• T K Alex

      Articles written in Sadhana

    • Attitude and temperature sensors

      G A Kasiviswanathan V P V Varadarajulu P R Venkateswaran T K Alex

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      Aryabhata was a spin-stabilised satellite. Attitude determination was required for the evaluation of the stabilisation system and for scientific experiments. Temperature sensors were required for the performance evaluation of the onboard systems and of the thermal control system. A detailed description of the sensors used for these functions inAryabhata is given.

    • An X band RF MEMS switch based on silicon-on-glass architecture

      M S Giridhar Ashwini Jambhalikar J John R Islam C L Nagendra T K Alex

      More Details Abstract Fulltext PDF

      Communication systems such as those used on satellite platforms demand high performance from individual components that make up the varoius systems and sub-systems. Switching and routing of RF signals between various modules is a routine and critical operation that determines the overall efficiency of the entire system. In this paper, we present the design and fabrication aspects of a direct contact RF MEMS switch designed to operate in the X band (8–12 GHz) with a target insertion of about 0·5 dB and isolation better than 30 dB. The actuation voltage is expected to be around 50 V. The die size is designed to be 3 mm (H) × 3 mm(W) × 2 mm(H). The switch is built from a low residual stress device layer of a highly conducting (0·005 Ohms-cm) silicon on insulator (SOI) wafer. After subsequent lithographic steps, the wafer is bonded to a Pyrex glass wafer which has been previously patterned with gold transmission lines and pull in electrodes. Being built from a single crystal silicon structure, the mechanical robustness of the actuator is much greater than the those in similar membrane-based devices. A 6 mask fabrication process utilizing Deep Reactive Ion Etching to achieve high aspect ratio stiction free structures was developed and implemented. Devices from the first fabrication run are being analysed in our laboratory.

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