Title :
A Compact Open-Loop Filter With Mixed Electric and Magnetic Coupling
Author :
Chu, Qing-Xin ; Wang, Huan
Author_Institution :
South China Univ. of Technol., Guangzhou
Abstract :
A novel cascaded microstrip open-loop resonator filter with controllable electric and magnetic mixed coupling is presented to have one or more transmission zeros. For two coupled resonators, the coupled sides with the maximum magnetic field are combined with their open gaps with the maximum electric field, creating the electric and magnetic mixed coupling. By adjusting the distances between resonators and the positions of open gaps in a mixed coupled filter, the coupling coefficients can be changed, and controllable transmission zeros can be produced in the lower stopband, upper stopband, or both. Design and fabrication of the proposed second-and fourth-order filters show the advantages: such as a smaller number of resonators, higher rejection level, as well as asymmetrical response; moreover, the location of the transmission zeros can be precisely controlled.
Keywords :
band-pass filters; cascade networks; coupled circuits; microstrip filters; resonator filters; cascaded microstrip open-loop resonator filter; coupled resonators; electric coupling; fourth-order filters; magnetic coupling; mixed coupled filter; mixed coupling; second-order filters; transmission zeros; Band pass filters; Costs; Coupling circuits; Design methodology; Filtering theory; Frequency; Magnetic resonance; Magnetic separation; Narrowband; Resonator filters; Bandpass filter; electric and magnetic mixed coupling; transmission zero;
Journal_Title :
Microwave Theory and Techniques, IEEE Transactions on
DOI :
10.1109/TMTT.2007.914642