Nonlinear circuits and antennas for microwave energy conversion

This thesis covers theory and experiment for four distinct applications involving RF-DC and DC-RF energy conversion between 1 and 18 GHz. Microwave circuits and antennas containing nonlinear elements are used with high-efficiency operation techniques in a microwave rectifier, broadband rectifying antenna array, switched-mode oscillator, and switched-mode oscillating antenna. The applications include dc-dc conversion at microwave switching speeds, broadband energy recycling with microwave rectifying arrays, and a high-efficiency transmitting antenna for free-space power combining.; Switched-mode operation for rectifiers is discussed in terms of nonlinearly driven diodes used with proper harmonic terminations and impedance matching. The results are organized in terms of classes of operation in the same way as is done for microwave amplifiers. What is unique for this thesis is the application of these switched-mode classifications to microwave rectifiers.; The next topic is a broadband rectenna for low-power ambient energy recycling (the term rectenna is simply a neologism for rectifying antenna). A broadband rectenna element and 64-element array are extensively characterized for energy recycling of arbitrarily polarized stray fields in the microwave region to usable DC energy. Concepts gathered from the rectifier analysis are used together with a nonlinear simulation technique and antenna analysis to design the rectenna and rectenna array.; Next, the class-E mode of amplification is applied to a free-running oscillator at 10 GHz. This highly nonlinear, switched-mode class of operation, which has been documented at 10 GHz for amplifiers, is analyzed further for application in a high-efficiency oscillator. The analysis techniques provide a framework for future, improved versions of the class-E oscillator and the oscillator is evaluated as the DC-BF stage of a DC-DC converter.; Finally, a class-E oscillating annular ring antenna for a high-efficiency transmitting array. An extensive characterization of this active antenna is presented for class-E operation, antenna geometry, and oscillatory behavior. Future work is proposed for a 24-element array with a concentration on the phase-locking and coupling of individual elements.; Future and related work is suggested for each of the four previously mentioned topics along with a proposal for new work on a DC-DC converter which makes use of the high-efficiency rectifiers and oscillators.