NORA-B1 series - System integration manual
UBX-20027617 - R02
Design-in
Page 25 of 58
C1-Public
Item
Requirements
Remarks
Return Loss
S
11
< -10 dB (VSWR < 2:1) recommended
S
11
< -6 dB (VSWR < 3:1) acceptable
The Return loss or the S
11
, as the VSWR, refers to the amount
of reflected power, measuring how well the primary antenna
RF connection matches the 50
Ω
characteristic impedance of
the
ANT
pin.
The impedance of the antenna termination must match as
much as possible the 50
Ω
nominal impedance of the
ANT
pin
over the operating frequency range, thus maximizing the
amount of the power transferred to the antenna.
Efficiency
> -1.5 dB ( > 70% ) recommended
> -3.0 dB ( > 50% ) acceptable
The radiation efficiency is the ratio of the radiated power to the
power delivered to the antenna input; the efficiency is a
measure of how well an antenna receives or transmits.
Maximum Gain
+5.3 dBi
Higher gain antennas could be used but must be evaluated
and/or certified. See Section 6 for more information on
regulatory requirements.
Table 9: Summary of antenna interface (ANT) requirements for NORA-B1
Observe the following recommendations when selecting external or internal antennas:
•
Choose antennas with an optimal return loss (or VSWR) figure across all operating frequencies.
•
Choose antennas that provide optimal efficiency figures across all operating frequencies.
•
Choose antennas that provide an appropriate gain figure; that is, combined antenna directivity
and efficiency figures that ensure that the electromagnetic field radiation intensity does not
exceed the regulatory limits specified in some countries. For example, the regulatory limits set by
the FCC in the United States.
4.3.2.1
RF connector design
If an external antenna is required, the designer should consider using a proper RF connector. It is the
responsibility of the designer to verify the compatibility between plugs and receptacles used in the
design.
Table 10 suggests some RF connector plugs that can be used by the designers to connect RF coaxial
cables based on the declaration of the respective manufacturers. The Hirose U.FL-R-SMT RF
receptacles (or similar parts) require a suitable mated RF plug from the same connector series. Due
to wide usage of this connector, several manufacturers offer compatible equivalents.
Manufacturer
Series
Remarks
Hirose
U.FL® Ultra Small Surface Mount Coaxial Connector
Recommended
I-PEX
MHF® Micro Coaxial Connector
Tyco
UMCC® Ultra-Miniature Coax Connector
Amphenol RF
AMC® Amphenol Micro Coaxial
Lighthorse Technologies, Inc.
IPX ultra micro-miniature RF connector
Table 10: U.FL compatible plug connector
Typically, the RF plug is available as a cable assembly. Different types of cable assemblies are
available; the user should select the cable assembly best suited to the application. The key
characteristics are:
•
RF plug type: select U.FL or equivalent
•
Nominal impedance: 50
Ω
•
Cable thickness: Typically, from 0.8 mm to 1.37 mm. Select thicker cables to minimize insertion
loss.
•
Cable length: Standard length is typically 100 mm or 200 mm. Select shorter cables to minimize
insertion loss.
•
RF connector on the other side of the cable: For example, another U.FL (for board-to-board
connection) or SMA (for panel mounting).
