HAMBENCH PRO · FIELD CALCULATORS
Three free, instant estimates for antenna length, coax loss and portable battery runtime. Change any value to update its results.
ANTENNA LENGTH
Estimate wire lengths from operating frequency and velocity factor.
Formula: (143 / frequency in MHz) × velocity factor. The vertical is half the dipole length; tune the installed antenna for its surroundings.
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FEEDLINE LOSS
See cable attenuation, mismatch loss and their combined estimate.
Nominal references at 100 MHz per 100 m: RG-58 (Belden 8219) 14.76 dB; RG-213 (Belden 8267) 6.23 dB; LMR-400 (Times Microwave) 4.10 dB.
Frequency scaling uses √(frequency / 100); cable length scales linearly. These are estimates: cable construction, connectors, temperature and installation affect real loss.
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POTA / SOTA POWER
Plan a field activation from battery capacity, current draw and transmit duty cycle.
Estimate assumes 80% usable battery capacity. Actual runtime varies with battery age, temperature, radio settings and operating conditions.
PDF sheets require HamBench Pro. View access options
HAMBENCH PRO · $7 / MONTH
Keep multiple station setups with every antenna, coax and battery input, then reopen any profile to refill the calculators.