VHF Radio and Antenna Separation - Moderated Discussion Areas

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Author Topic:   VHF Radio and Antenna Separation

chopbuster posted 03-23-2009 02:47 PM ET (US)
When applying the rule that three feet of separation is needed between a VHF Marine Band radio and its antenna, what portion of the antenna actually needs to be three feet from the radio? In other words, could the base of the antenna be within 1.5-feet of the transmitter without creating radio frequency interference?
chopbuster posted 03-23-2009 02:56 PM ET (US)
If this is not a solution, could one apply some sort of shielding to the housing of the radio ?
Phil T posted 03-23-2009 03:26 PM ET (US)
Chop--While the electronic geeks can give you the technical answer, here's my experience: on my Montauk, I had a fixed mount VHF Marine Band radio located in the face of the console and a three-foot Metz brand whip mounted one foot away without any [problem].
jimh posted 03-23-2009 03:51 PM ET (US)
Vertical spacing is the best. Get the antenna as high as possible. If the antenna is three feet above the radio, the separation will be perfect. An antenna three feet away and directly in line horizontally with the radio is not so good. Some antennas encased in fiberglass tubes really only have the top three feet operating as a radiator.

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Author	Topic: VHF Radio and Antenna Separation
chopbuster	posted 03-23-2009 02:47 PM ET (US) When applying the rule that three feet of separation is needed between a VHF Marine Band radio and its antenna, what portion of the antenna actually needs to be three feet from the radio? In other words, could the base of the antenna be within 1.5-feet of the transmitter without creating radio frequency interference?
chopbuster	posted 03-23-2009 02:56 PM ET (US) If this is not a solution, could one apply some sort of shielding to the housing of the radio ?
Phil T	posted 03-23-2009 03:26 PM ET (US) Chop--While the electronic geeks can give you the technical answer, here's my experience: on my Montauk, I had a fixed mount VHF Marine Band radio located in the face of the console and a three-foot Metz brand whip mounted one foot away without any [problem].
jimh	posted 03-23-2009 03:51 PM ET (US) Vertical spacing is the best. Get the antenna as high as possible. If the antenna is three feet above the radio, the separation will be perfect. An antenna three feet away and directly in line horizontally with the radio is not so good. Some antennas encased in fiberglass tubes really only have the top three feet operating as a radiator.