| A retrodirective antenna system is essentially a form of smart antenna systems where signals received from a source can be automatically sent back in the direction of the source. Bandpass sampling (also named undersampling) is a signal processing technique with which an RF signal can be directly sampled at a rate related to its bandwidth rather than its highest frequency.; This thesis proposes a new way to implement the retrodirective antenna array by applying that bandpass sampling, which gives us a new and simplified smart transceiving architecture. The two-antenna-element system is prototyped. In Non-Line-Of-Sight (NLOS), the Error Vector Magnitude (EVM) of the system with phase conjugation is about 4% better than the conventional single antenna system and 14% better than the system with no phase conjugation. In Line-Of-Sight (LOS), the EVM of the system with phase conjugation is about 3% better than the conventional single antenna system and 0.1% better than the system with no phase conjugation. Both simulation and experimental results are presented and they show the effectiveness of the proposed design.; In addition, two optimized phase detectors that relax the Automatic Gain Control (AGC) requirement and Digital Signal Processor (DSP) processing capability will be introduced. Two new methods for computing phase conjugation will be presented as well. Furthermore, a 400MHz patch antenna was designed for system implementation. |
