A Development of 146∼222 MHz Folded Dipole Antenna in an Immunity Test of Portable Transmitters on Road Vehicle Components

This study aims to describe the development of dipole antennas on a frequency band of between 146 MHz and 222 MHz, which can be used in an international standard for immunity test (ISO11452-9) [1] designed to check for malfunctions by applying radio waves generated from portable transmitters used in vehicles, such as portable radios or mobile phones, to electrical components in a vehicle. The monopole-type helical antennas currently in use fail to generate desired electric fields due to changes in resonance frequency and radiation patterns influenced by the setup and the ground. To mitigate this problem, this study has developed a folded dipole antenna, which is less influenced by the ground. The first edition of ISO11452-9 was published in 2012, and the working draft(WD) for the second edition is now under way at the CISPR/D and ISO international committee in 2018 where a technical report on the content of this study and the antennas were submitted.