LEXI-R422 - System integration manual
UBX-23007449 - R02
Design-in
Page 61 of 108
C1-Public
For an example of vehicle tracking application in a small form factor featuring cellular and short-range
connectivity alongside a multi-constellation GNSS receiver, with successful RF coexistence between
the systems, refer to the u-blox B36 vehicle tracking blueprint
. The distance between the cellular
and GNSS antennas for the u-blox B36 blueprint is annotated in
GNSS
antenna
5.5 cm
Cellular
antenna
SARA
module
Figure 39: PCB top rendering for the u-blox B36 blueprint with annotated distance between cellular and GNSS antennas
2.4.3
Antenna detection interface (ANT_DET)
2.4.3.1
Guidelines for ANT_DET circuit design
describe the recommended schematic / components for the antenna
detection circuit that must be provided on the application board and for the diagnostic circuit that
must be provided on the antenna’s assembly to achieve
antenna detection functionality.
Application board
Antenna cable
LEXI-R422
A3
ANT
A5
ANT_DET
R1
C1
D1
L1
C2
J1
Z
0
= 50
Ω
Z
0
= 50
Ω
Z
0
= 50 ohm
Antenna assembly
R2
C4
L3
Radiating
element
Diagnostic
circuit
GND
L2
C3
Figure 40: Suggested schematic for antenna detection circuit on application PCB and diagnostic circuit on antenna assembly
Reference
Description
Part number - Manufacturer
C1
27 pF capacitor ceramic C0G 0402 5% 50 V
GRM1555C1H270J - Murata
C2
33 pF capacitor ceramic C0G 0402 5% 50 V
GRM1555C1H330J - Murata
D1
Very low capacitance ESD protection
PESD0402-140 - Tyco Electronics
L1
68 nH multilayer inductor 0402 (SRF ~1 GHz)
LQG15HS68NJ02 - Murata
R1
10 k
resistor 0402 1% 0.063 W
RK73H1ETTP1002F - KOA Speer
J1
SMA connector 50
through hole jack
SMA6251A1-3GT50G-50 - Amphenol
C3
15 pF capacitor ceramic C0G 0402 5% 50 V
GRM1555C1H150J - Murata
L2
39 nH multilayer inductor 0402 (SRF ~1 GHz)
LQG15HN39NJ02 - Murata
C4
22 pF capacitor ceramic C0G 0402 5% 25 V
GRM1555C1H220J - Murata
L3
68 nH multilayer inductor 0402 (SRF ~1 GHz)
LQG15HS68NJ02 - Murata
R2
15 k
resistor for diagnostics
Generic manufacturer
Table 25: Suggested parts for antenna detection circuit on application PCB and diagnostic circuit on antennas assembly