An Innovative H-Plane Filtering Horn Antenna in Substrate-Integrated Waveguide Technology

In this work, we propose a method for designing an innovative H-plane filtering horn antenna (FHA) based on substrate-integrated waveguide (SIW) technology. The approach integrates a bandpass filter (BPF) directly into the flared section of the horn antenna, thus resulting in an efficient compact multifunctional filtering antenna. To demonstrate the concept, a third-order SIW H-plane FHA with an iris-coupled filtering structure is designed, fabricated, and tested at 5.8 GHz, achieving a 3% fractional bandwidth (FBW). The proposed approach significantly enhances the efficiency of conventional horn antenna from a modest 9.2% to 41.3%. The design concept is further extended to millimeter-wave (mm-wave) frequencies with an E-plane metal septum filtering structure, where a second-order H-plane FHA centered at 28 GHz is designed. Furthermore, the proposed design methodology is systematic and scalable to realize a higher-order FHA. Additionally, this approach offers substantial size and volume reductions, along with integrated multifunctionality, promoting overall system miniaturization.