EES3 Hardware Interface Description
4 Antenna Interface
75
EES3_HD_v01.100b
Page 72 of 118
2009-08-12
Confidential / Released
4
Antenna Interface
The RF interface has an impedance of 50
Ω
. EES3 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, modulation accuracy and harmonic suppression. Antenna matching networks are
not included on the EES3 module and should be placed in the host application.
Regarding the return loss EES3 provides the following values in the active band:
4.1
Antenna Installation
The antenna is connected by soldering the antenna pad (RF_OUT, i.e., pad #96) and its neigh-
boring ground pads (GND, i.e., pads #81 and #119) directly to the application’s PCB.
Figure 38:
Antenna pads
The distance between the antenna RF_OUT pad (#96) and its neighboring GND pads (#81,
#119) has been optimized for best possible impedance. To prevent mismatch, special attention
should be paid to these 3 pads on the application’ PCB.
The wiring of the antenna connection, starting from the antenna pad to the application’s anten-
na should result in a 50
Ω
line impedance. Line width and distance to the GND plane needs to
be optimized with regard to the PCB’s layer stack, as well as material constants.
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
GND
GND
RF_OUT
