Characteristics of Disaster Prevention Helmet Antenna Using Disk-loaded Monopole Antenna

Abstract

Many helmet antennas operating in the UHF band have been reported. In our laboratory, helmet antennas for disaster prevention that operates in the VHF band have been considered, and all of them have horizontal polarization and almost omnidirectional radiation patterns in the horizontal plane. In this paper, an antenna on the helmet for disaster prevention is created using a disk-loaded monopole antenna which is very low-profile and has a vertically polarized and omnidirectional radiation pattern in the horizontal plane. The VSWR characteristics, radiation pattern, and electric field distribution of this proposed antenna are analyzed using an electromagnetic field simulator, and the validity of the analysis results is confirmed through prototyping and measurement. As a result, it was confirmed that the proposed antenna can be used in the VHF band and has an omnidirectional radiation pattern in the horizontal plane. In addition, radiation in the direction of the head was reduced, and good VSWR characteristics were got even in close proximity to the human head phantom model.