Dual 7-port automatic network analyser with swept-frequency real-time response

The first prototype of a real-time swept-frequency multiport network analyser for general laboratory use is reported in the paper. It has been designed for use from 2 to 12.5 GHz, but has been operated mainly over the range 3.75 to 7.5 GHz with most results over a narrower range of 4 to 4.5 GHz. It makes simultaneous measurements of all four S parameters of a two-port device which are presented as an animated graph upon a high resolution colour display. Inaccuracies of ¿¿0.5 dB in 20 dB (transmission) and ¿¿0.1 dB (reflection) are obtained over an octave bandwidth. Complete 256-point stepped frequency measurements are completed every 0.7 s enabling the visual tuning of adjustable, active as well as passive devices. Calibration is considerably simplified by novel procedures using four calibrating terminations, three of which are independent of frequency along with a nonstandard variable power splitter.