Dispersion and Filtering Properties of Rectangular Waveguides Loaded With Holey Structures

TL;DR

This paper thoroughly analyzes the dispersion and filtering properties of periodic holey waveguides, demonstrating their advantages for low-loss phase shifters and filters in millimeter-wave applications through simulations and prototypes.

Contribution

It introduces a detailed parametric study of holey waveguides with glide and mirror symmetries, highlighting their superior dispersion characteristics and practical filter and phase shifter designs.

Findings

Holey waveguides with glide symmetry offer higher propagation constants and lower dispersion.

Glide-symmetric holey waveguides are less dispersive than those with glide-symmetric pins.

Prototypes validate the design of a wideband phase shifter and a band-reject filter.

Abstract

This paper analyzes thoroughly the dispersion and filtering features of periodic holey waveguides in the millimeter-wave frequency range. Two structures are mainly studied depending on the glide and mirror symmetries of the holes. A parametric study of the dispersion characteristics of their unit cells is carried out. Glide-symmetric holey waveguides provide a higher propagation constant and a low dispersion over a wide frequency range regarding hollow waveguides. This property is particularly useful for the design of low-loss and low-dispersive phase shifters. We also demonstrate that glide-symmetric holey waveguides are less dispersive than waveguides loaded with glide-symmetric pins. Furthermore, we perform a Bloch analysis to compute the attenuation constants in holey waveguides with mirror and broken glide symmetries. Both configurations are demonstrated to be suitable for filter design. Finally, the simulation results are validated with two prototypes in gap-waveguide technology. The first one is a 180$^{o}$ phase shifter based on a glide-symmetric holey configuration that achieves a flat phase shift response over a wide frequency range (27.5\% frequency bandwidth). The second one is a filter based on a mirror-symmetric holey structure with 20-dB rejection from 63 GHz to 75 GHz.