Design of Defected Ground Structure Band Stop/Band Pass Filters Using Dielectric Resonator

A square dielectric resonator element (SDR) with a defected ground structure (DGS) is investigated. The proposed DGS is composed of two rectangular slots connected by two transverse slots and is placed in the ground plane. It is fed by a strip line through the substrate layer. The objective of this structure is to design dielectric resonator band- stop filter (DRF) and enhance the performance in terms of better insertion loss and increased bandwidth. The DRF has been fabricated and measurements are taken. The results for band- stop filter show a cut-off frequency of 2.25 GHz, transmission loss of 2 dB and the 3-dB bandwidth ranges from 1.4 to 2.64 GHz. The effect of the transverse slot width on the filter response curve is studied. The same structure is modulated to be frequency reconfigurable DRF for achieving frequency agility by using ideal metallic switches. The cut-off frequency is shifted by 1 GHz, the 3-dB bandwidth by 1.5 GHz, while the transmission loss is decreased by 0.75 dB. Finally, the effect of loading SDR with metal plate is investigated. This structure combines the dielectric resonator antenna and the DRF to propose dielectric resonator antenna filter (DRAF), this structure is used to miniaturize the global-positioning-system receivers that contain both the antenna and filter. The DRAF has been fabricated and measured, it has 3-dB pass bandwidth of about 1 GHz. Factors such as return loss, insertion loss, radiation pattern and mutual coupling of DRAF are calculated using Finite element method. Comparison of calculated and measured factors of DRAF shows a good agreement.