The two major wavelengths used for point to point, or vehicle to base station are VHF (Very High Frequency) and UHF (Ultra High Frequency). Both types of radio signals can reach great distances, but each can be affected by the environment and obstacles. There are also other aspects to consider, including how the two affect antenna size and power requirements.
VHF’s frequency range is from 30 MHz to 300 MHz. VHF is less affected by atmospheric noise and interference from electrical equipment than lower frequencies. VHF radios are more power efficient but require a larger antenna than UHF radios. VHF radio transmissions suffer from signal degradation due to barriers in the landscape. These barriers can range widely from mountains, hills, trees, and even buildings. This reduces the range of VHF radios greatly, especially in urban locations.
Ideal applications are rural or marine applications with clear line of sight between locations with a low power requirement. Common uses for VHF transmission are two way land mobile radio systems, long range data communication of up to several tens of kilometres, radio modems, amateur radio, and marine communications.
UHF’s frequency range is from 300MHz to 3GHz. The UHF radio waves propagate mainly by line of sight; they are blocked by hills and large buildings although the transmission through building walls is strong enough for indoor reception. The higher frequency UHF waves also allow the transmission to travel between gaps and around small obstacles to reach the receiver.
Ideal applications are urban or rural applications with small obstruction, eg trees or crowds, or where it is an advantage to have a smaller antenna. Common uses for UHF are for satellite communication including GPS, personal radio services including Wi-Fi and Bluetooth and data communication. UHF radios tend to consume more power due to the higher frequency and this may be an issue for remote, or low power, applications.
The low profile antennas provided in this section are ideal for mounting to vehicles or fixed point station use. The VHF and UHF antennas do not require a ground plane and are fully waterproof. The antenna may also be mounted horizontally or vertically depending on your requirements. These antennas are ideal for a wide variety of different applications and can be easily incorporated to ABS and Steel enclosures for remote data logging applications.
||Vertical or horizontal
||1.5 to 1
||1.2 to 1
||40 x 280 x 420mm
||34 x 106 x 348mm
||5m of RG58 (others on request)
||as per requirements
Standard cable is fitted with an SMA connector but any standard radio antenna connectors can be fitted on request and the standard 5m cable can be amended to suit.