The Accu-Test™ products are a family of precision cable assemblies that are designed for use in the DC to 40 GHz frequency range, intended to facilitate accurate measurements and exhibit low loss characteristics at a competitive price for precision test and measurement applications. The family is currently comprised of cable assemblies for the 26.5 and 40 GHz areas, and feature exceptional phase and amplitude stability with flexure for more precise measurements. The new cables are crush and kink resistant to give them longer life, and are easy to use due to their flexibility. In addition, they are available with phase matching options making them ideal for highly accurate comparative measurements.
Performance
When measured at 40 GHz, the Accu-Test™ cable assemblies exhibit a phase stability under ±3° typical and ±6° max. The test method used to achieve these data is a 90° bend clockwise, followed by a 90° bend counter-clockwise, followed by a relaxed lay. The bend is around a 4" diameter mandrel. The typical values are reported at room temperature, while the maximum values are worst case from each position. Figure 1 shows typical phase vs. flexure performance to 40 GHz. SWR for a 6 ft. coil is 1.3 typ DC to 40 GHz.
Insertion loss, shown in Figure 2 , is specified at 0.94 dB/ft. or 3.1 dB/meter. Loss stability (that is, amplitude stability) is 0.1 dB max loss/gain relative to the zeroed cable after bending 90° in opposite directions around a 4" diameter mandrel.
The recommended operating temperature is primarily room temperature where the temperature is relatively stable. The cable assemblies are capable of operating from -55° to +125°C; however, Storm's Phasemaster™ line of phase stable assemblies are recommended for applications requiring consistent phase over a broad temperature range.
Cable Construction
The core cable construction, shown in Figure 3 , begins with expanded polytetrafluoroethylene (PTFE) on a silver-plated copper center conductor (1). This is covered with a silver-plated copper flat wire braid (2) and overlapped with aluminum-polyester ribbon (3). Special binding adhesive tape is applied next (4, 5), then covered with a silver-plated copper braid (6) and finally a fluoroethylene propylene (FEP) jacket (7) provides the outer cover. The Accu-Test cable assemblies are available with 2.4 mm NMD jack, 2.9 mm jack or 2.9 mm plug connector interfaces.
There is an armoring option designed for both inside and outside environments, where the application requires the ultimate in cut and crush resistance. This cable is covered with stainless steel interlock armor. An additional polyolefin jacket is standard.
A ruggedized option is also available designed for applications where weight, flexibility and abrasion resistance are critical. This cable is covered with a flexible wound helix of passivated stainless steel wire and an extruded polyurethane jacket.
Conclusion
A new family of precision cable assemblies has been introduced that offers more precise measurements due to their superior phase and amplitude stability with flexure. The cables are easy to use and feature longer life, largely due to increased flexibility and resistance to crushing and kinking, at a competitive price. More information may be obtained from the company's Web site at www.stormproducts.com.
Storm Products, Woodridge, IL (630) 754-3300. Circle No. 306