CABLE ASSEMBLIES have long been known as "the weak link" (forgive the pun) in any precision microwave test system. Experienced engineers have even resorted to creating fi xtures for their broadband test cables, keeping them from moving in a given test setup and changing the phase and amplitude values of a measurement. Such histrionics are no longer necessary with the Stability RF/microwave cable assemblies from Maury Microwave, which provide amplitude- and phase-stable measurements through 40 GHz even with fl exure. The Stability cable assemblies include the Series SC-35 cables (for use from DC to 26.5 GHz) and the SC-292 models (for applications from DC to 40 GHz).
These Stability cable assemblies (Fig. 1) are suitable not only for use with microwave/ millimeter-wave vector network analyzers (VNAs), but also for any kind of high-frequency prototype or production testing where measurement accuracy is a concern. The amplitude stability with flexure numbers for these cable assemblies are eye-popping, at 0.02 dB through 26.5 GHz for the SC-35 cables and 0.05 dB through 40 GHz for the SC-292 cables. Considering the upper-end frequencies of these cable assemblies, the typical phase stability with flexure characteristics are as impressive, at 3.5 deg. through 26.5 GHz for the SC-35 cables and 5.0 deg. through 40 GHz for the SC-292 cables. And these are not cable assemblies that have to be treated gently: They are designed for long operating lifetimes with minimal performance degradation.
The 50-Ω cable assemblies, which feature a silver-plated, copper-clad steel center conductor, have a minimum bend radius of 1 in. In addition to the center and outer conductors, the cables contain an inner braid layer, an inner jacket, a crush protection layer, a braided strength member, and a braided outer jacket. The combination adds to a crush resistance of greater than 260 lbs/in. of cable. The RoHs-compliant cable assemblies weigh 1.61 oz. per foot of cable and are available in standard lengths of 24, 36, 48, and 60 in. SC-35 cable assemblies are fitted with 3.5- mm male coaxial connectors while SC-292 cable assemblies are terminated with 2.92- mm male connectors.
The mechanically durable cables offer excellent overall electrical performance, with low insertion loss and low VSWR across their full frequency ranges. The typical insertion loss for the cables is 0.84 dB/ ft. for the SC-292 assemblies and 0.67 dB/ ft. for the SC-35 cable assemblies (Fig. 2). The typical VSWR for either cable assembly type is 1.25:1, with a maximum value of 1.40:1 through 40 GHz for the SC292 cables and maximum VSWR of 1.35:1 through 26.5 GHz for the SC-35 cables. In addition to their phase stability with flexure, the cable assemblies are also phasestable with temperature, at better than 4/m/GHz from -55 to +125C.
Series SC-292 and SC-35 Stability cable assemblies are also characterized by shielding effectiveness (SE) better than 90 dB from DC to 18 GHz. They exhibit nominal time delay of 1.3 ns/in. (4.4 ns/m) with nominal velocity of propagation of 76%. With their excellent electrical performance and outstanding durability, they will help lower the total cost of test for any prototype or production test setup.
MAURY MICROWAVE, INC., 2900 Inland Empire Blvd., Ontario, CA 91764-4804; (909) 987-4715, FAX: (909) 987-1112, www.maurymw.com.