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I am an amateur radio operator in central nebraska. I have been using a cage dipole antenna on 80 meters for over 17 years. I have found it to be a very broad-banded antenna as I have mine tuned for the middle of the band and it seems to operate with an SWR of less than 2:1 SWR from band edge to band edge. Mine is constructed of 17 gauge galvanized electric fence wire consisting of six wires spaced with rings made from cutting one inch slices from 8 inch plastic irrigation pipe. I use 10 spacers on each leg, which are approximately 61.5 feet long. Each end of the dipole is terminated with a porcelin corner insulator. I tie the two legs together with a nylon rope thru the eye's of the insulators in the center. I have always direcly connected an RG-8 type coax to each leg. I see in other data that a open wire feeder may be a better choice, but here in Nebraska I am told that my signal is very good. I am interested in others using cage dipoles. I also have one constructed for 40 meters.
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I have been puzzled that cage dipoles have not been more widely used by radio amateurs over the years, because they provide important advantages; the most important generally being wider bandwidth. As you mentioned, a cage dipole has significantly greater bandwidth than a single-wire dipole, which tends to be especially important on lower bands that have widths that are relatively large percentages of center-frequencies. Cage dipole bandwidth can be made very wide if desired by simply using a large diameter cage.
Smaller wire size can be used, because several small wires in a cage emulate a single large-diameter radiator. Small wires are difficult to see from the ground, which can have stealth advantages where neighbors or spouses fail to appreciate the beauty of an antenna. (Unfortunately, cage spreaders are not so easy to make invisible.)
Cage dipole end-voltages are lower, which reduces the risk of corona in high-power applications.
A cage dipole is a balanced antenna that should be fed either with balanced line or via a balun, but of course, the same is true of a single-wire dipole.
I have used cage dipoles in a variety of applications with excellent results. I highly recommend them in applications where bandwidth is important.
Fan dipoles provide even greater bandwidths. It isn't difficult to construct a fan dipole that will have a VSWR less than 2:1 from 14 to 30 MHz, for example. I am equally puzzled that radio amateurs rarely use them either.
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on 16 Nov 2006, 07:35, edited 1 time in total.
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I would like to try a 75/80 meter cage dipole, but don't want to have to find the bits and pieces needed to make one. Do any of you know of any commercial cage antennas designed for amateur use? I have seen websites offering military models for sale, but I don't want to pay a military price.
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