LOOP ANTENNAS

Full-wave loops are very popular antennas. They are especially useful on 80 and 40 meters where they perform well at modest heights. These are closed loops that are one full wavelength long. Horizontal loops may be fed at any convenient spot. For best performance, make your horizontal loop into a square, especially if it is to be used on several bands.

The Vertical Loop is a good DX antenna. The shape can be a circle, square, rectangle or a triangle. The larger the area of the loop the better it will work. Feed square and rectangular loops at a corner. For best results, triangular loops should be supported apex-down. This puts less of the antenna parallel with the ground and increased the effective height. Feed triangular loops either at a corner or in the case of apex-down loop, at the apex.

Use ladder line and a wideband transmatch (a naturally balanced tuner, like a Johnson Matchbox) for multiband operation. The RemoteBalun 4 is recommended if you will have problem getting ladder line to the operation position. Multiband operation is possible when feeding the loop with coax. The losses will be slightly higher, but the convenience of the coax may be worth the slight signal loss.

The design frequency, the feedpoint impedance, will be between 80 and 150 ohms. Coax fed loops will usually have an SWR between 2:1 and 3:1. You may feed this antenna with a 4:1 balun. If the loop is in the shape of square or large rectangle, the SWR can be below 2:1, but will not get much below 1.5:1.

If you decide to feed your loop with coax, I'd suggest using RG-8X or RG-213 and a high power, high performance 1:1 or 4:1 Current-type balun. Experiment with full-wave loops. You may find them to be excellent multiband antennas.

Antenna wire can be #14 hard-drawn antenna wire. Use #12 wire for large loops on 160 or 80 meters.

Center Frequency Total Length in feet
3.5 MHz 287
3.6 279
3.7 272
3.8 264
3.9 258
7.0 MHz 143
7.2 139
Center Frequency Total Length in feet
10.12 MHz 99
14.0 MHz 72
14.2 70
18.12 MHz 55' 6"
21.0 MHz 48' 10"
21.2 47' 6"
24.93 MHz 40' 4"
Center Frequency Total Length in feet
28.0 MHz 35' 10"
28.5 35' 3"
29.0 34' 8"
29.5 34' 1"
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With this particular antenna, a RemoteBalun and Ladder Line are used to permit multiband operation. If you have a naturally balanced tuner (i.e. a Johnson Matchbox), the RemoteBalun 4 is not needed. Click on the Balun Index do check out the the RemoteBalun's application notes.

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