Photonic choke-joint (PCJ) structures for dual-polarization waveguides have been investigated at NASA's Goddard Space Flight Center for use in device and component packaging. This interface enables the realization of a high-performance, non-contacting waveguide joint without degrading the in-band signal propagation properties. The choke properties of two tiling approaches — symmetric square Cartesian and octagonal quasi-crystal lattices of metallic posts — are explored and optimal PCJ design parameters are presented. For each of these schemes, the experimental results for structures with finite tilings demonstrate near ideal transmission and reflection performance over a full waveguide band.
A waveguide joint is the location where two waveguides are connected to produce a reliable contact between them. In general, two waveguides must be accurately aligned and have good electrical contact at the joint. This can be done by having two waveguide flanges with flat surfaces physically contact each other.
The purpose of this innovation is to produce a reliable, highly efficient, and noncontact joint for waveguides with dual polarizations. The dual-mode waveguide interface is comprised of two flanges. One waveguide flange is a flat surface perpendicular to the waveguide wall. The other flange is made of rows of metallic pillars tiled in either Cartesian or Archimedean patterns. The spacing between two flanges has to be lower than a certain value to ensure low-loss and spurious-free power transmission in the operating band. Since the waveguide photonic choke-joint is constructed from metallic conductor, it can be operated at a wide temperature range without much degradation in its performance. It provides power leakage of less than 3% and is suitable for low-power waveguide applications. The PCJ is constructed from a conductive metal and requires no maintenance or peripheral equipment to operate.
This technology can be used for thermal breaks for telecommunication equipment and instruments; non-destructive testing for thin materials; waveguide switches, phase shifters, and rotating feed networks; and to provide housing for planar circuits to increase functionality of the waveguide.