Aerial separation

JamesRollo

New Member
Hi all,

I have a UHF and a CelFi Go aerial mounted on the bullbar of my 4wd. The other day a bloke was telling me that I would be getting interference between the two because he thought they were too close (on the same side, approx 15cm apart).

What are your thoughts?

TIA
 

boobook

Well-Known Member
He's right. They should be at least 1/2 wavelength from each other. At 477mhz the wavelength is about 0.6m so the antennas should be at least 35cm apart.

They will have reduced reception and the UHF in particular will throw less signal down the road and more to the sides. It may not SWR up very well either. ( Bad Juju)
 

boobook

Well-Known Member
yeah okay then, thank you. The aerials I have are:
- Uniden ATX979
- GME AT4805B (2.5-7dBi)


I dunno the antennas, but doesn't matter, Just put them as far away from each other, any metal and as high as possible. Bullbars are a stupid place to put them if you want them to work as far as possible ( and isn't that why you use an antenna). Your Cel Fi go is a complete waste of money if you don't put the antenna on the roof IMHO.
 

Inigo Montoya

New Member
Actually the general wisdom is that a quarter wavelength of the lowest frequency - in this case about 16cm - is 'safe' and will avoid the worst effects such as overloading receivers and completely obliterating radiation patterns. Of course, Boobook is right, height is might, and more distance is better, so if you want the best possible results diagonally opposite corners of the roof rack is pretty hard to beat.
 

boobook

Well-Known Member
20210528_104555.jpg

20210528_104625.jpg
 
Top