Miniaturized synthetic rectangular waveguide

Abstract

An artificially engineered, dielectric-filled rectangular waveguide is presented. Such synthetic waveguide, made by conventional printed-circuit board (PCB) process, consists of two-dimensional periodical arrays at the top and bottom surfaces and two metallic sidewalls. A synthetic waveguide of cross-section 8.0 mm by 0.609 mm relative permintivity (epsilon(r)) 3.38, shows cutoff frequency at 4 GHz with normalized propagation constant asymptotically approaching 4.5 at frequencies much greater than the cutoff frequency. Rigorous measurements show that the extracted dispersion curves agree well with theoretical data, demonstrating the feasibility of size reduction of the synthetic rectangular waveguide breaking the well-known limit of 1/rootepsilon(r) imposed on the conventional rectangular waveguide. Measured data show that the slow-wave factor is 185% higher and cutoff frequency 61.9% lower when comparing the synthetic waveguide with the conventional waveguide of identical dimensions and material constant.