http://nopr.niscair.res.in/handle/123456789/12549 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/12556 Title: Design of circularly polarized edge truncated elliptical patch antenna with improved performance <br/> <br/>Authors: Sekra, Pratibha; Shekhawat, Sumita; Dubey, Manoj; Bhatnagar, D; Saxena, V K; Saini, J S <br/> <br/>Abstract: The performance of a circularly polarized edge truncated elliptical patch microstrip antenna has been investigated experimentally in free space and has been compared with the performance of a conventional elliptical patch antenna. Extensive optimizations in feed locations and in edge lengths along major and minor axes<b style=""> </b>of conventional elliptical patch antenna have been carried out to achieve best performance from modified elliptical patch geometry. In addition to circular polarization, proposed antenna presents impedance bandwidth close to 180 MHz or 6.54%. With proposed feed arrangement, right circular polarization with axial ratio 0.9 dB at frequency 2.751 GHz is realized and axial ratio bandwidth close to 2.17% has been achieved. The gain of proposed antenna is lower than desired value for modern communication systems. In entire bandwidth, the radiation patterns are identical in shape. <br/> <br/>Page(s): 227-233 Fri, 29 Jul 2011 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/12555 Title: Effect of saline water on emissivity of soil <br/> <br/>Authors: Gadani, D H; Rana, V A; Vyas, A D; Bhatnagar, S P <br/> <br/>Abstract: Complex permittivity (e’, e”) of sandy loam soil was measured in the frequency range 300 KHz - 1.5 GHz (using a vector network analyzer) and at 5.65 GHz (using microwave bench set up) for various moisture contents in the soil. Measurements for complex permittivity in this frequency range were also carried out for various salinity levels of water content in the soil. The emissivity of the soil for normal incidence was calculated from the measured value of complex permittivity. It has been observed that at a given microwave frequency, emissivity decreases with increase in moisture content in the soil. Further, the emissivity of the wet soil, above transition moisture, decreases with increase in salinity level in soil. The experimental data of complex permittivity and emissivity in this frequency range can be useful in detecting the salinity and moisture content in the soil. <br/> <br/>Page(s): 218-226 Fri, 29 Jul 2011 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/12554 Title: Micro scale site diversity over a tropical site in India and evaluation of diversity gain with synthetic storm technique <br/> <br/>Authors: Roy, Bijoy; Shukla, Ashish K; Sivaraman, M R <br/> <br/>Abstract: An experiment has been conducted to evaluate micro scale site diversity (MSD) at Ahmedabad, a tropical site in India. Rain data is collected by a linear array of tipping bucket rain gauges during 2007 and 2008 monsoon periods. Spatial variation of rain fall has been studied with the help of joint probability and correlation coefficients derived for the collected data. The results support the existence of micro rain cells (MRC), which are the closed contours of continuous rain with dimensions of few hundred meters. Large attenuation of signals (above 10 GHz) occursed while passing through MRCs. MSD is proposed to counteract attenuation and ensure higher link availability. An attenuation of 30 GHz signal has been estimated using synthetic storm technique (SST) in this paper and used to obtain diversity gain. The estimated diversity gain has been presented for different site separations to explore dimension of MRCs for different percentages of service availability. <br/> <br/>Page(s): 211-217 Fri, 29 Jul 2011 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/12553 Title: Measurements of PM₁₀ and PM_2.5 aerosols in Agra, a semi-arid region of India <br/> <br/>Authors: Satsangi, P Gursumeeran; Kulshrestha, A; Taneja, Ajay; Rao, P S P <br/> <br/>Abstract: Measurements of PM₁₀ and PM_2.5 have been carried out at three locations in Agra, <i style="">viz.</i> St. John’s College (SJC), Dayalbagh (DB) and Balkeshwar (BS). PM₁₀ and PM_2.5 have been collected by respirable dust sampler (APM 460DX) and Wins Anderson impactor (APM 550), respectively. The average 24 h PM₁₀ and PM_2.5 concentrations have been found to be 121.8 ± 28.3 and 73.5 ± 14.6 mg m^-3 for SJC; 68.7 ± 24.8 and 28.6 ± 14.6 mg m^-3 for DB; and 54.9 ± 20.3 mg m^-3 and 39.4 ± 16.3 mg m^-3 for BS, respectively. The mean coarse particle concentrations (<i style="">i.e.</i> PM₁₀-PM_2.5) have been found to be 39, 62 and 29% for SJC, DB and BS of the average PM₁₀ for respective sites suggesting that the sites are also influenced by re-suspended surface dust and soil. The average ratios of PM_2.5/PM₁₀ indicate that about 40-71% of PM₁₀ are made up of PM_2.5, <i style="">i.e.</i> fine particles comprise a large fraction in PM₁₀ at all the sites. PM_2.5 concentrations have been highly correlated with SO₂ and NO₂ at SJC and DB sites while no correlations have been found between PM₁₀ and these gaseous species. Regression analysis showed that at DB, 90% of PM_2.5 and 10% of PM₁₀ of the average particle mass concentrations contributed from the road traffic, whereas at SJC it was only 52% of the PM_2.5. The higher contribution at DB may be because the site lies downwind during the monsoon period. A source apportionment study has also been performed to characterize the particulate matter sources at both SJC and DB sites. At SJC site, rotated factor analysis grouped the variables into two factors: re-suspension of soil (42.6%); and traffic and secondary pollutants (36.3%) as major contributors. The long range transport has been found to be major source to the particulate mass (35.2%) together with crustal (34.9%) and biomass burning (20%) at DB site. <br/> <br/>Page(s): 203-210 Fri, 29 Jul 2011 22:58:59 GMT