Multifunction GaAs MMIC transmitter/receiver for onboard satellite equipment
This paper describes the development of a new GaAs MMIC to be used in transmit/receive modules for S band transponders. The IC, which includes five different functions, reduces the sue of the system whilst maintaining and even improving system performance. Amplification, phase shifting, and mixing are some of the functions integrated in the same chip. The goal of the work is to reduce the number, size, and consequently, the cost of the circuitry currently in use through an European commercial Enhancement/Depletion (E/D) pHEMT process, compatible with low noise reception. A maximum conversion gain more than 54 dB has been achieved with a gain control more than 27 dB. A 0 dBm output power at 1dB compression point (P1dB) has been measured when a CW stimulus was used as input signal, while more than 35 dB of Adjacent Channel Power Ratio (ACPR) was tested for a BPSK input signal.
Experience and new trends in MMIC's for space programmes
In the past twenty years a considerable amount of work has been done on microwave circuit integration, mainly using GaAs material. MMIC's were finally introduced to the space-borne equipment in the early 90s. They are now clearly unavoidable and many systems are presently in operation with GaAs chips on board. Now, with the maturity of MMIC, everyone agrees that packaging is the key issue. Micro-packages favored the penetration of MMIC space systems. They brought modularity and testability staying hermetic that were necessary for assessing their ability to respect space constraints.
Do Arab public opinion support policies of regional powers in MENA? View from Tunisia
ABSTRACT The Arab Uprisings and subsequent events continue to transform policies of regional and major powers toward the Middle East and North Africa. These powers have shown different approaches toward the Uprisings, ranging from support for the status quo to endorsing regime changes. Their policies have also exerted a significant impact on the course of events. Despite this growing importance and implications of policies of regional powers on the Uprisings and the Syrian conflict, we still do not know much about how the public assesses these policies and to what extent domestic cleavages shape these assessments. Using a nationally representative original survey conducted in 2014 in Tunisia, this study examines the perceptions of the policies of France, Turkey, and Saudi Arabia towards the Uprisings and the Syrian conflict. It finds that French and Turkish policies about the Uprisings have garnered substantial support among citizens, whereas most citizens negatively assess the Saudi policies. On the other hand, the majority of Tunisians negatively assess all these countries’ policies toward the Syrian conflict. Another major finding suggests that political identity reflecting secular/religious cleavages shapes how citizens view the policies of these three countries toward both issues, but its effect is higher in assessing the Uprisings.