Ublox SARA-R5 Series System Integration Manual

SARA-R5 series - System integration manual
UBX-19041356 - R04 System description Page 26 of 118
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1.7 Antenna interfaces
1.7.1 Cellular antenna RF interface (ANT)
SARA-R5 series modules provide an RF interface for connecting the external cellular antenna. The
ANT pin represents the RF input/output for transmission and reception of LTE RF signals.
The ANT pin has a nominal characteristic impedance of 50  and must be connected to the Tx / Rx
cellular antenna through a 50  transmission line to allow proper RF transmission and reception.
1.7.1.1 Cellular antenna RF interface requirements
Table 6 summarizes the requirements for the cellular antenna RF interface. See section 2.4.2 for
suggestions to correctly design antennas circuits compliant with these requirements.
⚠ The antenna circuits affect the RF compliance of the device integrating SARA-R5 series modules
with applicable required certification schemes (for more details see section 4). Compliance is
guaranteed if the antenna RF interface requirements summarized in Table 6 are fulfilled.
Item
Requirements
Remarks
Impedance
50  nominal characteristic impedance
The impedance of the antenna RF connection must match the
50  impedance of the ANT port.
Frequency range
See the SARA-R5 series data sheet [1]
The required frequency range of the antenna connected to ANT
port depends on the operating bands of the used cellular
module and the used mobile network.
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 antenna RF connection
matches the 50  characteristic impedance of the ANT port.
The impedance of the antenna termination must match as
much as possible the 50  nominal impedance of the ANT port
over the operating frequency range, reducing as much as
possible the amount of reflected power.
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 antenna input: the efficiency is a measure of
how well an antenna receives or transmits.
The radiation efficiency of the antenna connected to the ANT
port needs to be enough high over the operating frequency
range to comply with the Over-The-Air (OTA) radiated
performance requirements, as Total Radiated Power (TRP) and
the Total Isotropic Sensitivity (TIS), specified by applicable
related certification schemes.
Maximum gain
According to radiation exposure limits
The power gain of an antenna is the radiation efficiency
multiplied by the directivity: the gain describes how much power
is transmitted in the direction of peak radiation to that of an
isotropic source.
The maximum gain of the antenna connected to ANT port must
not exceed the herein stated value to comply with regulatory
agencies radiation exposure limits. For additional info see
section 4.
Input power
> 24 dBm ( > 0.25 W )
The antenna connected to the ANT port must support with
adequate margin the maximum power transmitted by the
modules.
Table 6: Summary of cellular antenna RF interface requirements

Ublox SARA-R5 Series Specifications

General

Brand	Ublox
Model	SARA-R5 Series
Category	Control Unit
Language	English