Stewart M. Perlow

Automatic Load Contour Mapping for Microwave Power Transistors

A technique for large signal characterization of microwave power transistors is described. A computer controlled apparatus is used to map contours of constant output power and efficiency, on a Smith Chart, for dynamic matching of both input and output circuits.

Silicon-based reconfigurable antennas-concepts, analysis, implementation, and feasibility

We report on an innovative reconfigurable antenna concept with significant practical relevance based on the dynamic definition of metal-like conductive plasma channels in high-resistivity silicon that are activated by the injection of DC current. The plasma channels are precisely formed and addressed using current high-resolution silicon fabrication technology. These dynamically defined plasma-reconfigurable antennas enable frequency hopping, beam shaping, and steering without the complexity of RF feed structures. This concept shows promise for delivering the performance and capabilities of a phased array, but at a reduced cost. However, challenges such as p-i-n biasing circuit complexity and their nonlinearities, as well as antenna efficiency, would still require further investigations.

Holographic antenna concept, analysis, and parameters

The paper describes a new holographic antenna concept that uses a diffraction pattern (hologram) formed on a dielectric substrate and fed by a surface wave. Analytical models and necessary design tools have been developed to investigate the feasibility of this new concept. A demonstration prototype antenna was designed, fabricated, and tested, and the measured radiation patterns at 35 GHz showed good agreement with the theoretical prediction.

Silicon based reconfigurable antennas

Summary form only given. Selects solid-state plasmas generated by PIN junctions to effectively implement various reconfigurable antennas. Other alternative technologies include MEMs switches to reconfigure antennas. PIN junctions can also be utilized as switches, and can replace MEMs to reconfigure antennas where speed of response is an issue. We have utilized these PIN junctions to dynamically define plasma regions with sufficient conductivity. Injecting high dc currents into these junctions in high resistivity silicon creates plasma regions (domains) with relatively high conductivity. The locations and shapes of these defined islands can be precisely controlled over the whole processed silicon wafer, as high resolution is a routine matter of todays silicon technology. The defined metallic-like patterns can include the radiating elements and the feed structures as well. The dipole antenna described is segmented into three different sections to allow wide frequency coverage from 1 to 20 GHz frequency range.

Large-signal MESFET characterization using harmonic balance

A method is described that combines large-signal load tuning (i.e. load-pull) measurements with harmonic balance and optimization techniques to characterize GaAs MESFET devices. An important advantage of the method is that device model parameters are obtained at the frequencies at which the device will operate in circuits. Consequently, ambiguities regarding any frequency dependencies of the parameters are eliminated, thereby improving the accuracy of the device model and simulation. The method is best suited as a supplement to previously reported DC and small-signal parameter extraction methods, and is also applicable for the characterization of other power device types, including bipolar-junction transistors (BJTs).<<ETX>>

An innovative semianalytical technique for ceramic evaluation at microwave frequencies

We have developed an innovative semianalytical technique for various substrate material characterization. The developed technique is a measurement procedure and data-reduction formulation that takes into consideration the radiation loss in a resonant structure, allowing for a more effective means of dielectric- and conductor-loss determination for a microstrip ring resonator and its substrate material. We separate dielectric and conductor loss precisely, evaluate the contribution of each term in the overall loss performance, and analytically predict the error in their respective predicted value.

A MMIC based 48 tap X-band adaptive transversal filter

An advanced adaptive transversal filter using 0.5 /spl mu/m MMICs has been developed and its performance fully evaluated at X-band frequencies. The design objective of the filter was to provide rapid frequency tuning, response programmability, and low phase distortion. The 48 tap filter was composed of 96 MMIC chips assembled in a MIC environment. Bandpass, bandstop, and all-pass filter characteristics were successfully obtained by adjusting the tap weight.<<ETX>>

Experimental demonstration of a 35 GHz holographic antenna

We have developed a novel two-dimensional grating antenna based on microwave holography. The two-dimensional grating (hologram) is formed on a dielectric substrate and fed by an integrated surface wave exciter. Various design issues will be presented, as will a 35 GHz demonstration prototype antenna designed, fabricated, and tested. Measured radiation patterns closely agreed with the theoretical prediction.