TOBY-L2 and MPCI-L2 series - System Integration Manual
UBX-13004618 - R07
Advance Information
System description
Page 37 of 158
Item
Requirements
Remarks
Impedance
50
nominal characteristic impedance
The impedance of the antenna RF connection must
match the 50
impedance of the
ANT2
port.
Frequency Range
See the
TOBY-L2 series Data Sheet
[1] and the
MPCI-L2 series Data Sheet
The required frequency range of the antennas connected
to
ANT2
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
secondary antenna RF connection matches the 50
characteristic impedance of the
ANT2
port.
The impedance of the antenna termination must match
as much as possible the 50
nominal impedance of the
ANT2
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
ANT2
port needs to be enough high over the operating
frequency range to comply with the Over-The-Air (OTA)
radiated performance requirements, as the TIS, specified
by applicable related certification schemes.
Table 9: Summary of secondary Rx antenna RF interface (ANT2) requirements
Item
Requirements
Remarks
Efficiency imbalance
< 0.5 dB recommended
< 1.0 dB acceptable
The radiation efficiency imbalance is the ratio of the
primary (
ANT1
) antenna efficiency to the secondary
(
ANT2
) antenna efficiency: the efficiency imbalance is a
measure of how much better an antenna receives or
transmits compared to the other antenna.
The radiation efficiency of the secondary antenna needs
to be roughly the same of the radiation efficiency of the
primary antenna for good RF performance.
Envelope Correlation
Coefficient
< 0.4 recommended
< 0.5 acceptable
The Envelope Correlation Coefficient (ECC) between the
primary (
ANT1
) and the secondary (
ANT2
) antenna is an
indicator of 3D radiation pattern similarity between the
two antennas: low ECC results from antenna patterns
with radiation lobes in different directions.
The ECC between primary and secondary antenna needs
to be enough low to comply with radiated performance
requirements specified by related certification schemes.
Isolation
> 15 dB recommended
> 10 dB acceptable
The antenna to antenna isolation is the loss between the
primary (
ANT1
) and the secondary (
ANT2
) antenna: high
isolation results from low coupled antennas.
The isolation between primary and secondary antenna
needs to be high for good RF performance.
Table 10: Summary of primary (ANT1) and secondary (ANT2) antennas relationship requirements
