Effect of Antenna gain and power level
Bob Witte, KBØCY
27 August 1997
Most mountaintop operators that hike in use handheld transceivers (HT) due to
their light weight and portability. However, the standard "rubber duck" antenna
is highly compromised in terms of efficiency and is not recommended for
use in the event. A much better choice is a 1/2-wave antenna such as a "twinlead
J-pole" or a HotRodÔ telescopic antenna. Some
operators will use a small beam antenna.
The following is a comparison chart to compare the relative transmitted
signal strength when using various power levels and antennas. The 0 dB reference
is arbitrarily chosen to be at the 1 Watt power level with a 1/2-wave antenna (a
nominal configuration when using an HT).
| Output
Power |
"Rubber Duck" Antenna
(-10dB gain relative to 1/2-wave) |
1/2-Wave Antenna (J-Pole,
HotRodÔ , etc.) |
Small Yagi beam antenna
(6 dB gain over 1/2-wave) |
| 100 mW |
-20 dB |
-10 dB |
-4 dB |
| 1 W |
-10 dB |
0 dB |
6 dB |
| 2 W |
-7 dB |
3 dB |
9 dB |
| 5 W |
-3 dB |
7 dB |
13 dB |
| 10 W |
0 dB |
10 dB |
16 dB |
Typical Rules of Thumb
Operators using an HT with only a rubber duck antenna may experience
difficulty making contact at distances as short as 50 miles. Use of a 1/2-wave
antenna allows contacts out to 150 miles. If longer distance contacts are
attempted, a beam antenna may be required. The longest distance between two 14er
summits is 218 miles (Longs Peak to Culebra Peak) Note: These performance
levels are estimates only, based on experience with contacts during previous
14er events. Your mileage may vary.
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