Time-Domain Measurements of Microwave Components

Recent advances in microwave component measurements using time-domain techniques are described. After reviewing the basic elements of a time-domain system, a substitution procedure is applied to determine the insertion loss of wide-band attenuators. Comparison of these measurements with frequency calibrations shows agreement to within 0.1 dB in 10 dB for attenuators between 10-50 dB, over the frequency range 0.4-8 GHz. Error sources are resolved by experiments designed to isolate and evaluate various contributions including: random errors due to noise and drifts; systematic errors caused by substitution attenuator inaccuracies, line mismatch, deflection nonlinearities, and inaccurate time window widths; time-to-frequency translation errors of aliasing and truncation; and mechanical errors due to connect-disconnect cycles. Results show that random processes are responsible for most of the observed error. The reported measurements establish the calibration capabilities and the expected magnitude of individual system errors for the particular system tested.