Abstract
Internet of Things (IoT) applications need wireless connectivity on devices with very small footprints, and in RF obscure environments. The antenna for such applications must work on multiple global system for mobile communication (GSM) bands (preferred choice for network connectivity), provide near isotropic radiation pattern to maintain orientation insensitive communication, be small in size so that it can be integrated with futuristic miniaturized IoT devices, and be low in cost to be implemented on billions of devices. This paper presents a novel 3-D dual-band near-isotropic wideband GSM antenna to fulfill these requirements. The antenna has been realized on the package of electronics through additive manufacturing to ensure efficient utilization of available space and lower cost. The proposed antenna consists of a meander line antenna that is folded on the faces of a 3-D package with two variations, 0.375\lambda length for the narrowband version and 0.67\lambda length for the wideband version. Theoretical conditions to achieve near-isotropic radiation pattern with bent wire antennas on a 3-D surface have been derived. The antenna has been optimized to operate with embedded electronics and a large metallic battery. The antenna provides 8.9% and 34.4% bandwidths, at 900 and 1800 MHz, respectively, with a decent near-isotropic radiation behavior.