Abstract
THE Internet of Things (IoT) is expected to connect billions of objects to the Internet so that they can take informed decisions without human intervention <xref ref-type="bibr" rid="ref1">[1] . These IoT devices usually implement wireless communication protocols under the IEEE 802 family of standards <xref ref-type="bibr" rid="ref2">[2] , <xref ref-type="bibr" rid="ref3">[3] , <xref ref-type="bibr" rid="ref4">[4] as Wi-Fi, Bluetooth Low Energy (BLE) and ZigBee. All these protocols communicate in the 2.4 GHz ISM free band using network structures made of two main nodes: A central node (CN) in charge of collecting the data from multiple devices and uploading it to the cloud, and multiple peripheral nodes (PN) which are simpler devices with limited power consumption so they can be battery operated. Typically, the larger amount of PN in any application are randomly placed sensors that communicate with a fixed CN. These PN are then expected to be highly integrated, cheap to manufacture, and energy efficient to extend their battery lifespan <xref ref-type="bibr" rid="ref5">[5] . On top of that, they are required to keep an orientation insensitive communication link so a change of the relative position with respect to the CN does not result in disconnection. Thus, the antenna design for such devices becomes challenging as it has to be compact, low cost as well as provide a radiation pattern which is not dependent on the orientation of the device.