NINA-B3 series - System integration manual
UBX-17056748 - R13
Design-in
Page 37 of 72
C1-Public
The following recommendations apply for proper layout of the connector:
•
Strictly follow the connector manufacturer’s recommended layout:
o
SMA Pin-Through-Hole connectors require GND keep-out (clearance or void area) on all the
layers around the central pin up to annular pads of the four GND posts.
o
UFL surface mounted connectors require no conductive traces (that is, clearance, a void area)
in the area below the connector between the GND land pads.
•
If the RF pad size of the connector is wider than the microstrip, remove the GND layer beneath the
RF connector to minimize the stray capacitance thus keeping the RF line 50
. For example, the
active pad of the UF.L connector must have a GND keep-out (clearance or void area)
–
at least on
the first inner layer to reduce parasitic capacitance to ground.
Integrated antenna design
If integrated antennas are used, the transmission line is terminated by the integrated antennas
themselves. The following guidelines should be followed:
•
The antenna design process should begin at the start of the whole product design process. Self-
made PCBs and antenna assembly are useful in estimating overall efficiency and the radiation
path of the intended design.
•
Use antennas designed by an antenna manufacturer providing the best possible return loss (or
VSWR).
•
Provide a ground plane large enough according to the related integrated antenna requirements.
The ground plane of the application PCB may be reduced to a minimum size that is similar to one
quarter of wavelength of the minimum frequency that needs to be radiated. The overall antenna
efficiency may benefit from larger ground planes.
•
Proper placement of the antenna and its surroundings is also critical for antenna performance.
Avoid placing the antenna close to conductive or RF-absorbing parts such as metal objects, ferrite
sheets and so on as they may absorb part of the radiated power or shift the resonant frequency of
the antenna or affect the antenna radiation pattern.
•
It is highly recommended to strictly follow the detailed and specific guidelines provided by the
antenna manufacturer regarding correct installation and deployment of the antenna system,
including the PCB layout and matching circuitry.
•
Further to the custom PCB and product restrictions, antennas may require tuning/matching to
comply with all the applicable required certification schemes. It is recommended to consult the
antenna manufacturer for the design-in guidelines and plan the validation activities on the final
prototypes like tuning/matching and performance measures. See also
•
The RF functional section may be affected by noise sources like hi-speed digital buses. Avoid
placing the antenna close to buses such as DDR or consider taking specific countermeasures like
metal shields or ferrite sheets to reduce the interference.
⚠
Take care of interaction between co-located RF systems like LTE sidebands on 2.4 GHz band.
Transmitted power may interact or disturb the performance of NINA-B3 modules.
3.3.3
On-board antenna
If a plastic enclosure is used, it is possible to use NINA-B3 with the embedded antenna. In order to
reach an optimum operating performance, follow the instructions for each variant,
NINA-B3x2
•
The module shall be placed in the corner of the host PCB with the antennas feed point in the corner
(pins 15 and 16), as shown in
. Other edge placements positions, with the antenna
closest to the edge, are also possible. These will however give moderate reduced antenna
performance compared to the corner placement.
