LENA-R8 series - System integration manual
UBX-22015376 - R02
Design-in
Page 58 of 116
C1-Public
Manufacturer
Part number
Product name Description
2J Antennas
2JW1483
Connector-mount ultra-wideband antenna, waterproof: IP67, IP69
617..960 MHz, 1525..2690 MHz, 3300..3800 MHz
192 x 20 x 18 mm
Table 22: Examples of external antennas
2.4.3
GNSS antenna RF interface (ANT_GNSS)
☞
LENA-R8001 modules do not include a GNSS receiver: GNSS antenna interface is not available.
The antenna and its placement are critical system factors
for accurate GNSS reception.
Use of a
ground plane will minimize the effects of ground reflections and enhance the antenna efficiency. A
good allowance for ground plane size is typically in the area of 50 x 50 to 70 x 70 mm
2
. The smaller the
electrical size of the plane, the narrower the reachable bandwidth and the lower the radiation
efficiency. Exercise care with rover vehicles that emit RF energy from motors etc. as interference may
extend into the GNSS band and couple into the GNSS antenna suppressing the wanted signal. For
more details about GNSS antennas, see also the u-blox GNSS antennas application note
Since LENA-R8001M10 modules already include an internal SAW filter, followed by an additional LNA,
followed by another SAW filter before the u-blox GNSS chipset (as illustrated in
), they are
optimized to work with passive or active antennas without requiring additional external circuitry.
2.4.3.1
Guidelines for applications with a passive antenna
If a GNSS passive antenna with high gain and good sky view is used, together with a short 50
line
between antenna and receiver, and no jamming sources affect the GNSS passive antenna, the circuit
illustrated in
can be used. This provides the minimum BoM cost and minimum board space.
LENA-R8001M10
31
ANT_GNSS
GND
Figure 37: Minimum circuit with GNSS passive antenna
If the connection between the module and antenna incurs additional losses (e.g. antenna placed far
away from the module, small ground plane for a patch antenna) or improved jamming immunity is
needed due to strong out-of-band jammers close to the GNSS antenna (e.g. the cellular antenna is
close to the GNSS antenna), consider adding an external SAW filter (see
for possible suitable
examples) close to the GNSS passive antenna, followed by an external LNA (see
suitable examples), as illustrated in
, provided that LENA-R8001M10 modules already
include an internal SAW filter, followed by an additional LNA, followed by another SAW filter before
the u-blox GNSS chipset (as illustrated in
), so that additional external SAW and LNA are not
required for most of the applications (see section
for further details and design-in guidelines
regarding Cellular / GNSS RF coexistence).
☞
An external LNA with related external SAW filter are only required if the GNSS antenna is far away
(more than 10 cm) from the GNSS RF input of the module. In that case, the SAW and the LNA
must be placed close to the passive antenna.
