Although these high-frequency transmission-line components are often overlooked, suppliers continue to invest in performance improvements.
Cables and connectors are among the most overlooked components in any high-frequency system. Since they must deliver signals from one point to the next, without altering those signals, these transmission-line components are generally only noticed when they fail. In spite of the low profile, however, manufacturers continue to invest in these components in the quest of improved performance and reliability, to ensure that their cables and connectors continue to go unnoticed in critical commercial and military systems.
For example, last year Micro-Coax (www.micro-coax.com) announced a TNC connector designed specifically for high-power applications. Built to exceed the requirements of the MILPRF- 39012 military standard, the highpower TNC connectors are aimed at applications with extreme thermal and radiation exposure, such as high-power satellite communications.
Last year, MegaPhase (www.megaphase.com) introduced its Warrier Cable line of rugged cable assemblies for ground-based electronic-warfare (EW) applications. Designed for applications from HF through X-band frequencies, the assemblies feature attenuation as low as 0.14 dB/ft and power-handling capability as high as 900 W CW at 6 GHz. The cable assemblies incorporate the company's proprietary GroveTube technology with an outer conductor that can withstand 250 lbs/in. of crush force. The rugged cables are available with a wide range of connectors, including BNC, TNC, Type N, SMA, 2.92-mm, and 2.4-mm connectors for applications through 50 GHz.
Recently, San-tron, Inc. (www.santron.com) launched a line of rugged Type N connectors capable of mode-free performance from DC to 18 GHz, in contrast to conventional Type N connectors, which are limited in performance to about 12.4 GHz. The 18-GHz Type N connectors are fully compatible with standard Type N connectors and adapters. They are based on precisionmachined components and PTFE dielectric and exhibit less than 0.2 dB insertion loss from DC to 18 GHz with maximum VSWR of 1.30:1. They are rated for operating voltages to 1000 V RMS and maximum dielectric withstanding voltage of 2500 V RMS. The connectors feature silicone rubber gaskets for environmental protection. According to the firm's director of engineering, Fred Hull, "In the past, we've developed some precision bead structures that were ideal for test and measurement applications, but at a premium price. For these new Type N connectors, we created a unique, balanced internal design that provides the high-frequency performance of precision connectors, but without the demanding requirements for tightly machined tolerances."
Times Microwave Systems (www.timesmicrowave.com), well known for its LMR families of low-loss flexible cables for wireless communications applications, provides one of the better free literature guides for cable specifiers on its web site, "A guide to the selection of RF coaxial cable." The 12-page handbook, part of the company's TechNotes series of technical literature, explains all of the standard parameters used in specifying coaxial cables, such as insertion loss, shielding, and power-handling capabilities. In addition, the TechNote covers lesser-known issues, including the generation of acoustical and electrical noise when a cable is flexed.
WL Gore & Associates (www.gore.com) offers a wide range of cable assemblies for commercial, military, and test applications through 110 GHz. The firm's PHASEFLEX test cable assemblies are designed for flexibility without measurement compromise. The 110-GHz test cable assemblies have been bent 90 deg. around a 1-in.-radius mandrel with only 4.3 deg. and 0.05 dB change in phase and insertion loss, respectively, at 110 GHz. The typical insertion loss for a 16-cm assembly is 2.1 dB at 110 GHz. The company also provides the GORE Microwave/RF Assembly Builder tool on its web site to help site visitors site in constructing their own cable assemblies for applications to 110 GHz. The tool provides onscreen buttons that guide a user through the process of building a cable, such as asking whether the assembly is new or based on an existing assembly (if a part number is known). Clicking on the "Build New Assembly" button prompts an operator to supply key parameters as length, maximum operating frequency, and types of connectors for the assembly.
Similarly, Lighthorse Technologies, Inc. (LTI, www.rfconnector.com) allows visitors to its site to build custom cable assemblies for commercial and military applications through the site's guidance. The company announced a line of reversepolarity SMA connectors, which will not mate with standard SMA connectors, the female connector houses the contact pin and the male connector houses the receptacle, which is the reverse of the standard convention. The connectors support FCC regulations that prevent consumers from replacing stock wireless antennas with higher-gain units.
Huber + Suhner (www.hubersuhner.com) has developed a cable-assembly product configurator. The WEB PCF tool allows visitors to the web site to design, specify, and request a coaxial RF cable assembly online. The tool allows visitors to create, save, and print a custom data sheet based on input information. It can also send a request for a quote and delivery timing to the factory.
Flexco Microwave (www.flexcomw.com) offers three grades of test and measurements cables: Blue Grade, Lab Grade, and SuperCable. The cables can be specified for applications from DC to 26.5 GHz and DC to 40.0 GHz. The Blue Grade cables are designed for standard production and everyday bench use. The Lab Grade cables feature cable that is protected inside a Kynar tube braided with Natvar. The lightweight and flexible assembly is cost-effective but rugged for engineering labs. The SuperCable assemblies are protected inside a stainless-steel conduit braided with stainless steel and jacketed with Neoprene for durability.
Finally, Tyco Electronics, M/A-COM (www.macom.com) introduced additions to its FE series of ruggedized mast cables for ground-mobile communications systems. The cable series features an internal wire-wound layer and rugged external jacket for protection in harsh military environments. The cables range in diameter from 0.25 to 1.40 in. and are available with a variety of connectors. According to the firm's cable technologist, Ray Schwartz, "Our M/A-COM FE ruggedized mast cables can withstand the rigors of extended use in harsh environments such as mishandling during spooling and unspooling, being dragged over rocks and ice, crushing forces such as stepping on the cables or vehicles driving over them. High resistance to damage is a primary goal of this cable family and we are proud to provide our customers with a line of equipment that will perform in the harshest conditions to support mission-critical communications."