| Author |
Message |
    
Biskybabyusa
Junior Member
Username: Biskybabyusa
Post Number: 40
Registered: 11-2006
| | Posted on Saturday, March 17, 2007 - 8:34 pm: | 
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Hi, This may be a silly question. Can you mount a 102" whip in the middle of a pole barn with a metal roof and make it work as a base antenna ? A friend of mine wants to make a base antenna out of his 102" whip because he is a little short of funds right now. Thanks, Jim |
1861
Advanced Member
Username: 1861
Post Number: 658
Registered: 2-2004
| | Posted on Saturday, March 17, 2007 - 9:42 pm: |
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OH YEAH , AND IT WILL WORK WELL . I HAD ONE ON A MAG MOUNT ON TOP OF MY 40 FOOT SHOP BEFORE I GOT MY BASE ANTENNAS . IT WAS A REAL TALKER |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2456
Registered: 9-2004
| | Posted on Saturday, March 17, 2007 - 10:52 pm: |
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ok, the "supposed to work this way" answer is that he should put the whip on a pole on the roof, and have 4 ground radials, 102" long, (can just be copper wire) connected to ground at the feedpoint (coax connector) of the antenna, sloping down at a 45* angle. (think of them like 102" guy wires with ropes on the ends going to the attatchment points.
this should give the right match for his radio.
now, most likely, if he just mounts it right above the roof, and uses that roof for the ground, it just might match up fine and get out great.
i would try it simple first, and then try the radials if the SWR is through the roof.
(2 to 1 or better is perfectly fine)
best of luck,
matt
anyone wanting a "clean signal", just look to the left and build one of these!!!
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Tech237
Moderator
Username: Tech237
Post Number: 728
Registered: 4-2004
| | Posted on Sunday, March 18, 2007 - 9:12 am: |
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Lets put it this way - it works when mounted in tof a car roof which is a lot smaller area, so why would it not work on a large shed roof.
In theory if you have at least 9sq ft of ground plane area it should work and give a reasonable swr.
I have a friend (a ham) in Baker City who has a 6btv directly mounted on the metal roof of his home. Not only is his SWR and bandwidth BETTER than advertised for that antenna but many times he could work station I could not hear
As KV said you have nothing to lose by trying it.
Simon
Tech237
KD7IEB
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Patzerozero
Senior Member
Username: Patzerozero
Post Number: 3542
Registered: 7-2004
| | Posted on Sunday, March 18, 2007 - 11:02 am: |
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if bisky's friend mounts the antenna TO the roof, not just ABOVE it/separated from it, it will work. there must be a mechanical (or in the case of a magnet mount, capacitive) connection between the ground of the antenna/feedline & the metal groundplane(roof). as with a vehicle, mounting off center will give a somewhat directional pattern from 'the most metal'. |
Biskybabyusa
Junior Member
Username: Biskybabyusa
Post Number: 41
Registered: 11-2006
| | Posted on Sunday, March 18, 2007 - 8:12 pm: |
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Thanks for the info guys ! I know when a long time ago I mounted a 102" on my car bumper,it was very "directional", and centered would worked best. Have a good one. |
Sitm
Intermediate Member
Username: Sitm
Post Number: 232
Registered: 1-2004
| | Posted on Thursday, January 29, 2009 - 10:31 am: |
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So will a 102 inch whip work well on just a rohn tower? I want to put another radio at the far end of the house (82 feet away from base) and was thinking that a fiberglass whip would work well. Is this the case? |
