The Internet of Things (IoT) consists of billions of connected devices. By 2025, it is estimated that global IoT connections will reach more than 42 billion devices, a 5-year Compound Annual Growth Rate (CAGR) of 24%.
Enabling this massive growth in connectivity is an unassuming, yet critical device component that enables data to be sent up to the cloud: the antenna. Central to an IoT system, the antenna is also one of the most difficult components to get right to address not only IoT edge device performance, but also cost and physical design requirements. Failure to successfully integrate and optimize the performance of the antenna component results in IoT devices not meeting certification requirements, time-consuming and expensive re-designs, or, in the worst cases, project failure because of faulty hardware.
IoT Antenna Considerations and Challenges
Considering the numerous technology and business challenges OEMs face, antenna choice and design is a critical element in IoT device deployment success. Antenna selection in a device comes down to a balance of three principal considerations: size, performance, and cost.
The size and form factor of the end device is frequently an inflexible condition. OEMs will typically start with the size of the PCB and the ground plane it carries, with on-PCB antenna implementations some of the most convenient. Antennas used in this category include PCB trace, Surface-Mount Technology (SMT) chip, or metal stamp antennas.
With respect to performance, antenna gain, efficiency, operating frequencies, impedance match, and radiation pattern are also crucial when selecting or designing an antenna system. These factors might condition whether a device will pass the certification processes, as well as determine the effectiveness of connectivity, optimal battery power consumption, and IoT solution performance. An important consideration for antenna performance is their exact placement on the PCB (surface clearance) or within the device (volumetric clearance) to ensure that antennas do not interfere with each other or with surrounding conducting components. Another important aspect of antenna performance is replicability: in other words, whether an antenna can be manufactured identically in large batches and in different production batches with the same performance.
Antenna cost is the last significant consideration for OEMs. The price of different types of antennas may vary from cents (e.g., PCB trace or wire antennas) to tens of dollars (e.g., high-end external antennas). This factor is important as device deployments reach high volumes, where small savings per antenna can translate to higher profitability. This impact grows further in importance for low-cost IoT: after the PCB board, the main processor, the radio modules, and the battery, the antenna can be the most expensive component in the Bill of Materials (BOM).
Low In-House RF and Antenna Expertise: The long tail of the IoT means that in-house engineering teams often do not have the specific RF or antenna expertise to successfully integrate an antenna within a device. While antenna datasheets are available, antenna performance measurements are typically taken in free space and on specific evaluation board sizes, which does not accurately account for device and use case-specific factors. As a result, datasheets act more as design guidelines than design rules. Module vendors, antenna vendors, and device design houses play an increasingly important technical support role in new product designs to ease this challenge through reference designs and the use of tuning mechanisms required when the design matures.
Decreasing PCB Real Estate: While a PCB-mounted antenna, such as a trace or SMT chip, may be a commonly-used path, the surface area of the PCB becomes a more important consideration as OEMs integrate more features, radios, and components within this small space. PCB design and antenna layout often require the input of antenna vendors and design houses to manage the design challenge.
Sub-Gigahertz (GHz) Design: Many IoT devices operate at frequencies under 1 GHz because of the higher range and penetration of radiation in lower spectrum bands. However, they also require larger antennas compared to devices connecting on higher spectrum bands due to the inherent physics of antenna design, where radio wavelength is inversely proportional to frequency, such that a lower frequency requires a larger antenna size. In addition, if external antennas are not an option, embedding larger antennas is more complicated, making the integration and isolation of these antennas within a device more challenging as well.
Managing Trade-Offs: OEMs need to balance antenna performance with power consumption, particularly when it comes to battery-powered devices. A more efficient antenna will require less power to transmit the same data payload. Moreover, if an antenna is not sufficiently efficient, the connectivity to the IoT network becomes a service-level issue for service providers. But antenna efficiency is affected by its integration within a device, which affects device design and costs. Trade-offs are an inherent requirement in antenna choice.
Iterative Process: Testing is necessary to ensure proper antenna performance. In many cases, this involves building a prototype board and testing the antenna in different setups with any modification to the device very likely to affect the antenna performance. This process is further complicated when antenna integration is left until the end of the design phase as options to change will have become more limited.
The Virtual Antenna™ as a Solution
Ignion offers a new approach to antenna technology called the Virtual Antenna™ , which aims to remove complexity for the hardware designer and help OEMs streamline their approach to building IoT solutions. It is comprised of three principal components:
Booster: A small, wideband chip that comes in a limited variety of form factors. It is mounted directly to the board using pick-and-place machinery and usually requires a clearance area around it. Unlike standard SMT chips, the booster's role is not to resonate at a specific frequency, but to maximize how much signal is passed on from the radio to the ground plane, and vice versa. Boosters support a frequency range from 698 MHz to 10.5 GHz.
Matching Network: The matching network is a series of very low-cost standard capacitors and inductors placed between the radio and the antenna. In a traditional resonant antenna, a matching network is used to retune the impedance of the radio with the antenna when shifted from its natural resonance due to suboptimal design or environmental factors. In the Virtual Antenna™, however, the purpose of the matching network is to select the required frequencies of operation and maximize the transfer of RF energy from the radio to the ground plane. For any Virtual Antenna™, the matching network is the only component that needs to be modified to operate at desired frequencies.
Ground Plane: The Virtual Antenna™ is “antenna less” in that the booster does not resonate like a traditional antenna. Instead, the required resonance that transmits radio waves for communications is achieved through use of the ground plane. All existing monopole (λ/4) antennas use the ground plane to reduce the required length of an antenna to provide the best performance (λ/4+ λ/4= λ/2). In contrast, the Virtual Antenna™ resonates purely through the ground plane and is often the smallest antenna option available on the market.
The Virtual Antenna™ does not require a larger ground plane than existing monopole antennas to achieve alike or better performance; in fact, the ground plane may be smaller than that required in a resonant antenna, with the matching network determining the frequency ranges and the booster optimizing the use of the ground plane. However, as with all antennas, a larger ground plane always means higher performance and efficiency.
In its implementation, a Virtual Antenna™ is an SMT-type antenna, sharing several similarities. At operation, however, is where differences begin to surface:
- The booster does not resonate, instead, covering a wide bandwidth and transferring the signal efficiently to the ground plane. SMT components need to feature a certain size to resonate, while boosters do not.
- Frequency selection is done through the matching network--the only part of the antenna setup that needs customization or modification. The matching network has a similar implementation as the SMT, but a different role from that used in resonant antennas.
- Because a Virtual Antenna™ can be tuned to anything in its stated frequency range, it can accommodate many protocols from cellular, non-cellular LPWAN, Bluetooth and Wi-Fi, GNSS, and others.
- SKU reduction. Because boosters cover a wide frequency range and any number of protocols, booster users avoid the need to shop around for different antenna types. Furthermore, the same booster can be used across different product SKUs, with modifications purely on the matching network side.
Regardless of the antenna technology, the IoT market represents a significant opportunity for antenna OEMs. Annual IoT antenna shipments are expected to grow from 2.6 billion in 2020 to more than 6.2 billion in 2025. While the vast number of “things” that can be sensorized, digitized, and connected is large, the top markets fueling antenna shipment growth will be wearables, smart home, and tracking/logistics. These three markets will make up nearly 73% of antenna shipments from 2020 to 2025.
The Virtual Antenna™ will provide the most benefit in IoT markets that prefer OTS components. OTS antennas are critical to device growth in the IoT because the IoT market is served by a long tail of device OEMs serving a broad range of use cases. Over the next 5 years, OTS antenna shipments will account for 40% of all antenna shipments. Depending on pricing levels, however, the Virtual Antenna™ can also target markets using complex custom antennas because of its ease of use and the ability to support complex frequency requirements. ABI Research expects that OEMs that have traditionally used SMT antennas will initially be the most likely to benefit from access to the Virtual Antenna™. The top SMT antenna markets are the same as the top selling IoT markets. Wearables and tracking/logistics are the largest markets followed by smart home. Shipments of SMT antennas will reach nearly 1.8 billion devices by 2025.
Outlook of the Virtual Antenna™
Antenna vendors are increasingly building out their OTS product lines to help the long tail of device OEMs get to market faster and for less development cost. Increasingly, device OEMs serving the IoT market are seeking to use flexible and miniature antenna components within their products. These demands are in response to an increasingly complex and competitive IoT market, driven by more radio complexity and band coverage, faster product SKU refresh cycles, and higher performance in battery-operated devices.
The Virtual Antenna™ technology can simplify and enhance the capabilities of on-PCB antenna design, help drive OEMs toward greater awareness of system-level design and simplify the antenna selection process for designers and business leaders. While product breadth in the IoT antenna market will remain, Virtual Antenna™ technology has the potential to transform the IoT device market through its single design providing both technology and business advantages.
Our whitepaper, Rethinking IoT Device Deployment with Virtual Antenna Technology, covers in greater detail the opportunities possible in IoT with virtual antenna technology. Both the whitepaper and this blog post are sponsored by Ignion.