B.A. 1973, Williams College
M.A. 1975, Cambridge University
Ph.D. 1980, University of California, Berkeley
Email contact: rutledge AT caltech DOT edu
Professor Rutledge's research group is building circuits and antennas for a range of applications at frequencies from 1MHz all the way up to 1THz. Radio and microwave circuits are the core of the wireless communications revolution and play a central role in radars, remote sensing, and satellite broadcasting. Our research is in quasi-optical power combining, and Class-E amplifiers for communications transmitters.
The goal of the work in quasi-optical power combining is to make powerful solid-state oscillators and amplifiers. In recent years, there have been spectacular increases in the operating frequencies of solid-state devices. Gallium-arsenide transistors are now available that operate at frequencies as high as 200 GHz. At the same time, however, the output powers at these high frequencies are very low, and it is clear that the outputs of hundreds or thousands of devices must be combined to make a high-power transmitter. Caltech has pioneered the development of radically different microwave circuits called active grids that directly produce and amplify microwave beams. Active grids are periodic metal patterns loaded with transistors and diodes. These circuits should greatly increase the output power of transmitters and improve the noise and saturation levels of receivers. The circuits are redundant, and this makes them less likely to fail. At the same time, active-grid circuits have fewer parts by far than conventional microwave circuits. We have recently demonstrated a grid with 72 transistors that produces 0.6 W at 40 GHz.
We also have projects in high-power Class-E amplifiers for communications transmitters, semiconductor plasma processing, and magnetic-resonance imaging. Our amplifiers use power MOSFETs. Our amplifiers have an efficiency of 90% and output powers of up to 500 watts. Recent work has indicated that it should be possible to use PHEMT devices in Class-E amplifiers at 10GHz.
For a current list of research projects, click here.
For a discussion on Hubbert's Peak, the Coal Question, and Climate Change, click here.
For a list of downloadable research papers in pdf format, click here.
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Last updated July 12, 2007.