Theoretical and practical validation tests for a Near-Field to Far-Field transformation algorithm using spherical wave expansion

• Eduardo Javier Páez Campo tecnológico de Sartenejas-Venezuela
• Juan Pedro Regina Universidad de Carabobo-Venezuela
• María Daniela Sandoval Universidad de Carabobo-Venezuela
• Paulino Del Pino Universidad de Carabobo-Venezuela
• Ciro Daniel Tremola Campo tecnológico de Sartenejas-Venezuela
• Barón Marco Azpúrua Campo tecnológico de Sartenejas-Venezuela

Palabras clave: near-field far-field, numerical transformation, spherical wave expansion, antenna radiation pattern, anechoic chamber

Resumen

The use of spherical wave expansion of the solution of the wave equation to predict Far-Field values from data measured in the Near-Field region is a well known technique, typically used to perform antenna measurements in compact anechoic chambers. However, when designing the computing algorithm it is fundamental to validate the results and to quantify the numerical error of the method. In this regard, a computer application that samples the electric Near-Field and calculates the values of the electric Far-Field region using spherical wave expansion was developed to measure antenna radiation patterns in the Fresnel zone inside a fully anechoic chamber. In order to validate the code, this paper describes three validation methods: firstly, using the theoretical electric Near-Field values of an infinitesimal dipole as the input to the algorithm to compare the output with the response analytically expected; secondly, using a Far-Field electric field data of a calibrated half wavelength dipole measured in an anechoic chamber and finally, using an electric Near-Field data of a calibrated half wavelength dipole measured in the same chamber. These methods provide simple procedures to calculate the error introduced by the code in different scenarios that should be considered to estimate the measurement uncertainty.