Introduction – ETS-Lindgren 3142B BiConiLog Antenna (Archived) User Manual

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MODEL 3142B BICONILOG™ ANTENNA

Introduction

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

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

REV C – PN 399229

Archived 09/23/10