Dual-mode bandpass filter using via less substrate integrated waveguide technology

Electroplating on dielectric is used to realize continuous metallic side walls of a substrate integrated waveguide (SIW). Thus the complexity of fabricating chain of metallic via using precise mechanical or laser drilling used in conventional SIW fabrication is avoided. To show effectiveness of the procedure, a single cavity dual-mode bandpass filter is designed and fabricated. A modified corner cut configuration, compatible with the via less fabrication technology, is used to obtain the dual-mode operation. The bandpass filter with microstrip lines as the external feed lines offers two transmission zeroes which is symmetrically placed on both sides of the passband. The filter has a fractional bandwidth of 5% at a center frequency 10 GHz.