NINA-B2 series - System Integration Manual
UBX-18011096 - R03
Contents
Page 9 of 30
1.8
Antenna interfaces
The antenna interface is different for each module variant in the NINA-B2 series.
1.8.1
Antenna pin – NINA-B221
The NINA-B221 modules are equipped with an RF pin. The RF pin has a nominal characteristic
impedance of 50
Ω
and must be connected to the antenna through a 50
Ω
transmission line to allow
reception of radio frequency (RF) signals in the 2.4 GHz frequency band.
Choose an antenna with optimal radiating characteristics for the best electrical performance and
overall module functionality. An internal antenna, integrated on the application board or an external
antenna that is connected to the application board through a proper 50
Ω
connector can be used.
While using an external antenna, the PCB-to-RF-cable transition must be implemented using either
a suitable 50
Ω
connector, or an RF-signal solder pad (including GND) that is optimized for 50
Ω
characteristic impedance.
1.8.1.1
Antenna matching
The antenna return loss should be as good as possible across the entire band when the system is
operational to provide optimal performance. The enclosure, shields, other components, and
surrounding environment will impact the return loss seen at the antenna port. Matching
components are often required to retune the antenna to bring the return loss within an acceptable
range.
It is difficult to predict the actual matching values for the antenna in the final form factor. Therefore,
it is a good practice to have a placeholder in the circuit with a ”pi” network, with two shunt
components and a series component in the middle, to allow maximum flexibility while tuning the
matching to the antenna feed.
1.8.1.2
Approved antenna designs
NINA-B2 modules come with a pre-certified design that can be used to save costs and time during
the certification process. To take advantage of this service, you have to implement the antenna
layout according to the u-blox reference designs. The reference design is available on request from
u-blox.
The designer integrating a u-blox reference design into an end-product is solely responsible for the
unintentional emission levels produced by the end product.
The module may be integrated with other antennas. In this case, the OEM installer must certify his
design with respective regulatory agencies.
1.8.2
Integrated antenna – NINA-B222
The NINA-B222 modules are equipped with an integrated antenna on the module for simpler
integration.
1.9
Reserved pins (RSVD)
RSVD pins should be left unconnected.
1.10
GND pins
Good connection of the module's GND pins with solid ground layer of the host application board is
required for correct RF performance. It significantly reduces the EMC issues and provides a thermal
heat sink for the module.
