MC75i Hardware Interface Description
4 Antenna Interface
78
MC75i_HD_v01.100a
Page 72 of 122
2009-08-13
Confidential / Released
4
Antenna Interface
The RF interface has an impedance of 50
Ω
. MC75i is capable of sustaining a total mismatch
at the antenna interface without any damage, even when transmitting at maximum RF power.
The external antenna must be matched properly to achieve best performance regarding radi-
ated power, DC-power consumption, modulation accuracy and harmonic suppression. Anten-
na matching networks are not included on the MC75i module and should be placed in the host
application.
Regarding the return loss MC75i provides the following values in the active band:
The connection of the antenna or other equipment must be decoupled from DC voltage. This
is necessary because the antenna connector is DC coupled to ground via an inductor for ESD
protection.
4.1
Antenna Installation
To suit the physical design of individual applications MC75i offers two alternative approaches
to connecting the antenna:
•
Recommended approach: U.FL-R-SMT antenna connector from Hirose assembled on the
component side of the PCB (top view on MC75i). See
for details.
•
Antenna pad and grounding plane placed on the bottom side. See
The U.FL-R-SMT connector has been chosen as antenna reference point (ARP) for the Cinte-
rion Wireless Modules reference equipment submitted to type approve MC75i. All RF data
specified throughout this manual are related to the ARP. For compliance with the test results
of the Cinterion Wireless Modules type approval you are advised to give priority to the connec-
tor, rather than using the antenna pad.
IMPORTANT: Both solutions can only be applied alternatively. This means, whenever an an-
tenna is plugged to the Hirose connector, the pad must not be used. Vice versa, if the antenna
is connected to the pad, then the Hirose connector must be left empty.
Table 19:
Return loss in the active band
State of module
Return loss of module
Recommended return loss of application
Receive
> 8dB
> 12dB
Transmit not
applicable
> 12dB