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RW3XA’s 9 Band HF Vertical Antenna

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ANTENTOP- 01- 2005, # 007

RW3XAs 9 Band HF Vertical Antenna



Fig.2. The basic unit



The design of the mast bearing is very similar to Obninsk high-altitude meteomast, which is put into operation in 1959 year, it's 310m high and the "ball" there is 1 meter in diameter. The given decision helps to neutralize mechanical resonance and vibration across the vertical tubing of the mast, wind loading is effectively extinguished. There're also 8 radials (4x21.5m, 4x10.6m) connected to the basic unit of the mast. There's also an aluminum die cast box near the basic unit sized 390x250x120 mm. This box includes matching network wiring. The relays are an anchor downwards type, i.e. in an inactive condition the anchor freely hangs between NO contacts. The relays controlled by UTP cable (network twisted pair) from two polarity power supplies 24V/1A (best choice for these military relay is 27V). To increase electric durability to the induced electricity all matching network circuits are galvanically connected to the ground. Because one the same matching network is used to match 14 and 21 MHz band, the left closing group of relay P5 is free (see fig.3), so it is used to switch a feed line over to another antenna. As mentioned before the 50-Ohm coax feed line can be of random length


Obninsk Meteomast

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