User's Manual

Cinterion
®
EHS8 Hardware Interface Overview Page 22 of 43
EHS8_HIO_v02.770 2014-08-11
Confidential / Preliminary
2.2 RF Antenna Interface
24
2.2.1 Antenna Installation
The antenna is connected by soldering the antenna pad (ANT_GSM, i.e., pad #59) and its
neighboring ground pads (GND, i.e., pads #58 and #60) directly to the application’s PCB.
The antenna pad is the antenna reference point (ARP) for EHS8. All RF data specified
throughout this document is related to the ARP.
The distance between the antenna ANT_GSM pad (#59) and its neighboring GND pads (#58,
#60) has been optimized for best possible impedance. On the application PCB, special
attention should be paid to these 3 pads, in order to prevent mismatch.
The wiring of the antenna connection line, starting from the antenna pad to the application
antenna should result in a 50
  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 application PCB, it is recommended to realize the antenna connection line
using embedded Stripline rather than Micro-Stripline technology. .
For type approval purposes, the use of a 50
  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 EHS8‘s antenna pad.