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

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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.

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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.

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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.

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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

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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.

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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”.

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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.

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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.

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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.

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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.

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MODEL 3301B ACTIVE ROD & FIELD ANTENNA Power Circuitry

Please be aware that it is unwise to use attenuation to measure very
low field strengths. When the field strength falls below the
minimum discernible signal, inaccurate field strength
measurements will result.

Both of the internal attenuators have a 10% tolerance, so they
should be calibrated before being used in critical applications.

One final WARNING about the internal 30 dB attenuator is in
order. With the 30 dB attenuator active, the unit resonates at 30
MHz. Therefore, the unit should not be used above 15 MHz with
the 30 dB attenuator active.

The usefulness of the internal attenuators for impulse response
testing is discussed in “Ante nna Impulse Response.”

POWER CIRCUITRY

The Model 3301B is powered by two (2) – six (6) VDC sealed
lead-acid batteries. A battery charger is supplied with the unit. The
battery charging port of the front of the unit allows for easy
recharging of the unit. Two (2) internal fuses protect the unit from
unintentional shorting.

VOLTAGE-SELECTABLE B ATTERY
CHARGER

OPERATION

The EMCO brand Voltage-Selectable Battery Charger is solely
intended for charging the sealed lead-acid batteries found in
EMCO products. The battery charger is a means of providing the
necessary charge voltage and current from either a 115 or 230
VAC 50/60 Hz source.

NOTE: It is necessary to select the proper input voltage PRIOR to
connecting the battery charger to the power mains. The voltage
select switch is located adjacent to the power input receptacle.

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Power Circuitry MODEL 3301B ACTIVE ROD & FIELD ANTENNA

To maintain safety requirements, use the CSA certified power cord
provided. If it is necessary to provide other means of attaching the
battery charger to the power mains it is required that a type HD 21
(PVC cord) or type HD22 (rubber cord) with a nominal cross
section of 0.75 mm are to be used.

The battery charger provides both fast and trickle charge operation.
Switching from one charge mode to the other is provided
automatically by the charger. The front panel indicator marked
“Fast Charge” lights when the battery charger is in the fast charge
mode. When the “Power On “ light is illuminated and the “Fast
Charge” light is extinguished, the battery charger is in the trickle
charge mode.

The antenna should be connected to the battery charger in “Trickle
Charge” mode when not in use. Charging time is approximately
eight hours when batteries are completely discharged. Note: The
antenna is not designed to operate using the Battery Charger as a
power source. Batteries should provide power to the amplifier for
approximately 16 hours before recharging is required.

The battery charger is protected against overcurrent by a 200 mA
250 VAC time-delay fuse. If it becomes necessary to replace the
fuse, use a fuse of the same type and rating to maintain safe
operations. The fuse is accessible by removing the two (2)
“Phillips” head screws on the underside of the unit. Always
remove main power before opening the housing. The output of the
battery charger is protected against overcurrent conditions by use
of “fold -back” circuitry.

SPECIFICATIONS

Input voltage: 115/230 VAC selectable
Input frequency: 50/60 Hz
Input power: 20 VA max
Protection class: Class II double insulated
Input fuse rating: 200 mA time-delay type 5x20 mm
Input power connection : IEC-320 power inlet
Output voltage: 12 VDC (13.5-15 VDC)
Output current: 350 mA

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MODEL 3301B ACTIVE ROD & FIELD ANTENNA Power Circuitry

Safety approvals: TUV, CSA

BATTERY LOW INDICATO R

A Battery Low Indicator/Power On Indicator is located on the front
of the unit. Should this LED not light when the power switch is
engaged, the batteries should be recharged.

FUSES

There are two fuses, one for each battery, located inside the Model
3301B. It is necessary to remove the bottom panel of the unit to
replace fuses. Disconnect the power cord and charger before
opening the unit. When fuse replacement is necessary, using a
Phillips head screwdriver carefully remove the screws around the
edge of the bottom panel and lift the panel off of the unit. Locate
the two fuses in their holders mounted on the circuit board. The
fuse holders provided will accommodate either Type AC Size 0.5
AMP Fast Acting or 5x20mm fuses. After the new fuses are
installed, replace the bottom panel of the unit and reinstall the
screws.

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Setup and Use MODEL 3301B ACTIVE ROD & FIELD ANTENNA

SETUP AND USE

The 3301B has been designed for ease of use. The unit has been
designed for five (5) accurate reading types in a variety of test
environments. However, precision measurements require an
understanding of the test parameters which will adversely affect
test results. No single test instrument can insure accurate results.
For best results, the user should become thoroughly familiar with
both the practical and theoretical operating parameters for this unit.

SETUP

Before beginning the setup procedure, ensure that the technician is
completely grounded using an ESD wrist strap at an ESD
protective workstation for protection of the antenna FET. Ensure
antenna power is OFF.

The 3301B is quite sensitive to test setup and proper use. Two (2)
grounding strips are provided on top of the unit. These are intended
to attach to a counterpoise, which is provided with the unit.

In order to assemble the unit, first touch the two metal
counterpoise mounting strips located on top of the antenna chassis,
then remove the two screws from each strip. The unit is meant to
be under the counterpoise. In this way the body of the unit does not
intrude into the field being measured. Open the counterpoise and
attach it to the mounting strips using the screws that were just
removed. Next, the rod should be attached to the fitting at the
center of the unit, through the hole in the counterpoise. The rod
should then be extended to 41”. The output of the unit should be
connected to a 50 ohm receiver, spectrum analyzer, or RF
voltmeter. The technician should remove the ESD wrist strap at
this time.

The unit is activated by pressing in the power switch on the front
panel. The switch will turn to green and the battery low/power
indicator light will come on. Should the indicator light not come
on, the level of the battery charge should be checked. Finally, the

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MODEL 3301B ACTIVE ROD & FIELD ANTENNA Setup and Use

state of the gain switch should be checked. It is anticipated that in
most applications the low gain setting will be used.

The unit housing hangs under the counterpoise with the antenna
rod passing through an opening in the counterpoise.

It should be noted that the brass tripod mounting bracket on the
bottom of the unit is not a ground location. The unit must be
attached to a counterpoise through the top grounding strips. In
screen room testing, the counterpoise should be solidly attached to
the screen room wall, as required for military testing.

If the unit is to be mounted on a tripod, it is recommended that the
tripod be non-conductive.

HIGH SENSITIVITY READINGS

The Model 3301B has been optimized to facilitate extremely
sensitive readings. For best performance all internal attenuation
should be OFF. The gain switch should be placed in the low gain
setting. The noise limiting factor on the 3301B is the high front
end impedance presented to the FET. So when the gain stage
output is increased with the gain switch, the noise is also amplified
and actually increased slightly due to additional noise added in the
gain state. The high gain setting is primarily intended to provide
additional signal strength for receivers which require it.

A set of minimum discernible signal graphs is included in this
manual. These graphs represent the smallest signal which can be
detected with the 3301B. The data plotted are the noise output of
the unit. Hence, this forms the noise measurement for a signal plus
noise to noise ratio of 3 dB. Several typical bandwidths are
presented. To calculate the expected sensitivity at some other
bandwidth a 10*log relation should be used.

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Setup and Use MODEL 3301B ACTIVE ROD & FIELD ANTENNA

Example:
Determine the sensit ivity with a 3 kHz bandwidth at 1 MHz. The
minimum discernible signal (MDS) at 1 MHz with a 1 kHz
bandwidth is read from the graph at –2 dBuV/m. The ration of the
bandwidth is 3/1=3. Taking 10*log(3) we get 4.77 dB. So the
expected sensitivity would be –2dBuV/m+4.77dB=2.77dBuV/m.

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MODEL 3301B ACTIVE ROD & FIELD ANTENNA Theory of Operation

THEORY OF OPERATION

THE ROD

There are three (3) factors which are of primary interest in
understanding a rod antenna. These factors are its effective
electrical length, the impedance it presents to the measurement
system, and the interaction of the rod with the ground. The
discussion here will contain itself to discussing an electrically short
antenna element. The 3301B is designed to be electrically short
over its measurement range. By electrically short, we mean an
antenna which is designed to have the physical antenna element be
short when compared to the wavelength of the highest frequency in
its measurement range. The current distribution on any rod antenna
will be sinusoidal. If a rod is short enough with respect to the
wavelength being measured, that distribution will approach a linear
distribution and may be assumed to be linear for all practical
purposes. The linear current distribution will allow for linear
scaling of the rod length. If the rod length is reduced by half, then
the received voltage will be reduced by half. The 41” rod is
approximately a meter long. Electrically it then is a half meter
long. The assumption of linearity will remain accurate at least to
one eighth (1/8) wavelength.

At this point some resonanc e behavior is possible. A rod which is
electrically a half meter is one eighth (1/8) wavelength at 75 MHz.
In order to keep the response of the unit linear and avoid resonance
behavior, the 3301B pre-amplifier is limited to roll off before this
frequency has been reached. However, this avoidance of possible
resonance carriers the penalty of 6dB on the antenna factor. Since
field strength is measured as volts per meter, the measurement
must be normalized to 1 meter. This means that 6 dB must be
added to a reading taken with a half meter rod.

The second factor which is of concern is the impedance the rod
presents to the measurement system. The resistive component is
non-significant in this situation. The controlling impedance is the
capacitance of the rod to ground. This capacitance may be
calculated by the formula:

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Theory of Operation MODEL 3301B ACTIVE ROD & FIELD ANTENNA

C = [55.63 * h] / [ln (h/a)]

Where “h” is the length of the rod and “a” is its radius, both
in meters. The natural logarithm of “h” over “a” is
represented by “ln”. For the 3301B rod, the capacitance is
12 picofarads. This capacitance is significant because it
combines with the total input capacitance of the amplifier
to form a voltage divider. It can quickly be seen that if the
FET input capacitance and circuit stray total 12 pF, there
will be a 6 dB loss through this stray capacitance. Even if
the total input capacitance where reduced to 4 pF there
would be a 2.5 dB loss.

Finally, the interaction of the rod with the ground must be
understood. The theoretical understanding of the rod assumes tha t
it operates in reference to an infinite ground at 0 Volt potential.
The closer the test situation is to this scenario the more accurate
will be the readings. A small vestigial ground is provided with the
unit in the form of a counterpoise. Care should be taken to
reference this counterpoise to true ground.

The procedures for this are carefully explained in various
standards. If the counterpoise is not well grounded, an impedance
may build up through the cabling and other instrumentation.
Reading differences of as much as 20dB can be found with
ungrounded counterpoises. This will be true for all rod antennas
regardless of their design.

Another counterpoise problem is the potential for positive
feedback. Good amplifier design calls for the output to be 180o out
of phase with the output signal so that the shield current is in phase
with the input. If the shield and counterpoise are tied through the
body of the unit, then the counterpoise will receive some of this
current. If the counterpoise does not have an extremely low
impedance to ground, then this return current can drive a potential
on the counterpoise in phase with the input resulting in errant
readings. The 3301B has an internal common mode choke to
minimize the impact of an inadequate test setup. However, proper
test configuration will always be critical to insure measurement
accuracy.

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

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MODEL 3301B ACTIVE ROD & FIELD ANTENNA Theory of Operation

Also of concern is the contribution of edge effects from the
vestigial ground plane. Most theory is developed on the
assumption of one infinite ground plane. How using a small
vestigial ground plane or counterpoise affects the theory has not
been well studied to date. Even more complicated is the effect of
this vestigial ground plane when the unit is used in a screen room
with the ground planes on all sides. In practice, the best results are
obtained by tightly typing the counterpoise to the screen room
through an ultra low impedance ground strap. This at least assures
that at the lower frequencies all of these surfaces are at an equal
potential.

THE PRE-AMPLIFIER

The 3301B pre-amplifier is designed in two (2) stages. The first
stage provides impedance transformation and current gain. The
second stage provides voltage gain and impedance mating on a 50
ohm output.

The first stage of the pre-amplifier contains an n-channel JFET and
an NPN bipolar silicon transistor. Through the use of extremely
precise layout techniques, careful parts selection and feedback to
virtually eliminate the Miller effect, the total input capacitance is
kept extremely low. This low capacitance in turn allows for an
extremely high input impedance.

It is the output impedance which determines the effective low
frequency cutoff of the unit. The 3301B is still usable at an
extremely low 30 Hz. In fact, artificial limiting had to be
introduced to protect the unit in situations where overloading from
power frequencies would be a problem. The low frequency roll off
switches in to unit allow the user to set the unit’s low frequency
cutoff according to his particular testing needs.

The second stage is made up of three (3) exceptionally high quality
transistors. The first is configured common emitter for voltage gain
and to give a precise 180o phase reversal for the output. The
second two transistors for a Darlington pair to drive the 50 ohm
output. The outp ut of this stage is then DC isolated, matched to 50

© ETS-LINDGREN L.P. – SEPTEMBER 2003 19
REV J – PN 399046

Theory of Operation MODEL 3301B ACTIVE ROD & FIELD ANTENNA

ohm and passed through a common mode choke. The result is that
cable VSWR and common mode noise problems are minimized.

The dynamic limits of the 3301B are set by the amplifier.
Sensitivity is determined by the noise developed in the first stage.
The ultimate limit on sensitivity is determined by the thermal noise
generated by the input impedance. The impedance presented to the
amplifier by the rod is almost entirely capacitive. A 41” rod
typically presents an impedance of about 12 pF. So the input
impedance presented to the amplifier will decline with increasing
frequency. At the low frequencies, where the input impedance is
high, the thermal noise generated by this impedance will also be
high. If the inp ut impedance of the amplifier is lowered to reduce
thermal noise then the rod will be loaded down and lose sensitivity.
This combination of thermal noise and rod impedance sets an
ultimate limit on the sensitivity achievable by active rod antennas.
The sensitivity of the 3301B improves with frequency in direct
relation to the declining input impedance.

A common mistake made in regard to sensitivity is to ask what the
noise figure of an active rod is. Noise figure is defined as “the ratio
of output noise of a unit over the output noise expected solely due
to the thermal noise of the resistance of the input impedance.”
Since the input in the case of a rod is primarily reactive, the
definition literally has no meaning. What is useful is to determine
what the minimum discernible signal of a unit is. That is, what is
the smallest signal which can be seen in the presence of the
amplifier noise? There is a trick here. The smallest signal seen
above the noise in a rod antenna is not determined by the noise of
the amplifier. Signal is drained away through capacitive loss before
it reaches the amplifier. An amplifier with more noise may actually
be more sensitive if it also loses less signal to capacitance at the
input.

The upper limit of the 3301B is determined by the ability of the
gain stage to amplify a signal. The gain stages capable of handing
field strengths of 0.7 V/M are available. Impulsive type signals
produce the same effect but in such a way as may not be
immediately obvious. An impulse signal presents the amplifier
with signals at a number of frequencies all in phase with each other

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

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MODEL 3301B ACTIVE ROD & FIELD ANTENNA The Antenna Factor

so that measurement of the field strength at any one frequency will
not appear to be very high. However, the amplifier is being called
upon to amplify signals at many frequencies simultaneously. In the
time domain, the amplifier would be seen to be presented with
quite a large power demand. The result is that impulsive signals
appear to saturate the amplifier at must lower signal levels. The
3301B has been measured to begin going non-linear at 64
dBuV/m/MHz.

A saturation indicator is provided on the unit. This indicator will
eliminate many false readings due to non-linear operation. The
saturation indicator has been carefully tested to give an accurate,
early warning of possible saturation. However, some types of
impulse signals may not trigger the indicator. The user must,
therefore, be careful to observe the published limits. Should these
be exceeded the internal attenuation provided will relieve the
problem.

THE ANTENNA FACTOR

The antenna factor data provided with the unit is simply a ratio of
the field strength presented to the unit to the voltage output from
the unit at that field strength. By adding the antenna factor to a
given output, the field strength may be derived. The antenna factor
in the 3301B combines several factors. The first factor is the 6 dB
required to normalize the rod to 1 meter. The next is the measured
capacitive loss at the front of the unit of about 4 dB. Then there is
the gain of the amplifier itself, 15 dB. Finally, 6 dB is required in
order to conjugate match the output to 50 ohm. The antenna factor
is the sum of these factors. A typical result might be:

-6 dB Rod Normalization

-4 dB Capacitive Loss
+15 dB Preamlifier Gain

-6 dB 50 ohm Matching Loss

-1 dB Gain Over Field Strength or Antenna Factor of 1 dB

© ETS-LINDGREN L.P. – SEPTEMBER 2003 21
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Antenna Impulse Response MODEL 3301B ACTIVE ROD & FIELD ANTENNA

ANTENNA IMPULSE RESPONSE

The Model 3301B was designed and optimized for the
measurement of CW type signals. However, this unit is fully
capable of dealing accurately with impulsive type signals, with
some special considerations. This section is intended to guide the
user who intends to use the 3301B to measure impulsive signals.
By following the guidance given here accurate measurements of
impulsive signals may be performed. The 3301B may be used to
measure all of the important characteristics of an impulse signal
which falls within its bandwidth and dynamic range. However, the
measurement of impulsive signals requires some special cautions
to avoid saturation of the antenna amplifier.

IMPULSE CHARACTERISTICS

Before discussing the 3301B response to impulse signals, a brief
review of the nature of impulse signals is appropriate. For our
purposes we will consider a specific type of impulse signal, the
periodic, rectangular pulse. The pulse may be described by three
(3) parameters: the pulse width, t, the pulse repetition rate, PRF,
and the pulse amplitude A (See Figure 1). By Fourier analysis, we
may convert this time domain representation into its frequency
domain equivalent. In the frequency domain, the impulse becomes
an infinite series of discrete spectral lines whose envelope is
described by the formula,
Y=K*sin(x)/X
Where,
K=A*t*PRF

The nulls occur at regular intervals spaced n/t apart, where n is an
integer. The discrete spectral lines are spaced evenly, at internal
multiples of the PRF (See Figure 2). Two (2) characteristics should
be noted. First, that increasing the pulse width, t, narrows the
separation of the nulls. So wider pulses tend to concentrate their
energy in a na rrower frequency span. Second, decreasing the PRF
decreases the frequency separation of the individual spectral lines
(See Figure 3).

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

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MODEL 3301B ACTIVE ROD & FIELD ANTENNA Antenna Impulse Response

By considering the frequency domain representation, any antenna’s
response to an impulse may be understood. The antenna will only
pass those spectral components which fall within its bandwidth. In
the case of the 3301B, components above 30 MHz will be
attenuated or not passed at all. Remember, that to fully describe a
rectangular pulse, an infinite bandwidth is required. The lack of
high frequency components shows up on the time domain as a
rounding of sharp corners and a slowing of the rise and fall.

In the same way the antenna will not efficiently pass spectral
components which fall below its bandwidth. For the 3301B, the
low frequency roll off which is selected will determine how
wideband the response is. The very low frequency components
basically describe the flat top and bottom of the time domain pulse.
So, when the waveform is band limited by the antenna, the
resulting waveform will have a decay constant returning the output
to ground rather than maintaining a flat topped pulse.

A third phenomenon which occurs when measuring impulse type
waveforms is that saturation of the amplifier is harder to detect. By
definition, impulsive type signals spread their energy over many
spectral components. So, when viewed in the frequency domain,
the energy demanded of the antenna amplifier may appear much
lower than it in fact is. The energy demanded of the antenna
amplifier to properly pass a pulse is not just the peak pulse in the
frequency domain waveform, but rather the sum of the energy
contained in all the spectral lines. By looking in the time domain, it
is easy to see that the amplifier must provide the energy to go from
ground to the pulse peak almost instantaneously. The impulse
delivers all its frequency domain spectral components in phase. So
the antenna must provide the vector sum of all the frequency
domain spectral lines. Thus extra care must be taken to protect the
antenna amplifier from saturation when making impulse
measurements in the frequency domain. The internal attenuators in
the 3301B allow it to overcome many of the barriers which earlier
units presented to such measurements. These attenuators allow the
user to safely keep the amplifier in its linear region.

The saturation indicator in the 3301B will provide an accurate
warning of impending saturation, provided two (2) conditions are

© ETS-LINDGREN L.P. – SEPTEMBER 2003 23
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Antenna Impulse Response MODEL 3301B ACTIVE ROD & FIELD ANTENNA

met. First, the product of the pulse width to pulse repetition rate
must be greater than 0.003. Second, the pulse repetition rate must
be less than the value listed for the applicable duty cycle given in
the following chart:

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

If an impulse falls outside of these two (2) parameters, the
saturation indicator will not accurately warn of saturation.
However, the antenna will accurately handle the impulse signal
within its bandwidth and dynamic range limitations.

The reasons for these requirements are two (2) engineering trade­offs which must be made, and are explained in the next two (2)
sections.

PULSE DESENSITIZATIO N

The 3301B saturation indicator operates by creating a DC level on
a capacitor feed through a rectifying diode. This DC level is then
compared to a second DC level which is set at the amplifier’s 1 dB
compression point. This circuit works extremely well for CQ type
signals. However, for fast transients the capacitor, like all
capacitors, has an integrating effect. The DC level established by a
fast transient is spread out in time. After the pulse passes, the
capacitor begins to discharge through its resistance to ground. If
the PRF is slow enough so that the capacitor is fully discharged
before the next pulse arrives, it may never trigger the indicator.
The antenna amplifier, on the other hand, must satisfy the
instantaneous energy demand. It must respond to the peak demand
without any integrating effect. If the product of the pulse width and

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

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MODEL 3301B ACTIVE ROD & FIELD ANTENNA Antenna Impulse Response

PRF is less than 0.003, the saturation indicator will fail to indicate
properly. The time constant of the saturation indicating capacitor
also sets the persistence of the saturation circuit. In order to have
the saturation circuit cease to indicate saturation within a
reasonable time after the antenna moves out of saturation, a
reasonable RC time constant must be maintained. This choice of
RC time constant also creates this limit for impulsive signals. In
this region, the user must closely monitor the antenna output for
saturation.

PULSE CHARGING

The second criterion which must be met is that the PRF must fall
below the rate listed in the previous section on “Impulse
Characteristics” for the appropriate duty cycle. This requirement is
created by the AC coupling in the 3301B circuitry. In order to
allow maximum dynamic range through the 3301B, the various
stages are AC coupled. Furthermore, in order to allow the
extremely broad bandwidth of the unit, large value, low impedance
capacitors are used to provide the AC coupling. When a pulse
passes through these capacitors, a charge is developed. After the
pulse passes, this charge drains through the associated resistance to
ground at an established RC constant. However, if the next pulse
occurs before the residual charge has fully discharged, then a
residual DC bias is created.

This bias artificially alters the DC level on the saturation indicator
comparison capacitor causing it to fail to properly indicate
saturation. Again, in this region, the user must closely monitor the
antenna output for saturation.

© ETS-LINDGREN L.P. – SEPTEMBER 2003 25
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Calibration Procedure MODEL 3301B ACTIVE ROD & FIELD ANTENNA

CALIBRATION PROCEDURE

ETS-Lindgren recommends the equivalent capacitance method of
calibration for its 3301B active rod antenna. In order to check the
calibration a 3301B calibration test fixture is req uired. This fixture
contains a resistive “T” and a capacitor. The “T” allows for
accurate reading of the input to the fixture. The capacitor feeds the
amplifier through the same impedance as the 41” rod presents to it.
The result is a simple, yet extremely accurate calibration.

Periodic checks of the unit’s performance are recommended. In
order to calibrate the unit, simply attach the calibration fixture and
ground it to the 3301B housing through one of the counterpoise
mounting holes. Place a signal source on one leg of the fixture and
a receiver on the other leg. Then terminate the output of the unit
with 50 ohms. Read the input signal strength. The input signal
strength measured through the calibration fixture must have 11 dB
added to it. The 11 dB is co mposed of 6 dB required to normalize
the rod to 1 meter and 5 dB of signal loss through the resistive
divider in the “T”. After the input is read, move the receiver cable
to the output of the unit and place a 50 ohm load on the now open
leg of the calibration fixture. Read the unit output. The antenna
factor is the input plus 11 dB minus the output, both readings
assumed to be logarithmic.

ETS-Lindgren recommends the following input voltage levels for
field calibration:

Voltage Internal Attenuation
250 mV 0 dB
450 mV 10 dB

8 V 30 dB

Table 1. Voltage Settings for Field Calibration

Example:
Suppose a reading is taken with a 1 MHz signal input to the
calibration fixture. The input is read as 50 dBuV and the output is

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

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MODEL 3301B ACTIVE ROD & FIELD ANTENNA 3301B Parts List

read as 59 dBuV. The antenna factor is then the input plus 11 dB
minus the output of 50 dBuV + 11 dB – 59 dBuV = 2 dB.

3301B PARTS LIST

Item Number

1. Collapsible Rod Element 41” 101263C

2. 24” x 24” Counterpoise 100692

3. Rod Antenna Pre-Amplifier 100697B

4. Battery Charger 102615

5. Model 3301B Manual 399046

ACCESSORIES AVAILABLE

Accessory Model Number

1. 3301B Calibration Fixture 3301CB

2. Tripod, Linen Phenolic 3-TR

3. Remote Status Monitor 3301B-RM

4. Extra 3301B Manual 399046

5. 25” Cable RG-223/U with BNC
Connectors

6. Replacement Batteries, 6V (2 required) 400009

MAINTENANCE

To ensure reliable and repeatable long-term performance, annual
recalibration of your antennas by ETS-Lindgren’s experienced
technicians is recommended. Our staff can recalibrate almost any
type or brand of antenna. Please call to receive a service order
number prior to sending an antenna to us for calibration.

For more information about our calibration services or to place an
order for antenna calibration visit our calibration website at
http://www.antennacalibration.com/.

C-BNC

© ETS-LINDGREN L.P. – SEPTEMBER 2003 27
REV J – PN 399046

Warranty Statement MODEL 3301B ACTIVE ROD & FIELD ANTENNA

WARRANTY STATEMENT

ETS-Lindgren L.P., hereinafter referred to as the Seller, warrants that standard EMCO products
are free from defect in materials and workmanship for a period of two (2) years from date of
shipment. Standard EMCO Products include the following:

v Antennas, Loops, Horns
v GTEM cells, TEM cells, Helmholtz Coils
v LISNs, PLISNs, Rejection cavities & Networks
v Towers, Turntables, Tripods & Controllers
v Field Probes, Current Probes, Injection Probes

If the Buy er notifies the Seller of a defect within the warranty period, the Seller will, at the Seller’s
option, either repair and/or replace those products that prove to be defective.

There will be no charge for warranty services performed at the location the Seller designates.
The Buyer must, however, prepay inbound shipping costs and any duties or taxes. The Seller will
pay outbound shipping cost for a carrier of the Seller’s choice, exclusive of any duties or taxes. If
the Seller determines that warranty service can only be performed at the Buyer’s location, the
Buyer will not be charged for the Seller’s travel related costs.

This warranty does not apply to:

v Normal wear and tear of materials
v Consumable items such as fuses, batteries, etc.
v Products that have been improperly installed, maintained or used
v Products which have been operated outside the specifications
v Products which have been modified without authorization
v Calibration of products, unless necessitated by defects

THIS WARRANTY IS EXCLUSIVE. NO OTHER WARRANTY, WRITTEN OR ORAL, IS
EXPRESSED OR IMPLIED, INCLUDING BUT NOT LMITED TO, THE IMPLIED WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE REMEDIES
PROVIDED BY THIS WARRANTY ARE THE BUYER’S SOLE AND EXCLUSIVE REMEDIES.
IN NO EVENT IS THE SELLER LIABLE FOR ANY DAMAGES WHATSOEVER, INCLUDING
BUT NOT LIMITED TO, DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER BASED ON CONTRACT, TORT, OR ANY OTHER LEGAL THEORY.

Note: Please contact the Seller’s sales department for a Return Materials Authorization (RMA)
number before shipping equipment to us.

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

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MODEL 3301B ACTIVE ROD & FIELD ANTENNA European Community Declaration of Conformity

EUROPEAN COMMUNITY
DECLARATION OF CONFORMITY

The EC Declaration of Conformity is the method by which EMC Test Systems, L.P. declares that
the equipment listed on this document complies with the EMC and Low -voltage Directives.

Factory: Issued by:
EMC Test Systems, L.P. EMC Test Systems, L.P.
P.O. Box 80589 P.O. Box 80589
Austin, Texas USA Austin, Texas USA
78708-0589 78708-0589

The products ma nufactured under the EMCO product name and listed below are
eligible to bear the EC Mark:

Model 3301B Active Rod Antenna
Part Number 102615 Battery Charger

Applicable Requirements:

Standard Criteria
EN61010-1 Safety requirements for electrical equipment for
measurement, control and laboratory use
EN60742/1989 Isolating transformers and safety isolating transformers
EN55022 Class B
IEC 801-2 Level 2 4/8kV
IEC 801-3 Level 2 3V/m
IEC 801-4 Level 2 .5 I/O, 1kV AC

Authorized Signatories

___________________________ ___________________________

Bruce Butler, General Manager James C. Psencik, Engineering Mgr.

___________________________

Charles Garrison, Quality Assurance Date of Declaration: December 10, 1996

The authorizing signature on the EC Declaration of Conformity document authorizes EMC Test Systems,
L.P. to affix the CE mark to the indicated product. CE marks placed on these products will be distinct and
visible. Other marks or inscriptions liable to be confused with the CE mark will not be affixed to these
products. EMC Test Systems, L.P. has ensured that appropriate documentation shall remain available on
premises for inspection and validation purposes for a period of no less than 10 years.

© ETS-LINDGREN L.P. – SEPTEMBER 2003 29
REV J – PN 399046

Data and Illustrations MODEL 3301B ACTIVE ROD & FIELD ANTENNA

FIGURE 1. PERIODIC RECTANGULAR PULSE TRAIN.

DATA AND ILLUSTRATIONS

T

E

A

TIME

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

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MODEL 3301B ACTIVE ROD & FIELD ANTENNA Data and Illustrations

FULLY DESCRIBE THE ENVELOPE.

SPECTRAL LINES

ANTENNA BANDWIDTH

LOW
FREQUENCY

HIGH
FREQUENCY
LIMIT

LIMIT

DC

FREQUENCY, f

FIGURE 2. SPECTRUM OF A RECTANGULAR PULSE. AMPLITUDES AND
PHASES OF AN INFINITE NUMBER OF HARMONICS ARE REQUIRED TO

© ETS-LINDGREN L.P. – SEPTEMBER 2003 31
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Data and Illustrations MODEL 3301B ACTIVE ROD & FIELD ANTENNA

CREATES WIDELY SPACED SPECTRAL LINES. FASTER RATES (3C, 3D) INCREASE

THE SPECTRAL LINE DENSITY.

FIGURE 3A.

FIGURE 3C.

FIGURE 3B.

FIGURE 3D.

FIGURE3. FIGURES 3A TO 3D DEPICT THE EFFECT OF ALTERING EITHER THE
PULSE WIDTH OR PULSE REPETITION RATE. A NARROW PULSE WIDTH (3A, 3C)
SPREADS THE PULSE ENERGY OVER A WIDER FREQUENCY BAND. WIDER PULSES
(3D,3D) CAUSE NARROWER LOBES. A LOW PULSE REPETITION RATE (3A, 3B)

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

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MODEL 3301B ACTIVE ROD & FIELD ANTENNA Data and Illustrations

330

1ZO

F

A

NALYZER50 OHM

S

IN

V

2

V

0

1

0

P

F

1

0

393

9

V

1

ACT

I

VE ELEC

TRI

C F

IELD AN

T

ENN

AMODE

L 3301

C

ALI

BRATI

O

N F

I

X

TUR

E

E

TS-

LIN

D

G

REN

Z OFANALYZER50 OHM

S

I

N

S

E

M

C

H

N

A

O

T

N

S

I

I
S

S

E

E

R

0

5

R

O

T

A

L

R

A

E

N

N

G

E

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S

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U

T

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X

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F

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L

L

L

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© ETS-LINDGREN L.P. – SEPTEMBER 2003 33
REV J – PN 399046

Data and Illustrations MODEL 3301B ACTIVE ROD & FIELD ANTENNA

VECTOR ANAYZERABFEEDUNI

T

TS-LINDGRENMODEL 3301ACTIVE ROD ANTENNA CALIBRATIONSETU

P

E

ACTIVE

ROD

ANTENNA

CALIBRATION

FIXTURE

GROUND

PLANE

SIGNAL GENERATOR

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

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MODEL 3301B ACTIVE ROD & FIELD ANTENNA Data and Illustrations

© ETS-LINDGREN L.P. – SEPTEMBER 2003 35
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Data and Illustrations MODEL 3301B ACTIVE ROD & FIELD ANTENNA

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

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MODEL 3301B ACTIVE ROD & FIELD ANTENNA Data and Illustrations

© ETS-LINDGREN L.P. – SEPTEMBER 2003 37
REV J – PN 399046

Data and Illustrations MODEL 3301B ACTIVE ROD & FIELD ANTENNA

A

N

T

E

N

N

A

FA

C

T

O

R

(d

B

)

FREQUENCY (Mhz)

1” ROD ANTENNA (0 dB ATTENUATION)TYPICAL ROLL OF CURVESGENERATOR OUTPUT 250 m

V

22 kHz ROLL OFF

4

170 Hz ROLL OFF

1.9 kHz ROLL OFF

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

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MODEL 3301B ACTIVE ROD & FIELD ANTENNA Data and Illustrations

1” ROD ANTENNA (10 dB ATTENUATION)TYPICAL ROLL OFF CURVESGENERATOR OUTPUT 250 m

V

FREQUENCY (MHz)

A

N

T

E

N

N

A F

A

C

T

O

R

(d

B

)

22 kHz ROLL OFF

4

1.9 kHz ROLL OFF

© ETS-LINDGREN L.P. – SEPTEMBER 2003 39
REV J – PN 399046

170 Hz ROLL OFF

Data and Illustrations MODEL 3301B ACTIVE ROD & FIELD ANTENNA

FREQUENCY (Mhz)

A

N

T

E

N

N

A F

A

C

T

O

R

(d

B

)

TENNA (30 dB ATTENUATION)

AL ROLL OFF CURVESGENERATOR OUTPUT 8000 m

V

TYPIC

41 ” ROD AN

22 kHz ROLL OFF

1.9 kHz

ROLL OFF

170 Hz ROLL OFF

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

REV J – PN 399046