http://nopr.niscpr.res.in/handle/123456789/25562 2026-09-15T17:50:53Z http://nopr.niscpr.res.in/handle/123456789/25793 Title: Study of antenna directivity Authors: Roy, Surendra Kumar Abstract: Although more rigorous treatments have been developed for the antenna directivity, the directivity, including phase shift factors, for several types of uniformly excited planar arraysis obtained. The agreement between the theory and experimental result is found to be excellent. Page(s): 177-181 2003-06-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/25792 Title: Design and fabrication of a low noise amplifier for a microwave receiver Authors: Raina, M K; Inamdar, S S; Raina, Sushil Abstract: A low noise amplifier employed in the microwave/mm-wave radiometers is used to amplify a signal to overcome the inherent drift in the synchronous detector to achieve a higher degree of stability. A low noise amplifier designed and fabricated is described. The amplifier has been designed for a gain of 60 dB with noise less than 10 mV peak-to-peak, having an output impedance of 100Ω and an input impedance of 1.5 MΩ. The supply used for design consideration was 24 V DC. Page(s): 172-176 2003-06-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/25791 Title: Some investigations on annular ring microstrip antenna Authors: Kanaujia, Binod K; Vishvakarma, Babau R Abstract: The various paramoters of annular ring microstrip antenna such as input impedance, VSWR, return loss, radiation pattern have been theoretically investigated as a function of frequency for different feed locations. It has been observed that resonance occurs at 3.285 GHz which is invariant with feed locations. The antenna behaves as RL network below resonance and as RC network above resonance and shows perfect matching at 3.35 cm feed location from the centre. The percentage bandwidth is found decreasing and the radiated power increasing with increasing <i>b/a </i>ratio. Page(s): 166-171 2003-06-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/25790 Title: Lidar observations on atmospheric dust transported from south-west Asia to Indian west coast region: A case study of colour rain event occurred during July 2001 Authors: Veerabuthiran, S; Satyanarayana, M Abstract: A dust storm, which originated in the dust bowl of Arabia, Iran, Afghanistan, Pakistan and north-western of parts of India during the month of July 2001, had lifted large quantities of dust into the atmosphere and got transported over long distances. The region on the west coast of India had experienced the interesting phenomenon of ‘‘colour rain’’ due to this dust loading. A typical dust layer had been detected in the lower troposphere using a lidar system located at Trivandrum (8° 33<i>'</i>N, 77°E) during the night of 24 July 2001 prior to the occurrence of colour rain. The lidar measurements indicated that the dust cloud was present in the 4-5 km altitude range with thickness of a few hundred metres. Air back trajectory computed by the HYSPLIT-4 model using NCEP wind data at the 4500 m level clearly indicated that the dust probably had its origin in the south-west Asia, nine days before the event. Page(s): 158-165 2003-06-01T00:00:00Z