ETS Lindgren 3301 User Manual

Model 3301B

Active Rod & Field

Antenna

MANUAL

© ETS -LINDGREN L.P. – SEPTEMBER 2003 REV J – PN 399046

MODEL 3301B ACTIVE ROD & FIELD ANTENNA

ETS-Lindgren L.P. reserves the right to make changes to any products herein to improve functioning,
design, or for any other reason. Nothing contained herein shall constitute ETS-Lindgren L.P. assuming any
liability whatsoever arising out of the application or use of any product or circuit described herein.
ETS-Lindgren L.P. does not convey any license under its patent rights or the rights of others.

© Copyright 2003 by ETS-Lindgren L.P. All Rights Reserved.

No part of this document may be copied by any means

without written permission from ETS-Lindgren L.P.

E-MAIL & INTERNET

[e-mail]

http://www.ets-lindgren.com

USA

1301 Arrow Point Dr., Cedar Park, TX 78613
P.O. Box 80589, Austin, TX 78708-0589
Phone [phone]
Fax [phone]

FINLAND

Euroshield OY
Mekaanikontie 1
27510, Eura, Finland
Phone + 358.2.838.3300
Fax + 358.2.865.1233

JAPAN

4-2-6, Kohinata
Bunkyo-ku
Tokyo 112-0006
JAPAN
Phone + 81 3 3813 7100
Fax + 81 3 3813 8068

CHINA

1917-1918 Xue Zhixuan Building
No 16 Xue Qing Road
Haidian District
Beijing Postcode: 100083
CHINA
Phone + 86 010 82755304
Fax + 86 010 82755307

© ETS-LINDGREN L.P. – SEPTEMBER 2003
REV J – PN 399046

MODEL 3301B ACTIVE ROD & FIELD ANTENNA

Table of Contents

INTRODUCTION .........................................................................................................................................................1

STANDARD CONFIGURATION ............................................................................................................................2

OPTIONS.........................................................................................................................................................................2

SPECIFICATIONS.......................................................................................................................................................3

OPERATIONAL SPECIFICATIONS.................................................................................................................................3

ELECTRICAL S PECIFICATIONS....................................................................................................................................5

MECHANICAL SPECIFICATIONS..................................................................................................................................6

PRINCIPLES OF OPERATION..............................................................................................................................7

DESCRIPTION.................................................................................................................................................................7

FRONT PANEL...............................................................................................................................................................7

INTERNAL O PTIONS...................................................................................................................................................... 8

POWER CIRCUITRY...............................................................................................................................................11

V OLTAGE-SELECTABLE BATTERY CHARGER........................................................................................................ 11

BATTERY LOW INDICATOR.......................................................................................................................................13

FUSES...........................................................................................................................................................................13

SETUP AND USE........................................................................................................................................................14

SETUP........................................................................................................................................................................... 14

HIGH SENSITIVITY READINGS.................................................................................................................................. 15

THEORY OF OPERATION ....................................................................................................................................17

THE ROD......................................................................................................................................................................17

THE PRE-AMPLIFIER..................................................................................................................................................19

THE ANTENNA FACTOR......................................................................................................................................21

ANTENNA IMPULSE RESPONSE.......................................................................................................................22

IMPULSE CHARACTERISTICS.....................................................................................................................................22

PULSE DESENSITIZATION.......................................................................................................................................... 24

PULSE CHARGING.......................................................................................................................................................25

CALIBRATION PROCEDURE..............................................................................................................................26

3301B PARTS LIST ....................................................................................................................................................27

ACCESSORIES AVAILABLE........................................................................................................................................27

MAINTENANCE.........................................................................................................................................................27

WARRANTY STATEMENT...................................................................................................................................28

EUROPEAN COMMUNITY DECLARATION OF CONFORMITY .........................................................29

DATA AND ILLUSTRATIONS ..............................................................................................................................30

© ETS-LINDGREN L.P. – SEPTEMBER 2003
REV J – PN 399046

MODEL 3301B ACTIVE ROD & FIELD ANTENNA

© ETS-LINDGREN L.P. – SEPTEMBER 2003
REV J – PN 399046

MODEL 3301B ACTIVE ROD & FIELD ANTENNA Introduction

INTRODUCTION

The ETS-Lindgren Model 3301B is a broadband, high sensitivity
Electric-Field Receiving Antenna. The unit is composed of a
monopole rod antenna with a counterpoise and a broadband, high
impedance pre-amplifier. The unit is designed to provide reception
of an electric field in a signal band without tuning or band
switching from 30 Hz to 50 MHz. The 3 dB roll off points for the
antenna factor are at 170 Hz and 30 MHz. Between 250 Hz and 20
MHz, the antenna factor is flat within +/- 1 dB. Despite the roll of
the unit’s antenna factor, the usable range is 30 Hz to 50 MHz.

The 3301B has been designed for maximum sensitivity and
dynamic range. The 3301B is capable of sensing fields of 2
dBuV/m at 1 MHz with a 1 kHz bandwidth. However, it will not
saturate below a field strength of 0.7 V/m. Hence, the unit boasts
an extremely wide dynamic range of 115 dB nominal at mid-band.
In addition, at 10 and 30 dB (+/-10%) internal attenuators are
provided. With the attenuators the unit is usable in fields of up to
22 V/m. Thus the dynamic range of the unit is expanded to 145 dB.
A saturation indicator is provided to alert the user to the need for
using the internal attenuators.

The Model 3301B has been designed to provide the user with an
extremely versatile measurement tool. Its flat antenna factor,
extreme sensitivity and ultra-wide dynamic range make it a state of
the art sensing instrument.

© ETS-LINDGREN L.P. – SEPTEMBER 2003 1
REV J – PN 399046

Standard Configuration MODEL 3301B ACTIVE ROD & FIELD ANTENNA

STANDARD CONFIGURATION

• Adjustable monopole element

• Antenna base with built-in preamplifier and an isolated

female BNC connector

• Counterpoise (60 cm)

• Base drilled to accept EMCO or other tripod mounts with

standard ¼” x 20 threads

• Batteries and battery charger

• Individually calibrated per ECSM or IEE Std. 291. Actual

individual calibration factors and signed Certificate of
Calibration Conformance included in Manual.

OPTIONS

Remote Monitor: A 10 meter (32.8 ft) fiber optic Remote Monitor
Option for remote display of power-on and saturation indicators.

Tripods: ETS-Lindgren offers two nonmetallic, non-reflective
tripods for use at both indoor and outdoor EMC test sites.

The Model 4-TR, constructed of linen phenolic and delrin, is
designed with an adjustable center post for precise height
adjustments. Maximum height for the 4-TR is 2.0 m (80.0 in),
while minimum height is 94 cm (37.0 in). This tripod can support
up to an 11.8 kg (26.0 lb) load.

The 7-TR tripod has several different configurations, including
options for manual or pneumatic polarization. This tripod provides
increased stability for physically large antennas. Its unique design
allows for quick assembly/disassembly and convenient storage.
Quick height adjustment and locking wheels provide ease of use
during testing. This tripod can support a 13.5 kg (30 lb) load. For
the 7-TR series, maximum height is 2.17 m (85.8 in), with a
minimum height of .8 m (31.8 in). The 7-TR is constructed of PVC
and fiberglass components.

2 © ETS-LINDGREN L.P. – SEPTEMBER 2003

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MODEL 3301B ACTIVE ROD & FIELD ANTENNA Specifications

SPECIFICATIONS

OPERATIONAL SPECIFIC ATIONS

Frequency Range: 30 Hz to 50 MHz (maximum usable

bandwidth)

Low Frequency Roll
Off:

High Frequency Roll
Off:
Antenna Factor: See attached graphs. The calibration

Saturation Level: 0.7 V/m narrowband w/o attenuation

Minimum Discernible
Signal:

Dynamic Range: 115 dB at mid-band (1 MHz). 145 dB

Saturation Indicator
Impulse Response:

The low frequency roll off is switch
selectable to be 3dB down at 22 kHz,

1.9 kHz or 170 Hz
Antenna factor is 3 dB down at 30
MHz.

graphs where taken with the unit in the
Low Gain setting. Unless otherwise
noted, the low frequency roll off is set
at the 170 Hz 3dB roll off point.

and at the low gain setting. 22 V/m
with 30 dB of internal attenuation
selected. 63 dBuV/m/MHz broadband
saturation level.
See attached graphs. For best
sensitivity the unit should be in the
Low Gain setting with all Internal
Attenuation off.

with the use of the internal attenuators.
The saturation indicator will properly
indicate saturation for pulsed signals
which fall within the following
boundaries:

1. The product of the pulse width
to pulse repetition rate must be
greater than .003.

2. The pulse repetition rate must
be less than value listed for the
applicable duty cycle.

See table 1.

© ETS-LINDGREN L.P. – SEPTEMBER 2003 3
REV J – PN 399046

Specifications MODEL 3301B ACTIVE ROD & FIELD ANTENNA

Duty Cycle Maximum PRF

10 19.7 MHz
20 14.0 MHz
30 9.2 MHz
40 5.6 MHz
50 420.0 kHz
60 130.0 kHz
70 87.0 kHz
80 57.0 kHz
90 30.0 kHz

Table 1. Acceptable Pulse Repetition Rates

4 © ETS-LINDGREN L.P. – SEPTEMBER 2003

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MODEL 3301B ACTIVE ROD & FIELD ANTENNA Specifications

ELECTRICAL SPECIFICATIONS

Input Impedance: The input impedance determines the

low frequency roll of point. Depending
on the low frequency roll off selected,
the input impedance is >20 Megohms,
1 Megohm or 100 Kilohm.

Output Impedance: 50 ohm (nominal)
Saturation Impedance: A red LED on the front panel will be

illuminated when the unit begins to
saturate or clip. The saturation indicator
will indicate accurately for any gain
and attenuator setting.

Battery Low Indicator: The power light on the front panel also

serves as a Battery Low Indicator. If the
green light does not come on when the
power switch is engaged, then the
battery requires recharging. It is
recommended that the 3301B be
connected to the battery charger at all
times when it is not in use.

Batteries: The unit is supplied with two 6 volt

sealed lead-acid batteries. The batteries
will operate for approximately 10 hours
between charges.

Battery Charger: 115/230 VAC 50/60 Hz switch

selectable, IEC input, two-stage battery
charger with fast and trickle charge
modes.

Fuses: Type 3AG size .5 Amp, fast acting

Or 5x20mm, .5 Amp, fast acting
Internally mounted.

© ETS-LINDGREN L.P. – SEPTEMBER 2003 5
REV J – PN 399046

Specifications MODEL 3301B ACTIVE ROD & FIELD ANTENNA

MECHANICAL SPECIFICATIONS

Size: 7.38” x 4.62” x 3.5”
Weight: Approximately 7 lbs.
Tripod Mounting: A ¼-20 hole is provided on the base for

tripod mounting. NOTE: This is not
intended as a grounding point.

Counterpoise
Mounting:

Antenna Element: The antenna element may be set up to

Four 6-32 holes are provided in the two
metal mounting bars on the top of the
unit.

41”.

6 © ETS-LINDGREN L.P. – SEPTEMBER 2003

REV J – PN 399046

MODEL 3301B ACTIVE ROD & FIELD ANTENNA Principles of Operation

PRINCIPLES OF OPERATION

DESCRIPTION

The ETS-Lindgren 3301B Electric Field Receiving Antenna is
composed of three (3) principal sections: a sensing rod, a ground
plane or counterpoise and a broadband, high input impedance pre­amplifier.

The rod and counterpoise function together as an electrically short
antenna over ground plane. The pre-amplifier provides impedance
transformation from the extremely high impedance at the base of
the rod to the 50 ohms required by most receiving systems and
provides power gain to allow the sensing of very low level signals.

FRONT PANEL

The front panel of the 3301B presents the user with:

1. Power Switch

2. Gain Switch

3. Saturation Indicator Light

4. Battery Low/Power on Indicator Light

5. BNC Output Port

6. Battery Charging Port

The Power Switch on the unit is located on the lower right side of
the front panel. Activating the power switch will turn on the green
Battery Low/Power On Indicator.

The Battery Low/Power On Indicator is controlled by a voltage
monitor circuit. Should the green indicator not turn on, or if it
should turn off during use, this indicates that the battery requires
charging.

In the middle left of the unit is the Gain Switch. This switch
increases the voltage output of the gain stage in the amplifier by 10
dB. However, best sensitivity is achieved in the Low Gain setting.

© ETS-LINDGREN L.P. – SEPTEMBER 2003 7
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Principles of Operation MODEL 3301B ACTIVE ROD & FIELD ANTENNA

The gain option provides additional output power for test situations
which require additional output.

A Saturation Indicator Light is located above the power indicator.
Readings should not be taken when the unit indicates it is in
saturation. Should this occur input to the unit should be reduced by
placing the unit in the low gain mode or by switching in internal
attenuation. Impulsive type signals present a particular problem in
that they may put the unit into a non-linear region without
triggering the saturation circuit. When dealing with impulsive type
signals the 63 dBu V/m/MHz should be strictly observed. Should a
signal exceed this limit the internal attenuation should be applied.
The limiting factor on handing impulsive signals is the unit output
capability. Hence, once the internal attenuators are engaged, most
higher impulsive signals may be measured. For example, with the
30 dB attenuator engaged, a 93 dBuV/m/MHz may be measured.

A battery charging port is provided for easy recharging of the
sealed lead-acid batteries internal to the unit. To charge the unit,
simply turn off the power switch and plug in the battery charger
provided. It is important that the power switch be turned off as the
charging circuit will not charge the batteries with the unit turned
on.

INTERNAL OPTIONS

Internal to the unit is a four (4) switch bank of slide switches.
These switches control the internal attenuation and the low
frequency roll off.

Access to the switch bank is gained by holding the unit upside
down and removing the bottom cover. With the unit upside down
and the front panel to the left, the top switch, closest to the fuse
holder, adds 10 dB of internal attenuation. The next switch down
adds 30 dB of attenuation. The third switch sets the low frequency
roll off of 3dB down at 1.9 kHz. The fourth switch sets the low
frequency roll off of 3 dB down at 22 kHz.

8 © ETS-LINDGREN L.P. – SEPTEMBER 2003

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MODEL 3301B ACTIVE ROD & FIELD ANTENNA Principles of Operation

FRONT PANEL

22.0 kHz

CAUTION The antenna rod terminal is directly connected to the
high impedance gate of a field effect transistor. Do not lift the
antenna by the rod or touch it before properly grounding out to the
unit case. Accumulated static charge on test personnel may damage
the FET. If the antenna is used in a location where static discharges
are likely to be prevalent, attach a grounding clip between the
chassis and the antenna rod while the antenna is being set up to
prevent damage to the amplifier circuitry.

Note: The diagram below reflects the sequence of functions as they
are connected on the board.

FUSE

10 dB

Atten.

30 dB

ON

Atten.

1.9 kHz

FUSE

LF Roll Off

LF Roll Off

OFF

10 dB (+/- 10%) Input Attenuator
30 dB (+/- 10%) Input Attenuator

1.9 kHz Low Frequency Roll Off

22.0 kHz Low Frequency Roll Off

Moving any switch to the extreme left, toward the center of the
unit activates the indicated function. Moving the switch to the
extreme right, toward the side of the unit, deactivates that function.
The most commonly used configuration will have the 22 kHz roll
off switch on and all other options off.

© ETS-LINDGREN L.P. – SEPTEMBER 2003 9
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Principles of Operation MODEL 3301B ACTIVE ROD & FIELD ANTENNA

FACTORY SETTINGS

The unit comes configured from the factory with the 22.0 kHz Low
Frequency Roll Off, set ON. All other switches are off.

It is anticipated that the unit will normally be used with one of the
roll off switches ON. Due to the abundance of low frequency
ambient noise, in most settings using the full bandwidth of the unit
will make it very susceptible to saturation. However, when
extremely low frequency measurements are required, the unit is
capable of providing these measurements.

If both roll off switches, are simultaneously set in the ON position,
the low frequency, 3 dB roll of point will be approximately 23
kHz.

PROPER SELECTION OF INTERNAL ATTENUATION

When dealing with CW type signals, no attenuation is needed to
measure field strengths below 0.7 V/m. At approximately this
level, the saturation indicator light will come on. This indicates a
need to switch ON the 10 dB attenuator.

When the 10 dB attenuator is switched ON the 3301B can measure
field strengths up to 2.2 V/m without saturating. The unit retains
115 dB of dynamic range, but the maximum reading before
saturation is raised by 10 dB while the minimum discernible signal
is also raised by 10 dB. At 2.2 V/m, with the 10 dB attenuator
active, the saturation indicator light will again come on. This
indicates a need to switch the 30 dB attenuator ON in place of the
10 dB attenuator.

The 30 dB internal attenuator will allow the unit to maintain it’s
calibration while measuring field strengths up to 22 V/m. Again,
the unit retains 115 dB of dynamic range. Both the maximum
reading before saturation and the minimum discernible signal are
raised 30 dB above their 0 dB attenuation values.

When using either of the attenuators, be sure to add the attenuation
to the antenna factor for accurate readings. Also, note that if both
attenuator switches are used, the resulting attenuation is
approximately 31 dB and not 30 dB.

10 © ETS-LINDGREN L.P. – SEPTEMBER 2003

REV J – PN 399046