Stay Tuned: Dynamic Band-Switching Seeing Growth in IoT Antennas

Dynamic band-switching is not new. Back in February 2013, Qualcomm announced its RF360 chipset, which included an antenna switch and dynamic antenna-matching tuner to enable smartphones to support and optimize performance on all Long Term Evolution (LTE) frequency bands between 700 MHz and 2700MHz in real time. What is newer is its increased adoption in the Internet of Things (IoT). Band-switching has been less of an issue in the IoT market because of the relative simplicity of device protocols: Bluetooth, Wi-Fi, Global Navigation Satellite System (GNSS), and Industrial, Scientific, and Medical (ISM) devices operate on a low number of frequencies, with the result that a relatively simple passive component can suit most requirements. Module vendors and antenna vendors have frequently partnered together to offer off-the-shelf joint solutions for Bluetooth, Wi-Fi, and GNSS, in particular: these frequently consist of a Surface-Mount Technology (SMT) chip or Printed Circuit Board (PCB) trace antenna mounted on the same board as a module, ready for integration into any device. Because of the simplicity of the frequencies covered, no complicated matching network needs to be designed, and an antenna can be “pre-detuned” to make sure that it resonates at the right frequency after it is integrated into an end node.

Where this becomes more of a challenge is on cellular deployments because of the much higher number of frequencies and bands covered: the challenge is both on frequency coverage in low (700 MHz to 960 MHz) and high (1700 MHz to 2700 MHz) bands, as well as the number of bands to be covered, with more than 40 currently in use for LTE, and more planned for 5G. In the IoT, this fragmentation becomes more of a challenge as more radios and better performance are required, as devices need to function in multiple regions, and as these requirements are needed in a smaller form factor device. The interest in dynamic band-switching for the IoT is beginning to grow, in part because of the proliferation of devices operating on cellular bands (aided by the spread of Low-Power Wide-Area (LPWA) networks). In the last 2 years, Ignion (formerly Fractus Antennas) has worked with several module vendors for reference designs and off-the-shelf module-antenna joint solutions using cellular (particularly LTE for Machines (LTE-M) and Narrowband-IoT (NB-IoT)); these include Cavli Wireless, Sierra Wireless (mangOH Yellow), Sequans (NEKTAR-B), and Nordic (Thingy:91), with these last two incorporating switching systems. ABI Research is aware of at least one other major module vendor working with an antenna vendor and antenna tuning chip vendor on a tuning solution, which will be deployed on IoT end nodes.

Why does this matter? For several reasons. The first is the impact on device design and performance, with several important benefits. Dynamic tuning chips allow devices to pack more cellular complexity into a smaller form factor by using a single wideband antenna, enabling size reduction in the device. Ethertronics, a leader with its Ether Switch&Tune solution, claims the ability to reduce the antenna’s physical volume by up to 50% without performance trade-offs. Optimizing the frequency also means that the device can be made more efficient by boosting data throughput and performance based on the available transmission bands. This means that the device can avoid interference or lower performance in certain challenging settings; this was one reason for the initial uptake in smartphones, optimizing performance when the phone was in a hand or when making a call, but has high relevance in the IoT because of the numerous scenarios when Radio Frequency (RF) paths may be impeded. Ultimately in the IoT, this optimization does not matter as much for data transfer (except in high data throughput applications) as it does for power consumption, with less power needed to transfer the same payload.

Secondly, the growing interest in band-switching is important as it shows a switch in focus from high-power wireless communication and consumer devices down to individual IoT end nodes, where the potential of connection numbers is much higher; particularly in small form factor, low-power, and complex RF devices, such as trackers or wearables. The involvement of module vendors also means that there are more reference designs for Original Equipment Manufacturers (OEMs) to play around with, increasing awareness and adoption. As antenna design becomes more complicated with more stringent device constraints, OEMs are increasingly looking at these active antenna solutions to simplify their task and reduce dependence on antenna datasheets for successful integration. This will be particularly important as LPWA cellular networks continue to spread and more cellular devices with low-power requirements enter the market.

Thirdly, the offer of joint solutions by antenna vendors and module vendors is interesting as connectivity standards evolve. These vendors are increasingly working in partnership to develop antenna systems, rather than discrete components, which helps to create a more integrated and higher-performing device, and is important as more complicated antenna arrays become necessary for 5G and Wi-Fi 6 Multiple Input, Multiple Output (MIMO) applications. This will further help drive the availability and uptake of integrated active antenna systems.

As noted, dynamic band-switching has been around for a while. However, it is worth highlighting for several reasons: because of the renewed interest of module and antenna vendors; because of the accelerated growth in IoT, particularly on the cellular side; because of the increasing technological complexity facing OEM designers, and the increasing pressure facing business leaders to simplify product development and reduce Stock-Keeping Unit (SKU) numbers; and because of the proliferation of SMT chip wideband antennas available on the market, which make this solution considerably simpler to implement. Band-switching is a technology of which OEMs should increasingly be aware.

One of the principal noted challenges of dynamic switching technology is the higher cost, requiring an additional tuning chip alongside the existing antenna components. At relatively low volumes, however, a tuning chip can reach US$0.50, which increasingly makes it accessible to low-cost IoT devices, especially given the potential benefits and cost savings. Increasing adoption of solutions from leading vendors like Ethertronics, Qualcomm, and Qorvo will further drive down the cost.

Component vendors are increasingly looking to take a greater share of the IoT stack. These vendors must work together to develop integrated systems that simplify design and performance for OEMs, with successful early partnerships between module and antenna vendors a crucial step. These two vendor types, both offering further services for integration to customers and both crucial for ensuring the RF success of a device at design and certification stages, are uniquely suited to increase these collaborations going forward, and will need to do so to bring to market more sophisticated antenna systems required in MIMO applications.