Increasing terahertz (THz) applications drive the development of the THz devices. Due to the high free space loss in the THz band. Hence, a large coherent transceiver array is appreciated to mitigate this loss. The challenge is how to achieve power efficient injection networks for arranging the large arrays. To address this challenge, this thesis proposes wireless antenna-in-antenna method to build the connection between the injection reference sources and the transceiver elements. Regarding the requirements in different applications, various novel wireless antenna-in-antenna injection models ranging from far-field to near-field, from low frequency to high frequency, from element to array, and from oscillator to detector, are developed in this thesis. During the injection design for the THz transmitter, resonant tunneling diode (RTD) oscillator is assumed within this thesis. An on-chip sub-harmonic transmitarray element is proposed for the first time. It features to receive the sub-harmonic injection signal and radiate the locked fundamental oscillation signal in opposite directions, which enables a high injection efficiency and a low system profile. The proposed on-chip antenna integrates the functions of dual-band signal isolation, impedance matching, parasitic oscillation suppression in the antenna only structure, which largely reduce the device size and the signal insertion loss. Furthermore, a 1-to-4 subarray model is developed in the following work, providing an elementary power upscale and antenna size reduction function at THz frequencies. To further reduce the system profile and injection efficiency, antenna non-radiative near-field wireless sub-harmonic injection (WSI) model is designed by a patch antenna relay-based chip-to-chip injection structure, resulting in a zero-injection distance. After that, a 4 × 4 sub-harmonic injection locking (SIL) array with beam steering function at 300 GHz is proposed. The developed antenna models are fabricated in the photolithography process by multi-layer deposition, and the on-chip measurements are performed to proof their efficiency. Free space coupled sub-harmonic coherent detector allows RF and LO signals to access the detector element through free-space coupling. It cancels the lossy LO power distribution network in high frequencies and enables the design of large detector array. The wireless antenna-in-antenna coupling configuration is ideal for such detector array design. A free-space coupled sub-harmonic coherent detector array is investigated by this work. Both 1-D and 2-D large scale sub-harmonic coherent detector array concepts are proposed based on our novel antenna design. The mixing experiment in 100/300 GHz bands verify that our antenna can receive the LO and RF signals from the opposite sides. A 30 dB dynamic range enhancement for the 300 GHz RF signal in the system is observed during the sub-harmonic mixing test. Overall, the proposed wireless antenna-in-antenna concept and novel antenna models in this thesis demonstrate significant potentials for building compact and efficient sub-harmonic injection systems that can operate in the THz band, making it suitable for various coherent transceiver array designs.