Flashlight compIn the microwave antenna world, everyone talks about the importance of the radiation pattern envelope (RPE), but what exactly does that mean?

The RPE is basically the guaranteed maximum signal level at a specified angle. Both the angle and the signal level are measured relative to the antenna main beam. Sounds complicated, but change microwave to visible light and it becomes much simpler to understand. Think of a torch, also called a flashlight. Look at it head-on (the main beam) – it’s really bright! As you walk to the side, the brightness drops away very quickly until you see very little light at all – effectively this is the RPE of the torch.

Now think of an application where you want to see far into the distance – effectively a searchlight rather than a floodlight covering an area. Keeping with the torch analogy – a great torch is one that puts as much light as possible in a tightly focused main beam. The same is true of microwave antennas – they are designed for point-to-point applications so the more energy that goes into the main beam and the less that gets wasted to the side the better.

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Various regulatory bodies (such as ETSI in Europe, or the FCC in the U.S.) define allowable antenna radiation pattern envelope masks for each frequency of operation. Normally their regulations allow several variations – think of them as the minimal, adequate and best types. In ETSI terms, Class 2 would be minimal, Class 3 adequate, and Class 4 is best.

The better the pattern, the greater the benefits to the user. Better patterns mean a lower risk of interference from adjacent networks. This maximises the performance of today’s highly sophisticated radios. Using antennas with the best patterns can allow links to be deployed in locations where interference thresholds simply preclude the use of any other antennas.

Check out the new range of Sentinel Class 4 USX antennas from Commscope to see how Class 4 antennas can help your long-haul network deployment. But when confused about patterns – just think of the flashlight!

About the Author

Donald Gardner

Donald Gardner is a product line manager within the Microwave Antenna Systems team at CommScope and is based in Lochgelly, Scotland. Holding a Master of Engineering degree from the University of Strathclyde and a Master of Business Administration from the University of Edinburgh, he has been involved in the wireless communications industry for over 20 years. Prior to his current position, Gardner held various positions in quality and engineering within our microwave antenna group. His key expertise includes mechanical and process engineering of microwave antennas and product management of microwave backhaul solutions.

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