Wednesday, Oct 28, 2020 at 13:55
I've linked one of our articles to this post (just editted as I posted the wrong one at first), and for your convenience have cut/pasted the relevant parts here.
The general rule of thumb when it comes to antennas is the higher the frequency the smaller the antenna. A good example is the antenna size of a mobile phone, which uses nearly twice the frequency of a
UHF Radio. Good antenna performance is important because it can assist your reception and transmission greatly. Antennas are also be made to have gain, which will increase the Effective Radiated Power (ERP) of the CB.
Helical Whip
The wavelength of 477MHz is around 62cm and the length of the antenna is very critical. This is the main reason why many 477MHz “Whips” usually come out of the factory pre-tuned. The most basic type of whip antenna is the quarter wave ground plane, which are about 15cm in length and are made of stainless steel or wire, for more flexibility. These relatively small antennas have a naturally high angle of radiation and are best used in hilly countryside. They work
well with repeaters because they are ideal for carrying the signal from a low point such as your vehicle to a high point where the repeater may be situated.
Gain
A 4.5 to 6 dB gain antenna is great for all types of terrain and is suitable for most situations. Gain is measured in decibels (dB) and the higher the gain, the more power can be transmitted. High gain antennas usually have coils wound into the steel or fibreglass rod, increasing the length considerably. The clear advantages are that a 5 watt radio with a 6dB antenna can perform like a 20 watt radio because 6dB results in 4 times more power.
Installation
Most UHF aerials require a ground plane, which means they should be mounted on top of a metal surface. The best spot in this regard would be the centre of your roof. Unfortunately for some people, this may not be a great idea because it could require drilling through the roof for installation. Travellers also prefer to utilise their roof rack space for carrying supplies. If the roof is not on the cards, then other good locations to mount an aerial can include: the roof gutter, side guard or on the bullbar, which is probably the most common.
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633907
Follow Up By: Member - Richard N4 - Wednesday, Oct 28, 2020 at 14:41
Wednesday, Oct 28, 2020 at 14:41
Thanks Michelle, I do get the idea.
It was more around the make up of the actual antenna, is there a performance gain to be had with the bigger thicker item than the thinner one?
Maybe you've answered my question there and I'm not able to decipher?
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Follow Up By: ExplorOz Team - Michelle - Wednesday, Oct 28, 2020 at 14:52
Wednesday, Oct 28, 2020 at 14:52
I can't say we've personally tested both that you link but I can say we have the thicker type, with the spring like the one you've linked. I agree, the descriptions look similar but the stainless spring base, thicker one should be the pick of the two.
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