| Author |
Message |
    
Scoobydoo
Member
Username: Scoobydoo
Post Number: 85
Registered: 8-2005
| | Posted on Tuesday, March 07, 2006 - 6:05 pm: | 
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Hi everyone,Im goin to be mounting a Maco V5/8 on top of some aluminum masting tubes I bought. The maco will be on the absolute top since it can mount inside of mast. I want to mount another antenna on the mast about 4 feet below the Maco, Its going to be a 10 foot 5 inch uhf antenna for my GMRS repeater, Im going to make a mount out of some square tube aluminum to get away from the mast, what my question is, how far should I mount it out from the mast?im sure the farther the better since the antennas will "see" eachother. I was thinking around 5-6 feet would be good enough. What do you think? I see towers with antennas less than a foot away from the tower but I am guessingthis hurts the performance quit a bit right? Maybe not? Thanks for the help. |
Tech833
Moderator
Username: Tech833
Post Number: 1258
Registered: 8-2002
| | Posted on Tuesday, March 07, 2006 - 10:18 pm: |
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The further you get it from the mast, the less effect the mast will have on the GMRS antenna's circularity.
For fun-
At 1/4 wave away (6 inches for GMRS) the mast will act like a reflector and the antenna will be directional away from the mast. At 1/2 wave away (12 inches for GMRS) the pattern will become directional perpendicular to the plane between the mast and antenna. |
Scoobydoo
Member
Username: Scoobydoo
Post Number: 87
Registered: 8-2005
| | Posted on Wednesday, March 08, 2006 - 1:23 am: |
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Ok, the antenna is very light so I should be able get it out quite a ways from the mast, as much as 8 feet I hope. The thing I'm most worried about is the Maco, 6.7 feet of the GMRS antenna will be in its sight. Im worried it might cause high SWR's on the maco. The GMRS antenna will be fiberglass so wont the Maco only see the thin wire inside? Fiberglass is RF invisible right? Thank you for the help Tech833. |
Tech833
Moderator
Username: Tech833
Post Number: 1261
Registered: 8-2002
| | Posted on Wednesday, March 08, 2006 - 10:16 am: |
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You really don't want the GMRS antenna to stick up above the Maco ground planes. |
Scoobydoo
Member
Username: Scoobydoo
Post Number: 89
Registered: 8-2005
| | Posted on Wednesday, March 08, 2006 - 12:59 pm: |
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Ok, what about if I mounted them both at the same height about 10 feet apart? |
Tech833
Moderator
Username: Tech833
Post Number: 1263
Registered: 8-2002
| | Posted on Thursday, March 09, 2006 - 12:38 pm: |
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That would be O.K. |
Scoobydoo
Member
Username: Scoobydoo
Post Number: 91
Registered: 8-2005
| | Posted on Thursday, March 09, 2006 - 2:20 pm: |
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Ok, cool, I'll even try for a little bit farther apart. Trying to keep everything as light as possible so it will be easy to put up. Thanks again. |
