Ultra-miniature Circularly Polarized Antenna with Omni-directional Pattern for Sat-IoT

This paper presents the design and performance of a lambda/15 x lambda/15 x lambda/25 antenna that radiates circular polarization with a dipole-like pattern. The simple antenna structure is composed of a miniaturized monopole loaded with a small loop. The radiation is optimized by controlling the coupling between the monopole and loop through reactive loading component calculation. While the circular polarization remains good (AR<3 dB) over the 0.75% fractional bandwidth, the total efficiency reaches 12% for such an ultra-miniature antenna with ka=0.32.