Installation Instructions

LISA-U2 series - System Integration Manual
UBX-13001118 - R19 Early Production Information Design-In
Page 129 of 175
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 sections 2.2.1.1 and 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
 Do not place the main antenna in close vicinity to end user since the emitted radiation in human tissue is
limited by S.A.R. regulatory requirements
 Do not use directivity antenna since the electromagnetic field radiation intensity is limited in some countries
 Take care of interaction between co-located RF systems since the GSM transmitted power may interact or
disturb the performance of companion systems
 Place antenna far from sensitive analog systems or employ countermeasures to reduce electromagnetic
compatibility issues that may arise
 The antenna for the Rx diversity should be carefully separated from the main Tx/Rx antenna, because signal
improvement is dependent on the cross correlation and the signal strength levels between the two received
signals. The distance between the two antennas should be at least greater than half a wavelength of the
lowest used frequency (i.e. distance greater than ~20 cm, for 2G/3G low bands) to distinguish between
different multipath channels