ANNA-B112 - System integration manual
UBX-18009821 - R09
System description
Page 18 of 66
C1-Public
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 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.
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 re-tune 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.
Approved antenna designs
ANNA-B112 module comes with a pre-certified design that can be used to save costs and time during
the certification process. The antenna path is routed to a U.FL connector and the external antenna is
connected to the U.FL connector.
To take advantage of the ANNA-B112 certification, the customer is required to implement antenna
layout according to u-blox reference design. The reference design is described in Appendix
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.
1.10.3
NFC antenna
The ANNA-B112 module includes a Near Field Communication interface, capable of operating as a
13.56 MHz NFC tag at a bit rate of 106 kbps. As an NFC tag, data can be read from or written to the
ANNA-B112 modules using an NFC reader; however, the ANNA-B112 module is not capable of reading
other tags or initiating NFC communications. Two pins are available for connecting to an external NFC
antenna:
NFC1
and
NFC2
.
Reserved pins (RSVD)
Do not connect reserved (
RSVD
) pin. The reserved pins can be allocated for future interfaces and
functionality.
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 EMC issues and provides a thermal heat
sink for the module.
See the Module footprint and paste mask and thermal guidelines sections for information about
ground design.
