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ContinuousWave: Small Boat Electrical
Range of hand held VHF radios
|Author||Topic: Range of hand held VHF radios|
posted 10-16-2007 09:01 PM ET (US)
My main radio pooped out last weekend so I had to rely on my hand held backup VHF.
I was trying to reach another boat approximately 6 miles away and my hand held VHF could not reach. Or the reception was very faint.
What is the range for a well made hand held VHF? Do I have a bum unit or am I expecting too much?
posted 10-16-2007 10:06 PM ET (US)
The range of most VHF Marine Band radios is limited by the height of their antennas. In most cases if the two radios in the circuit are in line of sight of each other, they'll have enough power to produce a decent signal. Once the radio path stops being line-of-sight, the path loss becomes very high and you will very rapidly lose signal strength. Some of this can be made up by higher power (as in 25-watts versus 1-watt) or by higher antenna gain (as in 3-dB versus unity gain, which in marine antennas becomes 6-dB or more of gain claimed), but typically the path loss increases very fast once out of sight of the other station. More power and more antenna gain always help, but antenna height is the dominant factor.
In the case of a hand held radio, if you had a microphone on a cord and could hold the radio above your head, you would increase its range significantly.
Also, antenna efficiency is not very good on most hand held radios, so you can expect their effective radiated power to be even lower than assumed from the transmit power.
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