Time-modulated Patch Antennas with Nonreciprocal Polarization Handedness

We propose the concept and design of a time-modulated antenna able to exhibit nonreciprocal polarization handedness during transmission and reception (for instance, the antenna radiates right-handed circularly polarized waves but receives left-handed circularly polarized waves) by exploiting the photonic Aharonov-Bohm effect. To demonstrate our approach, we combine a patch antenna fed from four symmetrical sides with an appropriate low-frequency modulation scheme to control orthogonal currents. We show that it is simultaneously possible to (i) obtain very high frequency conversion efficiency; (ii) independently tailor the phase of radiated fields that have orthogonal polarization with the phase of certain modulation signals, thus implementing any polarization state of the Poincaré sphere; and (iii) achieve nonreciprocity at the polarization level with a single antenna element. We envision that the proposed time-modulated device may find exciting applications in the next generation of sensing, radar, and communication systems.