Wideband and High-Gain Substrate Integrated Folded Horn Fed Open Slot Antenna

This article presents a novel substrate integrated folded horn fed open slot antenna with wide bandwidth and high gain for millimeter wave (mmW) applications. The antenna has a three-layer planar structure including a pair of open slot radiators and two substrate integrated H-plane horns (SIHs) which are incorporated as the feed to generate quasi-TEM wave excitations. A folded SIH structure is introduced which reduces the antenna size by 37%. To improve the gain and radiation patterns, the proposed antenna is designed with differentially fed excitations. The measured results validate that the antenna achieves a wide impedance bandwidth of 54.4% from 52.3 to 91.4 GHz and a peak gain of 16.3 dBi. Meanwhile, the radiation patterns are stable throughout the operating bandwidth with low cross-polarization, side lobe, and back lobe levels. The proposed wideband, high-gain, planar, and low-cost antenna is an attractive candidate for mmW applications.