Investigation on Beam Scanning Speed of Hybrid Leaky-Wave Antenna for Millimeter-Wave Application

A hybrid asymmetric folded substrate integrated waveguide (AFSIW) and spoof surface plasmon polaritons (SSPP) combined waveguiding structure is employed to design a dual-band frequency-scanning leaky-wave antenna with slower beam scanning speed at forward region $(30^{\mathrm{o}} < \theta < 62^{\mathrm{o}})$ and faster beam scanning speed at backward region $(-56^{\mathrm{o}} < \theta < -18^{\mathrm{o}})$ specifically. The waveguide structure is obtained by cutting a vertical AFSIW in half along its longitudinal symmetrical plane and adding SSPP structure along one side of middle copper layer of AFSIW. The n = 0 dominant mode remains at lower frequency band and the n = -1 space harmonic mode is generated effectively by sinusoidal modulation.