Rigid or Flexible? That is the question.

Jim Syme--cropped Jim Syme April 3, 2018

Microwave radomes compA radome is a microwave antenna component that protects the antenna feed system and reduces windloading on the antenna. This blog offers insight into the choice of radome material for microwave antennas. Before explaining what I mean in the headline, it might be worth reviewing how radomes have evolved in microwave antennas over the years.

In the early days of microwave communication (circa 1940s), radomes were very much an accessory to unshielded antennas. They had two functions – to protect the feed from damage and to reduce wind loading. These radomes were large, hemispherical moulded components, and thus rigid, but are still used on lower performance antennas today. Moulded radomes fulfil their design function but are vulnerable to impact damage and are difficult to handle and transport.

With the advent of high performance shielded antennas with tighter radiation pattern envelopes (circa 1970s), the impact of radomes on electrical performance became more significant. Manufacturers shifted to tensioned fabric radomes, which are more flexible. Moulded hemispherical type radomes remained on lower performing antennas, which are acceptable for certain applications such as rural microwave transmission systems where very low radio congestion makes interference concerns less important.

The growth of small diameter antennas for mobile backhaul led to the development of rigid moulded resonant radomes, a different type of moulded radome. Each of these matches uniquely to the frequency of the antenna on which it is used. This works from a performance perspective but becomes a logistical nightmare as the number of potential frequency bands and antenna diameters increases. This limitation has largely been overcome with the development of sophisticated moulded composite radomes with broadband performance.

CLICK TO TWEET: Rigid or Flexible? That is the question.

In modern antenna designs, the radome is an integral part of the antenna and, irrespective of the material used, must perform reliably over the life of the product and in all environments. This is proven by extensive testing during the development and qualification of the antenna.

Smaller antennas typically use moulded radomes – the smaller diameter allows the close tolerances required for electrical performance to be achieved in a way that is simply not possible for larger sizes.

Fabric radomes have certain advantages both in radio frequency performance and in the ability to shed ice and snow. In addition, they can be easily fabricated and handled in larger sizes. As a consequence, CommScope now regularly use fabric radomes where moulded radomes may have previously been the design choice (e.g. ValuLine 4ft and 6ft). Similarly our new long haul Class 3 compliant HX and Class 4 USX antennas use fabric radomes to obtain the required performance – check out the product sheet for more details.

Where does that then leave the answer to the rigid or flexible question? Easy! Leave it to CommScope. There are different radome solutions for different antenna types and diameters. They all have their place, but we’ll make sure you get the right radome for your particular antenna and application.

About the Author

Jim Syme--cropped

Jim Syme

Jim Syme is product line manager for CommScope’s Microwave Systems division, responsible for business development in the Middle East, Africa and Asia-Pacific regions with additional global management responsibility for several major OEM customers. Jim began his 27-year career with Andrew Corporation in the microwave antenna design engineering group and is a regular participant at conferences on all matters related to microwave antenna systems. Prior to joining Andrew Corporation, Jim was a design engineer for the United Kingdom Atomic Energy Authority.