Telit Wireless Solutions LE915A P Series, Руководство по конструкции аппаратуры

Страница: 29 / 51

LE915Ax-P
Hardware Design Guide
1VV0301680 Rev. 2
Page 29 of 51 2021-10-04
Not Subject to NDA
6. RF SECTION
Antenna Requirements
The antenna connection and board layout design are the most important aspect in the full
product design as they strongly affect the general performance of the product, so read
carefully and follow the requirements and the guidelines for a proper design.
Table 18: Antenna ports
The antenna and antenna transmission line on PCB for a Telit module shall fulfil the
following requirements:
Parameter Min. Typ. Max. Unit Note
Impedance - 50 - Ohm Antenna load impedance
VSWR - 2.1 3.1 VSWR recommended
Gain 0.5 dBi
Isolation 20 - - dB Between all antennas
Table 19: Antenna and Transmission line requirement
6.1.1. PCB Design Guidelines
When using the LE915Ax-P family, since there's no antenna connector on the module,
the antenna must be connected to the LE915Ax-P antenna pad by means of a
transmission line implemented on the PCB.
This transmission line shall fulfil the following requirements:
Item Value
Characteristic Impedance 50 ohm (+-10%)
Max Attenuation 0.3 dB
Coupling Coupling with other signals shall be avoided
Ground Plane Cold End (Ground Plane) of antenna shall be equipotential to the Telit module
ground pins
Table 20: Transmission line requirement
The transmission line should be designed according to the following guidelines:
•
make sure that the transmission line’s characteristic impedance is 50 ohm;
Pin Signal I/O Function description
4 ANT_MAIN I/O Main antenna port for both R/TX.
2 ANT_DIV I Auxiliary antenna port for diversity path.