These are usually the broom-handle-style aerials and are often fairly long. 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.
So, the Duplex repeater will receive on the high channel number and transmit on the low number. Radio transmissions are emitted from the centre of an aerial, not the tip as some people believe.
So, the higher the aerial can be mounted the better the signal and the further the distance you can send and receive transmissions. In hilly or mountainous terrain radio transmissions can be missed by others depending on the type of aerial gain you have. A 2dBi or 3dBi aerial is much better in these terrains as it has a rounder signal, and you have a better chance of contacting someone in your vicinity.
A 9dBi aerial is excellent for more open station country and is what you typically see on farm Utes, etc. Alternatively, some people have two UHF radios mounted in their vehicles, one connected to a 2dBi aerial, and one linked to a 6dBi or 9dBi aerial.
We use a 5 watt handheld UHF as a secondary radio in the vehicle as we already have and use these for our 4WD Training anyway. So, you have a few options depending on what your needs are. About 10 years ago, the UHF service was expanded from 40 channels wide band to 80 channels narrow band utilizing the same MHz spectrum by slotting 40 more new channels in between the existing 40 channels.
This has created a small problem many are not aware of but is noticeable when you are communicating with others using the old 40 channel units when using your 80 channel unit. It becomes a pain in the proverbial when you have to constantly adjust the volume to compensate when two different aged radios are being used in a conversation.
With my old 40 channel unit I find that I receive 80 channel transmissions with lower volume than for 40 channel transmissions. However, it seems they have backed down from that stand for now. If offered a second hand 40 channel unit for sale or free, it might be a wise idea to politely refuse the offer.
Channels 1 to 8 and 41 to 48 are Duplex or Repeater channels output. Channels 31 to 38 and 71 to 78 are Duplex or Repeater channels input. If you have thin steel aerials on your vehicle, corrugated roads have a tendency to shake the aerials to the point that they snap off at the base particularly aerials mounted on bull bars. These aerials are actually designed to be mounted on truck mirrors etc.
The Solution: Try using self-vulcanising tape wrapped around the aerial base and part way up the aerial. It seems to limit the whip affect at the aerials base that creates the right harmonics to shake the steel until it breaks and falls off. Unity gain 2. The broad radiation pattern of unity gain antennas is less likely to be obstructed by buildings, bushland and hilly terrain.
Therefore, a unity gain antenna is the best choice for rugged and hilly country. GME marks move into the Defence industry with sovereign partnership with Penten and the release of its updated pBox. What are you looking for? Learn More. View all products.
If you need it to be able to bend it to get it into a carport or bounce back after being pulled in tree branches you may opt for a whip and an antenna that is already flexible. A cheap cruddy cable is not going to last you very long and it may even prevent you from clear transmissions.
Do your best to keep the cable as short as possible and use a quality coax cable to reduce any signal loss or noise in transmissions.
You may have to invest in a more expensive one but trust me it is going to be worthwhile. This is probably the most important aspect of a UHF antenna. Gain is measured in decibels dB. If you are trekking through the hilly countryside or scouting across the vast outback it is going to determine what gain you need. This is around the dB range and is best suited for hilly terrain.
You need to picture the signal as an apple, it is wide but short in distance. This is great for hills as it give you the height and depth required for communication at different levels of elevation.
This is best used for terrain that is flat. The signal is more of a flat platter shape — it is long in distance but shallow in depth.
Amazing for adventures in the vast outback as it goes for long ranges. Your climate and the conditions you are traveling through can also affect the signal of your transmissions. If there is a lot of dust, cloud or electricity in the air it can cause interference as the signal tries to pass through it.
Your choice really comes down to what you need it for. You should ask yourself these questions to assist in deciding what is going to be the best option for your needs. Moderate gain antenna — Great all rounder for a combination of hilly and flat terrain. Around dB. Otherwise you can opt for both a low gain and high gain antenna to accommodate any terrain and ensure you have the required range you need.
This brings us to our next point. If you are in a convoy or a group where you are only going to be communicating with vehicles roughly 1km in front or behind you a short rubberised antenna, around mm should suffice. It is recommended to ensure at least one or two people in your group have a set up that can reach further distances in case of an emergency. If you are looking to communicate with those further than 1km radius you are more than likely going to want to invest in a fiberglass or aluminum antenna as they are a little sturdier than a rubberised one.
The length you need could be as little as 1m to one that is over 2m. This really depends on the gain your antenna provides as well as what is functional for you.
This is probably the best option if you know you are going to be exploring the outback to the hills and god only knows where else!
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