Characterization and Optimization of the Magnetron Directional Amplifier

This is a AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH SCHOOL OF ENGINEERING report procured by the Pentagon and made available for public release. It has been reproduced in the best form available to the Pentagon. It is not spiral-bound, but rather assembled with Velobinding in a soft, white linen cover. The Storming Media report number is A234073. The abstract provided by the Pentagon follows: Many applications of microwave wireless power transmission (WPT) require a high-powered electronically-steerable phased array composed of radiating modules. The phase output from each module must be accurately controlled if the beam is to be properly steered. A highly reliable, rugged, and inexpensive design is essential for making WPT applications practical. A conventional microwave oven magnetron may be converted into a two-port amplifier capable of delivering over 30 dB of gain, while remaining phase-locked to the input signal over a wide frequency range. This use of the magnetron is referred to as the MDA (Magnetron Directional Amplifier). The MDA may be integrated with an inexpensive slotted waveguide array (SWA) antenna to form the Electronically- Steerable Phased Array Module (ESPAM). The ESPAM provides a building block approach to creating WPT phased arrays. The size and shape of the array may be tailored to satisfy a diverse range of applications. This study provided an in- depth examination into the capabilities of the MDA/ESPAM. exhibiting its potential as an RF amplifier or as an element in a WPT phased array. The MDA was operated at over 75% efficiency and with a fractional bandwidth exceeding 1.7% at 2.45 GHz. A number of tools are provided to aide the WPT design engineer in predicting the MDA's optimum performance and limitations. A secondary effort examined the suitability of the ESPAM in satisfying system requirements for the solar power satellite (SPS).