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Antennas on mast

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#1
I am putting two Antennas on a mast. One is a Diamond F23A 144 MHz Single Band Vertical ans the other is a Comet CA-712EFC VHF 153-157MHz & UHF 460-470 MHz . How far away should a space them ? Can i put them side by side with space between them ?
 

mrsvensven

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#4
I had a simelar question so I figured I would add it to this thread rather than making a new one.

I am planning on putting a 2m transmit/recieve antenna on the side of my mast. Am I going to cause problems if I transmit
a) so close to the grounded mast. Am I just going to be pumping all my transmit power into the ground? Is there a good distance to keep the antenna from the mast? I don't care if my antenna is a little directional, I just want to keep the SWR down.
b) so close to my scanner antenna on top of the mast. I read that vertical seperation reduces interference better then horizontal seperation.
 

k8mcn

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#7
motolover said:
I am putting two Antennas on a mast. One is a Diamond F23A 144 MHz Single Band Vertical ans the other is a Comet CA-712EFC VHF 153-157MHz & UHF 460-470 MHz . How far away should a space them ? Can i put them side by side with space between them ?

The rule of thumb is--like polarized antennas should be one wave length to one half wavelength apart--
example: 1 wavelength is 80 inches @ 2 meters
26 inches @ 440
14 inches @ 800 mhz
 
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#8
Placing antennas on the side of a mast is a no-no in my book. Adverse mounting can cause sever signal distortion and even cause transmitters to crowbar back due to high SWR. Mounting antennas on a side bracket is a better idea. Putting antennas on separate masts in different locations is best. The transmitting antenna should always have the high ground and any others should be away from the transmitting antenna. Too much RF coming from a transmitting antenna into a receiving antenna just a short distance away can cause serious problems with a receiver, such as overload and sometimes are known to kill them. I have seen it and the remedy is separation of several feet and different mounting locations. Desensitization of a receiver can lead to long term deafness on the receivers part in a transmitters environment.
 
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#12
motolover said:
like this ?
That is the spirit.

You need to get the antennas a bit away from the mast using some sort of standoffs.

You need to have vertical separation between the two antennas.

If you can balance the weight so the mast does not lean, it may help, but that usually is overshadowed by the wind.
 
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#13
It may not be the best set up in the world but this what I came up with...
10 ft stick of PVC cut to 6 ft, I used the left over 4 ft cut in half for my two vertical masts.
Capped the ends to keep out water.
Fabricated the mount plate out of 3/16 stainless steel plate and used SS U bolts to mount everything
Even though the twin "Sputniks" are receive only, I wanted max separation with minimal mast droop... so far it's working pretty good
 
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