Custom Base for Mag Mount Indoors

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t13one12

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I apologize if this is in the wrong location. I thought this might be the most appropriate space.

I recently ordered a BCD536HP to go along with my trusty BC780xlt that I've had for several years. I moved from my parent's home in the suburbs to my own place in the "big city". As such, I had a need to update from the stock antennas to pick up a bit more "distance" than what I was used to.

At the suggestion of many I purchased a Spectrumforce Wideband Mag Mount antenna and it has worked great for me. So much so that I bought another to use with my new 536. The item I am looking for help is I had "acquired" a baking pan from my kitchen to use as the mount for the first antenna. It was intended to be a temporary solution but almost a year later it is still sitting there. The plan for both antennas is for them to sit on the window sill that is probably about 4-5 inches wide.

Any suggestion on building a custom ground plane base for these? Unfortunately the way the rooms are configured I wouldn't be able to get a filing cabinet or other large metal object near the windows and ultimately that is where I get the best reception for the antennas.
 

mmckenna

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A hardware store would have what you need. A piece of sheet metal or roof flashing would work. Secure it down to the window sill and put your antennas on it. Since it'll be fairly narrow, it won't be an ideal ground plane, but it'll work.

Other than the magnetic mount part, regular old aluminum foil would work just as well. All you need is a conductive material under the antenna.
 

LtDoc

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Think about it for a little. If you use a metal palte of some kind, it needs to be a 1/4 wave at the lowest frequency in some dimension. Pie-plate? Something like 19 inch radius works okay. A square plate? How about something like 39 inches from one corner to the other. If that magmount is in the center of the plate then the reception/radiation pattern would tend to be symetrical. 'Skootch' it in one direction or another then the reception/radiation pattern also get's 'skootched' off a little. In most cases, it won't make any difference at all. If it does become 'bad', then move the magmount a little, right?
The magnet on that mount is only to keep the thing from falling off of whatever it's put on. It has nothing to do with the 'groundplane'/counterpoise of the antenna. A simple straight wire will work as that 'counterpoise' just like a metal plate. So, slip a wire under that magnet and it should work okay too. That wire ought to be about as long as the antenna it's self, in general.
- 'Doc
 

Jay911

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All good ideas. I have a combination of them - I have a 4-port multicoupler that feeds a Spectrum Force which is on a sheet of tin, about 8.5" x 14", rescued from cutting up old furnace ducting.

Would that I had the ability to put up a decent outdoor antenna, but this will have to do. :)
 

LIScanner101

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What about this (sorry for the sketch, my $9M CAD system was down so I had to sketch it by hand :p )? The metal plate could be anything thin and metal that would fit (as mckenna suggested a piece of flashing would do), the "counterpoises" could be just metal rods with end caps cut to the "appropriate" length.

Would this need counterpoises on BOTH sides of the window, or would it be sufficient to just dangle a few on the inside as shown here?





 

t13one12

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Appreciate everyone's informative replies! I've listened to scanners for several years but have never taken the time to learn more about radios in general. With "some" spare time in my life after finishing a demanding work certification I'm looking to get a bit more into the hobby now. This forum has been a godsend with everyone's support!
 
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