Diff: WaveguideAntenna

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+A waveguide is a horizontally polarised omni antenna, typically being either 180 degrees, or 360 degrees. 

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+They are available commercially, but are rather expensive. 

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+{http://martybugs.net/wireless/images/wg_completed.jpg Rob Clark and Trevor Marshall antennas side by side} 

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+(http://trevormarshall.com/ Trevor Marshall) has a (http://trevormarshall.com/waveguides.htm web page) describing the design of the waveguide, and the theory behind their operation. 

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+A number of people have had waveguides (http://narx.net/~mike/projects/waveguide/ manufactured) out of aluminium, but the materials are still rather expensive. 

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+(http://members.iinet.net.au/~clark/FreeNet/Waveguide/ Rob Clark) came up with the bright idea of using commonly available downpipe to make waveguides. 

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+(http://planetaxis-web.sytes.net/wireless/downpipe.cgi Marcus) took the idea one step further, constructing a couple of 8-slot 180-degree waveguides, and (http://martybugs.net/wireless/antennacomp.cgi testing them thouroughly) to determine the performance. 

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+The (http://martybugs.net/wireless/antennacomp.cgi test results) show the downpipe waveguide has a gain of approximately 16-18dBi, with the azimuth plots matching Trevor's theoreticaly plots almost exactly.