Internet of Things (IoT) applications require AQ:1 1 orientation insensitive wireless devices to maintain stable and 2 reliable communication as well as the localization capability 3 using the global positioning system (GPS). For those reasons, 4 antennas providing near-isotropic radiation pattern with wide 5 circular polarization (CP) coverage are high in demand for IoT AQ:2 6 applications. In this work, we derive conditions for 3-D antenna 7 on package (AoP), through a combination of three orthogonal 8 dipoles model and particle swarm optimization (PSO) technique 9 to achieve near-isotropic radiation pattern and wide CP coverage 10 simultaneously. Design guidelines have been provided, and a 11 practical AoP has been designed on a 3-D cube package by 12 following this guideline. A prototype has been fabricated and 13 the measured results demonstrate an isotropy of ∼93% and 14 CP coverage of ∼18%, which matches well with the predicted 15 results from the theoretical analysis as well as the full-wave 16 electromagnetic simulations. 17 Index Terms-Circularly polarized antenna, near-isotropic 18 radiation pattern, orientation insensitive antenna. 19 I. INTRODUCTION 20 I NTERNET of Things (IoT) will bring connectivity to the 21 next level, where billions of smart devices to be designed 22 for making decisions for a large number of applications in an 23 automated fashion. These huge numbers of IoT devices will 24 depend on high speed and uninterrupted wireless communica-25 tion for their smooth functioning. Thus, a new generation of 26 antennas is required which are space-efficient, low cost, and 27 orientation insensitive in terms of stable performance. Low 28 cost and efficient space can be achieved through the antenna-29 on-package (AoP) concept.

A low-cost and additively manufactured 3D Antenna-in-Package (AiP) with quasi-isotropic radiation is proposed for a marine animals monitoring system. The antenna is based on a meandered dipole folded as a split ring resonator (SRR) structure, which can generate simultaneously a pair of orthogonal electric and magnetic dipoles, thus providing a quasi-isotropic radiation pattern. The antenna (integrated with a balun) has been inkjet-printed on a 3D-printed buoyant cone structure, which acts also as the system package to house the electronics and the battery. The antenna designed at 2.4 GHz is electrically small, with a = 0.49, and has a bandwidth of 70 MHz (2.9%). The measured gain deviation of the antenna (maximum to minimum) is near 3 dB in bandwidth, thus qualifying it as a quasi-isotropic antenna. Field tests of the antenna in the active state (integrated with the electronics) confirm a reliable communication range of 240 m in any direction in the azimuthal plane.

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 a wide quasi-isotropic and CP coverage simultaneously is challenging. In this work, we show that properly designed sloped dipoles on a 3D 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 3D 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 7dBisotropy of 92% and a CP coverage of 85%, which matches well with the predicted results from the theoretical analysis and full-wave simulations.

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