High permittivity circular dielectric resonator for 2-stage narrowband bandpass filter

The numerical investigation of 2-stage narrowband bandpass filter (BPF) constructed of high relative permittivity circular dielectric resonators (CDRs) is presented. Due to the use of CDRs, the filter which is proposed for microwave communication is expected to have better quality factor compared to lumped elements-based BPF. The used CDRs have resonant frequency of 3.6GHz±30MHz with dielectric constant of 45±1 and Q factor of more than 7000. To excite the CDRs obtaining the BPF response, microstrip lines deployed on an Arlon DiClad527™ dielectric substrate are applied. A metal shield made of aluminum is occupied surrounding the filter to avoid the electromagnetic interference. From the result, it shows that the proposed narrowband BPF has the fractional bandwidth of 2.9% with working bandwidth of 88MHz and center frequency of 3.07GHz. Moreover, the different configuration of microstrip lines excitation is also applied to investigate its effect to the working bandwidth as well as other filter parameters.