I have been looking at taking a single cavity tuned to TX, and a single cavity tuned to RX to lessen separation needed. This for a firepower installation with no duplexers.
I am also looking at using a VHF Engineering (OK, poor choice) with the PA Removed and mobile duplexer as a mobile repeater on out Red Cross Comm. van. This will yield around 2 watts into the mobile duplexer. It should cover a recovery village. In addition, low power FM broadcast station being considered also. The experimenting we do in times of calm gives us an idea of what may work in time of need. More in line with your idea would be a TX antenna on top of a water tower and an inverted RX antenna below the tower. Not near perfect, but with a pair of the $25.00 Radio Shack scanner antennas, it is an easy restoration for a repeater lost to storm damage, and using parts that are easy to store unassembled. There is still that feedline issue to deal with.... In all of these cases, we are not dealing with perfect solutions. The concept is making the best you can with available materials and remaining infrastructire. David KD4NUE -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Kris Kirby Sent: Tuesday, February 21, 2006 4:20 PM To: Repeater-Builder@yahoogroups.com Subject: Wierd Antenna Ideas (Was RE: [Repeater-Builder] Alinco Ham Repeater?) On Tue, 21 Feb 2006 [EMAIL PROTECTED] wrote: > I am sure that something could be assembled with low enough output to > handle the mobile duplexers that are so abundant for VHF; thre ones > designed for a 5 MHz split. However, I can't see the beauty of a > portable repeater that is 100% duty cycle at 2 watts output. Even if > you were able to get the power output to a level as high as 10 to 20 > watts, that portable tower structure is what I would like to hear about. What if you took two 1/4 wave ground planes, mounted the RX antenna up top, fed with hardline, and mounted the TX antenna pointing down, 1/2 wavelength (or 4/2 wavelegths) down from the mounting point of the first antenna? This, it would seem, would put the image of the antenna 180-out from the first antenna, plus the isolation of having to go through a common ground surface as it were. That might give you a few DB of seperation, if there aren't too many near-field or far-field reflections to have to overcome. -- Kris Kirby, KE4AHR <[EMAIL PROTECTED]> "BIG BROTHER IS WATCHING YOU!" This message brought to you by the US Department of Homeland Security Yahoo! Groups Links Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
