Advanced microwave/millimeter-wave system technologies for wireless communications

In this dissertation, three advanced system technologies are presented at micorwave and millimeter-wave frequencies.; Firstly, an adaptive power controllable retrodirective array system is presented. It is able to conserve battery power in an idle mode and wake up only when it needs to operate, extending the array system's lifetime. One application of this technology is for use as wireless sensor servers which act as a relay point between wireless sensors and remote data collectors. The proposed retrodirective array is fabricated and tested at 5.8-GHz and uses an integrated rectenna and an analog switch which controls a battery power source.; For the second topic, a metamaterial-based electronically-controlled transmission line structure is presented and demonstrated as a novel leaky-wave (LW) antenna with tunable radiation angle and beamwidth functionalities. This structure is in essence a composite right/left-handed (CRLH) microstrip structure incorporating varactor diodes for fixed-frequency voltage-controlled operation. Angle scanning at a fixed frequency is achieved by modulating the capacitances of the structure by adjusting the (uniform) bias voltage applied to the varactors. Beamwidth tuning is obtained by making the structure non-uniform by application of a non-uniform bias voltage distribution of the varactors. A rigorous analysis based on an extension of the CRLH concept is proposed and the corresponding dispersion curves, obtained by equivalent circuit formulas with LC parameters extracted from full-wave simulation, are shown.; Lastly, a 60-GHz retrodirective array system is proposed with an efficient power management. The system consists of three sections; a retrodirective array, a local oscillator (LO), and a power management. For efficient battery operation of the retrodirective array, the power management circuit controls the power of the LO by way of a rectenna technology. While there is no interrogating signal, it is initially in a sleeping mode where the system is off with extremely low power. When it is interrogated by an RF signal, the system is awaken and starts consuming full power. The proposed idea is experimentally demonstrated. (Abstract shortened by UMI.)...