Near-field to near/far-field transformation for arbitrary near-field geometry utilizing an equivalent electric current and MoM

Tapan Kumar Sarkar, Ardalan Taaghol

Research output: Contribution to journalArticle

168 Scopus citations

Abstract

Presented here is a method for computing near- and far-field patterns of an antenna from its near-field measurements taken over an arbitrarily shaped geometry. This method utilizes near-field data to determine an equivalent electric current source over a fictitious surface which encompasses the antenna. This electric current, once determined, can be used to ascertain the near and the far field. This method demonstrates the concept of analytic continuity, i.e., once the value of the electric field is known for one region in space, from a theoretical perspective, its value for any other region can be extrapolated. It is shown that the equivalent electric current produces the correct fields in the regions in front of the antenna regardless of the geometry over which the near-field measurements are made. In this approach, the measured data need not satisfy the Nyquist sampling criteria. An electric field integral equation is developed to relate the near field to the equivalent electric current. A moment method procedure is employed to solve the integral equation by transforming it into a matrix equation. A least-squares solution via singular value decomposition is used to solve the matrix equation. Computations with both synthetic and experimental data, where the near field of several antenna configurations are measured over various geometrical surfaces, illustrate the accuracy of this method.

Original languageEnglish (US)
Pages (from-to)566-573
Number of pages8
JournalIEEE Transactions on Antennas and Propagation
Volume47
Issue number3
DOIs
StatePublished - Jan 1 1999

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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