ANT (pin 61) is a 50 Ω single-end interface for the LTE antenna for cellular bands. 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.
The length of the transmission line from the antenna to the ANT pin should be kept as short as possible to minimize loss, because loss deteriorates the transmitted and received power in nRF9160 and leads to drawbacks in power consumption and network coverage. A maximum of 0.5 dB loss in the transmission line is acceptable.
nRF9160 includes an Electrostatic Discharge (ESD) circuit on the ANT pin. The ESD circuit is intended for 1.5 kV Human Body Model (HBM) level, but additional ESD protection is recommended, especially if there are 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. A matching network of a minimum of three components is typically needed close to the antenna. The component values and matching topology depend on the antenna application and antenna path impedance and need to be optimized individually for each design. For more information on the antenna interface, see nRF9160 Antenna and RF Interface Guidelines.