J.I. Upshur

A low-loss reflection-type analog phase shifter circuit is described, and experimental results are presented. The circuit incorporates several design features to produce nearly 360 degrees of phase shift at X-band while achieving an insertion loss of only 4.8 dB with +or-0.5 dB of variation over all phase states. These results improve upon previously reported X-band performance by demonstrating a large phase shift range together with low attenuation and low amplitude variation with phase state.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A proof-of-concept (POC) X-band active phased-array antenna was developed and fabricated to demonstrate the technology for potential use in future Defense Satellite Communication System satellites. The eight-element POC subarray was capable of producing two simultaneous independent beams using an MMIC-driven beam-forming matrix. A 2-W SSPA preceded every radiating element to produce the required EIRP. The design of the complete phased array to satisfy system requirements is discussed, and measured results for the array, including intermodulation patterns and bit error ratio response, are presented.

Terrestrial and satellite wireless systems require multicarrier operation of solid-state power amplifiers within specific linearity specifications. This paper evaluates candidate linearity measurement techniques that can be used for linearity characterization, including digital and analog noise-power ratio methods, and three-carrier intermodulation measurements. A correlation between these techniques is made for a specific power amplifier under accelerated life test conditions.

PL’s research and development efforts in high-effi ciency Ka-band solid-state power amplifi ers have positioned the Laboratory at the leading edge of this technology. APL reached this position through signifi cant contributions in several areas related to the design of power amplifi ers. Methods for applying harmonically controlled terminations for improved effi ciency (a fi rst at Ka-band) have been developed. To demonstrate this, an advanced transistor model capable of accurately simulating the transistor’s nonlinear behavior over a wide operating range was generated by our collaborative partner, Morgan State University. Through the creation of a software tool, the processes required to construct the model was standardized and documented. This device model was then validated by comparing measured performance with the model predictions.

An attempt was made to demonstrate a fully monolithic SSPA module for application to Ku-band direct-radiating array antennas. The module design approach incorporates the necessary tradeoffs to simultaneously achieve good performance in efficiency and linearity, in addition to meeting the necessary gain and output power requirements over the full 10.7- to 12.75-GHz band. The authors describe a three-stage monolithic microwave integrated circuit (MMIC) amplifier being developed for this application with a peak efficiency of 33% at a C/I3 of 16 dB, and a nominal gain of 20 dB. To achieve this performance, the FET structure was optimized for efficiency, using broadband harmonic terminations, and the first two stages were designed to operate at sufficient backoff to minimize their contribution to overall nonlinearity. The results show the validity of the basic SSPA design approach and prove that a high-performance amplifier suitable for satellite communications applications can be achieved in fully monolithic form.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>