UHF & Mobile Phone Antenna Separation

[Fozzy Senior Member Find all posts View Profile Close Fozzy]

How far apart should mobile and UHF antennas be mounted so that they don't interfere with each other, assuming that they do given they're different frequencies?

I have a UHF antenna mounted onto the ARB deluxe bar in the left hand hole supplied as standard. I'm looking to put an allband cellphone antenna on as well. My problem is that I had intended to mount the mobile antenna using a "Z" bracket halfway up the left hand bonnet line but now realise it will further raise my minimum height requirement for carparks (the antenna is 1120mm long, so I now lose another 120mm or so in height).

I've already ripped the box apart so don't think I can return the item, so I'm stuck with what I've got.

The missus doesn't want it out the front in line of sight on the top of the bar as she's already annoyed by the UHF so I have two options I think. First, put it into the right hand side mount hole on the bar which isn't a real problem but I think it contravenes some Dept of Transport reg somewhere or second to drill another hole just to the rear of the mount on the LHS, which will mean the two antennas are separated by 100mm or so.

Would this cause problems electromagnetically?

Cheers,

Dave

[ozwapet2 Advanced Member Find all posts View Profile Close ozwapet2]

Hi Dave, I would not mount the antennas that close together. Two reasons,
1) even though the frequencies are different you will get near field radiation effects between the two antennas at that distance, so transmitting on one may overload the receiver in the other. That is, if someone is on the phone and you transmit on the UHF, the phone call may drop out. I don't think you'd cause any damage to either but it is possible to damage a receiver front end with high injected signal.
2) the radiation patterns of both antennas will be affected.
I think you should try to mount them at least half a metre apart but preferably more.

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

Having the ariels that close together could be an issue with them hitting each other as they vibrate on rough roads!

Cheers Andrew

[Fozzy Senior Member Find all posts View Profile Close Fozzy]

Thanks for the replies - I did think that they'd probably whack each other at times, off to the RHS looks like!

Cheers,

Dave

[Bazza Senior Member Find all posts View Profile Close Bazza]

I've had my UHF & phone antenna very close to each other for many months and have never noticed any problems. The UHF doesn't seem to have lost any range or suffer from any induced interference. The phone also seems to work as normal ( not that the external phone antenna made much improvement anyway ) weather your using the UHF or not. There may be some known measurable issues regarding close proximity issues to each other, but I have not experienced any.
Bazza.

[Bushbasher Out of control poster! Find all posts View Profile Close Bushbasher]

Who's bloody car is it anyway? My work car has 4 aerials in close proximity to each other at the front and a Codan aerial at the back. The techies that install should know what they're doing. The CB/phone/digitals are only about 5cm apart. My Prado has UHF on left side of ARB bar and phone antenna on the right. I dropped down in height from a similar fibreglass aerial like yours to a smaller more flexible RFI one as I keep busting the fibreglass ones on the left side of car. That said I have just cracked the phone antenna. Even with the spring bases I seem to be able to snap them out bush.

[damonat Advanced Member Find all posts View Profile Close damonat]

i have read that they should be 600mm apart.

[Richoson Avid PP Poster! Find all posts View Profile Close Richoson]

Fozzy

Forget the phone aerial, we need a winch for the next GTG recce, then you won't have to worry about the interferance.

Regards, Richo.