Coaxial cables and connectors support and multitude of functions in modules, subsystems, systems, and test etups. In the simplest terms, they provide a transmission path for high-frequency analog and high-speed digital signals. How well they do this depends on a number of factors, including materials, design, and workmanship. As this short survey will show, choices for microwave cables, cable assemblies, and connectors are many and selecting a supplier is often a matter of finding a company that can deliver on time.
Astrolab, Inc, (www.astrolab.com) is a long-time leader in cables and connectors as well adapters and phase shifters. The company’s patented minibend® cable assemblies are flexible replacements for 0.086-in.-diameter semirigid cables and simplify the interconnection of components within microwave modules. Usable at frequencies to 24 GHz, the original minibend cables are 99.9 percent lead free and are triple shielded for high isolation. The loss for a 3-in. section is 0.19 dB at 2 GHz and 0.55 dB at 18 GHz. For flexure testing in which a minibend assembly was flexed 90 deg. just behind the connector in a 0.25-in. radius, the amount of phase shift was a mere 1.4 deg. at 24 GHz and 1.2 deg. at 18 GHz. For a test in which the same assembly was flexed 180 deg. with a 0.4-in. radius in the middle of the cable assembly, the phase change was 3.9 deg. at 24 GHz and 2.9 deg. at 18 GHz.
Micro-Coax (www.micro-coax.com) offers a wide range of RF and microwave cables and assemblies, including the UTiFlex flexible microwave cable assemblies. The firm’s UFA125 cable assemblies, for example, have an outer diameter of 0.125 in. (3.175 mm) and minimum bend radius of 0.2 in. (5.08 mm). They offer phase stability versus flexure of 3 deg. at 10 GHz and 5 deg. at 18 GHz. Rated for 10,000 flexures, they are usable to 50 GHz and feature shielding effectiveness (SE) of better than 100 dB at 1 GHz. The insertion loss is 0.14 dB/ft at 1 GHz, 0.82 dB/ft at 26.5 GHz, and 1.17 dB/ft at 50 GHz. The cables are designed for operating temperatures from –65 to +165°C.
Huber + Suhner (www.hubersuhner.com) is well known for its high-performance cables and cable assemblies, including the SUCOFORM-141-000 hand-formable microwave cables. Designed to provide the performance of semi-rigid cables but without the need for machine forming, these cables can be used with crimped, clamped, and soldered connectors at frequencies through 4 GHz. They can be hand formed to a bend radius as small as 8 mm.
IW, the former Insulated Wire (www.iw-microwave.com), is a veteran supplier of high-quality coaxial cables. The company’s 1501 cable operates to 45 GHz with an outside diameter of 0.15 in. and a bend radius of 0.75 in. The velocity of propagation is 84 percent and the time delay is 1.2 ns/ft. The company also offers cable assemblies based on this and other cable types, with combinations of straight and right-angle connectors.
EZ Form Cable Corp. (www.ezform.com) offers semi-rigid cable that it is easily bent to finished shape and still maintains its set after bending. This property makes it ideal for use with automated bending equipment as well as hand forming. The cable is qualified to MIL-C-17 and is listed on the United States Defense Logistics Agency’s Qualified Products List (QPL). Recent cable product-line expansions include EZ Form AL, an aluminum-jacketed semi-rigid cable that was granted MIL-C-17 qualification, and EZ Flex 250, 141, 86, 47 and EZ Flex 401, 402, and 405 flexible cables with the performance of MIL-C-17 semi-rigid cables. For harsh environments, the company launched a new EZArmored Ruggedized Cable series that combines EZ Flex high-performance cables with a nearly indestructible armor jacket.
RF DEPOT (www.rfdepot.com) is also a supplier of MIL-C-17 qualified coaxial cables from stock. Semi-rigid and flexible cable assemblies are assembled to exacting tolerances, with a typical flexible cable assembly tolerance of ±0.0375 in. or 1.5 percent, whichever is greater. The firm also offers pass/fall testing to 40 GHz.
SV Microwave (www.svmicro.com) supplies connectors and cable assemblies from DC to 50 GHz, with phase matching and space qualification available. The cable assemblies can be supplied with a wide range of connectors, including miniature SMA, ZMA, SVK 2.92-mm, 2.4-mm, SMB, SMC, and blindmate BMA, blind-mate BMZ, blind-mate BZ, subminiature MCX, SSMA, blind-mate BMMA, 1.85-mm, micro-miniature MMCX, Type N, TNC, 7-mm, BNC, C, 7-16, HN, SC, and LC connectors.
Meggitt Safety Systems (www.stablecable.com) manufactures silicon-dioxide (SiO2) cable for harsh environments such as aboard the Space Shuttle. The company’s cable assemblies have been installed on the majority of military aircraft since 1960 and used in space, cryogenic, and research applications where reliable, repeatable results are critical. The silicon-dioxide cable systems can be used at temperature extremes from –271 to over +1000°C and can withstand vibration levels to 45 g’s. The cables, which are usable to 26 GHz, feature 80-percent velocity of propagation and shielding as high as 120 dB.
Haverhill Cable and Manufacturing Corp. (www.haverhillcable.com) is a supplier of semi-rigid, hand-formable, and flexible coaxial cables for microwave, military, and telecommunications applications. The cables, which are available for 50- and 75-ohm systems and with diameters from 0.020 to 0.250 in., are fully qualified for MIL-C-17 and space applications.
The HPI 120 Interconnect Assembly from Semflex (www.semflex.com) is a cable assembly that provides low-loss performance through 50 GHz and is designed for use with a variety of connectors, including 2.4-mm, 2.92-mm, 3.5-mm, and SMA connectors. With a nominal outer diameter of 0.125 in., the cable employs triple shielding mechanisms to achieve better than –90 dB leakage at 18 GHz.
Gore (www.gore.com) is known for its material expertise in a wide range of industries, but is also a leading supplier of cables, connectors, and cable assemblies for aerospace, military, commercial, aircraft, and measurement applications. The firm’s PHASEFLEX® 110 GHz Test Assemblies help measurement systems such as vector network analyzers extract the most accurate broadband results at frequencies through 110 GHz. The cables offer torque and crush resistance and stability with flexure and temperature, all while remaining very flexible. For example, an assembly bent 90 deg. around a mandrel with 1-inch radius exhibited only 4.3 deg. phase change and only 0.05 dB amplitude change at 110 GHz. When the assembly was returned to its original configuration, phase and amplitude returned to their original values. The assemblies also offer very low loss; typical insertion loss of a 16 cm assembly at 110 GHz is 2.1 dB. A wide range of suppliers offer cable assemblies for test applications, including companies often associated with other product lines, such as Mini-Circuits (www.minicircuits.com) and Synergy Microwave Corp. (www.synergymwave.com).
M/A-COM (www.macom.com) is also a supplier of precision test cable assemblies as well as rugged cable assemblies for military, aerospace, and other demanding applications. The company’s electronic-warfare (EW) cable assemblies undergo 29 environmental tests, including vibration, temperature, altitude, and 100,000 flexures before being ready for shipment to a customer. With a full in-house cable manufacturing facility, the company supplies high-performance cables for Traffic-Alert Collision Avoidance System (TCAS) and MODE-S programs as well as a wide range of MIL-C-17 cables.
In addition to offering a wide range of coaxial cables, Tensolite Co. (www.tensolite.com) also supplies a wide range of RF/microwave connectors, including SMP, 2.92-mm SMK, SMA, SSMA, SSMP, TNC, Type N, 1.85-mm, and various specialty connectors.
Advanced Technical Materials (ATM, www.atmmicrowave.com) manufactures flexible microwave cable assemblies with solid, silver-plated copper center conductor and expanded PTFE dielectric material. The firm’s 135 flexible cable, for example, has an outside diameter of 0.145 in. and operates from DC to 40 GHz. The velocity of propagation is 70 percent and RF leakage is better than –100 dB to 18 GHz. The cable has a minimum bend radius of 0.25 in.
Flexco Microwave (www.flexcomw.com) features a wide range of phase- and amplitude-stable flexible cables for commercial, military, space, and test applications rated to 26.5 GHz and 40 GHz. The company’s unique outer conductor and dielectric designs keep the center conductor where it belongs under flexure: concentric with the outer conductor.
Low-cost hand-formable YouForm™ cables from P1dB (www.p1db.com) are available with straight and right-angle SMA plugs on each end (Fig. 1). The cables, which are marketed and distributed by RFMW Ltd. (www.rfmw.com), are available off the shelf in lengths from 2 to 18 in. for $9.95 each (any length in the range) with straight SMAs, $13.95 for straight-to-right-angle SMAs, and $14.95 for SMA right-angle-to-right-angle SMA connectors. The assemblies feature VSWR of 1.35:1 at 18 GHz for straight SMA connectors. Longer lengths are available at a slightly higher price.
Storm Products-Microwave (www.stormproducts.com) manufactures semi-rigid and flexible cable assemblies through 50 GHz, including the True Blue®, Phase Master®, and Storm Flex™ flexible cable lines. The firm meets low-loss semi-rigid requirements are met with our Maximizer Gold™ phase-stable products and Maximizer Silver™ RG-replacement cables. The company also offers phase and amplitude matching, armoring/ruggedizing, and custom cable routing.
MegaPhase (www.megaphase.com) offers extensive lines of precision cable assemblies, including GroveTube® high-performance vector-network-analyzer (VNA) test cables. The company’s VN® series cables are available for test systems operating from DC to 67 GHz with a wide range of standard connectors, including SMA connectors to 26.5 GHz and 2.4-mm connectors to 50 GHz.
Electro Technik (www.electrotechnik.com) supplies Wavetronix semi-rigid cables and semirigid cable assembles as well as MIL-C-17-qualified cables for military applications. The MIL-C-17 cables include 0.086-in.-diameter semi-rigid coaxial cables designed for operating frequencies to 40 GHz and operating temperature range of –40 to +125°C. The rugged cables are rated for average power levels to 750 W.
Times Microwave Systems (www.timesmicrowave.com) is a diversified supplier of cables and connectors for communications systems, including the firm’s well-known LMR series of flexible low-loss cables. The LMR-500 coaxial cables, for example, operate at a cutoff frequency to 12.6 GHz with better than 90 dB shielding effectiveness. With its low-loss insulation, the cable achieves a velocity of propagation of 86 percent. The cable is designed for indoor and outdoor use and can be used with a wide range of RF connectors.
The company also manufactures T-RAD-600 leaky feeder coaxial cables that serve as antennas for wireless systems in buildings, caves, mines, and other challenging RF environments. These cables show 1.34 dB/ft attenuation at 150 MHz and 6.4 dB/ft attenuation at 2.4 GHz. The cables are also useful for (buried) perimeter detection systems in highly sensitive areas that require special security, such as prisons, military facilities, and nuclear facilities.
Aeroflex Weinschel (www.aeroflex-weinschel.com), with a long history in precision attenuators and test equipment, added blind-mate connectors to their product mix several years ago. The firm’s 7008, 7034, 7035, and 7041 lines of threadless blind-mate connectors are ideal for integrating modules into larger subsystems. The connectors, which include SMA and 2.92-mm architectures, support applications from DC to 40 GHz. The model 7008 connectors, for example, are pressurized SMA-type connectors with maximum VSWR of 1.30:1 to 1.65:1 and maximum insertion loss ranging from 0.3 to 1.5 dB through 40 GHz. The connectors are generally used in a mated pair to provide electrical connections between multiple modules or a module and a subassembly.
Bird® Technologies Group recently released a new series of high power loads and attenuators that utilize the Bird 4200 Series “Quick Change” (QC) solderless connectors for hundreds of possible connector combinations. The new series of products allows users to quickly change the connectors for different applications while avoiding the need for special adapters, cables, or additional units with custom connectors. With power-handling capabilities beyond 150 W and frequency range past 2.5 GHz for the loads and attenuators, standard QC connector types include N, BNC, SMA, TNC, LC, 7/16 DIN, Terminal Lug (for DC applications), UHF, Mini UHF, HN, C, LT, SC, 7/8 EIA, and 1 5/8 EIA for both fixed- and swivel-mount applications.
IMS Connector Systems (www.imscs.com) has extended its range of Quick Lock Systems with SnapN connectors that are backward compatible with Type N connectors. They are suitable for applications up to 11 GHz and guarantee a minimum of 200 mating cycles. With their quick-lock mating mechanism, mounting tools are not needed. The connectors require less engagement force than Type N connectors and can be rotated in 360 deg.
Waterproof RF connectors from Intelliconnect (intelliconnectusa.com) have been successfully used in military locator beacon and radio applications. Tested to 10 m depth in an unmated condition for duration of four hours, the connectors (Fig. 2) have been shown to be highly effective and reliable in marine conditions in terms of both mechanical and electrical performance.
BMMA microminiature connectors are a new development from Delta Electronics Manufacturing Corp. (www.deltarf.com). The 50-ohm connectors, which are usable from DC to 28 GHz, feature dielectric withstanding voltage of 675 V RMS. The connectors exhibit VSWR of 1.25:1 at 20 GHz and insertion loss of 0.2 dB at 25 GHz. The leakage is –80 dB or better at 10 GHz.
Another trusted name in coaxial connectors, Southwest Microwave (www.southwestmicrowave.com), offers several lines of field-replaceable connectors, including the SuperSMA connectors. The SuperSMA connector provides mode-free operation through 27 GHz with better than –100 dB RF leakage. It is constructed in accordance with MIL-STD-348 requirements.
No story on cables and connectors would be complete without mention of Pasternack Enterprises (www.pasternack.com). The long-time supplier recently announced a series of MINI-SMP connectors that is about 70 percent smaller than standard SMP connectors. Capable of operating to 65 GHz, the 50-ohm connector is also suitable for high-speed digital systems operating to 40 Gb/s. The connector meets MIL-STD-202 testing requirements and mates with GPPO and SSMP devices.
Paternack also recently introduced microwave test cables for use with commercial vector network analyzers (VNAs). Usable from DC to 26.5 GHz, these test cables feature a unique interchangeable connector head that can be configured for a device under test (DUT) with a variety of connectors, including SMA, 2.92-mm, 3.5-mm, and 7-mm connectors.
Due to the number of different types of connectors used in RF and microwave applications, no workbench is complete without an assortment of coaxial adapters, Microwave Distributors Co. (MIDISCO, www.midisco.net) recently introduced a family of SMA-to-MCX adapters (Fig. 3). The 50-ohm adapters feature VSWR of 1.25:1 to 6 GHz and are rated for 500 mating cycles. They range in size from 0.832 to 0.942 in. and are fabricated from brass with a gold-plated finish.
Additional suppliers of cable assemblies include AAA RF Products (www.aaarfproducts.com), CST Cable (www.cstcable.com), Emerson Network Power (www.emersonnetworkpower.com), MegaPhase (www.megaphase.com), Microwave Devices, Inc. (www.mwdevices.com), RFMicrowavecable.com, and Spectrum Elektrotechnik GmbH (www.spectrum-et.org). Additional suppliers of connectors include Coaxicom (www.coaxicom.com), San-tron (www.santron.com), and Rosenberger (www.rosenbergerna.com). For the most complete listings of coaxial connectors and cable assemblies, please refer to the online version of the Microwaves & RF Product Data Directory issue, at www.mwrfpdd.com