Novel miniature slow-wave resonator filter using multilayer LCP circuit technology

This paper presents a novel microwave bandpass filter using microstrip slow-wave open-loop resonators and multilayer liquid crystal polymer (LCP) technologies. The new filter has not only very compact size due to the slow-wave effect, but also exhibits a ultra-wider upper stopband resulting from the dispersion property. A five-pole microstrip filter of this type, i.e., a bandpass filter centered at f
_c
=1.18 GHz with -3dB fractional bandwidth of 17%, has been designed and fabricated. No spurious response, which are at least 30-dB rejection, occurs for the frequency up to 10GHz. Moreover, the fabricated filter also has the compact size of 0.102λ
_g
× 0.081λ
_g
and the light weight less than one gram by using multilayer LCP circuit technology. Good agreement can be observed between the simulation and measurement.