User's Manual

Cinterion
®
ELS61-US Hardware Interface Overview
2.3 RF Antenna Interface
21
 ELS61-US_HIO_v00.281 2016-02-11
Confidential / Preliminary
Page 19 of 40
2.3.1 Antenna Installation
The antenna is connected by soldering the antenna pad (ANT_MAIN or ANT_DRX) and its
neighboring ground pads (GND) directly to the application’s PCB. The antenna pads are the
antenna reference points (ARP) for ELS61-US. All RF data specified throughout this document
is related to the ARP.
The distance between the antenna pad and its neighboring GND pads has been optimized for
best possible impedance. To prevent mismatch, special attention should be paid to these pads
on the application‘s PCB.
The wiring of the antenna connection, starting from the antenna pad to the application‘s anten-
na should result in a 50
Ω line impedance. Line width and distance to the GND plane needs to
be optimized with regard to the PCB’s layer stack.
To prevent receiver desensitization due to interferences generated by fast transients like high
speed clocks on the external application PCB, it is recommended to realize the antenna con-
nection line using embedded Stripline rather than Micro-Stripline technology.
For type approval purposes, the use of a 50
Ω coaxial antenna connector (U.FL-R-SMT) might
be necessary. In this case the U.FL-R-SMT connector should be placed as close as possible
to ELS61-US‘s antenna pad.