Integration Manual

AH3-US Hardware Interface Overview
5 Antenna Interfaces
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AH3-US_HD_v01.000 Page 29 of 42 2012-05-29
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5 Antenna Interfaces
5.1 GSM/UMTS Antenna Interface
The AH3-US RF antenna interface comprises a main GSM/UMTS antenna as well as an op-
tional UMTS Rx diversity antenna to improve signal reliability and quality
1
. The RF interface has
an impedance of 50
. AH3-US is capable of sustaining a total mismatch at the antenna pad
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 AH3-US module and should be placed in the host
application.
Regarding the return loss AH3-US 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 pad is DC coupled to ground via an inductor for ESD pro-
tection.
5.1.1 RF Antenna Pad
The RF antenna can be attached to the antenna pad via contact
springs such as the Rosenberger pogo pin series (Figure 5
shows the module’s RF antenna pad size; for more information
on the Pogo pin series see Section 5.1.1.1).
Note: The antenna pad resp. an SMA antenna connector sol-
dered to the antenna pad has been chosen as antenna refer-
ence point (ARP) for the Cinterion module AH3-US type
approval.
Figure 5: RF antenna pad size
Also, consider that according to the GSM recommendations TS 45.005 and TS 51.010-01 a
50
 connector is mandatory for type approval measurements. This requires GSM devices with
an integral antenna to be temporarily equipped with a suitable connector or a low loss RF cable
with adapter.
Please note that the GSM antenna must be isolated for ESD (to withstand a voltage resistance
up to 8kV air discharge).
1.
By delivery default the optional UMTS Rx diversity antenna is configured as available for the module.
Please refer to [1] for details on how to configure antenna settings.
Table 10: 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
Idle <
5dB not applicable