Azimuth Radiation Patterns and their uses...


Below VHF the change in the radiation characteristics of an antenna will change considerably from frequency to frequency, making antenna selection more complicated. Where broadband wire base stations are concerned, it is usually wise to examine radiation characteristics.

There are many types of radiation patterns that can be plotted to assist in making that all important decision of whether a particular wire base station antenna will be suitable to your needs. Azimuth patterns, while they make look a bit complicated to those who have not seen them before, can be very helpful indeed.

A set of azimuth patterns of four patterns – at 20, 40, 60 and 80 degrees elevation will normally suffice, but they can be plotted at other angles. From these patterns it is possible to determine the direction of radiation and the gain at the different elevation angles.

Also, if an antenna can be mounted in more than one configuration, for example horizontally or in an inverted V, the differences in radiation characteristics can be compared in detail to arrive at the best solution.

The patterns will also reveal how suitable the antenna is for short (NVIS), medium or long range communications. The pattern at 20 degrees indicates that long distances are possible, the 40 degree and 60 degree patterns show aptitude over medium distances and the 80 degree pattern NVIS performance.