Many of us have a fairly functional antenna farm. In my case, it is more like an antenna garden in relation to the size.
Well, not really a garden. My XYL would surely take exception to that description! She thinks that gardens should have some
sort of eye appeal. Why, sure there is eye appeal. Just looking out across the back yard beyond the tower with tribander and
dipoles, you can see trees, clouds and sky. There is something for the eye of each beholder. Regardless of the number of radiators
on one’s "farm," there is almost always another band or two that could be added. This article may help in adding more
bands with less antennas and feed lines to your aerial maze and do it simply and inexpensively.
One object stretched across the scenic view of my "garden" is a three band sloping dipole. It is basically three dipole
antennas fed with one common coax cable and designed to operate on 12, 17, and 30 meters. These three bands are sometimes
referred to as the WARC bands. I picked these three bands for a design because I already had a tri-band yagi for 10, 15, and
20 meters and dipoles for 40, 80, and 160 meters. I didn’t want three more coax cables but I did want to operate on
the three WARC bands.
A tri-band dipole fed with a single feed line is not a new concept. I have built multi-band antennas in the past. They
all worked very well with a couple of disadvantages. Drawback number one for this type of antenna is that they have several
leg ends to anchor. Drawback number two is the possibility of the wires becoming entangled. For sometime I pondered the idea
of building a better WARC tri-band dipole that did not have these two drawbacks.
During a lull in the sunspot activity and on a weekend when there were no contests and/or local hamfests, I went shopping
with the XYL. We went to a local discount department store. While she looked for some necessary household items, I looked
for items to enhance the back yard and "garden." I found something that I believed could be used to build a better WARC antenna.
This "fabulous find" was a dozen black plastic tubular clothes hangers for ninety-nine cents. I bought two dozen. I couldn’t
wait to get them home and start on my new project for the "garden." See figure 1.
I wanted to use the hangers as spacers to separate the legs of the three band dipole to be fed with a single coax. See
figure 2 for details. I drilled holes in the thin plastic tab at the apex of the hanger triangle using a drill bit that was
only slightly larger than the wire to be used for the dipole legs. Next, heavy wire cutters were used to snip off the hanger
hooks. They could have been left intact and possibly used in the construction. I decided to cut them off to help disguise
the real identity of the hangers. So far all observers have identified them for what they really are. Oh well, no big deal!
You may wish to leave them intact if you decide to construct this antenna. The beauty of a simple project like this is that
it can be modified to suit you own needs. You may want to add more bands or build it for different frequencies.
Twenty-two of the hangers were prepared as shown in figure 2. Eleven were used on each side of the center insulator. Be
sure to purchase the hangers with the reinforcement rods that run between the top and bottom at both ends. Try to find hangers
of a dark color because they are not near as conspicuous as the white ones. If a commercially made insulator is not available,
you may want to consider making your own. A center insulator can be fabricated using a scrap of PVC pipe. Any diameter in
the range of one to three inches and cut to any length between four and seven inches will work. Drill holes to accommodate
the attachment of wires and you are in business. See figure 4.
The next task is to cut the 30 meter legs of the dipole to size. Being the longest, they will be used as the suspending
elements. Almost any type of wire that is large enough to hold the weight of the completed antenna will do. Use your imagination
and anything you have lying around the shop or garage. I used zip cord; the kind made to replace lamp and small appliance
cords. I separated it into single conductors. It is economical and durable.