Paudel, BiswashLi, Xue JunSeet, Boon-Chong2025-12-172025-12-172025-12-04Electronics, ISSN: 1450-5843 (Print); 2079-9292 (Online), MDPI AG, 14(23), 4780-4780. doi: 10.3390/electronics142347801450-58432079-9292http://hdl.handle.net/10292/20412<jats:p>The terahertz (THz) band offers ultra-wide bandwidth for next-generation high-speed wireless communication systems. However, achieving compact, high-gain, and beam-symmetric THz antennas remains challenging due to fabrication and propagation constraints. This paper presents a simulation-based design and optimization of a stacked substrate-integrated waveguide (SIW) pyramidal horn antenna achieving equal half-power beamwidths (HPBWs) in both E- and H-planes. The design employs vertically stacked SIW layers coupled through optimized slot apertures to ensure dominant TE10 mode propagation with minimal reflection. Using full-wave electromagnetic simulations, the effects of layer number, dielectric loading, amplitude tapering, and phase distribution are systematically analyzed. The optimized five-layer configuration exhibits 10 dBi gain, 41° HPBW, and sidelobe levels around −3.2 dB at 210 GHz. This framework aims to develop high-performance, beam-symmetric THz SIW antennas compatible with standard LTCC/PCB technologies.</jats:p>© 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).https://creativecommons.org/licenses/by/4.0/4006 Communications Engineering40 Engineering4008 Electrical Engineering4009 Electronics, Sensors and Digital Hardware0906 Electrical and Electronic Engineeringterahertz bandhorn antennasubstrate-integrated waveguidebeam symmetrymulti-layeredJournal ArticleOpenAccess10.3390/electronics14234780