ETS-Lindgren 3142B User Manual

Archived 09/23/10

Model 3142B

BiConiLog

MANUAL

™

Antenna

© EMC TEST SYSTEMS, L.P. – MARCH 2002 REV C – PN 399229

Introduction MODEL 3142B BICONILOG™ ANTENNA

Archived 09/23/10

EMC Test Systems, L.P. reserves the right to make changes to any product described herein in order to
improve function, design or for any other reason. Nothing contained herein shall constitute EMC Test
Systems, L.P. assuming any liability whatsoever arising out of the application or use of any product or
circuit described herein. EMC Test Systems, L.P. does not convey any license under its patent rights or the
rights of others.

© Copyright 2002 by EMC Test Systems, L.P. All Rights Reserved.

No part of this document may be copied by any means

without written permission from EMC Test Systems, 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
Tel [phone] Fax [phone]

FINLAND

Euroshield OY
Mekannikontie 1
27510, Eura, Finland
Tel [phone]
Fax [phone]

SINGAPORE

Lindgren RF Enclosures Asia-Pacific
87 Beach Road
#06-02 Chye Sing Building
Singapore 189695
Tel [phone] Fax [phone]

© EMC TEST SYSTEMS, L.P. – MARCH 2002
REV C – PN 399229

MODEL 3142B BICONILOG™ ANTENNA Introduction

Archived 09/23/10

Table of Contents

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

ASSEMBLY & MOUNTING INSTRUCTIONS ....................................................................................... 4

APPLICATION WITHOUT THE OPTIONAL END PLATES .............................................................. 7

APPLICATION WITH THE OPTIONAL T BOW-TIE END PLATES ............................................... 9

TYPICAL DATA WITHOUT THE END PLATES ................................................................................ 10

TYPICAL DATA WITH THE END PLATES ........................................................................................ 13

SPECIFICATIONS .................................................................................................................................... 16

MAINTENANCE ....................................................................................................................................... 17

WARRANTY STATEMENT .................................................................................................................... 18

© EMC TEST SYSTEMS, L.P. – MARCH 2002
REV C – PN 399229

Introduction MODEL 3142B BICONILOG™ ANTENNA

Archived 09/23/10

© EMC TEST SYSTEMS, L.P. – MARCH 2002
REV C – PN 399229

MODEL 3142B BICONILOG™ ANTENNA Introduction

Archived 09/23/10

INTRODUCTION

The ETS-Lindgren EMCO brand Model 3142B

BiConiLog™ Antenna is designed as a dual-purpose

antenna that can be used for both emissions and immunity

applications. The Model 3142B is a hybrid linearly

polarized EMC antenna consisting of a log–periodic dipole

array (LPDA) and a single bow-tie antenna. Although bow-

ties have been used for all elements on log-periodic

antennas in the past, in EMC applications the advantage

gained is an extension of the useful low frequency range of

the typical LPDA’s from 100 down to 30 MHz. At 30

MHz, an efficient single dipole type antenna must be 5

meters long, whereas suitable performance is obtained here

with a 1.7 meter long bow-tie.

A simple wire outline bow-tie antenna is narrowband

compared to a sheet bow-tie or biconical, thus struts are

added to the Model 3142B bow-ties to better simulate the

broadband sheet bow-tie. The standard “self-balun” feed of

the log-periodic also provides a matched, balanced feed to

the bow-tie elements. Below 150 MHz, bow-tie radiation

dominates with a dipole-like pattern, while above 150 MHz

the radiation in the plane of the elements is directional.

To prevent cable pickup below 100 MHz, the Model 3142B

contains a “balun” which acts as a common-mode choke to

© EMC TEST SYSTEMS, L.P. – MARCH 2002 1
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keep unbalanced current off the coaxial feed cable outer

shield. Even though the Model 3142B is highly balanced,

in vertically polarized measurements cable position can

effect results so it is recommended that the cable be

Introduction MODEL 3142B BICONILOG™ ANTENNA

Archived 09/23/10

suspended horizontally back from the antenna at least 1

meter before any vertical drop.

The antenna has a mounting bracket and 1/4X20 UNC

knob for attaching to an ETS-Lindgren tripod or tower

adapter. Individual antenna factors and gain calibration data

is included with each antenna.

The Model 3142B optional end plates (Part Number

106572) are available to improve gain for immunity testing.

This option consists of two end plates that are easily

attached and detached by hand using captive screw knobs.

When the end plates are attached it creates a T shaped bow-

tie element.

For any dipole–type antenna to transmit or receive energy

most efficiently, its length must be nearly a half

wavelength, which is about 4.6 meters long at 30 MHz, and

2.8 meters long at 50 MHz. Unfortunately, this is too

unwieldy for many anechoic chambers and test sites. The

optional end plates of the Model 3142B make it look like

an antenna twice as long as its 1.4 meter length. The result

is about a 10 dB improvement in low-frequency transmit

gain and receive antenna factor compared to a same-length

regular bow-tie.

With the end plates attached to the Model 3142B bow-tie

elements the equivalent dipole electrical length is

2 © EMC TEST SYSTEMS, L.P. – MARCH 2002

REV C – PN 399229

increased, thereby decreasing resonant frequency and

increasing efficiency in the 20-60 MHz range. Similarly,

the regular bow-tie has a lower resonant frequency than an

MODEL 3142B BICONILOG™ ANTENNA Introduction

Archived 09/23/10

equal length single-wire dipole. The T end plate option has

its first resonance at a frequency where its length is about

0.22 λ, a regular bow-tie at a length of 0.3 λ, and a tuned

dipole at about a length of 0.48 λ. Thus at 50 MHz the 1.4m

long end plate option of the Model 3142B behaves like at

2.8 m tuned dipole. Cross-polar radiation is minimized

because current flow on one of the T end frames is almost

exactly cancelled by the oppositely-phased current on the

other T end.

© EMC TEST SYSTEMS, L.P. – MARCH 2002 3
REV C – PN 399229