Deconvolution of target signature for a scene with bistatic impulse radiating antennas and a sphere
A model for an impulse radiating antenna (IRA) has been developed in WIPL-D. A scene using a bistatic pair of these IRAs is modeled with a sphere target and is simulated in the frequency domain. The input to the antenna is a Gaussian pulse, and the current on the receive antenna is plotted vs. frequency. This receiver response is proportional to the scattered field from the sphere. The frequency domain data are processed to give the time domain response. The objective of this work is to deconvolve the signature of the scatterer from the receiver transient response. Additional separate simulations for each scene component and electromagnetic interaction were needed and were performed using WIPL-D. The process is successful for this scene, which does not include a ground plane. The analysis of the simulated data and deconvolution of the target signature are done in Matlab.
WIPL-D model and simulation results for a 46cm diameter impulse radiating antenna (IRA)
WIPL-D was used to model and simulate an impulse radiating antenna (IRA) with a 46cm diameter paraboloidal reflector and 45 degree feed arms. Model views are shown and the results of frequency domain simulation up to 20GHz are shown to agree with results from published measurements. Beam patterns at three frequencies show the highly directional behavior of this antenna. The simulated frequency domain data is inverse Fourier transformed to obtain the time domain response to a Gaussian pulse input. This response is integrated to obtain the response to a step input, which compares well with the theorized step input response of the IRA.
Convergence Anatomization of Aquaculture Production in Leading Fish-Producing Countries During the Period of 1997-2013
Growth and national importance of aquaculture production is empirically assessed as an important indicator of development. The present article aims to test whether the major aquaculture producing countries of the world are converging over time. The authors have applied the absolute and conditional beta convergence and sigma convergence approaches on the data of FAO for the period 1997-2013. The results show that there is an absolute beta convergence and sigma convergence among 25 major aquaculture producing countries; negative sign of coefficient of conditional beta convergence with per capita income is also noticed. It implies, the growth rates of aquaculture for developed nations are declining with rise in per capita income and backward fish-intensive countries are catching up with the giant producers like China and India. The cross-country variations are also going down which means that the countries' development gaps are getting narrowed by means of growth of aquaculture resources.