QRP Antennas

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From: Charles Kadesch (103202.3412@compuserve.com)
Date: Sat Dec 23 1995 - 13:52:28 EST


Peter N2KPY asked about improving the performance of his 40 meter
dipole on 80 meters. I pass along my experiences in hope that fellow
urban QRPers might find them of interest:

My experience with center fed antennas has been very good- even when
less than 1/2 wave long. I am presently using one about 85 ft long and fed
with 450 ohm ladder line and it works well on all bands including 80 meters.
The antenna is 25 feet up at the highest end.

I think that three things are important:
1. Make the antenna as long as you can but keep it in the clear.
    Don't worry about the specific length. At 1/4 wavelength the efficiency
    is down somewhat but the antenna can still be quite effective with a
    low loss feedline and matching network ("antenna tuner"). On the higher
    bands the radiation pattern will develop lobes but this makes for
interesting
    performance.
2. Feed with low loss balanced feed line.
3. Use a low loss balanced antenna tuner. Some tuners that use a balun
    on the output can have problems with high reactances. I have had
    very good results with an old link-coupled type of tuner.
    The following might also do the trick: An input side balun with
    an ungrounded T or L network. The Super Tee Tuner (SPRAT #72)
    is a compact high efficiency QRP tuner of this type.

I also use a 50 ft vertical antenna which is center fed with 450 ohm line and
a balanced tuner on all bands (including 80) with good results. A bonus:
no radials or traps are required.

72 and Happy Holidays

Chas W8KUX
103202.3412@compuserve.com

I also use a 50 ft center fed vertical with


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