ANTENTOP- 01- 2006, # 008

Field Antenna for the 40- meters

Proved in mountains of Northern Caucasus, March 2006.

By: Igor Lavrushov, UA6HJQ

Credit Line:

http://www.hamradio.cmw.ru/antenna/ant-hfp.htm

Before my QRP- pedition I have searched for an effective field antenna for 40 meters. I need antenna which can radiate both as vertical as horizon wave, which does not need antenna tuner and the same time which could be a resonant antenna. I have found such antenna. This one is designed by G3XAP. The antenna works well at my mountain QRP- pedition.

Figure 1 shows a design of the antenna. Table 1 gives data for ranges 20, 40 and 80 meters.

The maximum gain of the antenna is directed to side opposite L2. The difference in gain forward/back is small it is only near 3-dB. Two counterpoises have length 0.25 lambda each. For improving antenna efficiency use as more counterpoises as you can. The maximum of radiation lays in sector of 30 - 70 degrees. I get SWR 1:1 (at SWR meter of my FT- 817).

Tuning of the antenna is very simple. Reach minimum SWR with help of base capacitor C. I used a variable capacitor while tuning. Then change the variable to fixed one. The capacitor should be protected against atmospheric forcing.

UA6HJQ at a slope of the Elbrus,

Northern Caucasus

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