SARA-R4 series - System integration manual
UBX-16029218 - R20 Design-in Page 70 of 128
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Table 27 lists examples of LNA suitable for the GNSS RF input of SARA-R422M8S modules.
Low noise figure, up to 10 dBm RF input power
Low noise figure, up to 15 dBm RF input power
Low noise figure, very small package size (WL-CSP)
Low noise figure, small package size
Table 27: Examples of GNSS Low Noise Amplifiers
Table 28 lists examples of ferrite beads suitable for the supply line of an external GNSS LNA.
High impedance at 1.575 GHz
High impedance at 1.575 GHz
High impedance at 1.575 GHz
High impedance at 1.575 GHz
Table 28: Examples of ferrite beads for the supply line of external GNSS Low Noise Amplifiers
Table 29 lists examples of passive antennas suitable for the GNSS RF input of SARA-R422M8S.
Passive antenna
GPS / SBAS / QZSS / GLONASS
Passive antenna
GPS / SBAS / QZSS / GLONASS / Galileo / BeiDou
Ceramic patch antenna
GPS / SBAS / QZSS / GLONASS / Galileo / BeiDou
Embedded patch antenna
GPS / SBAS / QZSS / GLONASS / Galileo / BeiDou
Patch antenna
GPS / SBAS / QZSS / GLONASS
Ceramic patch antenna
GPS / SBAS / QZSS / GLONASS
Ultra-low profile patch antenna
GPS / SBAS / QZSS / GLONASS / Galileo / BeiDou
Table 29: Examples of GNSS passive antennas
2.4.3.2 Guidelines for applications with an active antenna
Active antennas offer higher gain and better overall performance compared with passive antennas
(without additional external SAW filter and LNA). However, the integrated low-noise amplifier
contributes an additional current of typically 5 to 20 mA to the ’ystem's power consumption budget.
Active antennas for GNSS applications are usually powered through a DC bias on the RF cable. A
simple bias-T, as shown in Figure 42, can be used to add this DC current to the RF signal line. The
inductance L is responsible for isolating the RF path from the DC path. It should be selected to offer
high impedance (> 500 Ω) at L-band frequencies. A series current limiting resistor is required to
prevent short circuits destroying the bias-t inductor.