A Compact Ultra-wideband Bandpass Filter Withultra-fine Conductor Trace Based On Liquidrncrystal Polymer Substrates

摘要

Purpose - Liquid Crystal Polymer (LCP) materials are considered to be promising substrates for wireless applications because of their excellentrnproperties. The purpose of this paper is to describe now a novel and compact microstrip ultra-wideband bandpass filter (UWB BPF) with ultra-finernconductor traces working over 22 to 29 GHz is fabricated on LCP substrates.rnDesign/methodology/approach - Using standard processing technology, such as photolithography, plasma pretreatment, sputter deposition andrnwet etching, a microstrip UWB BPF is fabricated on LCP substrates. In order to obtain better adhesion between LCP substrate and copper, the oxygenrnplasma pretreatment of the LCP substrate surface and a thin titanium adhesion layer are introduced before a copper layer is sputter-deposited onto thernsubstrate.rnFindings - The measured and the simulated results agree well. The measured insertion loss is about 8 dB in the passband of the bandpass filter, whichrnis a little high compared to the simulated result (～5 dB). The out of band performance at both the high frequency and low frequency is very good,rnalmost higher than 35 dB.rnOriginality/value - This paper presents the realization of (UWB BPF) working over 22 to 29 GHz based on an LCP substrate, which demonstrates thernfeasibility of the application of the LCP substrate in RF wireless systems and also gives some useful information for later research.