Integration Manual

LISA-U2 series - System Integration Manual
UBX-13001118 - R25 Design-In Page 132 of 182
2.4 Antenna guidelines
Antenna characteristics are essential for good functionality of the module. Antenna radiating
performance has direct impact on the reliability of connections over the Air Interface. A bad
termination of the ANT pin (main RF input/output) and the ANT_DIV pin (RF input for diversity
receiver provided by LISA-U230 modules) can result in poor performance of the module.
The following parameters should be checked:
Item
Recommendations
Impedance
50 Ω nominal characteristic impedance
Frequency Range
Depends on the LISA-U2 module HW version and on the Mobile Network used.
LISA-U260:
824..960 MHz (GSM 850, GSM 900, UMTS B5)
1710..1990 MHz (GSM 1800, GSM 1900, UMTS B2)
LISA-U270:
824..960 MHz (GSM 850, GSM 900, UMTS B8)
1710..2170 MHz (GSM 1800, GSM 1900, UMTS B1)
LISA-U200, LISA-U201, LISA-U230:
824..960 MHz (GSM 850, GSM 900, UMTS B5, UMTS B6, UMTS B8)
1710..2170 MHz (GSM 1800, GSM 1900, UMTS B1, UMTS B2, UMTS B4)
Input Power
>2 W peak
VSWR
<2:1 recommended, <3:1 acceptable
Return Loss
S
11
<-10 dB recommended, S
11
<-6 dB acceptable
Table 46: General recommendation for GSM antenna
⚠ The antenna gain shall be limited according to regulatory agency RF radiation requirements. For
example, see the maximum antenna gain value reported in section 1.15.1 for EU, in section 1.15.2.2
for US FCC, in section 1.15.3.1 for ISED Canada.
Some 2G and 3G bands are overlapping. This depends on worldwide band allocation for telephony
services, where different bands are deployed for different geographical regions.
If LISA-U2 series modules are planned for use on the entire supported bands, then an antenna that
supports the 824...960 MHz and the 1710…2170 MHz frequency range should be selected. Otherwise,
for fixed applications in specific geographical region, antenna requirements can be relaxed for non-
deployed frequency bands. See the operating RF frequency bands table in LISA-U2 series Data
Sheet [1] for the detailed uplink and downlink frequency ranges of each supported band.
LISA-U230 modules provide 2G and 3G dynamic receive diversity (Rx diversity) capability to improve
the quality and reliability of the cellular link. This feature can be optionally used connecting a second
antenna to the ANT_DIV pin, to receive an RF input signal that is processed by the module to increase
the performance.
☞ It is recommended to properly connect the Rx diversity antenna to the ANT_DIV pin of LISA-U230
modules unless the 2G and 3G Rx diversity feature is disabled by AT command (see the u-blox AT
Commands Manual [2], +URXDIV command).
All the antenna guidelines and recommendations reported for the main Tx/Rx antenna design are
applicable also to the Rx diversity antenna design, even if the antenna for the Rx diversity is not used
to transmit.