IoT manufacturers have a wide range of antennas to choose from in an increasingly competitive market. Previously, antennas were almost an afterthought, but the antenna stock has risen within the IoT ecosystem due to consumer demand for a seamless smart experience and advances in interoperability and machine-to-machine connectivity. As with most product lines, each antenna type has benefits and challenges. On the whole, antennas are notorious for design inflexibility because they are dependent on the operating environment. Thus, there are several factors to consider during the design and production processes. Antenna designers often confront a delicate balancing act between physical size, performance, and cost, which is highly dependent on many variables and IoT specifics. This article presents the pros and cons of common types of IoT antennas.
The popularity of trace antennas stems from their highly competitive price point, as they are one of the cheaper options within the antenna sector. They often perform well in single-band platforms and, in many instances, are already mounted on Printed Circuit Boards (PCB). Moreover, with minimal experience, they can be fully designed and integrated by yourself.
On the downside, their size means they occupy a considerable amount of real estate compared to other antenna designs and reducing their size will affect performance. Trace antennas are also susceptible to performance issues, especially with handheld and wearable devices. Both internal and external trace antennas may also have Radio Frequency (RF) issues, especially in moving environments.
Flexible Printed Circuit (FPC)
This flexible antenna is prevalent in many IoT electronic sectors, including wearables, telecommunications, and the automobile industry. The flexibility and compactness of FPC antennas give them the edge over their more rigid counterparts, especially during the R&D process. Additionally, they can be strapped via a cable to small IoT devices when little PCB space is available, and the flexible film can be placed on uneven surfaces. FPCs are also quite economically-priced and are lightweight. FPC antennas support various connectors such as UF cables, allowing for easy connection to IoT devices and PCBs.
Flexible Printed Circuits are delicate products and can be damaged if not handled with care. Furthermore, it is difficult to modify or repair them, and great care is needed during installation to avoid interference with other components. Ideally, Flexible Printed Circuit antennas should be placed at least 10 mm away from metallic materials to avoid performance issues. FPCs also have interoperability issues as many IoT manufacturers are not fully equipped to use them because they are a relatively new technology.
A wired helix antenna is a simple wire or helix-shaped monopole antenna with a very low price point. They can be placed in small spaces and are highly accessible due to their spiral shape. Wired helix antennas work best in portable communications equipment as they excel within lower frequency bands, including HF, VHF, and UHF. They are also robust and offer high directivity.
Yet these antennas are constrained to simple IoT devices with a single radio or frequency band. Furthermore, design challenges are prevalent because frequency decreases as the size and number of turns increase.
Surface Mount Technology (SMT) Antennas
The rise of handheld technology saw an uptake in SMT antennas and small antenna design. These lightweight antennas are typically soldered onto a PCB. They are lightweight, emit minimal noise, and are easily integrated using pick-and-place machinery. The reduced size of SMT antennas allows IoT designers to use PCB space for other components. The antennas can also incorporate multiple frequencies in a solid and embedded form. The SMT antenna production can generally reduce board costs, material handling costs, and controlled manufacturing processes.
SMT antennas do require a clearance area, extending space requirements, and, at low frequencies, need a substantial ground plane to resonate. Designers have to think carefully about PCB location and its subsequent clearance area for antenna optimization. Finally, price is dependent on size and required frequencies covered.
These antennas can be designed and produced onto a plastic 3D carrier or mold because of advanced engineering techniques such as Laser Direct Structuring (LDS). During the prototype stage, the 3D design allows engineers to modify and fine-tune the antenna to the specifics of their client. Additionally, the client can expect a quick design and turnaround time. These antennas are a great option when space is at a premium. Moreover, 3D printer antennas are compatible with SMT and have a low failure rate, allowing for non-stop mass production. Finally, antenna traces can be changed without altering the plastic molding, and therefore various frequencies can be incorporated into the mold.
As 3D printed antennas are customized products, colors and materials are sometimes hard to attain. Therefore, it is essential to discuss and execute 3D antenna production at the beginning of the IoT project.
Defined as a smart adaptive array of multiple antennas, smart antennas use liquid crystals to change their internal configuration and intelligent algorithms to compute the optimal antenna combination. The result is a smooth user experience due to the increased signal-to-interference ratio (SIR). These smart antennas have powerful directional capabilities that allow for a secure, uninterrupted service that excels in even the densest environments. Moreover, smart antennas are great for geo-location due to their spatial detection capabilities. They can be installed quite far apart without connectivity issues. They are somewhat hacker-proof and hard to manipulate, which provides extra security for the end-user.
Smart antennas use a communication technique known as beamforming, which requires incorporating a costly digital signal processor. The antenna’s transceivers are more complex than the ones of other antenna types, so they must be accurately and continuously calibrated.
Data derived from technology is growing at an exponential rate, resulting in more data transmission handled by antennas. Plus, with IoT and smart devices and cities all making inroads into society, the antenna is now a significant component of any technology solution. Higher frequencies, miniature-sized antennas, and intuitive configurations to receive radio waves from any position seem to be the future of antenna design. Eventually, the larger, bulky antennas will make way for the more contemporary smart antennas designed for the IoT-based, technology-driven smart future that awaits us all.