For several years, I have been playing around with carrying a high frequency radio in a backpack. One of the problems I have encountered is is the need for a small, simple antenna for frequencies that require long antennas. Obviously, the simplest and most compact is a wire antenna. The simplest of these is an end fed wire with a counterpoise. Since many modern transceivers have built in antenna tuners, these can be connected directly to the output connector. However, there are limits on what kind of impedances these tuners can match. If one starts out with a wire that is a quarter wave long on the 80 meter band, it will be a half wave long on 40 meters and the impedance will be almost impossible to match. What is needed is a length of wire that is not a half wave on any band in which one would desire to use it.

I came across a discussion ( https://udel.edu/~mm/ham/randomWire/ ) of end fed antennas which contained a very convenient chart of antenna lengths to be avoided for various band combinations. This past weekend was the ARRL Field Day event which gave me the opportunity to try it and compare it with previous years in which I used two 100 foot lengths of wire connected directly to the radio. I have two FD rigs, one of which has a built in tuner and one with which I use an external automatic tuner. This year I used the one with the external tuner.

Previously, there was always one band with which the auto tuners struggled and failed to find a match. This year, I selected from the chart a length of 72 feet for the antenna and 14 feet for the counterpoise. The antenna was strung through the trees behind my house, supported along the way by various tree branches at heights I could reach standing on the ground. At no point along the length was the antenna more than 8 feet above the ground (Got that one up there by pulling down the branch down, feeding the wire over it and then flipping the wire higher up the branch). For the last 10 or so feet of wire, there was no support so I tied the end to a heavy stick and laid that on the ground for an end anchor. This was done in a manner similar to that show in my FD 2012 video at http://www.youtube.com/watch?v=J5JKCPoZGKs&t=189s (starting at about the 7:19 minute mark). In the video I was zig-zagging through the trees. This time I tried to keep the antenna as straight as possible.

The results were quite pleasing. The external auto tuner that I used with the Yeasu 817 was able to find matches for the 80, 40 and 20 meter bands which I used this weekend. While my QSO count was fairly low (I was only out for fun, not for some bragging rights), I was able to easily hop between bands whenever I wished. Also, I believe I had good luck with NVIS. I live in northern Virginia and made a number of contacts with stations in the MDC (Maryland-DC) section which would mean they were fairly close but too far for ground wave. Simple. Compact. Inexpensive. And it does perform (I also had several California contacts on 20 meters using just 5 watts).