A 35 GHz low side-lobe leaky-wave antenna with periodic metallic grating structures of nonuniform width on the dielectric waveguide

A 35 GHz low side-lobe leaky-wave antenna has been implemented on an Inverted Strip Dielectric waveGuide (ISDG) by using periodic metallic grating structures with variation of the width of the metallic gratings. A method of mode matching is provided for determining the complex propagation constant of the leaky-wave antenna by Galerkin´s method. According to antenna theory, when the amplitude distribution of the aperture field on leaky wave antenna is designed as the rule of [I₀ cos²(θ·Z/L] along the Z propagation direction, the side-lobe level of -32.5 dB can be computed theoretically. The relations of amplitude variation as [I₀ cos²(θ·Z/L] in the leaky-wave antenna fields with the width variation of the metallic gratings have been derived numerically by computing imaginary parts [-ja] of the propagation constant. A 35 GHz low side-lobe leaky-wave antenna with periodic metallic gratings of nonuniform width on ISDG has been fabricated and measured