Application of dielectric resonator based metamaterial in waveguide coupler

In this study, an implementation of the metamaterial structure is used in a waveguide directional coupler. For this purpose, a four-hole waveguide directional coupler in X-band is designed. Then, the block of dielectric-resonator array is inserted between isolation port and holes of the coupler, and the performances of the coupler with and without dielectric resonators are compared in terms of the coupling and isolation. The obtained results show that the coupler with dielectric resonators significantly improves the coupling and isolation performances at a new operation frequency band at which the traditional coupler does not work. Therefore, the metamaterial structure attains multi-band characteristics to the coupler. Besides, this new frequency band can be shifted by arranging the distance between the dielectric resonators and holes. Finally, it is also observed that the bandwidth of the new frequency band can be increased by using more dielectric resonators in the array.