Top Trends in Military RF Connectors and Assemblies
By Andrew Robinson, Amphenol RF

Several trends are defining new RF connector designs for military applications. These trends reflect the increasing use of connectors in harsh conditions, which inspire more rigorous performance requirements. Designers of new RF interconnect systems must allow a sufficient margin of safety to ensure adequate performance, even at the most extreme edges of the design criteria envelope. In addition, adequate testing is mandatory to ensure the product will perform over the intended range.

RF interconnects are being specified for much harsher environments. No longer is compliance with Mil-Std-202 adequate. Corrosion testing at 48 hours is no longer sufficient. To survive a more corrosive environment, traditional plating styles need to be improved. Several methods have come into play to meet these requirements. One technique that balances performance with cost is using an electro-less nickel alloy plating with a high phosphorous content. By ensuring a minimum 10 percent phosphorous content in the nickel alloy, along with adequate thickness, plating performance will exceed 500 hours salt spray.

In addition to designing products with resistance to corrosive environments, guaranteeing their performance in submerged conditions is another concern. Common requirements specify that connectors must maintain a sealed state at greater than one meter water submersion (IP67) in the unmated and mated condition. This requires a cable assembly to be fully integrated into the connectors. This termination technique ensures no water penetrates the mated pair from the side of the cable, and the mated pair remains sealed even when being subject to a load. Testing to ensure integrity needs to be performed as a system and should incorporate dynamic elements that simulate field use.

Temperature is another top concern in these applications, and RF connectors are being specified to extended thermal ranges. No longer is -65C to 165C acceptable for non-space-rated applications. Extended temperature ranges up to 200C are common, as well as short excursions to 250C. At these high temperatures, traditional techniques and materials are inadequate for guaranteed performance. New gasket materials must be considered and designs need to be adjusted to accommodate the growth of the plastic insulators.

Cable assemblies are often utilized in high movement applications where flexibility and durability are critical. Enhanced design features, such as ruggedized cable strain relief configurations, protect the critical connection between cable and connector. Complex test fixtures are used to simulate field abuse to accurately predict product durability.

Today, RF connectors are being asked to perform in harsher environments than ever before. But with extensive testing and a solid vision of how the designs are expected to be used, designers are releasing new products that perform solidly at both the component and system level. Customers can count on the connector industry being agile enough to support their most rigorous design ambitions.