New Antenna Technologies Solve the IoT’s Most Critical Links

Regardless of the application it’s been designed for, every IoT device network depends on an antenna. This fact of engineering life is so basic that developers don’t always pay adequate attention to the antenna choice. Rote thinking on this all-critical component is an unfortunate oversight and often the cause of expensive failures in the field. No other aspect of the IoT design cycle has a greater impact on performance, efficiency, and reliability.

A 21^st Century IoT Antenna Solution at Last

Today’s popular IoT antenna solution, the Flexible Printed Circuit (FPC) sticker antenna, has been with us for decades. This technology requires cumbersome manufacturing processes that unavoidably add doubt to the development cycle. Test results achieved in the lab don’t always survive intact through the manual assembly and cable routing that FPC antennas require. As a result, many devices don’t work as expected in the field, or consume too much energy in trying. Ultimately, these are product failures.

Breakdown of an FPC Antenna Solution

Today, we finally have a modern advancement for IoT device antennas that overcomes this unpredictability and can provide accurate demonstrations of in-field performance before the product is manufactured. Virtual Antenna® technology brings important new development advantages to the IoT landscape. These include multi-band and multi-radio capabilities, streamlined manufacturing, optimized connectivity and greater energy efficiency, among many others.

Breakdown of a Virtual Antenna Solution

Beyond the technical benefits for the development team, Virtual Antenna® solutions also provide substantial business advantages of confidence, reliability, and economy. An influential study published by Forrester Research reported that for every dollar spent to resolve a problem during product design, $10 would be spent on the same problem during development, and $100 or more if the problem had to be solved after the product’s release. Smart decisions at the design outset, such as a Virtual Antenna® component, usually pay for themselves.

In comparison to FPC, Virtual Antenna® technology provides the following key advantages: 

• Predictable antenna performance: IoT devices operate the same in the field as they do in the lab.
• Agility: A single product design can be easily re-tuned across multiple radio frequencies.
• Smaller form factors: Requires only a fraction of the space of an FPC antenna.
• Greater thermal latitude: Stable operation at about 50% higher temperatures over FPC. 
• Less performance variance: Greater efficiency across the IoT frequency 
• Real-world previews: Accurate in-field simulations prior to product manufacturing.

Top 6 key advantages of the Virtual Antenna® technology

1. Predictability: Eliminate the Biggest FPC Antenna Wild Card:
FPC antennas may perform well enough in a development environment, where the antenna and the PCB are comfortably side by side. Those conditions change unpredictably once the device moves into production. The manual assembly processes required for an FPC antenna integration bear much of the blame. The necessary cable must be attached to a necessary connector, and even minute placement variances can produce serious degradations. Other tiny variances in the FPC folding or adhesion process – unknowable until too late – can easily sink the product.

The Virtual Antenna® component is a surface mount device (SMD), which is mounted using standard automated pick-and-place equipment and soldered onto the PCB like any other SMD part. No manual assembly is required. With Virtual Antenna® technology, devices in production are an exact replica of the finished prototype, ensuring predictable performance from the lab to the field. Additionally, a Virtual Antenna® product does not degrade over time, as an FPC solution may, as the result of shifting caused by enclosure heat and environmental conditions.

2. Agility: Any Frequency or Protocol, Anytime:
FPC antennas are inherently resonant and designed to work within specific, limited frequency bands. Because their bandwidth is fixed, designers must choose from the multitude of antenna options that are available for different protocols and frequency bands. A compromise choice at the outset is always a design risk, and any desired change of radios later in development can bring the antenna selection process back to the drawing board.

By contrast, Virtual Antenna® technology is easily tuned to almost any desired frequency band. Virtual Antenna® technology turns antenna design into RF circuit design. By simply adjusting the matching network of a few passive components, the operating frequency of the antenna can be tuned, switched to a different frequency or radio technology. Multiple bands can be supported with only one Virtual Antenna® product. No redesign of the PCB is needed for this breakthrough flexibility. Design budgets go further when product plans are repurposable.

3. Fitting In the Tight Spaces of IoT Devices:
An FPC antenna places demands on the product design that ideally, we could live without. FPCs have significant requirements of physical dimension if they are to communicate well, making them difficult for small enclosures. These physical demands extend to adjacent components; mounting must be >20mm from the PCB. This makes FPC problematic for extra small IoT product designs, such as sensors and trackers. Folding the antenna so that it fits into the enclosure degrades performance and introduces the uncertainties previously discussed.

The Virtual Antenna® solution uses the PCB as its radiating surface. As a result, the IoT antenna component fits in almost any board size. The antenna requires only a fraction of the space within a design, compared to an FPC solution. This allows developers to create bold new products that are smaller and thinner than would be possible with a legacy FPC antenna.

4. Virtual Antenna® Products Can Take the Heat:
Heat is the greatest enemy of all things electronic and IoT devices are no exception. FPC antennas can operate in temperatures of up to 85ºC. At first glance, this seems like a safe number, but once the components have been built into an enclosure, heat quickly becomes an issue. This is particularly true for devices that are subject to environmental conditions in hot or sunny settings. At higher temperatures, the adhesive from an FPC antenna becomes unstable and can shift the antenna, with predictably negative effects.

Virtual Antenna® technology is capable of reliable operation in temperatures up to 125ºC, nearly 50% higher than an FPC solution. This brings remarkable stability to the product. There is no adhesive to degrade and no shifting of the operation over time. Performance stays consistent, even in challenging environmental settings.

5. Greater Efficiency, Less Variance:
Even when an appropriate FPC antenna is included in the product design, its efficiency doesn’t match Virtual Antenna® technology. While this is true across the entire frequency spectrum, the contrast is deeply felt in the lower (698-960 MHz) and higher (1710-2690 MHz) bands commonly used for cellular IoT, such as NB-IoT and LTE-M. FPC antennas not only have an inherent efficiency variation of +/- 5dB, but they can also easily become detuned when the antenna mount overlaps the PCB or is even placed too close to it.

In a recent head-to-head faceoff between Virtual Antenna® technology and a popular FPC solution mounted on the same PCB in three different enclosures, the Virtual Antenna® delivered >17% efficiency in the lower bands, compared to only 0.5% by the FPC. In the higher bands, Virtual Antenna® achieved >56% efficiency, compared to the FPC’s 18%. In a real-world use case, this discrepancy would be the difference between passing or failing a cellular wireless certification.

6. Preview Real-World Performance:
As we’ve experienced, IoT devices are subject to many complex variables during the manufacturing process and later in the field. Until now, there was no real way to accurately portray the final robustness of devices without making the commitment to building them first – a risky business decision. Moreover, any changes to a device’s specification during the development process often force designers to evaluate and select yet a different FPC antenna.

With Virtual Antenna® solutions, developers can now validate design choices in advance of manufacturing. Ignion’s Antenna Intelligence Cloud™ service lets designers make assured decisions from initial feasibility through review of the board layout and fine-tuning of the matching network, all through a multi-dimensional representation of the antenna performance. These tools significantly speed up productivity and reduce risks throughout the design phase, even if product requirements change.

The Virtual Antenna® component, in tandem with its cloud-based digital twin design tool, the Antenna Intelligence Cloud™, are the innovations that IoT device makers have long needed to make RF design faster, easier, and much more reliable than designing with traditional FPC antennas.

Dr. Jaume Anguera, IEEE Fellow, is the CTO and Co-founder of Ignion. He invites developers to try Ignion’s Antenna Intelligence Cloud™ - Click here to try it out. The peer-reviewed technical paper on which this is based can be found here.