This section describes typical performance related issues in the end product's antenna
design and ways to reduce them.
- The placement of the antenna on the Printed Circuit Board (PCB) and ground plane
prevents from achieving good enough antenna radiation performance.
- Follow the antenna vendors recommendations for placing the antenna on the PCB and ground
plane.
- Verify the antenna radiation pattern and efficiency in an anechoic chamber to match the
datasheet.
- RF path routing loss between antenna and nRF9160 is too high.
- Verify 50 Ω impedance-controlled routing between the antenna and nRF9160.
- Target less than 0.5 dB for resistive loss between the antenna and nRF9160.
Note: Global Positioning System (GPS) is recommended to be used with an external
Low-Noise Amplifier (LNA). This means that resistive routing loss between the
GPS LNA and nRF9160 is not highly critical. However, it is highly critical to avoid
noise coupling from adjacent routings or components to GPS signal routing between the
GPS antenna and nRF9160.
- Mechanics, casing, battery, or wires deteriorate antenna performance.
- Co-design the mechanics to match the PCB and antenna design.
- Sharing a small PCB between several antennas, for example, GPS and LTE, causes mutual
loading between the antennas.
- Verify that the antennas do not cause mutual loading, for example, with passive antenna
measurements in an anechoic chamber. Terminating an unused antenna, for example the LTE
antenna during GPS, may have a noticeable impact on the mutual loading effect between the
antennas. To minimize the load effect, the LTE antenna can be terminated through the
AUX port (pin 64) to 50 Ω load during GPS.
- Active components on the PCB cause wideband noise coupling to the antennas.
- Verify that during reception, especially GPS, active components on the PCB do not radiate
noise to the GPS antenna. For example, DC converters and LEDs are typical sources of
radiating wideband noise. The RSSI scan testing method can be used. For more information,
see nRF9160 Hardware Verification Guidelines.
- The orientation of the end product in a typical use case is less than optimal for the
antenna radiation pattern.
- Consider in the design phase what the orientation of the end product is going to be in a
typical use case.
- Consider in the design phase the type of the GPS antenna, for example, omnidirectional or
linear and directive or Right Hand Circular Polarization (RHCP).
- Nearby objects deteriorate antenna performance.
- Instruct the end user to use the device in the manner it is designed for. For example,
inform the user not to expect the best possible radio performance when the device is used
inside a building, on a metal surface, or on their body.
- GPS signal environment is more challenging than assumed in the design phase.
- Instruct the end user to use the device in the manner it is designed for. The GPS signal
type must be line-of-sight (LOS), which is rarely available in places like city centers
with tall buildings nearby. The issue is even more severe in the polar regions because the
GPS system is designed to perform the best in the equatorial regions.