Reduction of losses in dielectric waveguide Y-junctions with wide aperture angles

Abstract

In this work, symmetrical Y-junctions made of rectangular dielectric guides are studied theoretically and experimentally. Using the effective dielectric constant method (EDCM), the dielectric guides are transformed into equivalent slab guides; after that, the junction is analysed as a discrete discontinuity located in a single plane transverse to the propagation axis. The experimental results agree very well with the theoretical predictions which indicate that there should be dimensions of the dielectric guide of the junction which optimize the transmission coefficient for a given angle and frequency. If wide aperture angles are required and image guides are used in making the junction, high losses appear; to diminish the former losses we have used Π guides in which the dielectric inside the window has a greater permittivity than the rest of the guide; metallic shields were also employed for the same purpose. These modifications improve the transmission coefficient, in some cases by nearly 5 dB