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International Journal of Antennas and Propagation
Volume 2014, Article ID 916927, 6 pages
Research Article

A Miniaturize Bandpass Filter with Harmonic Suppression Using Meandered Quarter-Wavelength Resonators

1Department of Information Science & Electronic Engineering, Zhejiang University, Hangzhou 310027, China
2Hangzhou RFID Research Center, Chinese Academy of Sciences, Hangzhou 310011, China
3Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China

Received 3 November 2013; Accepted 12 December 2013; Published 18 February 2014

Academic Editor: Said E. El-Khamy

Copyright © 2014 Yun-Long Lu 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.


A miniaturized bandpass filter with harmonics suppression is presented. The proposed filter consists of two quarter-wavelength microstrip resonators, which are meandered for circuit size reduction. An interdigital capacitor, loading at zero-voltage point, is employed to provide the desired coupling between the resonators at operating frequency, whereas the coupling coefficient at the third harmonic is realized to be zero. Besides, the second and fourth harmonics are suppressed since λ/4 resonators are adopted. Benefiting from these properties, a miniaturized bandpass filter with the second, third, and fourth harmonics suppression was designed and implemented. The final measured and simulated results show good consistence with the theoretical counterparts.