Gemalto M2M GmbH ELS51-V 사용자 설명서

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2.2 RF Antenna Interface

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ELS31-V_ELS51-V_HIO_v00.502

2015-12-07

Confidential / Preliminary

Page 15 of 35

The antenna is connected by soldering the antenna pads (RF_OUT, pad #59 and DIV_ANT, 
pad 56) its neighboring ground pads (GND, i.e., pads #55, #57, #58 and #60) directly to the 
application’s PCB. The antenna pad is the antenna reference point (ARP) for ELS31-V / 
ELS51-V. All RF data specified throughout this document is related to the ARP.

The distance between the antenna RF pads and its neighboring GND pads 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 an-
tenna should result in a 50

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 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

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 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 ELS31-V / ELS51-V‘s antenna pad.