A W-band homodyne vector network analyzer with variable measurement port distance

Abstract

A homodyne network analyzer is presented that covers the frequency range from 92 to 100 GHz. The W-Band waveguide setup consists of two identical measurement heads, one of which is movable in order to accommodate devices under test (DUT's) of arbitrary length. The millimeter wave signal is fed to the moving head through a novel quasi-optical line stretcher. A new calibration procedure has been de- veloped for the special setup. I. INTRODUCTION OMMERCIALLY available vector network analyzers C (VNA's) for the millimeter waveguide bands are based on the heterodyne principle with harmonic downconversion. The necessary components (microwave network analyzer, two mi- crowave sources with at least one of them synthesized, har- monic mixers, low-noise amplifiers, etc.) are very expensive. A homodyne analyzer that requires only a single source and a comparatively small microwave setup may be a cost-effective solution for measurement tasks where the necessary frequency coverage does not exceed a waveguide band. Former homodyne designs (l), realized as a waveguide setup, suffer from unflex- ible line lengths. The requirement of adapting a DUT to the VNA by special waveguides has been eliminated by making one of the measurement heads movable and feeding the signal to it through a quasi-optical line stretcher. Furthermore, the design presented here allows the measurement of all S-parameters' without reversing the DUT.