User Manual

Smart Machine Smart Decision
SIM7100_Hardware_Design_V1.02 2015-06-16
4.2 GSM/UMTS/LTE Antenna Design Guide
Users should connect antennas to SIM7100’s antenna pads through micro-strip line or other types
of RF trace and the trace impedance must be controlled in 50Ω. SIMCom recommends that the
total insertion loss between the antenna pads and antennas should meet the following requirements:
● GSM900/GSM850<0.5dB
● DCS1800/PCS1900 <0.9dB
● WCDMA 2100/1900<0.9dB
● WCDMA 900/850<0.5 dB
● TDSCDMA 1900/2100<0.5dB
● CDMA BC0<0.5dB
● LTE (F<1GHz) <0.5dB
● LTE (1GHz<F<2GHz) <0.9dB
● LTE (2GHz<F) <1.2dB
To facilitate the antenna tuning and certification test, a RF connector and an antenna matching
circuit should be added. The following figure is the recommended circuit.
Figure 33: Antenna matching circuit (MAIN_ANT)
In above figure, the components R1,C1,C2 and R2 are used for antenna matching, the value of
components can only be got after the antenna tuning, usually, they are provided by antenna vendor.
By default, the R1, R2 are 0Ω resistors, and the C1, C2 are reserved for tuning.
The RF test connector in the figure is used for the conducted RF performance test, and should be
placed as close as to the module’s antenna pin. The traces impedance between components must be
controlled in 50Ω.