Self-Packaged Millimeter-Wave Substrate Integrated Waveguide Filter With Asymmetric Frequency Response

Substrate integrated waveguide (SIW) technology provides an effective solution for the low-cost and high-performance interconnect and packaging of microwave and millimeter wave systems. In this paper, Ka-band four-degree bandpass filters having asymmetric frequency response, which are required in the design of transmit and receive diplexers for high rejection between neighboring channels, are proposed and realized on an SIW platform. The filters are self-packaged due to the fact that a conductor-backed coplanar waveguide is used to directly excite the filters. Higher-order resonant mode is used to achieve the required negative coupling on the basis of a single-layer SIW. The proposed filters, having the same center frequency of 35 GHz and pass bandwidth of 1.3 GHz, are fabricated on a conventional Rogers RT/Duroid 6002 substrate with thickness of 0.508 mm by using a low-cost printed circuit board process. Measured results of those filters, which exhibit high single-sided selectivity and minimum in-band insertion loss of about 1.25 dB, agree well with simulated results.