.3 Example: Gain/Phase Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . .24

4 Impedance/Reflection Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

4.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

4.1.1 General Formulas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

4.1.2 Equivalent Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

4.1.3 Quality Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

4.2 Example: Impedance/Reflection Measurement. . . . . . . . . . . . . . . . . . . .37

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Bode 100 User Manual

5 Frequency Sweep Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

5.1 Example: Frequency Sweep Measurement. . . . . . . . . . . . . . . . . . . . . . .46

5.2 Impedance Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57

6 Frequency Sweep (External Coupler) Mode . . . . . . . . . . . . . . . . . . . . . . . .63

6.1 Example: Frequency Sweep (External Coupler) Measurement . . . . . . .65

7 Calibrating the Bode 100. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75

7.1 Calibration Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75

7.1.1 Probe Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75

7.1.2 User Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76

7.1.3 Hierarchy of Calibration Methods . . . . . . . . . . . . . . . . . . . . . . . .77

7.2 Calibration in the Gain/Phase Mode

(Internal Reference Connection) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77

7.3 Calibration in the Gain/Phase Mode

(External Reference Connection – CH1). . . . . . . . . . . . . . . . . . . . . . . . .78

7.4 Calibration in the Impedance/Reflection Mode . . . . . . . . . . . . . . . . . . . .83

7.5 Calibration in the Frequency Sweep Mode . . . . . . . . . . . . . . . . . . . . . . .90

7.6 Calibration in the Frequ ency Sweep (External Coupler) Mode . . . . . . . .91

8 Common Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95

8.1 Toolbars, Menus and Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

8.2 Setting the Measurement Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98

8.3 File Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

8.3.1 Loading and Saving the Equipment Configuration . . . . . . . . . . .98

8.3.2 Exporting Measurement Data. . . . . . . . . . . . . . . . . . . . . . . . . . .99

9 Advanced Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101

9.1 Advanced Display Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101

9.1.1 Gain/Phase and Impedance/Reflection Mode . . . . . . . . . . . . .101

9.1.2 Frequency Sweep and

Frequency Sweep (External Coupler) Mode. . . . . . . . . . . . . . .104

9.2 Advanced Sweep Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .116

9.3 Level Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .120

9.4 Using Probes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .125

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Contents

10 Automation Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129

11 Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133

11.1 USB Cable and/or Power Sup ply to the Bode 100 Is Missing. . . . . . . .133

11.2 Lost Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133

11.3 Cannot Select Frequencies Lower Than 10 Hz. . . . . . . . . . . . . . . . . . .133

12 Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .135

12.1 Bode 100 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .135

12.2 Power Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .136

12.3 Absolute Maximum Ratings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .136

12.4 Computer Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137

12.5 Environmental Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137

12.6 Mechanical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137

Contact Information / Technical Support . . . . . . . . . . . . . . . . . . . . . . . . .1 39

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .141

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Using This Manual

This User Manual provides detailed information on how to use all functions of the Bode 100 vector network analyzer properly and efficiently. The Bode 100 User Manual is intended for all users of the Bode 100, providing instructions on the operation, usage, and measurement procedures.

Any user of the Bode 100 should have fundamental working knowledge of basic electronics, general measurement techniques, and the use of computer-based applications running under a Windows

Conventions and Symbols Used

In this manual, the following symbol indicates paragraphs with special safety relevant meaning:

Symbol Description

environment.

Equipment damage or loss of data possible

1 Introduction

1.1 Overview

The Bode 100 is a multifunctional test & measurement instrument designed for professionals such as scientists, engineers and teachers engaged in the field of electronics. Its concept – universal hardware controlled by the Bode Analyzer Suite software running on a computer – makes the Bode 100 an efficient and flexible solution for a wide spectrum of applications including:

• Gain/Phase measurements The Bode 100 measures the gain and phase of passive and active electronic circuits as well as complex electronic systems such as closed-loop control systems, video systems and RF equipment.

• Impedance/Reflection measurements The Bode 100 measures the impedance, admittance and reflection coefficient of passive and active electronic circuits. An internal bridge allows performing measurements by just connecting the device under test (DUT) to the Bode 100 source.

Introduction

• Frequency Sweep measurements In addition to single frequency measurements, the Bode 100 performs measurements in the Frequency Sweep mode. In this measurement mode, the Bode 100 is capable of measuring the complex gain, reflection coefficient and impedance of the DUT. The results are displayed as a function of the frequency in various display formats such as group delay curves or Smith charts.

• Frequency Sweep (External Coupler) measurements In this measurement mode you can measure the complex impedance, admittance and reflection coefficient of the DUT by using an external directional coupler or other external measurement bridge. Typical application examples include measurements of broadcast antennas and impedance measurements with signal levels above 20 mW.

The measurement results are available on your computer for processing and/or documentation.

The Bode 100 includes a DDS (direct digital synthesis) signal source with adjustable level and frequency for excitation of the DUT, two receivers processing the DUT’s response and a microcontroller. A DC power converter generates voltages for powering the circuitry involved. For the basic block diagram of the Bode 100, see Figure 1-1: "Block diagram" on page 10.

The Bode Analyzer Suite runs on a computer connected to the Bode 100 through USB interface.

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Bode 100 User Manual

1.2 Block Diagram

Figure 1-1: Block diagram

CH 2 INPUT

CH 2 receiver

CH 1 INPUT

CH 1 receiver

OUTPUT

DDS signal sourceMicrocontroller

CH 1

ADC

CH 2

ADC

DC power

converter

DC power

input

USB

interface

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Figure 1-2: Bode 100 front view

Introduction

1.3 Connectors

Caution: To avoid damage of the Bode 100, check 12.3 "Absolute Maximum Ratings" on page 136 for maximum input signals at the CH 1 INPUT and CH 2 INPUT connectors and maximum reverse power at the OUTPUT connector.

The Bode 100 provides the following connectors:

• OUTPUT (signal source output) on the front panel

• CH 1 INPUT (channel 1 input) on the front panel

• CH 2 INPUT (channel 2 input) on the front panel

• DC power input on the rear panel

• USB connector on the rear panel

Figure 1-3: Bode 100 rear view

OUTPUT CH 1 INPUT

DC power input USB connector

CH 2 INPUT

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Bode 100 User Manual

1.4 Standard Compliance

Table 1-1: Standard compliance

1.5 Normative Conformity

Table 1-2: Conformity documents

The Bode 100 complies with the following standards:

Standard Description

IEC 61326: Class B equipment Performance criterion B

Universal Serial Bu s (US B) Specification, Revision 1.1 and Revision 2.0

The Bode 100 conforms to the following normative documents of the EU:

Document Description

73/23/EWG Concerning electrical devices for use of certain voltage limits

with changes due to the CE designation standard 93/68/EWG

89/336/EWG About electromagnetic compatibility changed by

the standard of the Council from 1991-04-29 (91/263/EWG), the standard of the Council from 1992-04-28 (92/31/EWG), and the standard of the Council from 1993-07-22 (93/68/EWG)

EMC requirements

USB interface

1.6 Test Compliance

The Bode 100 passed the tests according to the EN/IEC 61010-1, IEC 61326.

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1.7 Delivery

Introduction

Bode 100 multifunctional vector network analyzer

Test objects on a PCB: quartz filter, IF filter

BNC straight adapter (f–f) BNC T adapter (f–f–f) BNC short circuit (m)

Bode 100 CD-ROM Wide-range AC power

supply including mains input plugs for different national standards

USB cable 4 × BNC 50 Ω cable

(m–m)

BNC 50 Ω load (m) Bode 100 User Manual

The delivered items may differ slightly from the picture.

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Bode 100 User Manual

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2 Getting Started

Caution: Before installing the Bode 100 , check the environmental and power requirements (see 12 "Technical Data" on page 135).

2.1 Installing the Bode Analyzer Suite

Caution: Install the Bode Analyzer Suite from the delivered CD-ROM before connecting the Bode 100 to the USB connector of your computer.

The Bode Analyzer Suite on the delivered CD-ROM controls the operation of the Bode 100. Install the Bode Analyzer Suite first, before you connect the Bode 100 to the computer. Put the Bode 100 CD-ROM in the CD-ROM drive and

follow the instructions on the screen. Select the 32-bit or 64-bit installation according to your computer’s hardware. For installation support, visit the OMICRON Lab Web site www.omicron-lab.com center (see "Contact Information / Technical Support" on page 139).

or contact your nearest support

Getting Started

2.2 Powering the Bode 100

Caution: Before powering the Bode 100 using a DC power supply different from the one delivered with the Bode 100, check the polarity of its output voltage (see 12.2 "Power Requirements" on page 136).

The Bode 100 is powered with an external wide-range AC power adapter. Before powering the Bode 100, select the adapter’s mains input plug fitting your power outlet. Plug the adapter’s DC output connector into the Bode 100 DC power input on the rear panel and the mains input plug into the power outlet. Alternatively, you can power the Bode 100 with any DC power supply meeting the power requirements specified on page 136.

2.3 Connecting the Bode 100 to the Computer

The Bode 100 communicates with the computer through USB interface (see

12.4 "Computer Requirements" on page 137). Connect the Bode 100 USB

connector on the rear panel to the USB connector of your computer using the USB cable delivered with your Bode 100.

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Bode 100 User Manual

2.4 How to Proceed

Now, you are ready to work with your Bode 100. You can proceed with Section 3 "Gain/Phase Mode" to make your first measurement with the Bode 100, and then go through the Bode 100 User Manual to learn the capabilities of your Bode 100 by doing practical examples. For the Bode Analyzer Suite basics, see Section 8 "Common Functions".

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3 Gain/Phase Mode

Gain/Phase Mode

Figure 3-1: Gain/Phase mode window

Menu bar

Allows access to all Bode 100 functions. See Table 8-1: "Menus and commands" on page 96.

Toolbar

Calibration toolb a r

Choose the calibration mode. Switch the calibration on and off. See Figure 8-2: "Calibration toolbar" on page 95.

Contains shortcuts to the most important Bode 100 functions. See Figure 8-1: "Toolbar" on page 95.

Results

Select the result format and get result values. See Figure 3-3: "Gain/Phase mode results" on page 18.

Split bar

Drag the split bar to resize the panes.

Configuration and me asurement setup

See Figure 3-2: "Configuration and measurement setup" on page 18.

Graphical display of measurement results

Use the shortcut menu to optimize the display. See Figure 3-4: "Graphical display of measurement results" on page 19.

Overload and connection indicators

See Figure 3-5: "Overload and connection indicators" on page 19.

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Bode 100 User Manual

Figure 3-2: Configuration and measurement setup

Set the output source generator frequency.

Set the output source generator level.

Select the channel 1 input attenuation.

Select the channel 2 input attenuation.

Select the receiver bandwidth.

Figure 3-3: Gain/Phase mode results

Hint: A higher receiver bandwidth allows faster measurements, a lower receiver bandwidth in creases the measurement accuracy.

Select the output format of measurement results.

Display of measurement results in the selected format.

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Figure 3-4: Graphical display of measurement results

Gain/Phase Mode

Right-click in the diagram to open the shortcut menu. Use the shortcut menu to optimize the diagram, select the grid and zoom in the diagram. After having zoomed in, click Optimize to get back to an optimized diagram.

Figure 3-5: Overload and connection indicators

Hint: Using the Copy and Copy with Settings function s y ou ca n ea si ly export your diagram into other Windows

applications. For more information, see

9.1 "Advanced Display Options" on page 101.

Overload indicators for the channel 1 and channel 2 inputs. If you see a red bar, increase the attenuation of the respective channel or reduce the source level to prevent the overload.

Serial number of the Bode 100

Hint: If the serial number field in the status bar displays No Device on red background, check whether the Bode 100 is powered and connected to your

computer, and then click the Search and Reconnect Device toolbar button to reconnect the Bode 100.

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Bode 100 User Manual

3.1 Basics

The gain and phase of the DUT is calculated from the measurement data obtained using the reference channel 1 and the measurement channel 2. You can connect the signal source to the reference channel internally or externally as described in 3.2 "Choosing the Reference Connection" on page 22.

The basic definitions and formulas related to the gain/phase measurements are summarized below:

Hf() abs Hf(){}=

φ f() Hf(){}arg=

Tgf()

----- 2π

φ f()•

φω()–=–=

ωd

where

…displayed gain/phase function

Hf()

…magnitude of

Hf() Hf()

…phase of

φ f() Hf()

…group delay of

Tgf() Hf()

OUT

• ij≠,=

OUT

-------------

Sjif() 2

HTf()

where

…S parameter from port i to port j of the DUT

Sjif() ij≠()

…transfer function of a two-port device, depends on the load of the

f() HTf()

OUT

CH1

CH2

Assumptions for measuring :

port where is measured

OUT

…voltage at the DUT’s output …open-circuit voltage of the source …voltage at the DUT’s input …voltage at the channel 1 input …voltage at the channel 2 input …input impedance of the DUT …50 Ω source resistance

Sjif()

(Eq. 3-1) (Eq. 3-2)

(Eq. 3-3)

(Eq. 3-4)

(Eq. 3-5)

• The source with resistance

•50Ω load (receiver resistance) at port j measuring , any other ports of

= 50 Ω is connected to port i.

OUT

the DUT are terminated with 50 Ω.

• Connections are made with 50 Ω cables.

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3.1.1 Internal Reference Connection

Table 3-1: Formulas for Internal Reference Connection

Gain/Phase Mode

The basic formulas for the internal reference connection are summarized below. Note: In the internal reference connection mode of the Bode 100, the reference

voltage for the gain/phase measurement is always .

V02⁄

Channel 2 Input Resistance 50 Ω High Impedance

Hf()

= of the DUT (Eq. 3-11)

----- -

CH1

CH2VOUT

= V

CH2

-------------

CH1

-------------

•==

OUT

Sjif()

(Eq. 3-6) (Eq. 3-7) (Eq. 3-8) (Eq. 3-9)

CH1

CH2

INV0

Hf()

•

= (Eq. 3-12)

Hf() 2 HTf()

If you make a through connection from the source to CH 2: 0 dB gain will be displayed since

CH2V0

2⁄= V

If you make a through connection from the source to CH 2: +6 dB gain will be displayed since

CH2

3.1.2 External Reference Connection

----- -

OUT

--------------------------

•=

ZINRS+()

CH2

-------------

CH1

OUT

-------------

--------------------------

•

V0=

OUT

-------------

•==

ZINRS+()

--------------------------

••=

ZINRS+()

(Eq. 3-10)

(Eq. 3-13)

Independent of the selected input impedance at the channel 1and channel 2 inputs, the following formulas apply:

Hf() HTf()

VIN=

CH1

CH2

OUT

CH2

===

-------------

CH1

OUT

-------------

(Eq. 3-14) (Eq. 3-15)

(Eq. 3-16)

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Bode 100 User Manual

3.2 Choosing the Reference Connection

Open the Configuration window by clicking Device Configuration on the Configuration menu or the Device Configuration toolbar button (see

3.3 "Example: Gain/Phase Measurement" on page 24). By default, the

Device Configuration tab is selected. To connect the reference internally, set the marked configuration field as shown

below.

Note: The source signal is internally connected to the channel 1 input in front of the 50 Ω source resistor (channel 1 voltage as defined in

3.1 "Basics" on page 20).

CH1

V02⁄=

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Gain/Phase Mode

To connect the reference exter nal ly :

1. Set the marked configuration field as shown in the following figure.

Note: The source signal is externally connected to the channel 1 input behind the 50 Ω source resistor (channel 1 voltage as defined in

CH1VIN

3.1 "Basics" on page 20).

2. Connect the reference point of the DUT to the CH 1 INPUT connector using a cable.

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Bode 100 User Manual

3.3 Example: Gain/Phase Measurement

Expected example duration: 20 minutes. In this example you will learn step by step how to use the Gain/Phase mode of

the Bode 100. How to:

• Measure the gain and phase of a DUT with sinusoidal signal at a frequency

• Set the bandwidth, attenuators and amplitudes of the Bode 100

• Optimize the diagram

• Compensate the connection cables in the Gain/Phase mode

Question: What is the magnitude in dB of the delivered IF filter at 10.7 MHz? These types of 10.7 MHz filters are used in FM radios.

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To find out the answer, proceed as follows:

1. Connect the Bode 100 and start the Bode Analyzer Suite.

2. Click the Gain/Phase toolbar button .

Gain/Phase Mode

Hint: If you see the Bode 100 serial number in the status bar on the lower

right side of the window then the Bode Analyzer Suite communicates with the Bode 100. Otherwise check whether your Bode 100 is connected and

powered properly, and then click the Search and Reconnect Device toolbar button .

3. Click the Device Configuration toolbar button to configure the Gain/Phase mode.

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Bode 100 User Manual

4. In the Configuration window, set:

•CH2: 50Ω ON (click the switch as shown)

• SOURCE: 10.7 MHz

• Receiver bandwidth: 10 Hz

• ATTN 1 (channel 1 input atten uato r): 20 d B

• ATTN 2 (channel 2 input atten uato r): 20 d B

• The switch (before ATTN1) to the internal source as reference

• Level: 0 dBm Hint: Setting the receiver bandwidth to 10 Hz makes the readout more stable

but also makes the measurement slower.

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5. Click the Connection Setup tab.

Gain/Phase Mode

The connection diagram shows how to connect the DUT to the Bode 100.

Hint: Set the voltage ratio in the box if you use a probe instead of cable connection (see 9.2 "Advanced Sweep Options" on

page 116).

6. Connect the IF filter to the Bode 100 as shown.

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Bode 100 User Manual

7. Click to close the Configuration window and to get back to the

8. For a better view of the Gain/Phase vector in the complex plane, right-click

Gain/Phase mode window.

in the diagram, and then click Optimize.

Result: The IF filter has a magnitude of –31.43 dB at 10.7 MHz. Your result may differ because each IF filter is slightly different.

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Gain/Phase Mode

The phase readout of 48.5º is not the value you want to measure because it is the sum of the phase shift of the cables and of the IF filter. To get the value of the IF filter only, use the Gain/Phase calibration to compensate the phase shift of the cables.

Continue the example and calibrate the Bode 100 to get the phase shift of the IF filter:

1. Replace the IF filter with the BNC straight adapter (f–f).

2. Click the User Calibration toolbar button to open the calibration window.

3. In the calibration window, click Start in the Gain/Phase area.

The calibration takes only a few seconds. The Gain/Phase mode is now calibrated for the current specific measurement setup.

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Bode 100 User Manual

4. Click .

5. Reconnect the IF filter.

Hint: If you change settings you must repeat the User Calibration. If you use the Probe Calibration instead you can change settings without

repeating the calibration. For more information, see 7 "Calibrating the Bode 100" on page 75.

Result: The transfer function of the IF filter has a magnitude of –31.49 dB and a phase shift of 61.8º at 10.7 MHz.

Again, your results may differ because every IF filter and measurement setup is slightly different.

Hint: You can toggle between the measurement results with calibration and without calibration by clicking the GAIN ON toolbar button .

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As OMIfuzius said: Only applied knowledge changes the world. We are responsible to change it to the better.

Gain/Phase Mode

Congratulation! You learned how to use the Gain/Phase mode. How to:

• Measure the gain and phase shift of a DUT using a sinusoidal signal at a certain frequency

• Set the bandwidth, attenuators and amplitude of the Bode 100

• Optimize the diagram

• Compensate the connection cables in the Gain/Phase mode

Go back to the overview chart at 3 "Gain/Phase Mode" on page 17 and try different settings to check out their effect on the measurement.

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Impedance/Reflection Mode

4 Impedance/Reflection Mode

Figure 4-1: Impedance/Reflection mode window

For the description of the menu bar, toolbar and calibration bar, see 8 "Common Functions" on page 95.

Results

Select the result format and get result values. See Figure 4-2: "Impedance/Reflection mode results" on page 34.

Graphical display of measurement results

Use the shortcut menu to optimize the display. See Figure 3-4: "Graphical display of measurement results" on page 19.

Reference resistance

Set the reference resistance (see

4.1.1 "General Formulas" on page 34).

Configuration and measurement setup

See Figure 3-2: "Configuration and measurement setup" on page 18.

Equivalent circuits

View the equivalent circuits (see 4.1.2 "Equivalent Circuits" on page 35).

Overload and connection indicators

See Figure 3-5: "Overload and connection indicators" on page 19.

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Figure 4-2: Impedance/Reflection mode results

4.1 Basics

4.1.1 General Formulas

Select the output format of the impedance measurement results.

Select the output format of the admittance measurement results.

Display of the respective measurement results in the selected format.

Select the output format of the reflection measurement results.

The general formulas related to the Impedance/Reflection measurements are summarized below:

---

-- -

(Eq. 4-1)

(Eq. 4-2)

–

---------------

VSWR

------

1 r+

-------------1 r–

----------------

where

V I Z Y r VSWR R

…voltage at the reference plane …current at the reference plane …impedance …admittance …reflection coefficient …voltage standing wave ratio …reference resistance …reference conductance

Y–

Y+

(Eq. 4-3)

(Eq. 4-4)

(Eq. 4-5)

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Impedance/Reflection Mode

Note: The reference res is t an ce can be set in t he Measurement area of t he Impedance/Reflection mode window.

4.1.2 Equivalent Circuits

The basic formulas for the serial equivalent circuit are:

Z Real Z() jImag Z()+ RsjXs+==

RsReal Z()=

Imag Z() 0<

If :

--------------------------- -

ω Imag Z()

If :

Imag Z() 0>

Imag Z()

-----------------------

where

The basic formulas for the parallel equivalent circuit are:

…series resistance …series reactance …series capacitance …series inductance

(Eq. 4-6) (Eq. 4-7)

(Eq. 4-8)

(Eq. 4-9)

Y Real Y() jImag Y()+

------------------ -

Real Y()

If :

Imag Y() 0<

--------------------------- -

ω Imag Y()

If :

Imag Y() 0>

Imag Y()

-----------------------

where

…parallel resistance

…parallel reactance

…parallel inductance

…parallel capacitance

1–

⎛⎞

------

----- -

+==

⎝⎠

(Eq. 4-10)

(Eq. 4-11)

(Eq. 4-12)

(Eq. 4-13)

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Figure 4-3: Resistor and inductor symbols according to

ANSI

Figure 4-4: Resistor and inductor symbols according to

IEC

Depending on the regional settings of your computer the elements of the serial and parallel equivalent circuits are displayed according to the IEC (International Electronic Commission) or ANSI (American National Standards Institute) standards as shown below.

Note: Capacitors have the same symbol in both standards.

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4.1.3 Quality Factor

An ideal inductor will be lossless irrespective of the amount of current flowing through the winding. An ideal capacitor will be lossless irrespective of the voltage applied to it. However, real inductors have a winding resistance due to the metal wire forming the coils and real capacitors have a resistance due to the used insulation material. These resistances cause a loss of inductive or capacitive quality. For serial equivalent circuits, the quality factor is defined as the ratio of the reactance to the resistance at a given frequency. For parallel equivalent circuits, the quality factor is defined as the ratio of the resistance to the reactance at a given frequency.The factor is a measure of the inductor’s and capacitor’s efficiency. The higher the factor of a capacitor or inductor, the closer the capacitor/inductor approaches the behavior of an ideal, lossless component.

The factor calculated using the serial equivalent circuit is given by

Impedance/Reflection Mode

Imag Z()

-----------------------

Real Z()

------- -

s s

(Eq. 4-14)

and using the parallel equivalent circuit is given by

Imag Y()

-----------------------

===

Real Y()

---------

------

---------

(Eq. 4-15)

4.2 Example: Impedance/Reflection Measurement

Expected example duration: 20 minutes. In this example you will learn step by step how to use the

Impedance/Reflection mode of the Bode 100. How to:

• Measure the reflection coeffi ci ent at a frequency

• Set the bandwidth and amplitudes used for the measurement

• Connect the DUT for the impedance and reflection measurement

• Optimize the diagrams

• Work with the serial and parallel equivalent circuits Question: What is the reflection coefficient in dB of the delivered IF filter input

at 10.7 MHz?

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Bode 100 User Manual

To find out the answer, proceed as follows:

1. Connect the Bode 100 and start the Bode Analyzer Suite.

2. Click the Impedance/Reflection toolbar button to switch to the

3. If necessary, adjust your window size. Move the mouse to the lower right

Hint: If you see the serial number of your Bode 100 on the lower right side of the status bar then your Bode 100 is working properly.

Impedance/Reflection mode.

corner of the w indow . By dragging t he corner you can adjus t the window.

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Impedance/Reflection Mode

4. Click the Device Configuration toolbar button to configure the Impedance/Reflection mode.

5. Set:

• SOURCE: 10.7 MHz

• Receiver bandwidth: 10 Hz

• Level: 0 dBm

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6. Click the Connection Setup tab.

The connection diagram shows how to connect the DUT to the Bode 100. Hint: In the Impedance/Reflection mode, the channel 1 and channel 2

inputs are not used. Consequently, the External Probe boxes are unavailable.

7. Connect the output of the Bode 100 to the input of the IF filter and the BNC 50 Ω load to the output of the IF filter as shown.

8. Click to close the Configuration window.

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Impedance/Reflection Mode

9. For a better view of the impedance, admittance and reflection vectors in the complex plane, right-click in the respective diagrams, and then click Optimize.

10.View the results.

Result: The measured values of the IF filter at 10.7 MHz are:

• Reflection coefficient: –31.4 dB

• Impedance: nearly 50 Ω

Again, your results may differ because every IF filter and measurement setup is slightly different.

Hint: To increase the size of the diagrams, make the window larger or hide the left pane by clicking the split bar. To restore the left pane, click the split bar again.

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Bode 100 User Manual

Hint: If you want to display the reflection in VSWR format select the VSWR

output format under Reflection as shown below.

Usually, the reference resistance of 50 Ω is used to calculate the reflection coefficient and the VSWR. The Reference Resistance box allows you to enter other reference resistance values if required.

The parallel and serial equivalent circuits give us an indication of the electrical components that would be required to rebuild the electrical characteristics of your DUT at the measurement frequency. In our example you would require a 39 nF capacitor and a 52.7 Ω resistor to build the series equivalent circuit.

Try it out, get yourself the required components and repeat the measurement. If the results do not match 100% keep in mind that you are using real components with a factor on their own.

After this example get a glass of water to increase your reflection mode and your attention bandwidth. Then try things out and right-click and left-click to everything that does not move on the screen.

For inform ati on on how to c ali bra te the Bode 100 in the Impedance/Reflection mode, see 7.4 "Calibration in the Impedance/Reflection Mode" on page 83.

Congratulation! You learned how to use the Impedance/Reflection mode. How to:

• Measure the reflection coeffi ci ent at a frequency

• Set the bandwidth and amplitudes used for the measurement

• Connect the DUT for the impedance and reflection measurement

• Optimize the diagrams

• Understand serial and parallel equivalent circuits

Go back to the overview chart at 4 "Impedance/Reflection Mode" on page 33 and try things out.

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5 Frequency Sweep Mode

Frequency Sweep Mode

Figure 5-1: Frequency Sweep mode window

weep settings

Set frequency sweep. See Figure 5-2: "Sweep settings" on page 44.

ursor settings

Set cursors and view measurement results. See Figure 5-3: "Cursor settings" on page 44.

race settings

Define measurement format and display options. See Figure 5-4: "Trace settings" on page 45.

Diagram setup

See Figure 5-5: "Diagram setup" on page 46.

Export traces data

Export traces as CSV file. See 8.3.2 "Exporting Measurement Data" on page 99.

Note: Only window areas specific for the Frequency Sweep mode are explained. For window areas common to other measurement modes, see Figure 3-1: "Gain/Phase mode window" on page 17 and Figure 4-1: "Impedance/Reflection mode window" on page 33.

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Figure 5-2: Sweep settings

In the Frequency Sweep mode you can perform a sequence of Gain/Phase and/or Impedance/Reflection measurements and examine the results in different types of diagrams.

Set the frequency sweep start frequency.

Set the frequency sweep stop frequency.

Set the frequency sweep center frequency.

Set the frequency sweep span.

Click Linear or Logarithmic to select the respective scale of measurement points.

Set the number of measurement points.

Copy from Zoom

See "Copy from Zoom" on page 107.

Figure 5-3: Cursor settings

Hint: The start frequency, stop frequency, center frequency and span are mutually dependent. After one of them has been changed, the others settings are recalculated by the Bode Analyzer Suite.

Select the check box to activate cursor 1.

Frequency marked by cursor 1

Frequency marked by cursor 2

Select the check box to activate cursor 2.

Trace 1 measurement result marked by cursor 1.

Trace 1 measurement result marked by cursor 2.

Difference of cursor frequencies

Difference of trace 1 measurement results

Trace 2 measurement result marked by cursor 1.

Trace 2 measurement result marked by cursor 2.

Difference of trace 2 measurement results

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Figure 5-4: Trace settings

Frequency Sweep Mode

Select the check box to activate trace 1.

Set the color of trace 1.

Click Gain, Reflection, Impedance or Admittance to select the respective trace 1 measurement.

Display

See "Data and Memory" on page 111.

Select the output format of trace 1 measurement results.

Set the maximum value on the trace 1 Y-axis.

Set the minimum value on the trace 1 Y-axis.

Data –> Memory

See "Data and Memory" on page 111.

Select the check box to activate trace 2.

Set the color of trace 2.

Click Gain, Reflection, Impedance or Admittance to select the respective trace 2 measurement.

Display

See "Data and Memory" on page 111.

Select the output format of trace 2 measurement results.

Set the maximum value on the trace 2 Y-axis.

Set the minimum value on trace 2 the Y-axis.

Data –> Memory

See "Data and Memory" on page 111.

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Bode 100 User Manual

Figure 5-5: Diagram setup

5.1 Example: Frequency Sweep Measurement

Click Auto to display both traces in one diagram, if possible.

Click Always Two Diagrams to display the traces in two separate diagrams.

Note: Diagram Setup is only available if both traces are activated.

Expected example duration: 30 minutes. In this example you will learn step by step how to use the Frequency Sweep

mode of the Bode 100. How to:

• Visualize measurement data in a graph

• Set configuration parameters like the input resistor and bandwidth

• Set sweep parameters like start and stop frequencies

• Use cursors to read single measurement points

• Calibrate and compensate the cables

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Frequency Sweep Mode

Let’s examine the12 MHz quartz filter on the delivered printed circuit board (PCB).

Questions:

• How does the gain of the quartz filter look if displayed as a function of frequency?

• How does the reflection coefficient of the quartz filter look in the Smith chart?

• What are the series resonance and the parallel resonance frequencies?

• What is the attenuation of the quartz filter at its series resonance?

• What is the group delay T

• What is the series resistance R

of the quartz filter at its series resonance?

of the quartz filter?

To find out t he answers, proceed as follows:

1. Connect the Bode 100 to the computer and start the Bode Analyzer Suite. Hint: If you see the Bode 100 serial number on the lower right side of the

status bar then your Bode 100 is working properly.

2. Click the Frequency Sweep toolbar button to switch to the Frequency Sweep mode.

3. Click the Device Configuration toolbar button to configure the Frequency Sweep mode. We want to measure the quartz filter with 50 Ω load.

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Bode 100 User Manual

4. Set:

•CH2: 50Ω ON (click the switch as shown)

• The switch (before ATTN1) to the internal source as reference

Hint: In the Frequency Sweep mode, the Bode 100 can measure the gain/phase as well as the impedance/reflection of the DUT versus frequency. The Gain/Phase and Impedance/Reflection buttons in the Configuration window are just used to show the respective device configurations. The buttons have no impact on the measurements performed by the Bode 100 – you select the measurement in the Measurement lists in the Trace 1 and Trace 2 areas (see Figure 5-4: "Trace settings" on page 45). To see the device configuration the Bode 100 uses for the Impedance/Reflection measurement just cl ick the Impedance/Reflection button.

Hint: With a narrow receiver bandwidth like 30 Hz, the measurement is very selective. Only little noise will affect the measurement and, consequently, the measurements will be more stable but the sweep will be slow. The receiver bandwidth of 3 kHz will perform the fastest sweep.

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5. Click the Connection Setup tab.

Frequency Sweep Mode

The connection diagram shows how to connect the DUT to the Bode 100.

Hint: Use the box to set the voltage ratio when you use a probe instead of cable connection (see 9.4 "Using Probes" on page 125).

6. Connect the quartz filter to the Bode 100 as shown.

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Bode 100 User Manual

7. Click to close the Configuration window and to get back to the

8. Set the sweep frequencies:

• Start frequency: 11.98 M Hz

• Stop frequency: 12.04 MHz

• Number of points: 401

Frequency Sweep mode window.

The other settings will be automatically calculated and the Sweep area of the

Frequency Sweep mode window should now look like below.

Hint: A setting which results in an out-of-range frequency for any other

parameter will be corrected to ensure that all sweep frequencies (start, stop, center) are within the range of 10 Hz…40 MHz or 1 Hz…40 MHz if you selected the extended measurement range (see 8.2 "Setting the Measurement Range" on page 98).

9. Set the referenc e re sistance. Default: 50 Ω

The reference resistance is used to calculate the reflection coefficient and the VSWR.

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Frequency Sweep Mode

10.Activate both traces and set the parameters as shown below.

11.If you have a larger screen you can adjust your window size. Move the mouse to the lower right corner of the window . and drag the corner.

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Bode 100 User Manual

Hint: In addition to resizing the window, you can click the split bar to hide the

left and right panes to increase the size of the diagrams.

In the upper graph you see the gain of the quartz filter. You can use the cursors to measure the series and parallel resonance frequencies.

12.Select the Cursor 1 and Cursor 2 check boxes to activate the cursors.

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Frequency Sweep Mode

13.To find the series resonance frequency of the quartz filter, right-click the curve in the upper diagram, point to Cursor 1, and then click Jump to Max.

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Bode 100 User Manual

14.To find the parallel resonance frequency of the quartz filter, right-click the curve in the upper diagram, point to Cursor 2, and then click Jump to Min. In the marked area of the Frequency Sweep mode window, the series and parallel resonance frequencies and the corresponding measurement data are now displayed.

Results: Cursor 1 marks the series resonance frequency of 11.997 MHz and an attenuation at the series resonance frequency of 0.871 dB. Cursor 2 marks the parallel resonance frequency of 12.023 MHz and an attenuation at the parallel resonance frequency of 87.725 dB.

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Frequency Sweep Mode

15.To measure the group delay of the quartz filter at its series resonance frequency, select Tg in the Format list. The following figure shows the group delay measured by Trace 1 at the series resonance frequency marked by cursor 1.

Result: The group delay T

at the series resonance frequency of the quartz

filter is 314.2 μs. Due to the high attenuation at the parallel resonance frequency it is not possible to measure the group delay at the quartz filter’s parallel resonance.

Your result might be slightly different because even quartz filters show variations in their electrical characteristics.

16.For the measurement of the series resistance of the quartz filter we will use the Smith chart. The Smith chart displays the reflection coefficient (see (Eq. 4-3) on page 34) in the complex plane. The horizontal axis represents the real component and the vertical axis the imaginary component of the DUT's reflection coefficient. The central point of the Smith chart corresponds to the

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Bode 100 User Manual

17.In the lower graph you see the Smith chart showing the reflection coefficient

case when the DUT’s impedance equals the reference resistance and, consequently, the reflection coefficient is zero. Additionally, the Smith chart contains circles with constant resistance ( ) and constant reactance ( ). This diagram format allows an easy "translation"

of any point of the reflection coefficient curve into the corresponding DUT’s impedance. The cursor values displayed in the Smith chart format are the real and imaginary components of the corresponding DUT’s impedance. For more information on the Smith chart, refer to the relevant technical literature.

of the quartz filter. To display only this chart, clear the Trace 1 check box to deactivate trace 1.

Since the output of the DUT (quartz filter) is connected to the channel 2 input, the measured impedance is the quartz impedance plus the 50 Ω input impedance of the Bode 100.

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For an idle quartz, the trace should be nearly symmetrical against the real axis. The reason why it is not is as follows: We have used a cable to connect the quartz filter to the Bode 100 and therefore we measure a phase shift of the reflected voltage (twice the shift of the cable itself). We can remove this unwanted phase shift by using the Impedance calibration. By calibrating the Bode 100 we move the Impedance/Reflection reference plane to the end of the cable connected to the input of the DUT.

5.2 Impedance Calibration

Now we perform the Impedance calibration. This type of calibration is also described in 7.4 "Calibration in the Impedance/Reflection Mode" on page 83.

1. Click the Probe Calibration toolbar button to open the calibration window.

Frequency Sweep Mode

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Bode 100 User Manual

2. Connect the cable you want to use for the measurement to the OUTPUT

3. Click the Start button next to Open in the Impedance area of the calibration

connector of the Bode 100. Plug the BNC straight adapter on the other end of the cable.

window. After the calibration has been finished, the field on the right displays Performed on green background.

With the measurement settings the calibration may take about 35 seconds. Hint: You can reduce the calibration time by setting fewer measurement

points, a wider receiver bandwidth, or by choosing the Probe Calibration.

4. Plug the BNC short circuit on the straight adapter connected to the cable.

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Frequency Sweep Mode

5. Click the Start button next to Short in the Impedance area of the calibration window. After the calibration has been finished, the field on the right displays Performed on green background.

6. Replace the BNC short circuit with the BNC 50 Ω load.

7. For very accurate measurements or if you use a load resistor different from 50 Ω, click the + symbol next to Advanced, and then enter the exact resistance of the load resistor.

Hint: For more information on the advanced calibration settings, see

7.4 "Calibration in the Impedance/Reflection Mode" on page 83.

8. Click the Start button next to Load in the Impedance area of the calibration window. After the calibration has been finished, the field on the right displays Performed on green background.

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Bode 100 User Manual

9. After the calibration has been finished, the calibration window looks like shown below.

Hint: The warning symbol indicates that the load resistor and/or the short delay time value differ from the factory settings.

10.Click . You have done the Impedance calibration in the Frequency Sweep mode.

11.Reconnect the quartz filter to the Bode 100 as shown below.

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12.View the calibrated Smith chart.

Frequency Sweep Mode

13.Calculation of the series resistance at the series resonance frequency:

To calculate the series resistance of the quartz filter you need to subtract 50 Ω from the real part measured with cursor 1. The reason for this is that the reflection measurement circuit "sees" the quartz filter in series with the 50 Ω termination of the channel 2 input. The Trace 2 columns of the table display the real and imaginary parts of the measurement results at the frequencies marked by the cursors.

Result: = 70.01 Ω – 50 Ω = 20.01 Ω

Your result may slightly differ because every quartz filter and measurement setup is different.

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Bode 100 User Manual

Frequency sweepers have an easier time to get the picture.

Congratulation! You learned h ow to u se the Frequency Sweep mode. How to:

• Visualize measurement data in a graph

• Set configuration parameters like the input resistor and bandwidth

• Set sweep parameters like start and stop frequencies

• Use cursors to read single measurement points

• Calibrate and compensate for the cable

Go back to the Frequency Sweep mode window in 5 "Frequency Sweep Mode" on page 43 and try things out.

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Figure 6-1:

Frequency Sweep (External Coupler)

mode window

Frequency Sweep (External Coupler) Mode

6 Frequency Sweep (External Coupler)

Mode

Note: The window areas and screen elements in the Frequency Sweep (External Coupler) mode are t he same as in t he Frequency Sweep mode. For

their description, see Figure 5-1: "Frequency Sweep mode window" on page 43.

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Bode 100 User Manual

Figure 6-2: Connecting external coupler

In the Frequency Sweep (External Coupler) mode you can perform a sequence of Impedance/Reflection measurements by using an external directional coupler only or in combination with an external amplifier.

For some impedance measurement applications, it is beneficial to use external couplers for an optimum adaptation of the Bode 100 to the test object (see Figure 6-2: "Connecting external coupler" below). Further on, impedance measurements on some test objects such as medium wave antenna systems require higher signal levels than provided by the Bode 100. By using an external coupler it is possible to utilize an external amplifier to boost the Bode 100 source signal to the required output level (see Figure 6-3: "Connecting external coupler and amplifier" below).

Figure 6-3: Connecting external coupler and amplifier

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Frequency Sweep (External Coupler) Mode

Hint: By using an external amplifier and an external coupler you can protect the

Bode 100 inputs from reverse power emitted by the DUT (e.g. radio waves received by a broadcast antenna).

6.1 Example: Frequency Sweep (External Coupler) Measurement

Expected example duration: 30 minutes. In this example you will learn step by step how to use the Frequency Sweep

(External Coupler) mode of the Bode 100. How to:

• Connect an external coupler

• Set configuration parameters like the input resistor and bandwidth

• Calibrate and compensate the connection system

• Display reflection in VSWR format

• Display impedance in polar format

• Remove the effect of noise Let’s examine the delivered IF filter when connected to the Bode 100 by a 50 Ω

directional coupler.

Questions:

• What is the VSWR of the IF filter within its passband?

• How does the impedance of the IF filter look in the polar format?

• What is the exact impedance and VSWR of the filter at its center frequency

of 10.7 MHz?

To find out t he answers, proceed as follows:

1. Connect the Bode 100 to the computer and start the Bode Analyzer Suite.

2. Click the Frequency Sweep (External Coupler) toolbar button to switch

to the Frequency Sweep (External Coupler) mod e.

3. Click the Device Configuration toolbar button to configure the

Frequency Sweep (External Coupler) mode.

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Bode 100 User Manual

4. Set:

•CH1: 50Ω ON

•CH2: 50Ω ON

Hint: To match the impedance of the directional coupler, the input resistances of the channel 1 and channel 2 are set to 50 Ω.

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Frequency Sweep (External Coupler) Mode

5. Click the Connection Setup tab.

The connection diagram shows how to connect the DUT as well as the directional coupler to the Bode 100.

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Bode 100 User Manual

6. Connect the directional coupler to the Bode 100 as shown.

7. Click to close the Configuration window and to get back to the

Frequency Sweep (External Coupler) mode window.

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Frequency Sweep (External Coupler) Mode

8. Set the sweep frequencies:

• Start frequency: 8.7 MHz

• Stop frequency: 12.7 MHz

• Number of points: 201

The other settings will be automatically calculated and the Sweep area of the Frequency Sweep (External Coupler) mode window should now look like below.

9. Set the referenc e re sistance.

Default: 50 Ω

The reference resistance is used to calculate the reflection coefficient and the VSWR.

10.Calibrate the measurement setup as described in 7.6 "Calibration in the

Frequency Sweep (External Coupler) Mode" on page 91. Hint: Due to the strongly varying parameters of directional couplers a

calibration is mandatory before performing a measurement. If you start a measurement in the Frequency Sweep (External Coupler) mode with out calibration, the following dialog box appears.

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Bode 100 User Manual

11.Connect the IF Filter to the Bode 100 and the 50 Ω load to the output of the

12.Activate both traces and set the parameters as shown below.

In this case, select the User Calibration or the Probe Cal ibration, and then proceed as described in 7.6 "Calibration in the Frequency Sweep (External Coupler) Mode" on page 91.

IF filter as shown below.

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Frequency Sweep (External Coupler) Mode

In the upper graph you see the reflection of the IF filter in VSWR format. Even outside its passband the VSWR of the filter is quite good – this indicates that the input impedance of the filter in the measured frequency range is very close to 50 Ω in general. The lower graphs shows the impedance of the IF filter in polar format, the so-called polar curve.

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Bode 100 User Manual

Hint: The effect of noise on the measurement results can be reduced by

narrowing the receiver bandwidth, by using less attenuation in the input channels and by increasing the signal level of the Bode 100 source output.

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Frequency Sweep (External Coupler) Mode

13.Select the Cursor 1 check box to activate the cursor, and then set the cursor

to the IF filter’s center frequency of 10.7 MHz by entering 10.7 MHz in the respective box of the cursor spreadsheet.

Result: The VSWR of the IF filter at its center frequency is 1.012. The impedance graph shows an impedance of 50.59 Ω and due to the very small positive phase shift a nearly pure resistive behavior.

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Bode 100 User Manual

Sometimes external couplers help to make a match and to enhance the power.

Congratulation! You learned how to use the Frequency Sweep (External Coupler) mode.

How to:

• Connect an external coupler

• Set configuration parameters like the input resistor and bandwidth

• Calibrate and compensate the connection system

• Display reflection in VSWR format

• Display impedance in polar format

• Remove the effect of noise Go back to the Frequency Sweep (External Coupler) window in 6 "Frequency

Sweep (External Coupler) Mode" on page 63 and try things out.

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7 Calibrating the Bode 100

The Bode 100 can compensate effects of the measurement setup like cables and probes. Further on the overall accuracy may be improved by calibrating the Bode 100 (e.g. if the operating temperature is outside the range specified in

12.5 "Environ men tal Requ ir em ents" on page 13 7) .

7.1 Calibration Methods

The Bode 100 supports two calibration methods: the Probe Calibration optimized for measurements which require frequent changes of measurement settings and the User Calibration for most accurate results.

Note: During startup, the Bode 100 executes an Internal Calibration algorithm. During this calibration, internal attenuators and amplifiers are measured and calibrated.

7.1.1 Probe Calibration

Calibrating the Bode 100

The Probe Ca libration of the Bode 100 allows you to change several measurement parameters without the need of recalibration. During the Probe Calibration, calibration factors are determined at factory defined frequencies within the complete frequency range. The calibration factors for the frequency points used by the current measurement settings are then obtained by interpolation.

Hint: The Probe Calibration compensates effects of cables and broad-band probes. If you want to compensate frequency selective probes or if your cable length exceeds 10 m it is recommended to use the User Calibration (see

7.1.2 "User Calibration" on page 76). The Probe Calibration allows changing the following parameters without the

need of recalibrating the Bode 100:

• Frequency values

• Sweep mode (linear/logarithmic)

• Number of measurement points (in the Frequency Sweep modes)

• Source level

• Attenuator 1 and attenuator 2

• Receiver bandwidth

•Zoom with & without the Copy from Zoom function

(see "Copy from Zoom" on page 107)

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Bode 100 User Manual

The Probe Ca libration will be switched off automatically if the following parameters are changed:

• Reference mode (internal/external reference)

• Conversion ratio of external probes (see 9.4 "Using Probes" on page 125)

• Input resistance of channel 1 and/or channel 2 (low/high impedance) Hint: Use the Probe Calibration if measurement parameters have to be

changed often during the measurements. You will save time because you do not need to recalibrate the Bode 100 each time you changed the parameters.

7.1.2 User Calibration

The User Calibration is the most accurate calibration method available with the

Bode 100. The User Calibration is performed directly at the exact measurement frequencies. In the Gain/Phase and Impedance/Reflection measurement modes, the Bode 100 is calibrated at the source frequency. In the Frequency Sweep modes, the calibration is performed at the exact frequencies specified by the measurement points.

The User Calibration allows changing the following parameters without the need of recalibrating the Bode 100:

• Source level

• Attenuator 1 and attenuator 2

• Receiver bandwidth

•Zoom without the Copy from Zoom function (see "Copy from Zoom" on

page 107)

The User Calibration will be switched off automatically if one of the following parameters is changed:

• Frequency values

• Sweep mode (linear/logarithmic)

• Number of measurement points (in the Frequency Sweep modes)

• Reference mode (internal/external reference)

• Conversion ratio of external probes (see 9.4 "Using Probes" on page 125)

• Input resistance of channel 1 and/or channel 2 (low/high impedance)

•Zoom with the Copy from Zoom function (see "Copy from Zoom" on

page 107)

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7.1.3 Hierarchy of Calibration Methods

Table 7-1: Calibration methods

Calibrating the Bode 100

Hint: Use the User Calibration for the highest accuracy of measurement

results or if you want to compensate for highly frequency selective components in your measurement setup such as narrow-band measurement probes.

The following table gives an overview of the Bode 100 calibration methods.

Measurement Mode User Calibration Probe Calibration Gain/Phase Calibrates at only one

frequency (measurement frequency)

Impedance/Reflection

Frequency Sweep Calibrates at the exact

frequency points used for the sweep

Frequency Sweep (External Coupler)

Calibrates the complete frequency range. Calibration factor for the measurement frequency is calculated by linear interpolation.

Calibrates the complete frequency range. Calibration factors for the measurement frequencies are calculated by linear interpolation.

Figure 7-1: Activating

User Calibration and Probe Calibration

7.2 Calibration in the Gain/Phase Mode

You can activate the User Calibration and the Probe Calibration at the same time as shown below.

If both the User Calibration and the Probe Calibration are activated, the more accurate User Calibration is used. If measurement parameters are changed and the User Calibration becomes void the Bode 100 switches automatically to the Probe Calibration; the User Calibration remains switched off until the Bode 100 is recalibrated.

(Internal Reference Connection)

For calibrat ing the Bode 100 in the Gain/Phase mode you find a practical example in 3.3 "Example: Gain/Phase Measurement" on page 24.

Note: The Probe Calibration is performed in the same way as the User Calibration.

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7.3 Calibration in the Gain/Phase Mode (External Reference Connection – CH1)

To compensate for the cable and connection setup effects in the Gain/Phase mode, proceed as follows:

1. Connect the Bode 100 and start the Bode Analyzer Suite.

Select the Gain/Phase mode.

2. Click the Device Configuration toolbar button to open the

Configuration window. In the Configuration window, set the parameters for your measurement. In our example we have chosen the following settings.

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Calibrating the Bode 100

3. Set:

• External reference CH1 (Click the switch symbol .)

• CH1 and CH2: 50 Ω (Click the switch symbols.)

• SOURCE: 10.7 MHz

• Receiver bandwidth: 10 Hz

• ATTN 1: 20 dB

• ATTN 2: 20 dB

• Level: 0 dBm

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4. Click the Connection Setup tab.

The connection diagram shows how to connect the DUT to the Bode 100.

5. Connect the cables you want to use for the measurement as shown below.

6. Click to close the Configuration window.

7. Choose either the Probe Calibration or the User Calibration and click the

respective toolbar button.

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Calibrating the Bode 100

8. In the respective calibration window, click the Start button next to Thru to

calibrate the Bode 100.

Note: In the Gain/Phase mode, no Impedance calibration is possi bl e. The Gain/Phase mode is now calibrated for the current specific

measurement setup. Refer to 7.1 "Calibration Methods" on page 75 to learn in which cases you have to repeat the calibration if a parameter is changed.

9. Click .

In our case we read 101 close to zero your results may differ from this example. Nevertheless the displayed values should be very small.

μdB (0.000101 dB) and 0.001º. Because we are

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10.The calibration is done and you can replace the BNC straight adapter with

your DUT as shown below.

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Calibrating the Bode 100

7.4 Calibration in the Impedance/Reflection Mode

By calibrating the Bode 100 you can remove the effects of the connection setup on the accuracy of the measurement results in the Impedance/Reflection mode. Without calibration the reference plane of the impedance measurements is at the BNC connector of the Bode 100 source output. Therefore if a DUT is connected through a cable, the measured impedance is the combination of the cable's impedance and the DUT's impedance. By calibrating the Bode 100 you can move the reference plane for the impedance measurement to the end of the connection cable and fully remove the influence of the cable.

In the Impedance area of the calibration window, you can set the resistance of the load resistor and the short delay time as shown below.

Enter the exact

Enter the delay time of the short circuit used for calibration Factory setting valid for the short circuit delivered with the Bode 100: 50 ps

resistance of the load used for calibration Factory setting: 50

Hint: If the entered values of the load resistor and/or the short delay time differ from the factory settings a yellow warning symbol appears after the Advanced area has been collapsed.

Example: M eas ure t he i npu t im ped anc e of the IF f ilt er at th e BNC con nec tor of the PCB (and not the impedance at the input of the cable connecting the filter).

Expected example duration: 20 minutes. In this example you will learn step by step how to use the calibration of the

Bode 100 in the Impedance/Reflection mode.

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Bode 100 User Manual

How to:

• Eliminate the effect of the cable

• Connect the cable in the open, short and load condition

• Connect the DUT

Questions:

• What is the real part of the impedance in Ω?

• What is the reflection coefficient in dB? To find out t he answers, proceed as follows:

1. Click the Impedance/Reflection toolbar button to switch to the

2. Click the Device Configuration toolbar button to open the

3. Because we want to test the 10.7 MHz IF filter, set:

• SOURCE: 10.7 MHz

• Receiver bandwidth: 10 Hz

Impedance/Reflection mode.

Configuration window.

• Level: 0 dB

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Calibrating the Bode 100

4. Click .

5. Choose either the Probe Calibration or the User Calibration and click the

respective toolbar button.

6. Connect the cable you want to use for the measurement to the OUTPUT

connector of the Bode 100. Plug the BNC straight adapter on the other end of the cable to have the same reference plane for calibration.

7. Click the Start button next to Open in the Impedance area of the calibration

window. After the calibration has been finished, the field on the right displays Performed on green background.

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8. Plug the BNC short circuit on the straight adapter connected to the cable.

9. Click the Start button next to Short in the Impedance area of the calibration

Hint: If you use a short circuit other than the one delivered with your Bode 100 you can enter the short delay by clicking the + symbol next to Advanced and typing the short delay time.

window. After the calibration has been finished, the field on the right displays Performed on green background.

10.Replace the BNC short circuit with the BNC 50 Ω load.

11.For very accurate measurements or if you use a load resistor different from

50 Ω, click the + symbol next to Advanced, and then enter the exact resistance of the load resistor.

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Calibrating the Bode 100

12.Click the Start button next to Load in the Impedance area of the calibration

window. After the calibration has been finished, the field on the right displays Performed on green background.

13.After the calibration has been finished, the calibration window looks like

shown below.

Hint: If the entered values of the load resistor and/or the short delay time differ from the factory settings a yellow warning symbol appears after the Advanced area has been collapsed.

14.Click . You have done the Impedance calibration.

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Bode 100 User Manual

15.Open the Configuration window by clicking the Device Configuration

toolbar button to see how to connect your DUT to the Bode 100.

16.Connect the test object.

Note: The IF filter is a two-port device. To ensure that the impedance of the filter is measured correctly, its output must be terminated. For measuring a one-port device like a capacitor or an inductor, no termination resistor is needed.

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17.Read the results.

Calibrating the Bode 100

I had my first cable problem when I was born but luckily the midwife solved that problem.

Answers:

• The real part of the impedance is 51.8 Ω.

• The magnitude of the reflection coefficient is –35.1 dB. Your results may differ because every IF filter and measurement setup is slightly

different. Congratulation! You learned the calibration of the Bode 100 in the

Impedance/Reflection mode. How to:

• Eliminate the effect of the cable

• Connect the cable in the open, short and load condition

• Connect the DUT

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7.5 Calibration in the Frequency Sweep Mode

In the Frequency Sweep mode, you can perform Gain/Phase and Impedance/Reflection measurem ents. Ther efore bot h the Gain/Phase and the Impedance calibration are available. The actually performed measurements

depend on the measurement type assigned to Trace 1 and Trace 2.

To perform the Gain/Phase calibration in the Frequency Sweep mode, proceed as described in 3.3 "Example: Gain/Phase Measurement" on page 24. For the Impedance calibration, see 5.2 "Impedance Calibration" on page 57.

Hints:

The calibration time for the User Calibration depends on the number of measurement points and the selected receiver bandwidth.

The calibration time required for the Probe Calibration depends only on the selected receiver bandwidth.

When working with the Bode 100 at frequencies below 10 Hz, the calibration can be quite long.

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Calibrating the Bode 100

7.6 Calibration in the Frequency Sweep (External Coupler) Mode

By calibrating the Bode 100 in the Frequency Sweep (External Coupler) mode you remove the effects of the connection setup including the external coupler and, if used, the amplifier on the accuracy of the measurement results. Due to the strongly varying parameters of directional couplers a calibration is mandatory before performing a measurement.

In the Frequency Sweep (External Coupler) mode, you can perform only Impedance/Reflection measurements. Therefore only the Impedance calibration is available in this mode.

Hint: Some directional couplers show nonlinear behavior at the edges of their passband. If your measurement frequency range is close to such nonlinearities, we recommend to use the User Calibration to remove the nonlinear effects.

To calibrate the Bode 100 in the Frequency Sweep (External Coupler) mode:

1. Click the Frequen cy Sweep (External Coupler) toolbar button to switch

to the Frequency Sweep (External Coupler) mod e.

2. Click the User Calibration toolbar button to open the

calibration window.

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Bode 100 User Manual

3. Plug the BNC straight adapter on the end of the cable.

4. Click the Start button next to Open in the Impedance area of the calibration

window. After the calibration has been finished, the field on the right displays Performed on green background.

5. Plug the BNC short circuit on the straight adapter connected to the cable.

6. Click the + symbol next to Advanced, and then enter the short delay time

(only if you use a short circuit other than the one delivered with your Bode 100).

7. Click the Start button next to Short in the Impedance area of the calibration

window. After the calibration has been finished, the field on the right displays Performed on green background.

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Calibrating the Bode 100

8. Replace the BNC short circuit with the BNC 50 Ω load.

9. For very accurate measurements or if you use a load resistor different from

50 Ω, enter the exact resistance of the load resistor in the respective box in the Advanced area of the calibration window.

10.Click the Start button next to Load in the Impedance area of the calibration

window. After the calibration has been finished, the field on the right displays Performed on green background.

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Bode 100 User Manual

11.After the calibration has been finished, the calibration window looks like

shown below.

Hint: A yellow warning symbol displayed close to Advanced indicates that the short delay and/or the load resistance entered in the Advanced area differ from the factory settings.

12.Click . You have done the Impedance calibration in the

Frequency Sweep (External Coupler) mode.

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8 Common Functions

In this section you can find the Bode Analyzer Suite basics. The section provides an overview of the toolbars, menus and commands common to all measurement modes. Further on, this section explains how to change the measurement range, how to export the data and how to store and load configuration files.

8.1 Toolbars, Menus and Commands

Common Functions

Figure 8-1: Toolbar

Figure 8-2: Calibration toolbar

Search and Reconnect Device

Continuous Measurement

New Save

Open

Print Preview

Start User Calibration Start Probe Calibration

Switch Gain/Phase calibration on/off

Device Configuration

Switch Impedance calibration on/off

Single Measurement

Contents

Impedance/Reflection

Stop Measurement

Switch Gain/Phase calibration on/off

Switch Impedance calibration on/off

Frequency Sweep

Gain/Phase

Frequency Sweep (External Coupler)

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Bode 100 User Manual

Table 8-1: Menus and commands

Menu Command Description

Opens the

New

NewBodeMeasurement.Bode file containing default settings.

Opens a .Bode file containing

Open

saved settings and measurement data.

Save

Saves the device configuration, measurement settings ,

File

Save As

calibration and measurement data and the graphical display settings.

Print a report containing the

diagram, measurement results, and device configuration data.

Print Preview

Previews the print report.

Exit

Gain/Phase

Impedance/Reflection

Frequency Sweep

Measurement

Frequency Sweep (External Coupler)

Continuous Measurement

Single Measurement

Stop Measurement

1. Only available in the Frequency Sweep modes

Enables you to exit the Bode Analyzer Suite.

Selects the Gain/Phase measurement mode.

Selects the Impedance/Reflection measurement mode.

Selects th e Frequency Sweep measurement mode.

Selects the Frequency Sweep (External Coupler) measurement mode.

Starts continuous measurements.

Starts a single frequency sweep measurement.

Stops measurement. The last result remains di splayed.

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Menu Command Description

Device Configuration

Configuration

Calibration

Tools Options

Help

Connection Setup Search and

Reconnect Device

User Calibration

Probe Calibration

Contents

Bode 100 Web site

About

Enables you to configure the Bode 100.

Shows the connection of the DUT to the Bode 100.

Reconnects the Bode 100 with the computer.

Starts the User Calibration (see 7 "Calibrating the Bode 100" on page 75).

Starts the Probe Calibration (see 7 "Calibrating the Bode 100" on page 75).

Enables you to set the startup configuration (see

8.3.1 "Loading and Saving the Equipment Configuratio n" on page 98), to select the measurement range (see

8.2 "Setting the Measurement Range" on page 98) and to set the CSV export options (see

8.3 "File Operations" on page 98).

Starts the Bode Analyzer Suite Help.

Opens the OMICRON Lab Web site

www.omicron-lab.com.

Displays the Bode Analyzer Suite version.

Common Functions

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Bode 100 User Manual

8.2 Setting the Measurement Range

Figure 8-3: Setting the measurement range

With the Bode 100 you can perform measurements within 10 Hz…40 MHz (default frequency range) and 1 Hz…40 MHz (extended frequency range). To select the measurement range, click Options on the Tools menu, click the

Measurement tab, and then select the frequency range for your measurement.

8.3 File Operations

The Bode 100 supports the following file operations.

8.3.1 Loading and Saving the Equipment Configuration

You can store all settings of the Bode 100 including the device configuration, measurement settings, calibration and measurement data and the graphical

display settings by clicking the Save toolbar button (see Table 8-1: "Menus and commands" on page 96).

Hint: This functionality allows you to store multiple equipment configurations for repetitive measurement tasks. With the equipment configurations stored, you can load the respective files for each measurement instead of setting the Bode 100 manually.

A saved file containing the Bode 100 settings has the .Bode extension. The file is stored in XML format and can be viewed with standard Web browsers or a simple text editor tool.

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Figure 8-4: Setting the startup configuration

Common Functions

After loading a .Bode file the stored measurement data is displayed. To preserve these values, the measurement is held (the Stop Measurement toolbar

button is activated). In this state you can change display options and use cursors to read measurement data. To continue with your measurement, click

the Continuous Measurement toolbar button . Hint: To ensure that the Bode 100 starts with the same configuration as in your

last session, click Options on the Tools menu, click the Startup Configuration tab, and then select Settings from last session.

8.3.2 Exporting Measurement Data

In the Frequency Sweep and Frequency Sweep (External Coupler) modes, you can export the measurement data by clicking the

button. In addition to the trace (measurement) data, all equipment settings are exported into a comma separated .csv file. This file format can be easily

processed by standard spread-sheet analysis tools such as Excel always contains the real and the imaginary part of the measured parameter (e.g. gain). Additionally, the measurement data in the selected output format is included.

Hint: If you have selected Settings from last session the calibration settings of you last session are NOT loaded. This is done on purpose since your measurement setup might have changed since you last used the Bode 100. If you want to load measurement settings including the calibration data, use the Bode 100 file functions (see 8.3.1 "Loading and Saving the Equipment Configuration" on page 98). However, we recommend to recalibrate the Bode 100 each time you start a new work session.

. The .csv file

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Bode 100 User Manual

Figure 8-5: Displayed CSV file data

Figure 8-6: Selecting the separators

100

To adapt the .csv file to your requirements, you can choose between different decimal and value separ at or s. To sele ct the sep ar ato rs you want to use, clic k Options on the Tools menu, click the CSV Export tab, and then select the decimal and value separators.