[TowerTalk] 7 MHz antenna
T. A. Russell
Sat, 22 Feb 1997 17:43:35 EST
One of my favorite Simple Effective Antennas is
the Vertically Polarized DELTA LOOP.
This antenna is easy to build and install, has an (almost)
omni-directional pattern, radiates well, and you can't beat the cost.
If the bottom of the loop is near ground (3M or 10 ft) then make the
loop 3.5% shorter than the L=1005/F formula length (feet). Feed
1/4 wavelength down one side from the apex.
Feed impedance is around 100 Ohms and is easily matched
by an odd number of quarter wavelengths of 75 Ohm cable.
RG59 works well even with 1200 watts.
An equilateral loop for 40M takes 40 ft (12M) of vertical space.
If that height is not available, the base side can be lengthened
while the sides are shortened, keeping the total length constant.
On 80 meters, I notice many of the strongest signals from Europe
come from stations using vertically polarized Delta Loop antennas.
de Tom - N4KG
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