A Simplified Method to Synthesize UWB Compact Bandpass Filter with Dual Notch Bands

Abstract

This paper presents a simplified method to synthesize a new and compact UWB bandpass filter with good selectivity, wide bandwidth and two notched frequencies at 5.2GHz and 7.8GHz. UWB bandpass is created by cascading highpass and lowpass filters. The proposed work uses network synthesis techniques to design highpass and lowpass filters with Chebyshev transfer function using insertion loss method. The optimized low pass and high pass circuits are implemented with the help of hairpin line and interdigital structure (IDS), respectively. The open ended stub and spurline are loaded on the outermost fingers of IDS to create notches at 5.2GHz and 7.8GHZ frequencies, respectively. The size of the filter is highly miniaturized and compact in shape when compared with the other existing structures. The insertion loss in the pass band of the filter is smaller than 0.4dB and stop band is wide. Filter is fabricated on FR4 with dielectric constant 4.4 and thickness of 1.6mm.