Design of microstrip‐line bandpass filter based on reflected characteristics in time domain

As an inverse scattering problem using the one-dimensional Transmission-Line Matrix (TLM) method, it is possible to derive the transmission line shape from an arbitrary reflection characteristic in the time domain. In this paper, a bandpass filter consisting of microstrip lines is designed based on this TLM method. In the designed filter, there is a frequency shift of the filter characteristics toward the lower frequencies, which is caused by the phase shift at the discontinuity. An improvement method is proposed in which transmission line correction is performed on the basis of the LC equivalent circuit of the impedance discontinuity. Its usefulness is experimentally verified. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 89(3): 1–9, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20221