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Evaluation of the Radiation Efficiency and the Noise Temperature of Low-Loss Antennas

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Author: Maaskant, R. · Bekers, D.J. · Arts, M.J. · Cappellen, W.A. van · Ivashina, M.V.
Type:article
Date:2009
Institution: TNO Defensie en Veiligheid
Source:IEEE Antennas and Wireless Propagation Letters, Vol. 8, 1166-1170
Identifier: 463707
doi: doi:10.1109/LAWP.2009.2035148
Keywords: Physics · Antennas · Moment methods · Noise temperature · Radiation efficiency · Surface impedance.

Abstract

An accurate evaluation of the noise temperature of noncooled antenna systems is of great importance, particularly if the specifications of the antenna alone are a fewKelvins as in applications for radio astronomy. This evaluation requires an accurate analysis of the radiation efficiency, which we evaluate through the computation of the dissipated power from a method-of-moments (MoM) solution.We examine the numerical accuracy and the mesh sensitivity of the computed efficiency. Moreover we show that the efficiency is numerically smaller than or equal to 100%, contrary to results obtained with several commercial solvers. To describe the antenna loss, we employ the surface impedance of a thin sheet. For arrays of loops and for a tapered-slot antenna (TSA), we compare our efficiency results with those obtained by commercial solvers and by numerical far-field integration for the radiated power.