ABSTRACT
In order to compensate huge propagation loss of THz signal, and realize wideband and high sensitivity receivers, effective THz imaging/communication systems also require antenna an antenna array with high-directivity radiation pattern [229] and high efficiency with sufficient bandwidth, which imposes grand challenges for an on-chip antenna design in CMOS. Firstly, the realization of highly directive radiation is not trivial. The conventional right-handed antennas (patch, dipole and etc.) [230, 32] have a positive phase-and-length relation that usually results in non-in-phase radiation and large-sized design. Secondly, due to close distance between the top metal layer and ground, the radiation efficiency of on-chip antenna is not high. Moreover, each antenna element must be as compact as possible to form antenna array in limited chip area. The previous on-chip antenna works [32, 230, 90, 231] have either low gain or narrow bandwidth and ignored the polarization issue. For example, given the THz source with linearly polarized radiation, the longitudinal polarization may be turned into transverse direction after penetrating through the tissue [16]. If the antenna at the receiver is also linearly polarized, the detection efficiency may be largely reduced due to the mismatch in the polarization directions.
