Courtesy of Pasternack : Antenna Polarization Options
Antenna polarization may be one of the least understood properties of a wireless signal. If you are installing many antennas in one location, like on a tower, polarization is an important piece of the puzzle that you’ll need to take into consideration. Here we give you a quick overview on antenna polarization.
Polarization is determined by the way an antenna is mounted, usually horizontally or vertically. To ensure optimal network performance only like-polarized antennas should be used in point-to-point wireless applications. It is possible to establish a wireless link using antennas with different polarities but network performance and connectivity will suffe.
The big advantage of using different antenna polarization schemes is to reduce interference. For example when mounting several antennas on a tower, it is best to stagger vertically and horizontally polarized antennas to reduce interference.
If horizontal or vertical polarization won’t work for your wireless application there are dual-polarized, cross-polarized and circular-polarized antenna options to explore.
Dual-polarized antennas feature two antenna elements in a single physical package (radome), one that is vertically polarized and one that is horizontally polarized. When properly installed, dual polarized antennas can communicate with both vertically and horizontally polarized antennas. An advantage of dual polarity antenna is that you get basically two antennas in one package, this saves space and money. These types of antennas are often used with MIMO (multiple-in/multiple-out) wireless access points and CPE devices.
Cross-polarized antennas sometimes referred to as X-Pol antennas, feature two elements in one package. One element is +45° polarized and the other is -45° polarized. The two opposing 45° angle of the elements produces a cross or X orientation. Using a cross polarized antenna with vertically and horizontally polarized antennas further reduces interference.
Circular-polarized antennas have equal response to either horizontal or vertical polarized antennas. These antennas are designed to either support right hand or left hand polarization to suit varied wireless connectivity applications. Using a circular-polarized antenna on a fixed access point can be beneficial if the linear-polarized remote links are constantly moving.
Antenna Polarization Options