A compact dualband filter with wide upper stopband using folded stepped impedance resonators (SIRs) and open stub is presented in this letter. The anti-parallel coupled SIRs are used for the realization of the dual passband and open stubs for the widening of the upper stopband. The SIRs are folded for the compact filter size. Two different folding structures are investigated for the size compactness and the frequency response of the filter. The wide stopband is useful for suppressing harmonics and noise in the RF circuit. Dualband filters at frequencies of 2.45/5.25 GHz and 2.45/5.75 GHz are realized. The wide and deep upper stopband as well as deep mid-stopband are achieved. The size of the filters are less than 190 mm2 on a RO 4003C (εr = 3.38, h = 0.81 mm) substrate.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Condensed Matter Physics
- Electrical and Electronic Engineering