Radiation Characteristic Improvement of Ku-Band SIW Horn Antenna using Probe-Feeding Technique

In this paper, a coaxial to substrate integrated waveguide (SIW) transition is integrated with Ku-band SIW H-plane horn antenna to improve the radiation characteristic over the desired operating band. The probe-fed SIW horn is realized on a λ
₀
/13 (λ
₀
, being calculated at the center frequency) thin substrate and loaded with a multi-layer multi-dielectric impedance transformer (MLMDIT) at its aperture. The MLMDIT is basically a three-layer multi-dielectric structure which reduces the aperture mismatch over a wide operating band. The materials of high dielectric values are used to realize the top and bottom layers of the MLMDIT, while the substrate extended from horn aperture acts as its middle layer. The use of high dielectric constant material to realize the top and bottom layers of the MLMDIT facilitates the wideband operation while maintaining the overall thickness to 0.2λ
₀
at 15 GHz. The fabricated prototype is relatively simple, compact and thin. The experimental result show -10 dB reflection coefficient bandwidth of 34.73% (12.9-18 GHz). The observed end-fire radiation pattern is fairly stable and undistorted throughout the operating band with maximum gain of 7.5 dBi.