Computer-aided design of quadra-ridged waveguide transformers for full-band matching of half-height rectangular waveguides

A quadra-ridged waveguide transformer (QRWT) is proposed for full-band matching between a standard and half-height waveguide, which meets the need compact components multiple sections of irregular transmission lines better in wider operation bands. Unlike conventional circuits with monotonically changing impedances, QRWTs form abrupt cross-section changes line steps. The initial configuration QRWT built by CST MICROWAVE STUDIO, system-level electromagnetic compatibility general high frequency passive device simulation software, according to basic (EM) concept then optimized optimization functions from an advanced EM simulator, during optimization, releasing restrictions as many possible. To explain concept, sample designed match rectangular WR34 waveguide. reflection coefficient less than −24 dB full bandwidth, 21.7 33 GHz. has length 3.088 mm, 0.218 times wavelength at its center 27.35 For comparison, two-stage quarter-wave circuit optimized. similar coefficients same 57% shorter one, it easier manufacturing method using wire-electrode cutting. verify design, back-to-back was fabricated brass material without extra dielectric material. Its measured reflections are −16.6 dB, insertion loss 0.2 dB.