ANTENTOP- 01- 2017 # 021

Cliff Dweller’s Antenna

Cliff Dweller's Antenna

By K. E. Hughes, W6CIS

Credit Line: Radio and Television News, January, 1956

The accompanying diagram of the author's "Four- Band Cliff Dweller's" is self explanatory and might be of interest to other readers.

Let me say at the outset that such an antenna will not replace a good three- element beam on 20 or 60-foot high doublet on 80; however, considering the space, cost and easy of adjustment, it gives a very good account of itself.

Basically, the antenna functions as an 1/8 wave on 80, ¼ wave on 40, ½ wave on 20 and ¾ wave on 15, being base loaded on all except 20 meters where it is voltage- fed from the parallel resonant tank. The vertical radiator is made up of five six-foot length of 0.5 inch diameter surplus whip. In the author's case, the whip is guyed with two sets of three guys each (light sash line, spring loaded at the lower ends to allow for shrinkage) at 12 and 24 foot levels.

The antenna can be used at ground level (if well clear of buildings, trees, etc.) or well off the ground, using ground plane wires as an effective ground.

In the author's installation, the tuning unit is 8 ½ feet off the ground, at the same height as the aluminum patio roof. This roof, plus a heave copper ribbon running to a good ground rod, makes up the "ground system."

The cold end of the coil is truly cold on all bands. The switches, S1, S2, and S3 are actually heavy copper clips, although relays or knife switches could be used if available. The capacitor can be any variable type with a maximum capacity in the neighborhood of 100 pF. A National TMS- 100 would be suitable.

Adjustment of the tuning unit was extremely simple. A grid dipper should be used in determining the proper setting for the S1 tap, as well as getting the correct number of turns in the complete coil for resonance at 3.5 MHz.

The next step is to determinate the correct feed point for the coax. If a SWR bridge is available, it amounts to finding the point which gives the lowest SWR on the feedline. If no bridge is available, the feed point can be found by observing reflected reactance in the final amplifier tank. With correct tap points at the antenna, the PA tuning will be very nearly the same with or without the feedline coupled to the transmitter.

Results have been excellent, considering the size of the system. The transmitter was free from TVI and no change was noted when switching to this vertical radiator.

As an example of its possibilities, only Europe is needed for WAC on 3.5- MHz while running 450 watts input. It is hoped that this idea may be of some help to those amateurs living in so- called "impossible locations."

73! W6CIS

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