Effects of effective dielectric constant of printed short dipoles in electric field probes

The parameters of antennas printed on electrically thin ungrounded substrate are usually found by simulations or by trial and error method because the value of its effective dielectric constant is unknown. In this paper the effective dielectric constant of a dipole printed on some commonly used substrates, with standard thickness and relative permittivity, was found and its eventual effect on antenna parameters was demonstrated. To emphasize the importance of substrate choice, the thorough investigation of its influence on electric field probe characteristics was performed. Three standard electric field probe constructions, often used in various EMC measurements, were examined. The results obtained by SEMCAD X simulation software showed that dielectric substrate selection has considerable effect on probe´s sensitivity, cut-off and resonant frequency and consequently the major impact on probe´s bandwidth.