UHF Aerials

bubba

4x4 Earth Contributer
UHF antenna

I am looking for advice on the best antenna for a UHF radio?

How big or small
Which amount of power or dB gain, 4.5, 6 or 9?
I don't have much knowledge on this subject, so I would appreciate any advice I could get.

Thanks
Bubba
 

Gunna

Well-Known Member
The key is a good quality antenna that is ground independent it dosen't have to be to high just above vehicle hight would be sufficient make sure you have good connections 4.5 /6 db would be more than enough for most cases. Find out what repeater stations and their channels are in the areas that you plan to travel in.
Hope this helps
 

Joe

Active Member
When I had my van, I had a 6.5db groung independant antenna, and it worked like a treat. From where I lived in Ringwood, I could get out towards Cambllfield and Blackrock every night. And on the right night could even get down to Geelong. A good quality aerial makes a big difference.
 

Pure Yobbo

Moderator
When we went travelling last Xmas 6500km we were losing 300km off a tank of juice with the big wank areil on. 2200mm off the bull bar. Swapped back to the little ariel in Adelaide and saved heaps on fuel. Was getting great reception with the wank ariel but weasn;t worth the fuel bill. Now run a 1200mm ariel.

Cheers
 

sdollery

New Member
We run about a 900mm unit. A UHF is really for inter-vehicle comms anyway. If you need long distance for emergencies etc, I'd suggest a HF radio or even better a sat phone, even more reliable... Take a mate.
 

bubba

4x4 Earth Contributer
Thanks

Thanks everyone for the feedback. This is a big help.

Is is a bit difficult trying to work out what,s the best equipment, when you have all these facts & figures bandied around which I don't quite inderstand.

I can narrow my search a bit now

Thanks once again

Cheers
Bubba
 

grit

Member
Most of the guys I wheel with get best results with a 1200 (4ft) ant. with 6dB gain, the 9dB is usually more bulky and less forgiving when flexing around obstacles on the trails.
 

wtf

New Member
Two things to consider.

1. What sort of area are you 4wheeling in?
2. What style of antennae do you like?

1. The main issue is for flat areas, a 9db will get distance, but suffers in hilly areas. In hills a 4.5 db is good. I personnally use a 6db as a compromise. The main reason for difference is the radiation pattern of each Antenna. A higher gain antenna is a flatter "donut" than a lower gain so will tend to shoot over the receiving person when the car is angled i.e. on a hill.

Definately go ground independant.

Hope this helps.
Cheers
Rob
 

grit

Member
Just get one that can take a bit of a pounding and if it does hit the duco doesnt take the bark off. You will be happy with the performance of 6dB gain and as you come down from that the performance drops off noticably.
 

bubba

4x4 Earth Contributer
thanks

Thanks Rob. Yes this is great help. I think I will look for the 6 db gain to provide that compromise situation.
Thanks for your assistance

Cheers
Bubba
 

bubba

4x4 Earth Contributer
Thanks

Cheers grit

Thanks for your help.

It's time to go shopping I reckon.

Bubba
 

Grey Ghost

5th Annual Victorian Gathering member
Got a 4.5 db gain with elevted ground independant base on a heavy duty spring base.
Seem to get good reception wherever and so far has been used to prune many a tree on the side of the road with no ill effect
 

grit

Member
1.2M (4ft) is ideal for bumper mount - just watch your height if its mounted on a bar etc. that is much higher than bumper height. The results you get with a 5w UHF through a 6dB antenna will be better than satisfactory on any group outing.
 

Airbags

New Member
Mate, find a good quality retailer and ask them for advice! There are many different types, sizes, lengths, ranges, and they all have a specific job to do! Bye the wrong aerial for oyur new radio and your reception will be crap! Match the corrct aerial with any radio and you stand to gain the best service! It aint that easy as black or white!!!!
Cheers!
 

grit

Member
A good place to start is where you want to locate the antenna. 6dB, not too high with some flex to handle the rough going is well worth considering.
 

mickyd213

New Member
it depends on the type of terrain, distances involved etc. A 9db antenna will give you very good range but doesn't have a big radiation pattern... mainly for open flat terrain.

The 6db will give a bigger pattern than the 9db but loses range.
The 3db will give you a bigger pattern again but has a very limited range. This type of antenna is good for bush driving where you are relatively close to the other vehicles.

You have other antennas as well but the 4.5db antenna would be the main one used over the ones already mentioned.
Mounting position also has an effect on the radiation pattern. But for general comms, mounting the antenna on the bullbar gives good coverage all around the vehicle.

I've done a little sketch to highlight the radiating patterns... (I'm no artist as you will see)

antennadwg.jpg


The actual distances from a 9db to a 6db and a 3db would be in the vicinity of...

9db... 20km
6db... 12-14km
3db... 6-8km

These distances would be approximately the maximum for each of the antennas. Ranges could vary depending on how well the antenna is grounded and how good your radio is... etc etc. The pic doesn't really show this to any sort of scale... sorry.
There was a good article in 4wd action about a month or so ago... worth reading if your interested...

Cheers,
Mick
 
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