The best place on a vehicle is to put the antenna smack bang in the middle of the roof, using the roof as a ground plane and using the highest point of the vehicle as the lowest point of the antenna. Db can help but the position of antenna is more important.ģ) The location of your antenna. Then there is the db rating and which without going into too much detail, basically it means how tall or long the antenna is, meaning how much of the UHF frequency wave that the antenna can catch. This will increase the range at least two or three fold but only in one diection. You can also use uni directional or Yagi antenna which extends the range of the antenna by changing the doughnut shape to a cone shape eminating from the tip of the antenna in the direction that you point it. Imagine a doughnut shape eminating from your antenna where your antenna is like an arrow shot through the center of the doughnut hole. If you use a dipole antenna (omni directional like the ones most 4WD use) you can get an equal spread of signal both for transmision and reception in all directions. No disrespect I am a closet radio geek!!!!!!!Ģ) The type of antenna you use. (It's really only important if you are using handhelds which rely on inbuilt batteries) You need to find a friendly radio geek who can tweak your radio and make sure it is putting out 5 watts, they'll usually do it for free cause its kinda nice to talk to some real people every now and again. Most Radios can be tweaked and adjusted to put out more power but you will reduce battery life if you do this. The maximum Power output from a CB radio, legally, is 5 Watts and in practice many "5 Watt" radios only put out 3 to 4 Watts. This will help how far you can send your signal, but not what it can hear (your antenna does that and it is crucial with transmission also). In my opinion there are 3 things to consider.ġ) The power output of your radio. End of the day however you can't count on these situations. It also definitely happens with HF where you can speak to someone 3,000km away but not 200km away. This also used to happen on AM side band radios and was often referred to as skip. I have heard of UHF signals being received over several hundred kilometres because of this bounce. There are also some odd atmospheric conditions that can assist UHF, such as inversions, where a warmer air mass traps a cooler air mass close to the surface of the earth (I think that's right I am not a meteorologigist) and UHF waves can bounce or skip off the inversion layer. I can give you an example, some years ago I was on the North East tip of Dirk Hartog Island and with a hand held UHF radio (approx 3 watts power) I was able to clearly talk to people in Carnarvon about 95km over the sea, a very nice flat terrain. UHF is line of sight, so the higher you are or the flatter the terrain between you and the reciever the better chance of you getting reception. Having been a bit of a Radio Geek in the past, I have to agree with earlier posters, and say that "Height is Might". I would be interested in your thoughts and advice. and was thinking the other day about the benefits of mounting higher up on the vehicle Mine is a GME 4703 on the bullbar ,the tip of it is barely over the roof line. Then on top of all this there is the various different types of aerials and their db gain for the different terrains you drive etc. I would also expect, good quality coax, length of coax, not wrapped around a power lead, etc also make small differences as well ie How much extra range and senstivity to do you get if your aerial is above your roof line. IE easy to mount on a bullbar, a tall aerial on the roof rack will cause height issues around town and may collect trees in the bush etcīut reception must be one of the the most important drivers. The bullbar, the roof gutter/roof rack or on the rear say on a kaymar or rear bar bracket. There seems to me three main options generally. Traditionally it was just put it on the bullbar and be done with. I am interested to hear from others about UHF aerial placement (and the science behind it) for best reception.
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