The Right Blend: Mixed Wireless Technologies

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A common trend recently is to employ as many radios as possible on a single PCB. With the increase of wireless standards and the downscaling of PCB size, it can be difficult to know what the most critical design parameters are to focus on.
In this article, we’ll discuss the most important considerations to make when designing with mixed wireless technologies, such as Bluetooth, GPS, and Wi-Fi, on a single PCB. These considerations include antennas, frequencies, FCC compliance, shielding, and layout with and without transition vias. Although the most common wireless standards have been mentioned previously, the following design considerations can be applied to other wireless spaces like Z-Wave, LoRa, or Zigbee.

Consider the Antenna

One of the biggest design challenges for wireless products is the antenna, or antennas. The decrease in size of wireless devices presents the problem of a reduction of necessary ground plane real estate for the antenna. There is also the choice of using multiple antennas for each standard or a dual or tri-band antenna for the Wi-Fi and Bluetooth applications to save space.
Where multiple antennas are used, the following should be considered: the potential for an increase in harmful cross interference and the need to achieve the required polarity for desired directionality. Also, will each antenna be inside or outside the final device enclosure? If it’s internal, the composite material of the enclosure will affect the signals. For example, polycarbonate can be very attenuative. The frequencies selected (especially for Wi-Fi since there are several bands available) will determine the length of the antenna—whether full, half, or quarter wave—which, along with proper impedance matching, is important for optimal performance. Finally, the compactness of the design depends on the application of the final product. Will it be long or short-range?

GPS is a long-range receiver, capturing signals from satellites in space. In contrast, Bluetooth is a transceiver with a much shorter range. The example design shown in Figure 1 demonstrates a Bluetooth design. Other important antenna characteristics to consider include the required gain, bandwidth, and radiation pattern for each signal.

To continue reading this article, which appeared in the April 2025 edition of Design007 Magazine, click here.