Publications

Accurate circuit models derived from electromagnetic simulations have been used to fabricate photomixer sources with optimized high-impedance antennas. Output powers on the order of 1 uW were measured for various designs spanning 0.6-2.7 THz. The improvement in output power ranged from 3 to 10 dB over more conventionally designed photomixers...

The performance is reported for a new microelectromechanical structure (MEMS) cantilever microswitch. We report on both dc- and capacitively-contacted microswitches. The dc-contacted microswitches have contact resistance of less than 1 ohm, and the RF loss of the switch up to 40 GHz in the closed position is 0.1-0.2 dB. Capacitively-contacted...

The design of a high combining-efficiency spatial power-combined array is described in this paper. A multilayered stacked stripline architecture enables a compact stable design. An array incorporating antenna active impedance and proper amplifier matching is measured with a combining efficiency of 87%, radiating 6.8 W of an available 7.8 W...

A revolutionary device technology and circuit concept is introduced for a new class of reconfigurable microwave circuits and antennas. The underlying mechanism is a compact MEMs cantilever microswitch that is arrayed in two-dimensions. The switches have the ability to be individually actuated. By constructing distributed circuit components from an array...

This paper describes a method of enhancing the bandwidth of two different electromagnetically coupled microstrip antennas by utilization of a tuning stub. An approximate theory and equations are developed to demonstrate the potential bandwidth improvement and required stub impedance characteristics. A novel dual-stub design is presented that achieves better characteristics...

We report the first successful demonstration of a photomixer local oscillator (LO) integrated with a superconducting heterodyne detector. The photomixer LO generated the difference frequency of two diode lasers by optical heterodyne conversion in low-temperature-grown GaAs. The measured receiver noise temperature, 331 K at 630 GHz, compares favorably with that...

This paper describes the design and testing of an aperture-coupled circularly polarized antenna for global positioning satellite (GPS) applications. The antenna operates at both the L1 and L2 frequencies of 1575 and 1227 MHz, which is required for differential GPS systems in order to provide maximum positioning accuracy. Electrical performance...

The explosion of interest in high data rate communications places great demands on current antenna designs. Antennas used for transmitting signals can require high gain with high radiated power. An efficient means to accomplish these goals is the free space combining of many amplifiers via elements in an antenna array...

Spatial power combining of many MMIC amplifiers at millimeter wave frequencies using a fixed array of microstrip antenna elements places unique demands on dielectric media. The substrate must be relatively thick to allow space for MMIC placement, must provide rather high thermal conductivity to disipate MMIC heat, and be of...

We describe the design and measurement of a hybrid-circuit, tile-approach subarray for use in spatial power-combined transmitters. The subarray consists of 16 monolithic millimeter-wave integrated circuit (MMIC) amplifiers, each feeding a circularly polarized cavity-backed microstrip antenna. The average performance across the 43.5-45.5 GHz band is as follows: EIRP 18.3 dBW...