Terahertz performance of integrated lens antennas with a hot-electron bolometer

Radiation coupling efficiency and directive properties of integrated lens antennas with log-spiral, log-periodic, and double-slot planar feeds coupled to a hot-electron bolometer were experimentally studied at frequencies from 1 to 6 THz and compared with simulations based on the method of moments and physical-optics ray tracing. For all studied antennas, the modeled spectral dependence of the coupling efficiency fits to the experimental data obtained with both Fourier transform spectroscopy and noise temperature measurements only if the complex impedance of the bolometer is explicitly taken into account. At high frequencies, the radiation pattern of integrated antennas exhibits sidelobes, which are higher than those predicted by the antenna model.