Enhanced Flexible Terahertz Microstrip Antenna Based on Modified Silicon-Air Photonic Crystal

•High radiation characteristics of non-conventional photonic crystalbased terahertz patch antennas.•The photonic crystal substrate proposed reduces the effects of surface waves.•Improved return loss, bandwidth, gain and radiation effectiveness substantially.•The proposed antenna is based on the silicon photonic substrate.•The antennas can be employed for terahertz applications at 0.65 THz window.