6
|
Introduction
1.0 Introduction
The
ETS-Lindgren Model 3159C High-Power Biconical Antenna
is a broadband, linearly polarized biconical antenna
with a 20 MHz to 100 MHz frequency range. This antenna exhibits a wide beamwidth and is designed to continuously
handle up to 10 kW input power for generating high electric field strength over a large uniform area.
The pedestal is assembled with two fixed and two freewheeling casters that allow the antenna position on the test range
to be easily adjusted, or rolled into or out of the chamber for storage when not in use. The dual mast features regularly
spaced mounting holes so that the height of the boom can be adjusted. Slots below the base allow for easy transport with
a pallet jack or forklift. Horizontal and vertical polarization rotation is performed by a toggle switch on the back. The air
valve assembly for pneumatic polarization is mounted on the mast. The base is a steel plate covered in 137 ferrite tiles.
Each tile has a 10 mm hole in its center.
Unlike the top hat, capacitive-loaded, log periodic dipole antenna normally used in this frequency range, the phase
center/source distance is the same for low and high frequencies. This ensures high field strength at frequencies as low as
20 MHz. The design of the Model 3159C takes advantage of the wide beamwidth feature of a biconical antenna. In
addition, the optimized design provides low VSWR and high radiation efficiency.
The 3159 was developed to support high field strength immunity measurements in anechoic chambers of varying sizes.
Versions of this antenna have been used in various sized chambers from those small enough to support the ISO 11452-2
component testing, up to full sized chambers with at least 8 m of clear internal height, large enough to support ISO 11451-
2 vehicle testing.
The BiConical antennas of different sizes are broadband adaptations of a half wave dipole antenna optimized for use in
the 20 MHz to 300 MHz frequency range. Over this range, they are still electrically very short. To overcome this limitation
in radiation efficiency, there are several variants of the 3159 antenna, each designed to optimize the antenna performance
based on the available space and test distance, with the available amplifier power used to estimate the best case
performance.
The standard
configuration for the
Model 3159C consists of:
Two
open-end
adjustable biconical
elements
High-power
balun
Pedestal with casters
and polarization
control
Two Biconical
elements
(shown with
extensions)
Pneumatically
assisted
polarization
cylinder
Casters
Balun unit
Ferrite floor
