Multi-beam systems are a key technology for the high-speed links of the next-generation communication standards. Due to the stringent space constraints for allocating antennas on a platform, it is of paramount importance to assess - with respect to the physical size - the multi-beam performance of the antenna in terms of the maximum number of simultaneous orthogonal beams. This is done by resorting to the concept of the observable field, which is here extended to planar domains. Then, this concept is used to assess the multi-beam performance of a wideband phased array prototype developed for mobile communications. The Signal-to-Interference Ratio (SIR), computed from the measured radiation patterns of the prototype, is analyzed versus the frequency and the number of beams and compared to the benchmark case of an ideal antenna radiating the observable field.

Photoconductive antennas (PCAs) are promising candidates for sensing and imaging applications. In recent years, our group has investigated their properties under pulsed laser illumination in transmission using a time-domain (TD) Norton equivalent circuit. Here, we extend this analysis to the link between a photoconductive source and a receiver introducing for the latter a second TD Norton equivalent circuit. We also evaluate the transfer function of a dispersive quasi-optical (QO) link. Specifically, a field correlation approach based on the high-frequency techniques is used to evaluate the spectral transfer function between two bow-tie-based PCAs, including the QO link. The detected currents in the receiving circuit are reconstructed using stroboscopic sampling of the modeled THz pulses, equivalent to what is actually performed by THz TD systems. Both the amplitude and the waveforms of these currents are evaluated. The QO link is then experimentally characterized to validate the proposed methodology. The comparison between the simulations and the measurements is excellent.