Multilayer LCP Millimeter-Wave Broadband Reflectionless Bandpass Filter Based on Broside Coupling

This report proposes a millimeter-wave broadband reflectionless bandpass filter which is integrated by a bandpass filter and a bandstop filter. The bandpass filter is constructed by cascaded coupling lines, and the bandstop filter is constructed by a coupling line and a stub line. By adopting the hybrid broadside coupling structure of a coplanar waveguide and a microstrip, the broadband characteristics of the filter can be realized. At the same time, broadband reflection wave absorption is introduced in the auxiliary channel by two cascaded bandstop filters. The reflectionless bandpass filter centers at 47GHz with a fractional bandwidth of 62%, insertion loss of 1.04dB, and out-of-band suppression of more than 17dB. The return loss of the reflectionless bandpass filter is better than 10dB from 22.88GHZ to 68.52GHz, meanwhile, high frequency selectivity is also realized.