This paper proposes asymmetrical step-impedance resonators bandpass filters (ASIRs) for suppressing a wide stopband, ensuing in size reduction and ease of fabrication. The filters have been designed at the operating frequency around 2.0 GHz using half- and quarter-wavelength asymmetrical step-impedance resonators. The concept of existent odd- and even-mode characteristics is used to approve the proposed filter structure. The filter can not only suppress the unwanted signals more than 10 f0, but also produce low passband insertion loss and high return loss. A good agreement is obtained between the simulation and measurement results.
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