Helmet Antenna Design Using Characteristic Mode Analysis

摘要

The helmet antenna is required to achieve hands-free operation for disaster prevention. The helmet antenna is not only low profile with a small configuration, but it also suppresses radiation toward the human head. This paper presents the characteristic mode analysis of the helmet, which is a hemispherical conductor shell to achieve the omnidirectional pattern in the horizontal plane. By deleting the weak part of the electric current on the hemispherical conductor shell, the shape of the folded dipole was obtained with a low resonant frequency. The folded dipole antenna with a slit-loaded copper ring structure with high radiation efficiency and a low SAR value was designed.