Antenna interface

nRF9160 has one Single-Ended (SE) 50 Ω antenna interface (ANT) for all supported bands. nRF9160 is evaluated with a 50 Ω antenna load.

To ensure good performance, antenna impedance and the characteristic impedance of the transmission line connecting the antenna to the ANT pin must be 50 Ω. Impedance mismatch leads to performance deterioration.

For the antenna, a maximum of VSWR 2:1 is preferred, but VSWR 3:1 is acceptable. The return loss value in VSWR 2:1 is 9.5 dB, and in VSWR 3:1 it is 6.0 dB. The length of the transmission line from the antenna to ANT pin should be kept as short as possible to minimize losses, as loss deteriorates the module’s transmitted and received power and leads to drawbacks in power consumption and coverage. A maximum of 0.5 dB transmission line loss should be targeted.

To minimize impedance mismatch, it is recommended to use a low-loss matching circuit that uses High-Q and tight tolerance components next to the antenna. Catalog antennas are tuned on the antenna vendors' reference boards. The differences between the antenna vendor reference boards and device mechanics may impact antenna impedance. For example, device mechanics may change in the development phase, and these modifications may impact antenna impedance. Matching components can be used to compensate the impact of device mechanics, for example, casing, Printed Circuit Board (PCB), or battery, on the antenna impedance.

nRF9160 includes an Electrostatic Discharge (ESD) circuit on the ANT pin, but additional ESD components may be used if the impact on RF frequencies is negligible. ESD filtering may be necessary for some active components, such as switches or antenna tuners, in the antenna path. For the ESD requirements, see the component datasheets. The ANT pin is DC grounded.

Note: The nRF9160 System in Package (SiP)'s internal ESD protection is intended for 1.5 kV Human Body Model (HBM) level.

To run conductive RF tests, a test connector or cable is needed. The connector or cable is recommended to be located as close as possible to the ANT pin. For more information on RF testing, see Antenna and RF test. Antenna detection can be used in device production or when debugging the device. For more information, see Antenna tests.