Time domain processing of mutual coupling measurements

The benefits of modern network analyzers with time-domain processing are illustrated. An HP 8510B network analyzer was used to measure the isolation of waveguide apertures between 8 and 12 GHz. Waveguide to coax adapters used as antennas were mounted on a support beam in a lab room devoid of RF absorber. The measurements proceed by determining the 0-dB coupling level and zero time delay, which is measured by joining the connecting test cables together to obtain a calibration set. The system noise level is then measured to determine the dynamic range; the receiver requires a noise-only match load. E-plane coupling data for parallel waveguide apertures separated by 6 ins are shown. Time-domain processing for mutual coupling measurements is found to have two important advantages. First, displaying the individual coupling paths separated in time has diagnostic advantages. Second, removing facility reflections with windowing techniques permits measurements in existing facilities without the risk and expense of moving hardware to a specialized RF facility.<>