Integration Manual

TSD-19090601 - R15 Contents Page 39 of 143
The radiation efficiency of the secondary antenna needs to be roughly
the same as the radiation efficiency of the primary antenna for good RF
performance.
Envelope
Correlation
Coefficient
< 0.4 recommended
< 0.5 acceptable
The Envelope Correlation Coefficient (ECC) between the primary (ANT1)
and the secondary (ANT2) antenna is an indicator of 3D radiation pattern
similarity between the two antennas: low ECC results from antenna
patterns with radiation lobes in different directions.
The ECC between the primary and secondary antennas needs to be low
enough to comply with the radiated performance requirements specified
by related certification schemes.
Isolation
> 15 dB recommended
> 10 dB acceptable
The antenna to antenna isolation is the loss between the primary (ANT1)
and the secondary (ANT2) antenna: high isolation results from low
coupled antennas.
The isolation between primary and secondary antenna needs to be high
for good RF performance.
Table 10: Summary of primary (ANT1) and secondary (ANT2) antennas relationship requirements
1.7.2 Antenna detection interface (ANT_DET)
The antenna detection is based on ADC measurement. The ANT_DET pin is an Analog to Digital Converter
(ADC) provided to sense the antennas(ANT1/ANT2) presence.
The antenna detection function provided by ANT_DET pin is an optional feature that can be implemented
if the application requires it. The ANT_DET pin generates a DC current and measures the resulting DC
voltage, thus determining the resistance from the antenna connector provided on the application board to
GND. So the requirements to achieve antenna detection functionality are the following:
 an RF antenna assembly with a built-in resistor (diagnostic circuit) must be used
 an antenna detection circuit must be implemented on the application board
See section 2.4.2 for the antenna detection circuit on the application board and the diagnostic circuit in the
antenna assembly design-in guidelines.
1.8 SIM interfaces
1.8.1 SIM interfaces
TOBY-L3 series modules provide one SIM interfaces for the direct connection of external SIM cards/chips:
 SIM0 interface (VSIM, SIM_IO, SIM_CLK, SIM_RST pins)
Both 1.8 V and 3 V SIM types are supported by the SIM interfaces. Activation and deactivation with an
automatic voltage switch from 1.8 V to 3 V is implemented, according to ISO-IEC 7816-3 specifications.