UHF range

Ger08 · Senior Member

UHF range

ABNER · Veteran Member

Ger08 wrote:
hi all
i have just installed a new UHF radio in the tug and was wondering what sort range I can expect. I have used an 6.6dB antenna. What should etc of range/distance is everyone getting out of their set ups?

UHF is a line of sight transmission, you have to look at the radiation pattern of the antenna to get an idea of which is the better aerial, the higher you mount it the further it will transmit, 5 watts limits you a bit, 25watts is a lot better, I use a 4.5db antenna as it is a good general purpose pattern 6db should be good also.

ds. Related image

PeterD · Guru

Bob, do you have a link to your diagram? I would like to be able to use it in a larger size.

Ger, as bob said VHF and UHF radio signals are largely line of sight but the radiation does also follow the earths contour a bit after that line of sight distance. Other things that effect the path are reflections from objects that assist in increasing transmission range. The other things that effect the range is how high you have mounted the antenna on the vehicle. A rubber ducky antenna mounted on a roof rack is far more effective than a high gain antenna mounted on the bull or bumper bar.

Another big thing is your location. If you are in a gully you will not talk very far. If you are working through the Mount Canobolas repeater (or sitting next to the repeater) you can talk to around 20% of NSW. On a dead flat road you should manage 2- 3 km car to car.

In other words there are too many factors that will effect your range to give you a maximum range figure. Transmit power doses not have as much range effect as many claim. Back in the days when the AC Police used Pye PF2UB portable radios (1/2 W TX) on the the bikes they could operate in most of the places the 25 W car radios could.

-- Edited by PeterD on Friday 29th of September 2017 09:01:00 AM

ABNER · Veteran Member

Sorry , no I cant find it. If you want just log in to UHF Aerial radiation patterns, that might find it.

Bob

Ger08 · Senior Member

Thanks for all the responses. I have now managed to do some testing and it seems that in a heavily built up area we are getting around 4-5 ks and upwards of 7 on a fairly flat open road. Im pretty happy with these numbers as we really only use it for truckies and convoys etc.

macka17 · Guru

Propogation is Normally.

Tall ant. High. with a"UNIVERSAL(unidirectional) base post. IE, NON Directional,
gives range. 9DB was strongest 6ish gave best range
Usually. Hills change it.

I also have a 6in "stubbie" in glove box..
Which taxi's used for between Tall buildings in city areas.

Tall mast = Flat oval.
Stubbie = on end.. Egg shape\on end oval. Pretty much.
I've used a 2 w H\Held set, round Katherine.
giving 7km walking dist while checking with missus in van.
and lost signal at around 2\3km's on rolling ground (low hills) t'ween vans. travelling.

You can never tell.
Which is why we usually use Marine VHF sets on OFF channels)
STRONGER L.O.S.

yogi · Veteran Member

how does uhf work with vhf .?

PeterD · Guru

yogi Paul, please explain yourself. They are two different things.

Perhaps you may mean does HF CB (27 MHz) work alongside UHF CB. There is no problem there providing you space your antennas a little apart.

rockylizard · Guru

Gday...

Here ya go Pete ... this one do ??

Cheers - John

Peter_n_Margaret · Guru

Frankly, having a high gain antennae in order to get longer range UHF performance is a mistake, in my view.
Low gain antennas are generally much more durable and will give clearer reception than high gain antennas. I use the little zero gain rubber ones. They are almost bullet proof and are cheap, so I carry a spare.
The last thing I want to do is to listen to every transmission from a 30km or more radius. he truckies that you need to talk to are less than 1km away and the people you are travelling with won't be a lot further. Clarity is more important than range.
We do carry a high gain antennae for longer range communication, but I have never needed to fit it.
What is critical is where it is mounted.

Cheers,
Peter