Hybrid microstrip/NRD-guide filter with enhanced upside stop-band rejection

Abstract

This paper presents a new technique relative to the design of hybrid planar/NRD-guide filter for millimeter-wave integrated circuits and systems. Spurious moding problems of the previous design approaches are studied and a new mode-suppressing scheme is proposed and used in this filter design. The filter performance is effectively improved, especially for the upside stop-band rejection. It is shown that both the hybrid planar/NRD transition and the developed mode suppressor are able to reduce all the spurious modes to a required level. This design technique provides a useful solution to higher performance planar NRD-guide filter at millimeter-wave frequency.