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8-band Windom HF antenna PDF Print E-mail
The multiband Windom antenna has been described in 1929 by W8GZ. In the HF amateur community is very popular FD-4 antenna. It’s a simple wire antenna for the most popular HF bands. DL1BBC has extend the available bands of FD-4 antenna adding two wire radiators. The result is an 8-band antenna for bands from 80m till 10m.
8-band FD-4 antenna

The new radiators are 4,69m and 9,38m long and are connected to the balun 1:6 and going down to the earth. The angle between both wires is around 100°. DL1BBC and DJ7SH have built and prove this antenna with a good results.

The main radiator is calculated by formula: L/2 = 142,5/f, whereby is valid that the radiator works on the harmonic bands too (e.g. 30m radiator is working on 15m too). Antenna design wasn’t aimed for 18 and 24MHz bands, but it’s working fine also on these bands.

Construction: there are two hanging points at least 5m up from the ground level needed with the distance at least 40m. Some experimentators has proved that cranking ends of the wire does not effect very much on the antenna effeciency. DL1BBC hanged the antenna around 8m above the ground level, DJ7SH only 5m above the ground level and over the garage.

First check the SWR and resonance on the base bands - 80m, 40m and 20m. In case of the resonance out of band cut the longest (or prolong) the longest wire – 27,7m. The antenna must resonate in the center of bands. You might see that the resonance on the 30m band is higher than required. It’s correct.

When adjusting the antenna be careful and don’t spool the ends of wire in the coil, it can affect the antenna. The coaxial feeder must go straight down to the earth. DL1BBC has insert the coax into the plastic tube.

Measured antenna SWR

The height of DJ7SH’s antenna causes that the adjusting of lenghts was not reqired but the SWR on 40m band is bad and SWR on other bands is higher than by DL1BBC. But both stations could work without any tuners on all bands.

Searching for the ideal multiband antenna: antenna was proved and compared to the horizontal dipole. The effeciency is good. The inverted Vee part of antenna is much better on 30m band as horizontal dipole. DL1BBC and DJ7SH has made many stateside contacts with 100W. The usual report was S7 or S8. For the short distance contacts within Europe wasn’t observed any difference between both antennas.

This article is simlified and doesn’t give a professional answer on the multiband antenna. But antenna is working well, prove it!

Based on:
[1] – Eine Doppel-Windom-Antenne fur acht Bander, Hubert DJ7SH and Rolf DL1BBC, CQ-DL 9/83
 
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