Design and performance comparison of various terahertz microstrip antennas on GaN-on-low resistivity silicon substrates for TMIC

In this paper we demonstrate various configurations of THz microstrip antenna on GaN-on low resistivity silicon substrates (ρ <; 40 Ω.cm). To reduce the losses caused by the substrate and to enhance the antenna performance, the driven patch is shielded by a ground plane and silicon nitride, with BCB as the inset layer between them. Second patch (elevated patch) is suspended in air using gold posts, which makes the design stack configuration. Here, study of various design performances has been represented by changing the shape of the antenna between rectangular and circular, optimising the BCB and stack height and evaluating performance of stack using air and BCB as dielectric. Better fabricated performance was obtained when the patch was elevated in air and by using rectangular-circular stack configuration with BCB and elevation height of 5 μm. 3D EM model showed directivity, gain, and radiation efficiency as high as 8.3 dB, 3.4 dB, and 32 % respectively, a significant improvement over single or stack configuration antenna. Better simulated gain (6.7 dB) was obtained with the BCB height of 30 μm using a single antenna and highest gain and directivity (7.5 dB and 8.8 dB respectively) for stack antenna of height 15 μm. To the authors' knowledge this is the first time such a study has been carried out at Terahertz frequency and this developed technology is suitable for high performance III-V material on low resistivity/high dielectric substrates