It's an array of horizontal cage dipoles fed in phase by parallel wire
feedline. The dipoles are out in front of a reflector screen. I
don't know how many there are but the size of the entire steel
structure makes it look like there are a lot of them. Many sw bc
stations such as VOA use antennas of similar design but usually they
are vertically polarized wire dipoles suspended out in front of a
reflector screen, with the whole thing held up between two substantial
towers, 200 to 300 feet tall. These are often called "curtain"
antennas for this reason and typically there are around sixty dipoles
in phase with each other, or the phasing is altered slightly to affect
the direction of the antenna's lobe. Besides its size, what is
remarkable about the Duga antenna is the rigid cages which offer a
wider low impedence range over frequency. If you had his
remarkable antenna, which few private citizens could afford, on the
east U.S. coast pointing west, 100 watts to it on 20 meters would have
hams on the west coast accusing you of running illegal power for you
would seem to be running many tens of kilowatts. The antenna had to
have enough gain to develop a huge ERP because as over the horizon
radar on HF, it had to put out a field strong enough to get a
reflection from a relatively small surface (such as a missile)
thousands of km distant.
73,
rob / k5uj
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