Channel Dropping and Branching Filters Using NRD-guide for Millimeter-Wave Integrated Circuits

As is generally known, dielectric waveguides have low-loss characteristics in the millimeter-optical-frequency range. The dielectric waveguide is necessary to be bent when it is used for a filter. However, it has radiation losses due to the bend. In order to lower the bending losses, nonradiative waveguides are being studied widely. This paper describes applications of nonradiative dielectric waveguides to filters and presents the measured characteristics of newly designed filters. A comparison of the bending losses is also presented for three kinds of waveguides, namely dielectric waveguide, aluminum plated dielectric waveguide and nonradiative dielectric waveguide. As a result, 0.7 dB of insertion loss was obtained for a ring type channel dropping filter, and 0.5 dB for a periodic branching filter in 20 GHz band.