Antenna Systems Can Make Or Break An Wireless - Clear-com

Transcript

Antenna Systems can make or break an wireless system installation. Below is a list of common antenna types. Each antenna has it's own advantages and disadvantages. It's not really possible to say that any one antenna is best or worst. That determination can only be made on a case by case basis for each installation. Other Accessories such as multicouplers, line amplifiers, passive combiner / splitters and filters are also part of the antenna system. 0 dbi gain All other antennas are compared to this ideal radiator. Infinite Bandwidth Typically 360ƒ beam width (non directional) Isotropic The isotropic antenna is the theoretical perfect radiator, it radiates all frequencies in all directions with no losses. All other antennas are compared to this theoretical standard. A gain of 3 dbi means that an antenna receives twice as much signal as an isotropic radiator. 0 dbi gain Narrow RF bandwidth Nearly omnidirectional This antenna is the basic model shipped with all wireless systems. It is designed to be mounted near a large metal ground plane such as the chassis of a receiver. This antenna should never be mounted at the end of a cable unless some type of ground plane is provided. Standard Whips 0 dbi gain (Models WDA-1 and WDA-2) Relatively narrow bandwidth Nearly Omni directional (doughnut pattern) Used primarily in the VHF band this low profile antenna is best for remote operation where the advantage of physical height and its affect on extending range is desired. Unfortunately, greater antenna height sometimes means a greater probability of RF interference. Dipole 0 to 1.5 dbi gain (Model AN-723) Relatively narrow bandwidth (doughnut pattern) Ground Plane This antenna is primarily used in the UHF band when remote antennas are required. Modeled after standard whips, the ground plane is designed to be used at the end of a cable. The "ground plane" is self contained within the antenna so it doesn't need to be mounted near the chassis of the receiver. 1 to 3 dbi gain Very wide bandwidth (doughnut pattern) Discone The Discone is used where a wide range of radio frequencies and 360 degree coverage is required. The bandwidth is typically 3:1 to 4:1 (i.e., 160 MHz to 640 MHz or 300 MHz to 1.2 GHz). This antenna does not provide any rejection, but it is possible to use a single antenna for parts of both the VHF and UHF bands. 6 to 9 dbi gain (depending on the number of elements) (Model AN-725) Very wide bandwidth (450 to 975 MHz for the model shown) Typically 50ƒ to 70ƒ beam width Log Periodic The "Log Periodic Dipole Array" is ideally suited for use with multiple receiver installations covering a wide band of UHF frequencies and where directivity, long range or back end rejection of interference is desired. Compare this antenna to a choir microphone. 6 to 10+ dbi gain (depending on the number of elements) Narrow bandwidth (506 to 536 MHz for the model shown.) Typically 40ƒ to 70ƒ beam width Yagi-Uda (Yagi) This antenna is ideally suited to installations in which the range of frequencies in use is fairly small. This antenna provides long range (from the front) and high rejection (from the rear). The tight RF bandwidth and narrow beamwidth of this antenna make it ideal for custom applications with high demand requirements. Compare this antenna to a shotgun microphone with a tight acoustic filter.