We present a hybrid full-wave/quasi-optical electromagnetic model for the design of lens-integrated THz antennas for high frequency non-contact device characterization (0.1-3 THz). The new non-contact probe setup consists of on-chip receiving and transmitting THz antennas in a co-planar waveguide environment. Commercially available THz-frequency extension modules are used in conjunction with microwave vector network analyzers to excite the probes. A hemispherical lens couples the signals into device-under-test using the on-chip antennas. To maximize antenna-to-device coupling over a wide bandwidth, we developed a hybrid electromagnetic model to optimize the THz antenna topology. This paper is focused on the system level computational analysis of the probe structure. The overall signal coupling performance of the non-contact probe is analyzed in a hybrid fashion by propagating the antenna fields computed from the moment method throughout the quasi-optical system.