Antenna Characterization by the Back-Scattering Measurement Method Using the Integrated RF-Frontend as Load Modulation Device

We demonstrate the feasibility of characterizing an antenna over-the-air by measuring its back-scattered field while modulating this field using the integrated RF-frontend which acts as a variable antenna load. This eliminates the requirement for implementing dedicated load switching circuitry commonly utilized for this purpose. Numerical results are presented for a 100 GHz on-chip antenna and for two example frontends: (i) a Tx frontend employing only a power amplifier, and; (ii) a transceiver frontend employing a Tx/Rx switch, a power amplifier and a low-noise amplifier. Using the proposed procedure with both frontends, the input reflection coefficient of the Device Under Test is recovered with a relative numerical error of less than $10^{-11}$. Also, the procedure for estimating the realized gain demonstrates a relative error of less than 5%, primarily attributed to the accuracy of the electromagnetic simulation model. Furthermore, the impact of measurement uncertainties is analyzed.