Lens-coupled dual polarization sinuous antenna for quasi-optical terahertz balanced mixers

摘要

Sinuous antennas can provide ultra-broadband operation, frequency-independent embedding impedances and isolated dual polarizations, making them suitable for many applications in the terahertz frequency regime. In this paper, a lens-coupled planar sinuous antenna has been designed and fabricated for terahertz balanced mixers. Simulation results show that the antenna exhibits a nearly frequency-independent embedding impedance of ∼100 Ω over a broad frequency range. To verify the aforementioned antenna properties at THz frequencies, a Schottky diode was mounted to the center of the antenna to realize a direct detector. The radiation patterns of the lens-coupled sinuous antenna were studied at 196 GHz and 585 GHz. A responsivity of 300–1000 V/W was measured up to 900 GHz demonstrating the ultra-broadband operation of the antenna. In addition, an isolation of larger than 15 dB between the two polarizations has been demonstrated for both the frequency ranges of 190–210 GHz and 570–630 GHz.