NOPR Community:

A 2x2 element planar phased array of rectangular microstrip antenna for Ni-Co ferrite substrate at 10 GHz

2016-09-06T06:37:17Z

Title: A 2x2 element planar phased array of rectangular microstrip antenna for Ni-Co ferrite substrate at 10 GHz Authors: Pourush, P K S; Dixit, Lata Abstract: A comprehensive study of 2x2 planar phased array of rectangular microstrip antenna on Ni-Co based ferrite substrate at 10 GHz is presented. The far-zone field expressions have been derived using vector wave function technique and pattern multiplication approach. The pattern characteristics and other important antenna parameters like half power beam width (HPBW), direction of maximum radiation, total shift of major andminor lobe, side lobe level (SLL), radiation conductance, directive gain and impedance bandwidth are estimated for the two values of progresseive phase excitation difference, i.e, β_x=β_y=π/2 and 2π/3. The results of ferrite based array geometry are compared with those of dielectric based (PTFE quartz reinforced) array antenna. The results are quite interesting and the antenna geometry is suitable to be employed as a scanned array for radar applications. Page(s): 289-296

The effects in the lower ionosphere during particle precipitation evnts

2016-09-06T06:29:47Z

Title: The effects in the lower ionosphere during particle precipitation evnts Authors: Kai, Li; Xiezhong, Zhao Abstract: The effects in the lower ionosphere during particle precipitation events have been studied by utilizing the VLF observations in Changcheng site in the South Pole region and Xinxiang site in China. The results obtained confirm the effects in the low- and middle-latitude regions of the lower ionosphere. Particular attention was devoted to “Omega B-station to Changcheng site” propagation path which passes through the geomagnetically disturbed regions of the South Atlantic Geomagnetic Anomaly (SAGA). Page(s): 285-288

Algorithm for atmospheric correction of remote sensing VNIR data

2016-09-06T06:19:00Z

Title: Algorithm for atmospheric correction of remote sensing VNIR data Authors: Kant, Yogesh; Badarinath, K V S Abstract: A simple atmospheric correction method which requires inputs that are commonly available in the form of dark surfaces in blue and red region bands has been described. The method consists of an inversion algorithm based on a simplified radiative transfer model in which the characteristics of atmospheric aerosols are estimated by the use of path radiance in blue and red bands. On the basis of this information, the retrieval of true digital number (DN) values from satellite images is possible. The method can be applied to all scenes in which some dark object can be realistically supposed to be present which is practically advantageous in retrospective studies. The comparison of the values of aerosol optical thickness estimated from this method with the ground measured values showed a substantial agreement in the accuracy of the values, suggesting the possible use of the method for practical applications. Page(s): 274-284

Application of quality control algorithms to the Indian MST radar wind data and comparison with rawinsonde wind data

2016-09-06T06:09:46Z

Title: Application of quality control algorithms to the Indian MST radar wind data and comparison with rawinsonde wind data Authors: Rao, D Narayana; Kishore, P; Reddy, K Krishna; Hareesh, M; Rao, T Narayana; Rao, S V Bhaskara Abstract: For the first time quality control algorithms have been applied to the Indian MST radar data for studying / estimating accuracy of wind under different atmospheric weather conditions. To assure the quality of the MST radar wind data, consensus averaging and continuity algorithms have been applied successively for 18 days in March 1996 between 1000 and 1100 hrs LT during PSLV launch from SHAR Center, Sriharikota. These winds have been compared with the wind profiles obtained by ordinary averaging procedure and rawinsonde wind measurements. The statistical analysis of the wind data shows that the mean average increased from 6.52 to 9.45 m/s for the zonal winds and 3.29 to 3.56 m/s for the meridional winds when the consensus continuity algorithms were applied. Also, the standard deviation decreased from 7.69 to 4.08 for the zonal winds and 3.16 to 2.11 for the meridional winds after utilizing the quality control algorithms. Application of quality control algorithms to the Indian MST radar wind data shows improved agreement with the rawinsonde data compared to the ordinary averaging. Page(s): 264-273