How to select and apply antennas for IoT devices
Figure 2: VSWR and RL are dependent on frequency. RL should be minimized at the intended operating frequency. Image source: Amphenol
dramatically influences the end product’s transmit power and receive sensitivity. For an internal antenna, design guidelines recommend placement at the top of the IoT device on the printed circuit (PC) board edge and as far as possible from other components that could generate electromagnetic interference (EMI) during operation. Impedance matching
design guidelines, see “How to Use Multiband Embedded Antennas to Save Space, Complexity, and Cost in IoT Designs .”)
Boosting performance An antenna with poor performance restricts how much electrical power is transformed into radiated energy at the transmitter and how much energy is harvested from incoming RF signals at the receiver. Poor performance at either end reduces the wireless link’s range.
Antenna types
Specifying the antenna is a critical part of the IoT device design process. The antenna should be
The primary factor affecting the antenna’s performance is
Written by Jeff Smoot, VP of Apps Engineering and Motion Control at Same Sky losses by matching the impedance of the transmitter power sources with that of the antenna. The impedance is typically 50 ohms (Ω) for a low-power IoT product. The antenna’s position also A well-designed impedance matching circuit minimizes the VSWR and subsequent power impedance. A significant mismatch between the antenna’s impedance (which is related to voltage and current at its input) and the impedance of the voltage source driving the antenna results in poor energy transfer.
components are an exception, as these are proximal to the antenna by necessity. The pc board pads and traces connecting the antenna to the rest of the circuitry should be the only copper conductors in a defined clearance area (Figure 3). (For more detail on antenna
Figure 3: A PC board-mounted antenna should be placed close to the pc board edge. The antenna should also be placed away from other components (apart from those used for the impedance matching circuit) by incorporating a clearance area. Image source: Amphenol
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