RF Responds to Many Market Needs
By Lynda Nolen, Bishop & Associates Inc.

2008 was a very good year for most manufacturers of RF/microwave connectors. Excluding F-type RF connectors used primarily in CATV applications, worldwide sales of RF/microwave connectors grew 5.5 percent from 2007 to 2008. Representing 4.5 percent of worldwide connector sales in 2008, all regions, except North America, experienced a percentage growth rate above the overall total connector growth rate for that region. Even North America, where RF/microwave sales declined by 2.3 percent, made a respectable showing, considering the total connector market in North America declined by 4.7 percent.

2007 and 2008 RF Connector Sales by Region

It wasn’t just one end-use equipment sector or connector type that experienced growth from 2007 to 2008. Except for the automotive and consumer end-use equipment sectors, all other end-use equipment sectors grew, with the medical equipment sector exhibiting double-digit growth. The same can be said about RF connector families. Although some families grew at a much greater rate than others, not one RF product family declined from 2007 to 2008. So, what contributed to this growth? We spoke with several RF connector manufacturers to answer this question, and it’s clear that the new, exciting, and interesting developments in the microwave/RF world made an impact.

One of the most interesting RF connector products recently introduced was the composite RF connector. One of the companies introducing this product was Radiall AEP Inc. Christophe Masnou, marketing manager for Radiall, said, “Radiall has always been looking at a composite material as a substitute to brass and stainless steel, with three targets in mind: weight savings, improved corrosion resistance, and lower cost. The issues we faced with composite was first, the cost of the composite, molding vs. brass or stainless steel, and machining; and secondly, the challenge of metal plating for composite parts, which need to be conductive. The cost issue disappeared when brass and steel prices skyrocketed a couple of years ago.”

To address the second challenge, Radiall looked at a process they had already developed. “A few years ago Radiall developed a proprietary reliable metal-plating process for rectangular composite parts like the EPX series, which is geared towards avionic interconnect applications. Today, thousands of EPX composite multi-pin connectors fly on commercial aircrafts. The price of composite plating and resistance to wear becomes an issue, though, when dealing with RF coaxial connectors. For example, to design composite threaded parts for screw-on connectors is not a problem, but when it comes to finding the right metal plating process which can achieve a durability of say, 500 mating cycles, it becomes too costly. Thus the win-win equation for composite and RF coaxial connectors is to have non-conductive parts and a high percentage of brass in the connector composition,” said Masnou.

When asked about particular applications which composite RF connectors are geared toward, in particular the DIN 7/16, Masnou said, “Antenna systems and RF module manufacturers were the first users of composite connectors.” He explained that they chose “composite RF connectors for two reasons. Weight savings was the first reason. As more and more wireless equipment is installed on towers and building roofs, the weight savings realized by using a composite connector vs. a brass connector is significant. The second reason is color coding, which allows manufacturers to improve the ergonomics of their systems with coded interfaces.” Masnou notes that the price is affected accordingly: “The more brass material you have on a standard connector, the more savings that will be incurred. On standard 7/16 receptacles, you can expect the composite version to be 20 to 30 percent cheaper than traditional brass connectors.”

A deduction in material costs is not the only savings a customer switching to a composite RF connector will enjoy. Masnou said, “There is also a savings in shipping cost (lower weight) and labor costs due to an easier installation process.” There can also be a reduction in lead-time and inventory costs. Because the system is modular, “it is possible for a customer to have a single housing and several inserts in inventory, and produce a variety of connector styles.” Composite RF connectors are also corrosion-resistant and intermateable with standard metal connectors.

In the realm of precision coax, one of the most exciting new products to enter the RF coax market is Southwest Microwave’s SSBP series. Generally classified as a 0.9mm precision RF connector/contact, the SSBP is a “millimeter wave coax contact with the same electrical performance from DC to greater than 65 GHz as a standard Super SMA, 2.92mm and 2.40mm wave connector,” but, also “fully interchangeable with the standard, miniature MIL-C-39029 (non-coax) signal contacts specified for Mil-DTL-38999, Series I, III, and IV, and MIL-DTL-24308 connectors.” David Shaff, general manager, MPD, Southwest Microwave Inc., said, “SSBP contacts allow industry standard connectors to become high-performance, relatively low-cost, hybrid connectors with function complements, including signal, shielded signal, power, fiber optic, and millimeter wave coax.” What makes these microwave coax contacts even more exciting is that SSBP contacts are easily installed and removed using the same standard MIL-I-81969 insertion/extraction tools as specified for their corresponding signal or power contacts, and require no special installation training.

As detailed in a paper by Bucky Clyatt, SSB product development manager at Southwest Microwave Inc, “SSBP High Performance Blind-Mate Millimeter Wave Coax Contacts in Standard Multi-Contact Connectors,” “the SSBP pin coax outer conductor mating end is a solid, heat-treated beryllium copper tube with a nose-radiused edge.” Plated in gold over nickel, this beryllium copper part has “no exposed spring fingers or slots that could be damaged or allow EMI emission. In standard host connectors, the alignment of SSBP coaxes is triple redundant. As the host connectors are initially mated, the pin coax outer conductor tube encounters the closed entry socket contact insulator chamfer, the SSPB socket coax alignment bushing chamfer, and the entry chamfer of the SSBP socket coax outer conductor spring fingers. This sequence occurs before the center contacts engage, and the outer conductor tube of the SSBP pin coax butts against the reference plane in the SSBP socket coax outer contact. Each SSBP socket coax has an integral stainless steel compression spring preloaded to a higher force than the maximum mating force for that size coax. As the host connectors are fully mated, the resultant increasing compressive force at the pin and socket coax interface overcomes the socket coax spring preload and depresses the socket coax. The final spring force at the interface is a compressive force greater than preload. This design guarantees matched impedance, EMI tightness, highly reliable and repeatable mating.”

In addition to using SSBP coax contacts in industry standard circular Mil-DTL-38999 Series I, III, and IV connectors and rectangular Mil-DTL-24308 connectors, Shaff says that these precision microwave coax assemblies can also be used in a variety of custom applications. One custom application that SMI has already provided involves using SSBP contacts in the popular micro-D. Starting with housing dimensions for a 25-size micro-D shell per Mil-DTL-83513, SMI-machined custom insulators that accept six, size 20HD SSBP coax contacts. The initial versions were a cable plug and a special PCB end-launch receptacle, but the success of this design prompted SMI to also develop a cable receptacle for cable-to-cable applications. An interesting feature is that SMI designed the special Micro-D to use the same SSBP size 20 cable coax contacts used in the standard rear-insertion/rear-release size 20 cavities of D-subminiature connectors per Mil-DTL-24308.


In summary, SSBP coax contacts solve a variety of problems generally associated with the use of high reliability RF/microwave coax connectors in demanding applications. This is especially true when environmental factors, such as dust, dirt, vibration, and shock, often cause other connectors to eventually fail, and they do it utilizing a connector system that is industry recognized for its reliability and durability. This doesn’t even include the fact that the circular and rectangular connectors chosen to accept these microwave coax contacts are readily available, allow for increased packaging density and extreme application flexibility, as well as provide the lowest VSWR, lowest inline per unit length, and the highest EMI isolation of any available blind-mate coax from DC through 65 GHz.

Another exciting RF development that contributed to the growth of RF connectors was the expansion of the popular quick-connect mating system. IMS Connector Systems was one of the manufacturers that expanded their product offering with their SnapN and MedEasyLock® products. As shown in information provided by Steve Drexler, sales representative for IMS Connector Systems, the SnapN connector system provides a variety of advantages over standard N connectors, including faster installation time, greater packaging density, easier mounting, and the ability to both rotate the cable 360 degrees, and reposition the cable, if necessary. Geared towards a variety of applications, including “filters for mobile base stations, cable connections for mobile base stations, wireless LAN and measurement equipment,” the SnapN is “backwards compatible with N connectors, meaning SnapN female jacks can be mated with standard male N plugs.” Besides the standard plug and jack SnapN product, IMS also offers an IP68 version that is not only totally waterproof when mated, but also waterproof when unmated.

Geared toward “medical therapeutic devices, like magnetic field therapies, as well as RF-controlled medical measurement and monitoring systems,” IMS’s MedEasyLock connectors are another example of the expansion of the popular quick-connect mating systems. Designed with an “extended connector housing, which provides strain relief and prevents bending and damage to the cable, the MedEasyLock is suitable for applications up to 5,800 MHz, with a service load at 2.4 GHZ at 500 watts, and offers high reliability and easy, fast mounting.

In addition to the products discussed above, other RF connectors products recently introduced include:

Molex’s Multi-port SSMCX—Designed for cable-to-board applications and available in 4- and 8-port options.

Pasternack’s N Series—Designed specifically to terminate to the LMR series of cable widely used in wireless, WiFi, and GSM base station applications.

Bomar’s V-Bite™ Edgeboard Sealed Type N Connector—Designed for outdoor antennas and portable test equipment.

Amphenol Connex’s high-performance 75 ohm BNC—Designed for video applications, including video routers and switching equipment, video control panels, video display and monitoring applications, and video add-on cards.

Lynda Nolen Product Specialist, Bishop & Associates Inc. Lynda Nolen has been in the interconnect industry for over 28 years. She has worked in sales, sales management, marketing, and product management for such companies as TRW Electronics Components Group, Sunbelt Components, Cinch Connectors, Arrow Electronics, PEI Genesis, and Delphi Interconnect. Nolen has extensive experience in competitive cross-referencing, drawing, web and catalog review, new product introduction programs, harness and connector assembly programs, account management, and customer service programs. Lynda received her Bachelor of Arts degree from Roger Williams University in Rhode Island in 1979, and has completed various electrical engineering courses.