Hardware Interface Description - KORE Telematics
Hardware Interface Description - KORE Telematics
Hardware Interface Description - KORE Telematics
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XT55/56 <strong>Hardware</strong> <strong>Interface</strong> <strong>Description</strong><br />
Confidential / Released<br />
s<br />
5 GSM and GPS antenna interfaces<br />
5.1 GSM antenna installation<br />
The RF interface has an impedance of 50Ω. XT55/56 is capable of sustaining a total<br />
mismatch at the antenna connector or pad without any damage, even when transmitting at<br />
maximum RF power.<br />
The external antenna must be matched properly to achieve best performance regarding<br />
radiated power, DC-power consumption and harmonic suppression. Matching networks are<br />
not included on the XT55/56 PCB and should be placed in the host application.<br />
Regarding the return loss XT55/56 provides the following values:<br />
Table 20: Return loss<br />
State of module Return loss of module Recommended return loss of application<br />
Receive > 8dB > 12dB<br />
Transmit not applicable > 12dB<br />
Idle < 5dB not applicable<br />
The connection of the antenna or other equipment must be decoupled from DC voltage.<br />
5.1.1 GSM antenna connector<br />
To suit the physical design of individual applications XT55/56 offers two alternative<br />
approaches to connecting the GSM antenna:<br />
• Recommended approach: U.FL-R-SMT antenna connector from Hirose assembled on<br />
the component side of the PCB (top view on XT55/56). See Chapter 5.3 for details.<br />
• Antenna pad and grounding plane placed on the bottom side. See Chapter 5.1.2.<br />
Antenna ground<br />
Antenna pad<br />
Figure 31: U.FL-R-SMT connector<br />
Figure 32: Antenna pad and GND plane<br />
XT55/56_hd_v02.06a Page 80 of 125 17.12.2004
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