LISA-U1 series - System Integration Manual
3G.G2-HW-10002-3
Preliminary
Design-In
Page 102 of 125
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
ANT
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-U1 series module HW version and on the Mobile Network used.
LISA-U100/U120:
- GSM 850: 824..894 MHz = UMTS B5: 824..894 MHz
- GSM 1900: 1850..1990 MHz = UMTS B2: 1850..1990 MHz
LISA-U110/U130:
- GSM 900: 880..960 MHz = UMTS B8: 880..960 MHz
- GSM 1800: 1710..1880 MHz
- UMTS B1: 1920..2170 MHz
Input Power
>2 W peak
V.S.W.R
<2:1 recommended, <3:1 acceptable
Return Loss
S
11
<-10 dB recommended, S
11
<-6 dB acceptable
Gain
<3 dBi
Table 36: General recommendation for GSM antenna
To preserve the original u-blox FCC ID antenna gain shall remain below 3 dBi.
Please note that 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 the LISA-U110/U130 modules are planned for use on the entire supported bands, then a tri-band antenna
(880..960 MHz, 1710..1880 MHz, 1920..2170 MHz) should be selected. If the LISA-U100/U120 modules are
planned for use on the entire supported bands, then a dual-band antenna (824..894 MHz, 1850..1990 MHz)
should be selected. Otherwise, for fixed applications in specific geographical region, antenna requirements can
be relaxed for non-deployed frequency bands.
GSM antennas are typically available as:
Linear monopole: typical for fixed applications. The antenna extends mostly as a linear element with a
dimension comparable to lambda/4 of the lowest frequency of the operating band. Magnetic base may be
available. Cable or direct RF connectors are common options. The integration normally requires the
fulfillment of some minimum guidelines suggested by antenna manufacturer
Patch-like antenna: better suited for integration in compact designs (e.g. mobile phone). These are mostly
custom designs where the exact definition of the PCB and product mechanical design is fundamental for
tuning of antenna characteristics
For integration observe these recommendations:
Ensure 50
Ω
antenna termination, minimize the V.S.W.R. or return loss, as this will optimize the electrical
performance of the module. See section 2.4.1
Select antenna with best radiating performance. See section 2.4.2
If a cable is used to connect the antenna radiating element to application board, select a short cable with
minimum insertion loss. The higher the additional insertion loss due to low quality or long cable, the lower
the connectivity
Follow the recommendations of the antenna manufacturer for correct installation and deployment
Do not include antenna within closed metal case
