Need antenna mods for use in large pipe (underground)
10-19-2002, 11:50 PM
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Need antenna mods for use in large pipe (underground)
Help: I am trying to use an RC truck to crawl down large buried pipes. My 27 mhz radio seems to lose contact after 200' (still line of sight though). I am looking for ideas on modified antennas to extend the range. Thanks. Cam. 
10-20-2002, 12:03 AM
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Need antenna mods for use in large pipe (underground)
Souns like you need a yagi antenna. Do a google search on yagi and you will find all kinds of construction articles
10-20-2002, 02:56 AM
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Not on 27 MHz!
A metal pipe needs to be a certain size in order for a radio wave to travel through it without becoming rapidly attenuated. For 27 MHz the pipe would need to be on the order of 15 feet in diameter!
You don't need a different antenna, you need a different frequency. A 12 inch diameter pipe, for example, would propagate frequencies at or above about 500 MHz.
Microwave engineers call a pipe that is used to transmit radio signals "waveguide".
You don't need a different antenna, you need a different frequency. A 12 inch diameter pipe, for example, would propagate frequencies at or above about 500 MHz.
Microwave engineers call a pipe that is used to transmit radio signals "waveguide".
