PT Unknown AU Sievert, B TI Equivalent Circuit-Based Efficiency Enhancement of On-Chip Antennas for Wideband mm-Wave/THz Radar Systems PD 02 PY 2023 DI 10.17185/duepublico/81323 LA en AB The free space path loss at millimeter waves inherently limits the reading range of radar systems. In this thesis, on-chip antennas operating in frequency ranges between 220 GHz and 450 GHz are developed, which cover the radar systems’ bandwidth and are geometrically small enough for assembly in an antenna array. The antennas are based on microstrip topologies in Silicon Germanium (SiGe) Monolithic Microwave Integrated Circuits (MMICs), where capacitive discontinuities are embedded into the antenna design to increase the radiation efficiency. Using a tailored feeding- and matching network, the overall antenna bandwidth is artificially increased by combining multiple resonant antennas of different operating frequencies. To explain the antenna operation, prove the additional radiation contributions of the discontinuities, and enhance the physical insight, a thorough equivalent circuit model separating dissipation losses and radiation contributions is developed. Furthermore, the radiation and coupling of the discontinuities in the microstrip antenna are shown to describe the antenna far field thoroughly. Thus, the equivalent circuit description can be used to calculate circuit and radiation parameters such as input impedance, current distribution, radiation pattern, and radiation efficiency. The proposed model is confirmed by full-wave and measurement results highlighting both the applicability of the presented antenna prototypes in the radar context and the capabilities of the circuit model. ER