You can select the optimum connectivity, design-in the ideal balance of computing capability and power consumption and use clever materials to minimize weight and the form factor of an IoT device – but if you neglect the antenna, much of this effort doesn’t translate to real world performance. Poorly sited antennas, the wrong choice of antenna type and designing in ways that expose the antenna to greater interference mean throughput, power consumption and overall device performance are all negatively impacted. It’s time to take IoT antenna structure seriously and take the appropriate steps to ensure your antenna choice suits your application and device.

An antenna shouldn’t be an afterthought added to an already designed device in a hurry. Instead, it should be an integral part of the design process allowing you to select external or embedded antennas. Being able to make the right choices relies on understanding IoT antenna structure and the variations that are available.

IoT antenna structure – a matter of polarity

You might already know the basics – that antenna size is strongly related to the initial frequency it can operate within and that lower initial frequency means extended wavelength, so larger antenna size equals extended wavelength, while smaller antennas operate at lower wavelength. Different antenna types therefore map to different wavelengths and introduce specific resonance modes. Typically, most antenna designs that are commercially adopted are based on the principle of the dipole antenna.

A dipole antenna offers many advantages as RF engineers try to create a ‘standing wave’ that continuously distributes the electric field in the space. The next decision in considerations over IoT antenna structure is to choose an external or embedded antenna. Selection can be a challenge and depends on understanding the real-life use case in contrast to simply looking at theoretical conditions.

Embedded or external?

Engineering efficiency can enable smaller external antennas to be used. Some applications might need 150mm for a 1GHz dipole antenna, but it might be possible to gain sufficient performance with a smaller antenna. Designers should assess carefully what their deployment needs.

Embedded antennas also have many variables that must be considered. These extend from the shape of the antenna to decisions on monopole or dipole designs. Each of these designs will affect the space occupied in the device by the antenna, the performance of the antenna and potentially the cost of the overall device.

There are various types of embedded antennas to consider but there are common constraints that Quectel has encountered across a massive range of different types of deployments. Space in a device is always limited and often it cannot fit a dipole antenna, so monopole or PIFA antennas are good options. Quectel has helped to address this challenge by enabling the main board in the device to be used as part of the antenna design thus saving space while adding performance.

Quectel experts have recently covered IoT antennas in greater depth in a Quectel APAC Masterclass on IoT antenna structure. The Masterclass, presented by Quectel FAE Cell Chiou and Colin Newman the director of business development for antennas at Quectel, detailed many of the challenges and also answered questions from attendees at the live session. You can listen to the Masterclass in full here https://quectel-development.oriel-agency.dev/library/masterclass-apac-iot-antenna-structure.