Hello to all,
I am happy to see the amount of replies to the "What about hams with small
lots?" question.
To continue let me add some notes on my personal experiences. As stated
before the antenna area is my back yard which is 25 feet by 44 feet. The
bands I enjoy the most are 160-80-40 meters. As it happens I was introduced
to an antenna that was used during the Vietnam War. Tried and forgotten by
Hams because I believe poor construction practices and the lack of the
needed materials during that time.
The antenna is a Small Magnetic Loop. With today's availability at any
plumbing supply house for copper pipe this antenna becomes a simple home
construction project. I am not about to get into the details on antenna
construction. There are certain things that are a must do and certain
operating precautions to follow.
The presentation of this antenna has always been for multi band operation. I
feel this is the wrong approach for the use of this type of antenna. Single
band operation is the key. I have found that the length of pipe should be
the band in feet. 40-meter band 40 feet of pipe, 80-meter band 80 feet of
pipe, 160-meter band 160 feet of pipe. Using a square shape the antennas now
become 10 x 10 for 40 meters, 20 x 20 for 80 meters, 40 x 40 for 160 meters.
Using 1 inch copper pipe the efficiency becomes, 89% for 40 meters, 88% for
80 meters, 84% for 160 meters. The antennas can be made smaller with the
same efficiency if a larger pipe diameter is used.
I have found these antennas to work very well for me on all the Ham Bands.
In my first reply I stated my feelings about forgotten antenna designs. I
use the Small Magnetic Loop as an example. New types of materials become
available to us each day. What was felt to be impossible in the past now
becomes possible. I am shore there are many excellent antenna designs just
waiting to be constructed with the now available materials. I am hoping this
reflector will be our means to finding them.
Rich AA2MF
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