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In this letter, a hybrid analytical and numerical simulation method is presented for the time-efficient calculation of bistatic scattering from the buried targets. This computation is used for a fixed transmitter and target location but for a moving receiver to generate the data set for a 3-D synthetic aperture radar (SAR) simulation. In this method, initially, the current distribution on the target when illuminated by the transmitter (in the absence of the receiver) is calculated. Then, the receiver is used as a transmitter and its field is calculated everywhere in the lower half-space. The reciprocity is then used to find the open-circuit voltage across the receiver terminals due to the equivalent current distribution on the target. This approach substitutes $\boldsymbol {N}$ full-wave simulations for $\boldsymbol {N}$ sampling points required in SAR imaging with two simulations leading only to a factor of $\boldsymbol {N/2}$ reduction in the simulation time. The proposed method is validated by comparing it with the brute-force full-wave simulation method as well as by image reconstruction from the data set generated by the method.

Retrodirectivity have several important applications in communication and in wireless power transfer. In this paper, frequency sensitive retrodirective transceiver is proposed. It receives a signal and infers its direction from its frequency spectrum, then it can transmit a new signal back to the same or other direction at the designer wish. To determine the direction of the coming signal, a 0.85-1.15GHz frequency scanning phased array antenna is used so that the received signal would have a distorted spectrum with the maximum amplitude frequency component linked to the direction of the signal. Based on the frequency scanning, the retrodirectivity system can be used for wireless power transfer or for reactive jamming. Special circuit is designed to receive the signal with strongest power and to isolate the frequency component with maximum amplitude. Phase-locked loop (PLL) circuit is used to link such frequency to specific phase shift that is introduced to the transmitter array antenna to send a new signal to the same direction of the received signal. ADS simulation is performed to demonstrate the performance of each block.