ETS-Lindgren 3103 Conical Log Spiral Antenna - Manual (Page 7)

www.ets-lindgren.com Introduction 7
1.0 Introduction
The ETS-Lindgren Model 3100 Series Conical Log Spiral antennas are
circularly polarized broadband antennas covering the frequency range of
100 MHz to 10 GHz. This family of antennas includes the Model 3101,
Model 3102, and the Model 3103. The Conical Log Spiral antennas are designed
specifically for EMI measurements and compliance testing as called for in various
Military Standards.
Each antenna is constructed of a fiberglass cone upon which two logarithmic
spirals of 50-ohm coaxial cable are securely fastened. Outside windings improve
heat dissipation. The coaxial connectors are located in the phenolic base plate of
the cone. A 1/4–20 adapter for a tripod or other mounting configuration is
attached to the antenna near its horizontal center of gravity or at the antenna
base plate.
The Conical Log Spiral antennas receive both circular polarized and linear
polarized fields (with a 3-dB variance for linear fields) under normal operating
conditions.
Model 3101, Model 3102, and Model 3103 are right-hand wound, and transmit
and receive a left-hand circularly polarized wave. Model 3101L, Model 3102L,
and Model 3103L are left-hand wound, and transmit and receive a right-hand
circularly polarized wave.
During the manufacturing process each antenna is individually calibrated at
1 meter per SAE ARP 958. Typical antenna data is included beginning on
page 21. Actual factors and a signed Certificate of Calibration Conformance are
shipped with each antenna.
Standard Configuration
 Left-hand circular polarization
 Support rod
 Support base configured to accept ETS-Lindgren or other tripod mount
with standard 1/4–20 threads