Antennas for LPWAN, NB-IoT and LTE-M

LPWAN is a wireless network technology that is designed for low-power IoT applications. It consists of a star topology, which means all devices connect to a central access point or base station, similar to a cell tower for cellular technologies. There are a range of LPWAN technologies that operate on both licensed and unlicensed frequency bands, but are usually on the low end of the scale, such as NB(narrowband)-IoT.

The main features of LPWAN are low power, long range, and low cost. Many small-scale IoT devices and networks are remote, battery powered and inexpensive. Sensors, for example, are often in locations without traditional LTE coverage, powered by a compact battery, and are part of a mass network of cheap individual sensors. LPWAN ticks the boxes of being long-range (2 km-15km) and low power, which are usually mutually exclusive for other wireless technologies like Wi-Fi and Bluetooth.

With many wireless technologies, there is often a dichotomy between the connectivity range and power efficiency of an antenna; Bluetooth antennas have impressive power efficiency but lack range and signal penetration. That said, there is a high demand for both of these features in a wide range of compact IoT applications. Smart metres, asset trackers, and smart building sensors, for example, represent large IoT networks that have significant power draw but are a distance apart, requiring an efficient large-scale network.

There is a selection of LPWA antenna types that benefit individual applications, especially in the case of NB-IoT and LTE-M antennas. As many LPWAN applications are compact, remote, and have limited battery capacity, many of them have embedded LPWA antennas integrated to enable the miniaturisation of designs. Embedded SMD, FPC and PCB antennas all suit different designs by providing different integration benefits.

SMD

Surface mounted antennas (SMD) are a form of embedded antenna that is mounted directly onto the host PCB alongside other components. SMD chip antennas are simple to integrate with low part cost and compact size, as well as being suitable for high-volume manufacturing using pick-and-place machinery. These enable simple integration and manufacturing for compact IoT devices.

FPC/PCB

Flexible printed circuit (FPC) and PCB antennas have their own ground plane on the antenna, along with an adhesive strip that can be placed on the inside of the product housing. FPC antennas are unique in that their surface is malleable, allowing them to be placed on curved surfaces. This solves ground plane and interference complications through being placed away from PCB components. For standard and curved IoT devices with limited PCB space, PCB/FPC solutions are perfect.