Antenna selection

Finding the right antenna

Finding and integrating an antenna can be one of the most problematic steps in creating a wireless product. In any successful wireless design, the antenna’s performance is critical. However, it behaves unlike any other digital component.

There are several types, sizes and configurations of antennas available, with advantages and disadvantages to each choice.

What are the key types of antennas?

Despite the wide range of antennas available, knowing the key categories can get you well on your way to selecting the right one.

Terminal Antennas

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During the 1980s and 1990s, terminal antennas (sometimes known as external antennas) were widespread. Early wireless technologies used them exclusively yet they still have many advantages over alternative antenna types today.

Key Benefits:

  • Outperform embedded antennas across most RF parameters
  • Offer higher efficiency levels
  • Provide immunity from product-generated noise, as they’re located typically outside of the product’s housing

Surface-mount device (SMD) antennas

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As technology began to shrink, embedded antennas quickly became the most popular solution. They offer high levels of performance within a compact form, and can be integrated onto a circuit board without added manufacturing complexity.

Key Benefits:

  • SMD antennas are tiny, measuring just a few millimeters in some cases
  • They’re inexpensive, making them great for mass produced technologies
  • They are easy to assemble with standard pick and place machinery
  • Offer high levels of performance within a compact form

Wireless modules

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Taking the concept of an SMD antenna even further, wireless modules bring a number of RF components into a single part. Sometimes these include filters, too, which means the parts can offer near-on drop-in solutions for wireless connectivity.

Wireless modules can speed up integration times and simplify the RF architecture within a circuit board. The radio and the antenna are co-located, meaning they take up less real estate on a circuit board.

Flexible printed circuit (FPC) antennas

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Where space is extremely limited on a compact circuit board, FPC antennas offer easy integration while saving space. Using a layer of polymer film and conductive material, they can be placed around the contours of a device, offering a degree of integration flexibility unrivalled by other antenna solutions.

Case mounted antennas

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Responding to growth in smart grid and connected outdoor products, Antenova created a novel solution to products housed by metal. Using a ferrite-like layer to isolate an antenna from material underneath, case-mounted antennas perform as if they were in free space, even when placed on metal. The antennas are being used on products like connected bicycles and smart meters, offering performance where other antennas fail to perform well.

Which antenna is right for your application?

The best choice of antenna will depend on your application, PCB size, your budget, the required range and the technologies you need to support. Use our antenna selector tool to find out which antenna is best for your application.

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Considerations when selecting an antenna

Mounting

Surface-mounted (SMD) antennas can affix directly to the PCB while Antenova’s REFLECTOR series can be mounted to the exterior of the product housing while remaining non-detuning.

The best choice depends on the availability of space on your circuit board. SMD antennas take up a considerable footprint in a tiny device to operate efficiently. However, housing-mounted and FPC antennas offer more flexibility and thus reduce the space required on the PCB.

Placement

The recommended placement will vary for each antenna. Some antennas will perform best on the long-side edge, whereas others will perform better placed on a corner. Check the data sheet for information about the optimal placement for every antenna.

Ground plane clearance

For antennas to operate at Sub-1GHz frequencies, they need ground plane lengths of 100mm or larger to perform well. For embedded antennas, the ground plane constitutes part of the antenna. To ensure an antenna can perform well, follow the ground plane guidelines within the antenna's data sheet.

Chip dimensions

Innovative antenna designs are shrinking the real estate required to house an embedded antenna. While the dimensions of the chip itself are important, the integration guidelines should play an equally important part in your selection criteria.

Antenna type

Antennas are available in a number of forms. Not just the surface-mount device forms that you see here. If you want to guarantee high levels of performance, have you considered a flexiiANT antenna? Or a case-mounted antenna? These can save space on your circuit board, while offering high levels of performance.

MOUNTING ANTENNA TYPE PLACEMENT CHIP DIMENSIONS GROUND PLANE CLEARANCE