High gain and improved waveguide slot antenna using a metallic superstrate as main radiator

A new waveguide slot antenna using radiating surface as the superstrate has been proposed. A simple metal sheet as the ultimate radiating surface due to its larger size leads to higher gain compared with a standalone slot. The proposed configuration is composed of an extended wall on a waveguide, incorporating a slot together with a metal sheet as superstrate. The proposed antenna, which can be classified as a resonance cavity antenna, compared with the conventional one, has improved antenna gain and bandwidth simultaneously. Based on cavity model, the distribution of currents on the radiating surface has been explained. It has been shown that the proposed configuration enhances the antenna peak gain from 6.7 to 12 dBi and in the same time, antenna bandwidth from 5.8% to around 23% compared with the conventional one. The design method is straight forward and based on optimisation using simulation software. In addition to gain and bandwidth enhancement, the proposed configuration has some advantages in terms of simple design method and fabrication cost. To validate the simulation results, the proposed antenna is designed, fabricated and measured. Measured and simulated results are in good agreement that confirms the performance of the proposed structure.