14-foot end-fed halfwave antenna for 10-20 meters
a 5-band compact antenna
short_efhwa.JPG

This is one of the shortest electrical halfwave antennas I've ever tried. It was designed around the Cabelas 14-foot crappie pole. This fishing pole collapses down to 15.5 inches, so it's very compact and portable. In fact it is what I'm using on my new sea kayak for marine mobile operating. I had my doubts about the fishing pole because it is made of graphite. In fact, initial tests showed wildly varying swr as the wire slapped against then away from the pole in a breeze. I solved that by wraping the wire lightly around the pole a few times and taping it down near the coils. Now I get rock solid swr readings, and the conductive graphite doesn't seem to affect the sent or received signal (although it must be to some degree). I tune all of my EFHWA antennas with a homebrew L-C matching unit. Look at the bottom of that page.

I had made some CW contacts earlier in the Fall with the new antenna, but October 20, 2006 was the first time I tried it with a microphone. I was out with my sea kayak in a lake near Golden, Colorado and running 5 watts on 20 meters. It was satisfying to hear signal reports coming in confirming the very shortened antenna was getting out coast-to-coast. Here is a rundown of the first eight sideband contacts and the signal reports:
Call            state    report
N6KKS     CA        59
WD9EML   IL         53
W7DK/90   WA      59
W8ELG       MI       54
WB6LNH    NC      51
W9H            IL        57
NA4BH       AL       53
WB7EXB     NV      57

While I was working special event station W9H, a TI2 station broke in to say, "Tell the kayak mobile he's making it into Costa Rica." Unfortunately, it was a busy frequency and I never got a chance to have him QSY with me.

Construction notes:
The antenna is made from stranded, 26 ga. Teflon-coated wire. There are three sections of wire connected by two loading coils. The outer sections are 36.5 inches in length, and the center section is 88.5 inches long. Adding both 3" coil forms gives 14 feet, 4.5 inches total length.

The coils are stranded, 22 ga. wire wrapped around 3 inches of thin-walled 3/4-inch (schedule 20) PVC tubing. Then it's covered with black electrical tape. Alligator clips allow switching of taps for different bands.

I recorded the number of turns I used to tap for each band for future reference:
10 meters = 8 turns
12 meters = 12 turns
15 meters = 17 turns
17 meters = 24 turns
20 meters = 41 turns (full coil)

This is certainly a compromise antenna at only 42 % of full size on 20m, but even on it's lowest band it appears to perform well enough. I can't wait to try it out on 10 meters.

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