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International Journal of Antennas and Propagation
Volume 2017 (2017), Article ID 2398610, 7 pages
Research Article

Hybrid Microstrip/Slotline Ultra-Wideband Bandpass Filter with a Controllable Notch Band

1School of Information Engineering, East China Jiaotong University, Nanchang 330013, China
2Department of Electrical and Computer Engineering, University of Macau, Taipa 999078, Macau

Correspondence should be addressed to Xuehui Guan

Received 13 March 2017; Revised 1 June 2017; Accepted 2 July 2017; Published 31 July 2017

Academic Editor: Angelo Liseno

Copyright © 2017 Xuehui Guan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


An ultra-wideband (UWB) bandpass filter (BPF) with a controllable notch band is presented by using hybrid microstrip/slotline structure. Firstly, a slotline resonator with symmetrically loaded stubs is fed by two microstrip lines to produce a UWB bandpass filtering response. Secondly, a microstrip triangular loop resonator is externally loaded over the slotline, and a notch band is introduced in the UWB passband. The notch band is determined by the perimeter of the loop resonator. Thirdly, two patches are added as the perturbation element to the corners of the microstrip resonator to excite a pair of degenerate modes. Bandwidth of the notch band can be tuned by properly selecting the patch size. Circuit model for the microstrip resonator loaded slotline is given and studied. Finally, the filter is designed, simulated, and measured. Measured results have agreed well with the simulated ones, demonstrating that a UWB filter with a controllable notch band has been realized.