New Method for Transformation of Microstrip Lowpass Filter to Compact Bandpass Filter Using Defected Ground Structure(DGS) Coupled Resonators

摘要

In this letter, bandpass filter development with the assistance of the Multi-Layer Transformation method, on the basis of the known Chebyschev-Lowpass Filter, is presented [1]. A new compact microstrip bandpass filter using three coupled Arrowhead-slots in Bottom-layer and a discontinuous 5012-microstrip Transmission Line in top-layer is Proposed [1]. Both microstrip lines are coupled by means of a J-Immitance inverter. If the width of the gap is changed, the center frequency would shift to the left or to right within a certain frequency range, and we can easily realize a tunable BPF. Three-pole-Chebyschev bandpass filter is fabricated, and tested at 7.25GHz.