Compact Robust Antenna Composed of Metal Case with a Slot and Inner Folded Dipole Element

This paper presents an antenna composed of metal case with a slot and inner folded dipole antenna. The proposed antenna structure simultaneously achieves the miniaturization of the metal case and the wide bandwidth. The impedance bandwidth of $15.9 \%$ with the size of $0.36 \lambda_{0} \times 0.36 \lambda_{0}$ $\times 0.03 \lambda_{0}$ ($\lambda_{0}$ is the wavelength of low frequency) can be realized by the proposed structure. The proposed structure is validated by the comparison of the simulation and measurement result.