Elecraft KXAT1 - Manual (Page 9)

9
Antenna Considerations
The KXAT1 will work with coax-fed dipoles, verticals, etc., but it's optimized for use with random-length
wire antennas. These are often the easiest antennas to set up in the field. However, certain wire lengths
must be avoided, and ground radials are required (both issues are discussed below). You should test your
chosen antenna system ahead of time, if possible, to be sure the KXAT1 can achieve an acceptable match.
No-feedline operation: At QRP power levels, feedline is not always necessary. In many cases you can
connect a wire antenna directly to the KX1 and toss it into a tree, then lay out at least one ground radial, as
shown below. This antenna can be set up quickly, and compares favorably to a low, coax-fed dipole or
inverted V. It also minimizes station weight (see further details on wire and accessories on page 10). If you
toss the wire into a tree, try to keep all but about one foot of wire exposed. A wire that is mostly in a tree
will still radiate, but not as well.
Wire antenna length: Since the KX1 can only match a moderate range of impedances, a given random
wire length is not guaranteed to provide an acceptable match on all three bands. Results will vary
depending on the wire length, height, type of support, and ground system. But for backpacking use on
40/30/20 meters, a wire length of 24-28 feet will generally provide good results. For use on 30/20 m only,
as little as 12 ft. can be used, and for 20 m only, as little as 8 ft. Avoid lengths which are close to a half-
wavelength long or any multiple thereof, which will be out of the KXAT1's matching range. For example,
you should avoid using close to 33' if 20 m operation is planned, or 46' if you'll be using 30 m.
Ground system: Use a at least one ground radial, cut to at least 1/8th wavelength on the lowest band used
(16' on 40 meters). When possible, use two or more radials, with one cut to 1/4 wavelength on each band.