Long Slots Array Antenna Based on Ridge Gap Waveguide Technology

Ridge gap waveguide (RGW) technology is used in the design of a frequency scanning antenna with high gain and directivity. A Quasi-TEM horn with shaped ridge is designed as a guiding structure between two metallic surfaces. The waves are suppressed beyond the shaped ridge area between the metallic surface and the artificial magnetic conductor (AMC); realized by a bed of conducting nails. The ridge is shaped to generate uniform field distribution in the enclosed air gap. Non-resonance radiating long slots are introduced in the top metallic layer. Since the slots are separated by a guiding wavelength, a grating lobe in the visible region exists. The structure is built and tested. Good agreement between measured and simulated results is obtained with an average gain of 14.5 dBi within a bandwidth of 22%. To reduce the grating lobe, two different techniques are proposed. These techniques achieve a reduction in the grating lobe and enhance the antenna gain to an average gain of 18.5 dBi.