Wavecom WISMO Quik Q2501, Руководство по дизайну для клиентов

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WM_PRJ_Q2501_PTS_002 - 001
March 2004
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3.5.2.2 Antenna implementation
The antenna should be isolated as much as possible from the analog & digital
circuitry (including the interface signals).
On applications embedding an internal antenna, a poor shielding could
dramatically affect the sensitivity of the terminal. Moreover, the power emitted
through the antenna could affect the application (TDMA noise for instance).
As a general recommendation, all components or chips operated at high
frequencies (microprocessors, memories, DC/DC converter), or other active RF
parts shall not be placed too close to the module. In such a case, correct
supply and ground decoupling areas shall be designed and validated.
One shall avoid placing components around the RF connection and close to the
RF line (between the module and the antenna).
RF lines shall be as short as possible in order to minimize losses.
3.5.3 GPS antenna connection
3.5.3.1 Active antenna specifications
Compared to the GSM antenna, the GPS antenna is active, what means it
embeds a LNA just after the antenna (ceramic patch) itself in order to have
better performance (lower NF).
Figure 33: Block diagram of the GPS antenna connection