Compact dual-band microstrip band pass filter design based on stub loaded resonator for wireless applications

A simple, compact design of dual-band bandpass filter is introduced in this paper. The proposed filter is based on stub loaded resonator (SLR). It is composed of two stub loaded half wavelength open ring resonators. The design is performed in two steps to obtain the required dual-band response. The first band is produced by using two half wave open ring resonators while the other band is obtained by loading a stub to the half wave open ring resonator. The resulting bands are at 2.4 GHz and 4.3 GHz. The two bands are independent and can be tuned by varying the dimensions of the open ring and the stub respectively. The modeled filter was designed using Rogers TMM10 substrate with relative dielectric constant of 9.2 and thickness of 0.635 mm. The dimensions of the designed filter are found to be about 0.3λ
g
× 0.32λ
g
. Simulated results show that the proposed filter offered good transmission and reflection responses as well as high out of band rejection. Measured results are found to be in reasonable agreement with those predicted by the simulation. The parametric study performed for the designed filter shows that the dual band resonant behavior has a significant ratio of the resonant bands. This feature yields an adequate filter to be used for many wireless communication applications.