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1-3 of 3 messages
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Replacing Rubber Duckies
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by OBIWAN on April 17, 2005
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I have an Icom T7H Handheld 2M/440 handheld.
What antennas are recommended as replacement to the standard issue Rubber Duck?
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RE: Replacing Rubber Duckies
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by N3PAQ on April 17, 2005
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In general, a whip antenna is a good replacement for a rubber duck, there are several on the market that are a quarter wave two meter antenna and a 5/8 wave 70 centimeter antenna. The whip would probably be your best bet for day to day use. I keep a 5/8 wave two meter telescoping antenna for my HT with me when camping or hiking, but it is rarely connected to my HT. The telescoping antenna performs excellently, but it isnt practical to carry around and there is always the fear of breaking the BNC connector from the radio due to stress of the heavy antenna.
73
N3PAQ
Joe
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RE: Replacing Rubber Duckies
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by KE4SKY on April 21, 2005
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In marginal operating locations a telescoping, half-wave is much more effective than a standard helical antenna, because it provides unity gain without a ground plane, whereas a typical helical antenna is about -5dB NEGATIVE gain. A telescoping half-wave increases useable simplex range of a typical 5 watt, 2-meter portable from about a mile with the stock flexible antenna to 3 miles or more, depending upon terrain. Adding a counterpoise wire to a standard helical also helps.
Telescoping antennas are more fragile and work best when stationary or in the open, avoiding side impacts or rough handling. Avoid mobile use of telescoping antennas on window clip mounts at highway speed, because excessive flexing loosens their internal electrical connections. Never collapse a telescoping antenna by whacking it down with the palm of your hand. Gently pull it down with your fingers. If you note wobbling or looseness in the sections, replace the antenna.
Flexible antennas are safer when working in close quarters around people and are more durable when walking through dense vegetation for wildfire suppression or search and rescue operations. They better for dual-band transceivers because telescoping antennas are usually mono-band. Dual-band flexible antennas approximate a 1/4 wave on 2 meters and a 5/8 wave on 70 cm, but are usually optimized for one band and may resonate poorly on the other. How efficient a particular antenna is can be determined only by testing. Just sweeping VSWR with your MFJ459 doesn't tell the whole story. you should do field strength tests under operational conditions and make side-by-side comparisons under the same conditions.
I keep a three spare antennas, a Larsen telescoping half-wave, and a 39" metal Comet CH722A dual-band mobile antenna with BNC connector mag mount, and a flexible 15" Diamond DH55, in addition to the stock antenna.
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