http://nopr.niscair.res.in/handle/123456789/2412 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/2491 Title: Design and development of wideband gap-coupled slot rectangular microstrip array antenna <br/> <br/>Authors: Mulgi, S N; Konda, R B; Pushpanjali, G M; Satnoor, S K; Hunagund, P V <br/> <br/>Abstract: A novel design of four-element gap-coupled slot rectangular microstrip array antenna (FGSRMSA) is presented for broadband operation. The elements of antenna are fed using aperture coupled technique. From the experimental results it is seen that the antenna operates at single band of frequencies and shows broadside radiation characteristics. The overall impedance bandwidth is found to be 26.72 %, which is 1.114 times more than that of four-element gap-coupled rectangular microstrip array antenna (FGRMSA). This shows the effect of slots in enhancing impedance bandwidth of FGSRMSA. The slots in FGSRMSA also improve the antenna input impedance and increase the gain by 20.8% when compared to FGRMSA. Details of antenna designs are described and experimental results are discussed. <br/> <br/>Page(s): 291-295 http://nopr.niscair.res.in/handle/123456789/2489 Title: A method for calibration of space borne passive microwave sensors using a desert area <br/> <br/>Authors: Calla, O P N; Parihar, Vikas; Joshi, Naveen Dutt; Chakravorty, Gitanjali; Rathore, Usha <br/> <br/>Abstract: A new method is suggested in this paper, for on-flight calibration of passive sensors, using a desert area, from satellite data obtained over a uniform terrain. The satellite data of OCEANSAT I MSMR payload operating at 6.6 GHz in both horizontal and vertical polarization and having look angle of 49.7 have been used for the present study. <br/> <br/>Page(s): 285-290 http://nopr.niscair.res.in/handle/123456789/2487 Title: Plasma drift motion in the F-region of the ionosphere using photometric nightglow measurements <br/> <br/>Authors: Mukherjee, G K; Shetti, D J <br/> <br/>Abstract: The equatorial ionospheric plasma irregularities have been studied in the last few years by different ground based (radar, digisonde, GPS, optical instruments) techniques and in situ rocket and satellite measurements. The time evolution and propagation characteristics of these irregularities have been used to study the important aspects of ionospheric dynamics and thermosphere-ionosphere coupling. In this study the plasma drift motion has been inferred in zonal and meridional directions at Kolhapur (16.8°E, 74.2°E, dip latitude 10.6°N) by measuring the OI 630.0 nm intensities at three directions in zenith using tilting filter photometers. Also, the observed zonal plasma drift velocities are compared with the thermospheric zonal neutral wind velocities obtained from the HWM-93 model to investigate the thermosphere-ionosphere coupling. In general there is good agreement between the model predictions and the observations. The HWM-93 model also reproduces well the altitudinal and latitudinal variations of the neutral wind velocity in the low latitude region. The dominant periodicities observed in OI 630.0 nm intensity fluctuations on a Spread-F night were typically varying between 30 and 50 min. <br/> <br/>Page(s): 249-257 http://nopr.niscair.res.in/handle/123456789/2486 Title: Study of MSMR retrieved data using map generation and representation methodology over Rajasthan, India <br/> <br/>Authors: Calla, O P N; Rathore, Usha; Chakravorty, Gitanjali; Joshi, Naveen Dutt; Parihar, Vikas <br/> <br/>Abstract: The microwave radiometer MSMR (Multi-frequency Scanning Microwave Radiometer) data available in the months of June 1999-2001 have been studied. These data have been represented on the map of Rajasthan. The map has been generated using layered approach. The data available at 6.6 GHz for both horizontal and vertical polarization have been used for this study. The brightness temperature TB within 150 km diameter circle is displayed on the map of Rajasthan at the longitude and latitude obtained from the data set. The longitudes and latitudes are grouped in three zones A, B and C, depending on the geophysical parameters of the different sites. <br/> <br/>Page(s): 279-284