UHF Radios are a great accessory in our vehicles or even homes, enabling us to contact others in the community, such as road users, truck drivers, and possibly someone who can come to our aid, especially in remote regions and if we can contact them because we have a good set-up UHF radio

If your UHF CB radio reception is patchy and unreliable, it is often due to a poor setup.

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What's the go, what DB antenna should I use? 
For simplicity in this UHF radio guide, aerial gain is typically measured in dBd or dBi. We’ll explain the gain in dBi because it’s easier to understand, and most aerials are advertised with just the dBi rating. The term dBi technically means ‘decibels relative to an isotropic radiator'; however, the significant part for us is the number. Think of dBi in aerials like a torch with a focusable beam: the bulb or LED is your 5W UHF unit, and the focusing ring is your aerial. The torch is still putting out the same 5W, but if you focus the beam (say 9 dBi) and it goes a long way, only illuminating a small area way over the other side of camp, but you can’t see your feet or the roof of your awning. Go the other way with the focusing ring (say 3 dBi), and you can now see next door’s camp, your roof, your feet, and what the kids are up to, but you can’t see the Boobook owl 400m away anymore. That’s dBi in a nutshell.

High Gain - 6- 9 dB 
These are usually broom-handle-style aerials and are often fairly long. They’re great for long-distance travel on open plains and on highways where the terrain is flat. The doughnut on this one is flat and wide, so it’ll throw a long way with line-of-sight, but put a building, hill, or forest in the way, and you’re going to have comms issues.

Mid Gain 3-6db 
These fellas are usually the ‘black fishing rod blank with copper wrapping’ whip-style or the three-foot stainless-steel rod with a ‘pig's tail‘ in the middle. Anywhere within this dBi range will be a good compromise between distance and terrain/obstructions to line-of-sight. The signal output of this range would closely resemble an actual doughnut – not too flat, but not perfectly round either – right in the middle. These are the all-rounders.

Low Gain 0-3db 
These are more often seen in cities and alpine/mountainous areas. The "Unity" part of the name means that the aerial pattern radiates equally in all directions. They’re usually short and stubby, with a heat-shrink coating. This aerial will push a signal quite happily over trees, mountains, buildings, whatever – but you’re sacrificing range to do it. Their doughnut is essentially perfectly round, and it’ll bounce over hills (or 60-story buildings) as high as it will throw a signal horizontally.

A general rule of thumb is either a CD34 or a 6.5bd elevated feed for everyday around-town use.

If you are going to use it only in the bush, then CD34 or a 3 dB solution is a better choice. 

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Antenna Placement

Antenna Placement is a compromise between the optimal transmit location and the mounting location on the vehicle.  The best position is in the middle of the roof, but who wants to drill a hole in their roof. For ease of fitting, many people attach their CB aerial to their bull bar. However, this creates an uneven radiation pattern that spreads behind the car and to one side if fitted to one side of the bull bar. Your signal forwards can also be shadowed by any vehicle in front of you. Ironically, poor antenna location means that only a low percentage of users realise their radio’s full potential. Even an expensive, high-gain antenna mounted above roof level on a bull bar suffers because its tips radiate very little energy. The general rule of thumb is to place the bottom half of the aerial at a point where it can ‘see’ the most significant distance, even to the horizon if possible. In other words, the ideal place to achieve this is up on the vehicle’s roofline or roof racks. If you’re at ground level, on flat terrain, the horizon is about 5 km away. If there is nothing between your antenna and the visible horizon, that would be the limit of your transmission range, but if you raise your antenna by just 1 m (i.e. from your bull bar up onto your vehicle's roof), you may increase the range over that visible horizon