Rich Campbell, Professor, Portland State University

Rich is an internationally-recognized designer of Radio- Frequency Integrated Circuits, Radio-Frequency Electronics, Instrument and Measurement and Remote Sensing Systems. He is the principal designer of first commercially successful cell phone GaAs ASICs for TriQuint Semiconductor. During his career at Cascade Microtech, he was the principal designer of wafer probes for emerging THz market. Currently, Rick is a professor at the Portland State University, Department of Electrical and Computer Engineering. Rick received the Ph.D. degree from the University of Washington in 1984.

Modulated Scatter Array Measurements and Signal Processing from UHF to THz

We have been exploring theory and measurements at UHF through Microwaves using arrays of modulated scattering elements. The illuminating signal arrives at an array of elements in space, and various signal processing products are then scattered in different directions.  The reflection coefficients of the scattering elements are modulated at a low baseband frequency, but the modulation products are near the illumination frequency.  Since the reflection coefficients change very slowly relative to the illumination frequency, we achieve high frequency signal processing using slow electronics. The incoming and outgoing signals are in the space-angle domain, which avoids the frequency limitations and losses of waveguide, coax, and connectors. The basic technique may be scaled from VHF to THz.  Array dimensions are on the order of several wavelengths, which makes this technique particularly attractive at sub-mm wavelengths. Our initial measurements at 70 cm wavelength used a 2-element array to suppress one modulation sideband. Follow-on measurements using more elements and shorter wavelengths demonstrate our ability to suppress higher order distortion products. The unwanted products are not attenuated, they simply radiate from the array at different angles.