http://hdl.handle.net/2289/7842 Thu, 19 Mar 2026 09:40:52 GMT 2026-03-19T09:40:52Z http://hdl.handle.net/2289/7865 Title: 50 – 500 MHz Low Noise Amplifier with FM band rejection Authors: Rao, K.B. Raghavendra; T.S., Mamatha; Deshpande, A.A. Abstract: Observing the radio sky at low frequencies, particularly in sites where FM signal and other RFI dominates, is highly challenging, since the radio receiver is prone to be driven to saturation by these strong signals. So it is required that the receiver should have high dynamic range and / or very low sensitivity to FM signal for proper observation. We have developed a low- noise amplifier with about 40 dB rejection to the FM signal, in the frequency range of 50 – 500 MHz for use in the Sky Watch Array Network (SWAN). It has a noise temperature ranging from 40-80 K, a gain of 20 dB with a variation of ± 1.5 dB around the band center and around 60 dB dynamic range over the specified band. The design details and test results are presented in this report. Description: Restricted Access Fri, 27 May 2016 00:00:00 GMT http://hdl.handle.net/2289/7865 2016-05-27T00:00:00Z http://hdl.handle.net/2289/7864 Title: Detector Development for X-Ray Polarimeter Authors: Sandhya; T.S., Mamatha; Paul, Biswajit; Rana, Vikram; P.V., Rishin Abstract: POLIX is an X-ray Polarimeter for astronomical observations in the energy band of 5-30 keV. The instrument is made of a collimator, a scatterer and four X-ray proportional counter detectors surrounding the scatterer. The scatterer is made of low atomic mass material which causes anisotropic Thomson scattering of incoming polarised X-rays. The collimator restricts the field of view to 3 degree x 3 degree so as to have only one bright source in the field of view for most observations and it is also designed to minimize the dead area between the cells and also to minimize the mass. These requirement are met with a collimator made of tapered hexagonal cells with a flat top angular response. This flat top response helps in mitigating any small pointing error of the satellite. Description: Restricted Access Mon, 15 Jun 2020 00:00:00 GMT http://hdl.handle.net/2289/7864 2020-06-15T00:00:00Z http://hdl.handle.net/2289/7863 Title: Front End Integrated RF Unit for Efficient Linear array Imager Authors: T.S., Mamatha; B, Ramesh Abstract: Efficient Linear array Imager (ELI)is a cross telescope capable of producing 64 beams simultaneously in the sky. It uses 16 receivers and each is likely to use 4 IF chains, making a total of 64 numbers. Clearly, such a large number of receiversrequire optimisation of volume, power and cost. Following the model of commercial LNBCs, we have made a prototype front end Integrated RF unit for use with ELI. This integrates front end filters, mixer section and postsamplifiers, all in a board size of 6 cm x 5 cm. This integrated RF units has avoided multiple SMA connectors and thereby improving reliability at the cost of inter-changeability. In this technical report, we describe the effort put in development of this prototype. Description: Restricted Access Mon, 15 Jun 2020 00:00:00 GMT http://hdl.handle.net/2289/7863 2020-06-15T00:00:00Z http://hdl.handle.net/2289/7862 Title: A Wide-band RF Receiver system for Sky Watch Array Network Authors: Rao, K B Raghavendra; Sandhya; Arasi, A; Nagaraja, H N; Deshpande, A A Abstract: The Indian SWAN (Sky Watch Array Network) initiative aims to significantly enhance Indian observing capabilities in radio, and importantly, also to sustainably build & nurture future generations of talented radio astronomers in India to take up the challenges and lead in exciting research in astronomy. The SWAN focus is to design, develop and use a wide-band interferometric array of antenna across different parts of India to facilitate and conduct deep searches & studies of fast and slow transient radio radiation from astronomical sources, also enabling high angular resolution (VLBI) imaging of discrete galactic & extragalactic sources at low radio frequencies. It also facilitates hands-on experience to a large number of undergraduate/postgraduate students through their direct & active participation, starting from the design stage to competitive research using the array network. The proposed competitive network, with nominally 1000 sq. m array area at each location and operation spanning a decade in frequency (50-500 MHz). In view of the above proposal, a broad-band RF receiver system has been built in EEG laboratory and interfaced with the broad-band digital receiver system. Description: Restricted Access Sat, 02 Oct 2021 00:00:00 GMT http://hdl.handle.net/2289/7862 2021-10-02T00:00:00Z