CAT-7 Cable Evaluation for Square Kilometre Array Analogue Signal Transport

Abstract

Data-cable systems are essential for an evolving Square Kilometre Array (SKA) phasedarray demonstrator project. Loss, dispersion and channel coupling are the characteristics of interest. We evaluate a Category 7 (CAT-7) cable system, which incorporates a 20 m CAT-7 cable, balun transformers, and ARJ45 connectors. Measurements from 30 MHz - 1.5 GHz are made using a calibrated Vector Network Analyzer (VNA). Through, Reflect, Line (TRL) as well as Short, Open, matched Load, Through (SOLT) calibration techniques were performed, which separately test the cables and the entire system performance respectively. A further measurement isolates the baluns. The connectors and baluns are mounted on customised printed circuit boards. We investigated phase dispersion, return loss, attenuation, near-end crosstalk (NEXT) and far-end crosstalk (FEXT). The best system was found to have a linear phase response in the 30 MHz to 1.4 GHz band, with NEXT and FEXT levels below -50 dB and -63 dB respectively. Such performance makes this cable class a candidate for high-volume data streams anticipated for the SKA.