Differential phase shifters using corrugated, ridge, and fin loaded waveguides

Abstract

One means of converting the port conditions of a magic-tee into those of a 908 hybrid is to introduce external sections of waveguide at the symmetrical H-plane output ports having the necessary 908 phase difference. The purpose of this article is to describe a number of realizations of such differential phase shifters (DPS), including an exact synthesis procedure not requiring computer optimization. A typical design consists of a capacitively loaded waveguide for one section and an essentially inductive waveguide for the other. The latter is simply a uniform waveguide of reduced width when compared with that of the capacitive section. An example capacitive ridge DPS exhibits a maximum phase error of 628 over a 20% bandwidth in WR75 waveguide with a return loss of better than 40 dB and an insertion loss <0.06 dB.

Parametric Design of a Class of Full-Band Waveguide Differential Phase Shifters

“…Depending on this shift accuracy, a DPS with the same electrical performance may show different bandwidths. Corrugation-based DPSs [8][9][10] exhibit a quadratic-like phase difference curve that rapidly deviates from the desired phase value; however, ridge-based DPSs show a cubic-like curve, which widens the frequency range with controlled phase error. This feature, together with the aforementioned increased mono-mode bandwidth, clearly points at ridge DPS as the best solution for waveguide wideband applications.…”

“…Unfortunately, this configuration requires a reference line with a different physical length, which may affect the circuit symmetry and integration. The use of waveguide corrugations [8][9][10] has demonstrated good electrical results in designs with up to 30-35% bandwidth. The combination of high return loss, small shift errors and large bandwidths in these structures requires a large number of corrugations, thus affecting the compactness and easy-machining concepts.…”

“…The combination of high return loss, small shift errors and large bandwidths in these structures requires a large number of corrugations, thus affecting the compactness and easy-machining concepts. Finally, metallic ridges synthetized with fins or pins following stepped or continuous profiles have emerged as the best solution for their electrical performance [10][11][12][13]. However, among these last DPSs, those implemented with pins or smoothed profiles are more challenging during their design stages and show a noticeable increase in mechanical complexity, resulting in higher costs.…”