Numerical and analytical model of standard dipole antennas from 30 MHz to 2 GHz

The Antenna Factor (FA) of a half wavelength dipole is evaluated between 30 MHz and 2 GHz. Generally the ANSI-63.5 [1] method for EMI antenna calibration supposes a perfect sinus current density along the dipoles and the mutual effects on AF are taken into account with the simples correction factors. The perfect sinus form of current density is not correct for the real thick dipoles. For these dipoles i.e. no-resonant and thick, supposing the sinus current density introduces errors around 1dB on AF. Two theoretical methods are presented: a numerical approach based on MoM (Method of Moments) to model two dipoles in a Standard Site, and an analytical method based on a simple new current distribution along the dipoles to evaluate their radiation characteristics. The necessary dipoles have been designed for this work. The frequency range is covered by only two baluns. In 350 MHz - 2 GHz range, we have used for the first time a wide-band taper balun. The experimental results are presented.