Novel planar lowpass filter using microstrip rectangular patch and high-impedance cells for wireless communication systems

摘要

This paper presents a novel microstrip lowpass filter. The proposed filter consists of two high impedance cells, which are integrated by a stub loaded transmission line. A rectangular stub is utilized to reduce the overall circuit size so that it has a compact size of 0.0135 λg 2 where λg is the guided wavelength calculated at -3 dB cut-off frequency of 2.5 GHz. In comparison to the published papers referred in this paper, a good figure-of-merit is obtained, which indicates this filter is designed correctly. An approximated LC circuit is introduced to analysis the configuration of proposed structure. Based on transmission line theory, the lumped elements are calculated. Then the LC model is simulated where the obtained results are similar to EM simulator approximately. To verify the design methodology, the proposed filter is fabricated and measured. There is a good agreement between the simulation and measurement results.