Millimeter-Wave High-Gain Substrate Integrated Multi-Slot Antenna Array with A Low Cross Polarization Level

In this paper, a Q-band substrate-integrated waveguide (SIW) based multi-slot antenna array with a very low cross-polarization level is developed. The proposed antenna element is composed of a 2×2-slot subarray in the top substrate layer, fed through a transverse coupling slot from the feeding SIW in the bottom substrate layer. Following this, a two-layer antenna array with eight subarrays is fed with a star-shaped eight-way SIW power divider with a centrosymmetric geometry, which contributes to an enhanced low-cross polarization level. Good agreement is achieved between the simulation and the measurement, which shows that the proposed antenna array covers an impedance bandwidth (|S
₁₁
|<; -10 dB) of 4.9% from 44.1 to 46.3 GHz with a peak gain of 19.9 dBi and a co-to-cross polarization ratio more than 45 dB and 44 dB in E-and H-plane, respectively. The measured antenna efficiency at 45GHz is 85.1%.