A Fully-Printed 3D Antenna With 92% Quasi-Isotropic and 85% CP Coverage

The Internet-of-Things (IoT) applications require orientation-insensitive wireless devices to maintain stable and reliable communication. For those reasons, antennas providing a wide quasi-isotropic and circular polarization (CP) coverage are very attractive. However, achieving wide quasi-isotropic and CP coverage simultaneously is challenging. In this work, we show that properly designed sloped dipoles on a 3-D structure can maximize the CP coverage (theoretically up to 100%) even with equal-phased feed to the dipole elements. We derive the conditions and present the design graphs for the optimum slope angle for the dipole elements on a 3-D hexagonal-shaped package to achieve a wide quasi-isotropic and CP coverage simultaneously. Based on the proposed theory, a practical antenna has been designed and fabricated using additive manufacturing. The measured results demonstrate a 7 dB isotropy of 92% and a CP coverage of 85%, which matches well with the predicted results from the theoretical analysis and full-wave simulations.