User's Manual

WM_PRJ_Q2400_PTS_002 - 004
March 5, 2004
2.21.1 RF connections
2.21.1.1 General
There are two possible ways to connect an antenna to the module:
• The antenna can be directly connected to the module on the "Antenna pad" by using a spring
contact.
• The antenna can be connected to the module through a coaxial cable. The coaxial cable is
connected to both the "Round pad" and the "Ground pad".
Spring contact
Two land patterns set on the PCB support the RF connection which can be used by the
application through spring contacts or a soldered RF cable.
Since no standard spring contact is available for WISMO Quik Q24x6 sub-series, this solution
requires a specific part to be developed.
Soldered solution
The soldered solution will preferably be based on a RG178 coaxial cable.
Antenna
pad
Ground
pad
Antenna pad
Antenna connection by spring contact. Antenna connection by coaxial cable.
Figure 6: Antenna connection
Note:
• The WISMO Quik Q24x6 sub-series does not include any antenna switch for a car kit but
this function can be implemented externally and it can be driven using a GPIO.
• The antenna cable and connector should be chosen in order to minimise losses in the
frequency bands used for GSM 850/E-GSM 900MHz and DCS 1800/PCS 1900MHz.
• 0.5 dB can be considered as a maximum value for loss between the module and an external
connector.
2.21.1.2 Antenna directly connected to the module: matching circuit
The goal of the matching circuit is to link the antenna (impedance ZA) to the receiver and transmitter
access of the module (impedance ZL = 50 Ohm real).
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