Comparative Optimization of Terahertz Microstrip Patch Antennas With 2D and 3D Photonic Band Gap Structures on Polyethylene Substrates

ABSTRACT This study presents the design and performance analysis of terahertz (THz) microstrip patch antennas incorporating photonic band gap (PBG) structures on polyethylene substrates operating around 0.65 THz. Four PBG‐based configurations, two 2D structures with cylindrical and cuboid air holes and two 3D structures with the same air gap shapes, are compared against a homogeneous polyethylene substrate antenna to evaluate their impact on return loss, bandwidth, gain, and radiation efficiency. The proposed antennas feature compact dimensions of 270 × 330 × 20 μm 3 . The results demonstrate that 2D PBG substrates with cuboid air gaps deliver the best overall performance, achieving a peak gain of 7.36 dB, radiation efficiency of 85.5%, and a 32.94‐GHz bandwidth, with a return loss of −27.64 dB. The parametric study on the lattice constant reveals that denser lattices in 2D PBG substrates significantly enhance antenna characteristics, whereas 3D PBG structures exhibit only marginal improvements with lattice compaction. These findings underscore the potential of 2D cuboid air gap PBG substrates as efficient, cost‐effective, and practical solutions for miniaturized THz wireless communication and sensing applications.