W-band EBG Loaded Band-pass Filter with Broadband and Low Loss Operation

A low insertion loss W-band band pass filter based on EBG structure is proposed in this paper. The stop band characteristic of EBG is adopted to achieve the low pass filter property, and the inherent high pass characteristic of rectangular waveguide is used to determine the lower limit of pass band. By combination of low pass and high pass structure realized by loading reduced width rectangular waveguide with micro-strip EBG structure and proper design of impedance matching, the broadband operation of the proposed filter covering 75 ~110 GHz is achieved. The EBG structure is fabricated on one side of a 5mil thick Rogers5880 substrate with a certain amount of E-plane periodically loaded resonators. A prototype of the filter is fabricated and measured. The measurement results show that the typical return loss is about -20 dB and -15 dB in 75 GHz～100 GHz and 100 GHz～110 GHz respectively, and the insertion loss is within 1 dB over the 75 GHz～110 GHz band. This filter can be widely used in a variety of W-band application systems and general test instruments.