Telit Wireless Solutions LE915A P Series, Руководство по конструкции аппаратуры

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LE915Ax-P
Hardware Design Guide
1VV0301680 Rev. 2
Page 30 of 51 2021-10-04
Not Subject to NDA
• keep the line on the PCB as short as possible, since the antenna line loss shall be
less than about 0,3 dB;
• the geometry of the line must have uniform characteristics, constant cross
section, avoid meanders and abrupt curves;
• any type of suitable geometry / structure (Microstrip, Stripline, Coplanar,
Grounded Coplanar Waveguide...) can be used to create the printed transmission
line relating to the antenna;
•
if a Ground plane is required in the geometry of the line, this plane must be
continuous and sufficiently extended, so that the geometry can be as similar as
possible to the related canonical model;
•
keep, if possible, at least one layer of the PCB used only for the Ground plane; If
possible, use this layer as reference Ground plane for the transmission line;
• it is advisable to surround (on both sides) the PCB transmission line with Ground,
avoiding that other signal tracks face directly the antenna line track.
• avoid crossing any un-shielded transmission line footprint with other signal tracks
on different layers;
• the ground surrounding the antenna line on the PCB must be tightly connected to
the main Ground Plane through holes (at east once every 2mm), placed near the
edges of the ground facing the line track;
• place EM noisy devices as far as possible from antenna line of Telit module;
• keep the antenna line far away from the power supply lines of Telit module;
• if EM noisy devices (such as fast switching ICs, LCD and so on) are present on the
PCB hosting the Telit module, take care of the shielding of the antenna line by
burying it in an inner layer of PCB and surrounding it with the Ground planes, or
shield it with a metal frame cover.
•
if EM noisy devices are not present around the line, the use of geometries such as
Microstrip or Grounded Coplanar Waveguide is preferable, since they typically
ensure less attenuation if compared to a Stripline of the same length.
6.1.2. PCB Guidelines in Case of FCC Certification
If FCC certification is required for an application using XX123Z4, according to FCC KDB
996369 for modular approval requirements, the transmission line must be similar to the
one implemented on the XX123Z4 interface board and described in the following chapter.