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← Antennas ← R&S DF Bugs
Portable active directional antenna
The EH-100 was a set of portable active antennas, developed by
Rohde & Schwarz
in München (Germany) in the 1980s. The antenna set was used for locating
interferences and radio bugs,
and was initially developed
for use in combination with the
EB-100 portable surveillance receiver.
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The HE-100 is suitable for all frequencies from 20 MHz to 1 GHZ
and consists of a
handheld pre-amplifier
in the shape of a pistol grip, and three plug-on antenna's.
Each of the antennas covers a different
frequency range. The pre-amplifier is powered by internal
batteries and is activated by pressing a trigger switch in the grip.
The three antenna's use the terminated loop principle developed in 1938 by
Harold Beverage in the USA [1]
[2].
Due to the nature of these antennas they
are far less sensitive to signal reflections, especially when used indoors.
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The antennas were designed to match the frequency coverage of the
EB-100
from 20 MHz to 1 GHz. For most bugs of the 1980s, the largest
antenna (20-200 MHz) was used.
In practice, the middle antenna (200-500 MHz) could also be used when
in close proximity of the transmitter. It made the antenna slightly
less sensitive but that was often considered a bonus.
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When using the HE-100 in combination with the
EB-100 reciver,
the field strength meter at the rear of the HE-100 would show the
signal strength of the signal, duplicated from the signal strength
indicator of the EB-100. The meter could also be used to test the
HE-100's batteries.
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When the HE-100 antenna and the EB-100 receiver were used in the dark,
the meter could be illuminated by pressing a second switch in the
pistol grip of the HE-100 (i.e. the lower one).
Although the HE-100 antenna was initially designed for use in combination
with the EB-100 receiver,
it could very well be used with other TSCM
devices, such as the Rohde & Schwarz
FSH-3 portable spectrum analyser
shown here.
➤ More about the FSH-3
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The HE-100 antenna was later superceeded by the HE-300 active directional
antenna, which has an extended frequency range from 20 MHz to 7.5 GHz.
At the lower end, the frequency range can be further extended down to 9 kHz
by adding the optional HE-300-HF module.
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- US Patent 2247743, Broadband Uni-directional Shortwave Antenna
Harold H. Beverage. Filed 10 December 1938.
- DARC Verlag, Rothammels Antennenbuch
ISBN: 3-88692-033-X. 2nd print 2002.
p. 269-270.
- Rohde & Schwarz, Active Directional Antenna HE-100
652.1803.02 (German/English). March 1986.
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© Crypto Museum. Created: Tuesday 15 April 2014. Last changed: Friday, 05 October 2018 - 21:40 CET.
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