On Synthesis of Orientation Insensitive Antennas

Internet of things applications require orientation insensitive wireless devices to maintain stable and reliable communication. The devices developed can also require positioning or a special protocol communication as Global Positioning System, Bluetooth Low Energy or Wi-Fi, which all implement a specific polarization, namely right hand circular (RHCP) and linear (LP) for the last two. For those reasons, antennas providing near-isotropic radiation patterns along with wide far-field sphere polarization coverage, including LP and RHCP, are highly demanded in IoT applications. In this paper, we present some theoretical limitations on the synthesis of an antenna with near-isotropic radiation and polarization patterns. We consider two models: a set of orthogonal Hertzian electric dipoles located at different points, as well as a model of Hertzian magnetic dipoles located on faces of a perfectly electric conducting cube. These models allow synthesizing the near-isotropic radiation and polarization patterns of an antenna based on short dipoles, as well as a cubic antenna with radiating patches on the cube faces.