http://nopr.niscpr.res.in/handle/123456789/19300 2026-10-09T15:26:14Z http://nopr.niscpr.res.in/handle/123456789/19327 Title: Higher order mode analysis of circular coaxial waveguides using finite difference Authors: Pandey, Anil Kumar; Adinarayanan, Kartik; Chakrabarty, S B; Kumar, Arun; Sharma, S B Abstract: This paper presents a simple technique to evaluate the cut-off wavelengths of circular coaxial waveguides employing the method of finite difference. Curvilinear rectangular meshing has been employed to subdivide the cross-sectional region between the two conductors. Helmholtz equation in polar form is solved with the appropriate boundary condition to evaluate the cut-off wave numbers and correspondingly the cut-off wavelengths for TE and TM modes. Plots of cut-off wavelengths of few modes for various ratios of outer-to-inner radii are depicted.The data obtained from analytical expressions are compared to justify the validity of the analysis. Page(s): 285-288 2005-08-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/19326 Title: Shorting pin loaded microstrip antenna for dual-band operation Authors: Vishwakarma, Rajesh K; Vishvakarma, Babau R Abstract: The series and shunt inductivity introduced by the probe and shorting pin respectively, in a single-feed shorted rectangular microstrip antenna has been evaluated theoretically using transmission line method. The proposed structure provides compact dual band operation using single feed mechanism. The input impedance, VSWR, is calculated theoretically. It is found that the ratio of the resonant frequencies highly depends on the position of shorting pin. Page(s): 281-284 2005-08-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/19325 Title: Heat storage at sub-surface soil and microclimate at Thiruvananthapuram, India Authors: Raja, S Abraham Thambi; Renuka, G Abstract: During heat flux study at Thiruvananthapuram, in order to attain an accurate value for ground heat flux <i>G</i>, heat storage term Δ<i>S</i> of the energy balance equation was estimated and found to vary between 40 and 70% of ground heat flux, and 4 and 6% of the net radiation. Also, value of &nbsp;Δ<i>S</i> was found to have a maximum of 117 W/m²<i> </i>and a minimum of 0.4 W/m²<i>. </i>An empirical relation between <i>G</i>^* (<i>G</i> + Δ<i>S</i>) and <i>R, </i>net radiation, is deduced and compared with avail able results. From a detailed picture of microclimate near soil -air interface. it was found that the surface energy budget was governed by the surface condition and evaporation was the most important factor in the energy balance during humid conditions. Also intense solar heating and wetness of surfaces were factors influencing ground heat flux. Page(s): 274-280 2005-08-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/19324 Title: Estimation of sub-soil temperature using air temperature Authors: Chacko, P Tessy; Renuka, G Abstract: Extreme variability in the temperature of soil and air affects plant life. An attempt has been made to develop regression models to estimate the soil temperature at 5 and 10 cm depth using air temperature. Soil and air temperature data for the period 1998-2002 were collected from Vellanikara and Vellayani stations in central and south of Kerala state, respectively. A close resemblance in the weekly observed and computed sub-soil temperatures has been established. Page(s): 269-273 2005-08-01T00:00:00Z