Mounting multiple omnidirectional antennas on Will-Burt mast

[Medic805]

This may be better suited to the commercial antenna forum, but I felt like it also had some stake here as well, so please move if posted in the wrong area. I have been tasked with putting together a plan for mounting several antennas on a pneumatic Will-Burt mast for my job. Antennas aren't my strongest expertise and need some assistance with how to best go about this project. Currently we are operating: two multi-band mobiles, two VHF mobiles, one of which is a statewide trunked system, and a VHF low band mobile. We also have a portable UHF repeater that we can quickly set up if the need arises. All of this equipment is currently installed in a command trailer if you will. All of the antennas are currently mounted and spaced on the front of the trailer without issue. My boss has suggested the installation of a pneumatic mast and would like to have the two multi-band antennas, as well as the UHF repeater antenna installed on said mast. All other antennas would remain in their current location. There is quite a bit of conflicting information available about proper antenna spacing. Has anyone else completed such an installation before? Is an installation with these parameters even possible without issue?

Thanks for your input.

 

[PACNWDude]

I used to work for a company that had many mobile communication suites, and used Will-Burt pneumatic masts. We also used commercial band VHF and UHF, as well as marine VHF radios. We had a pitch fork type of configuration on some of these masts, and only separated antennas by about 8 feet or so. As long as you are not using similar band radios at the same time, you should not have too much of a problem.
The metal of the mast was not even an issue, as we still managed to get about 16-20 miles on VHF and 16-18 on UHF using CDM-1250 mobiles at 55 watts (VHF) and 45 watts (UHF). As long as your range needs are realistic, it should not be a huge problem. Although, you will get many that will state you must have x wavelengths of separation and antennas must be more than 5 MHz apart.....etc. (This is still an online forum and what works real world is often far from the answers you will receive).

Be careful if using TDMA radios though, desense on other antennas/radios can be an issue if you lack enough horizontal physical separation. Vertical separation is even better than horizontal, placing antennas at different heights can be beneficial and easier on a pneumatic mast.