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 some measurements are taken. The cutoff frequency of the band-stop filter is 2.25 GHz, with transmission loss of 2-dB. The 3-dB of the band-stop filter is 1.24 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 to achieve frequency agility by using ideal metallic switches. The cut-off frequency is moved to 1GHz, and the 3-dB bandwidth in 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 (DRA) 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 in 1GHz. Factors such as return loss, insertion loss, radiation pattern and mutual coupling of DRAF are calculated using finite element method (FEM). Comparison of calculation and measurement factors of DRAF shows a good agreement. [ABSTRACT FROM AUTHOR]