Field effect transistor circulators

Field-effect-transistor circulators that are compatible with monolithic microwave integrated circuit technology are described. These passive nonreciprocal components are formed with inductors, capacitors, transmission line sections, and microwave transistors, and all can be integrated on a single IC chip the size of a pinhead. The operating principle, power-handling capability, and noise performance of these components are discussed for both narrowband and wideband applications, and examples of their practical implementation are given. The transistor-based 2-, 3-, and 4-port passive nonreciprocal components described offer an alternative to ferrite miniature circulators with potential advantages of small size and lower cost in production volume     

Monolithic 2?20 GHz GaAs travelling-wave amplifier

A two-stage monolithic GaAs travelling-wave amplifier operating in the 2?20 GHz frequency range with 12 dB flat gain is reported.     

High-speed, 100+W RF switches using GaAs MMICs

A low-loss, inductive gate bias network structure which allows a very high stacking level of FET devices for high-power RF switching applications is reported. The design, implementation, and performance of S- and C-band SPDT switches based on this structure are described. Multiple GaAs MMIC chips integrated into a suspended-substrate hybrid circuit are used. At S-band, switch risetimes/falltimes of less than 40 ns and an RF power handling capability of 300 W CW have been demonstrated. This input signal level could be maintained during the switch state transitions (hot-switching), while being switched between the two output ports at rates of up to 500 kHz     

SEKE: A computer model for low altitude radar propagation over irregular terrain

SEKE, a new site-specific propagation model for general terrain, makes use of the original Lincoln Laboratory models geometrical optics (GOPT), low altitude propagation spherical earth (LAPSE), and low altitude propagation knife edges (LAPKE) to compute multipath, spherical earth diffraction, and multiple knife-edge diffraction losses. The proper algorithm is selected based on terrain geometry, antenna and target heights, and frequency. Comparison of model predictions with measurements over several paths ranging from level to rough at five frequencies (X-band through VHF) is presented. A brief discussion on the performance of SEKE over general terrain with respect to the expected performance of the two other general terrain-specific models (Longley-Rice and terrain integrated rough earth model (TIREM)) is given.     

Monolithic GaAs travelling-wave amplifier

A monolithic GaAs travelling-wave amplifier with distributed input and output lines is described, and its experimental performance in the 0.5?14 GHz range is reported.