Input impedance increase of a very small meander line antenna

Meander line antennas are commonly used as small antennas in commercial handy phones. In the case of meander line antennas of size less than 0.1 wavelength, input impedances become very small. Hence, antenna efficiencies become very low. Therefore, increase of input impedance is very important. The paper proposes a folded dipole antenna configuration that can increase input impedance. First, antenna configurations less than 0.1 wavelength and their input impedances are clarified through EM simulations. Next, increases of input impedance by folded configurations are shown. An antenna of 0.1 wavelength and its folded configuration were manufactured. Measured and calculated resistances agree rather well. Antenna efficiencies of the conventional meander line antenna and the folded configuration were 28.9% and 67.8%. respectively. Increase of antenna efficiency is ensured by the folded configuration.