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Integrating an antenna is a crucial step in a wireless product design. Antennas behave differently to digital integrated circuits (ICs). This creates a unique set of design challenges and considerations that traditional design cycles do not account for.
With devices getting smaller, designs are becoming intrinsically less RF-friendly. Circuit boards are shrinking, yet are tightly packed with noisy components. An antenna cannot be simply ‘added’ at the end; RF must be a priority from the outset.
More product designers are facing this challenge. To design great wireless products, designers need to change their approach. Our proven cycle considers wireless design first, and it’s suitable for projects of all scopes and sizes. Here’s how we recommend that you approach your wireless product design.
The wireless design cycle starts at the same time a design project does. Wireless technologies are the enablers of connectivity and there’s lots of them. Likewise, antennas are also available in a variety of forms. Designers that are aware of the variety of options available will be more empowered to fulfil a brief.
There are wireless technologies available to suit any sort of device. Whether you require long-range connectivity without large power requirements, or precision tracking, there is sure to be a technology to suit:
While selecting a technology, there are a number of factors to consider:
There is no one-size-fits-all wireless technology. The right choice will depend on data throughput requirements, range, power consumption and certification needs. More designs are incorporating multiple wireless technologies, too. This makes the choice of complementary antennas crucial.
It’s the antenna that makes it wireless. Antennas are therefore crucial components in the Internet of Things. The diversity within IoT reflects the availability of antennas; antennas in a huge variety of configurations are capable of connecting devices.
For a deeper look at the different types of antenna, and the benefits and drawbacks of each, download our Wireless Antennas: Compared guide.
Surface-mount device (SMD), sometimes known as surface mount technology (SMT), antennas are far and away the most popular type of antenna available today. These mount directly to the PCB, and come in a variety of shapes, sizes and materials.
These are commonly available in high-grade dielectric laminate substrates, ceramic, or even stamp metal. There are some advantages that come with their use:
As SMD antennas are inexpensive, yet offer great performance within a compact form, their popularity is logical. However, to enable a surface-mounted antenna to perform well, the design must be optimised.
Like an SMD antenna, modules can be placed directly on the PCB. The advantage these have over standard surface-mounted antennas is that they come pre-assembled. The antenna will already have a chip and other key components.
These work excellently for GNSS applications. They effectively offer a ‘drop-in’ solution, which means that designers do not need to spend time designing in complex RF circuitry.
For applications that require tiny circuit boards, surface-mounted solutions are not always the most appropriate antenna solution.
And, for applications that use non-RF friendly materials – like metal – it will always prove difficult to achieve strong wireless performance levels with an embedded antenna.
Antenova’s patented REFLECTOR technology isolates case-mounted antennas from noise. By using a layer of material for isolation, the antenna can perform with minimal losses, even when mounted on metal.
With just a single connection to the circuit board, these antennas do not require ground plane space on the circuit board. This frees up space for other components. It also means the designer is more free to place switches and other noisy components where is most convenient.
With any antenna, understanding where it’s placed will impact how it performs is essential. Particularly for an embedded antenna, the antenna needs to be positioned clearly away from the rest of the circuit – otherwise noise and other components can detune and impedance performance.
Most antennas perform best when positioned on the corner of the PCB. However, there are some antennas that operate best along the long-side edge. The data sheet of each antenna will detail the optimum placement of the antenna, as will the design of the evaluation board.
The gap between the casing/housing and the antenna is also an essential consideration. Plastic has a higher dielectric constant than air, so placing an antenna too close to it is likely to detune the signals.
We’ve written an article that covers all of the essential considerations for placing your antenna.
Placing the antenna on the circuit board should be the first step in your board design. Antennas may be the only component that must be located in a specific physical position on the circuit board. This means you’ll need to consider:
Antennas have unique keep-out requirements. Some suggest certain keep-out zones which should be free of any components.
Prevention is better than cure. Following the completion of the first version of a board design, the designer can make a number of checks to ensure wireless performance is well optimised. There are several key questions to address: