User's Manual

LE910 V2 HARDWARE USER GUIDE 1VV0301200 Rev.2 Preliminary • 2015-08-04 57 of 81
Reproduction forbidden without Telit Communications PLC written authorization – All Rights Reserved
The following image is showing the suggested layout for the Antenna pad connection:
6.4.2 PCB Guidelines in case of FCC Certification
In the case FCC certification is required for an application using LE910 V2, according to FCC KDB 996369 for
modular approval requirements, the transmission line has to be similar to that implemented on LE910 V2 interface
board and described in the following chapter.
6.4.2.1 Transmission line design
During the design of the LE910 V2 interface board, the placement of components has been chosen properly, in
order to keep the line length as short as possible, thus leading to lowest power losses possible. A Grounded
Coplanar Waveguide (G-CPW) line has been chosen, since this kind of transmission line ensures good impedance
control and can be implemented in an outer PCB layer as needed in this case. A SMA female connector has been
used to feed the line.
The interface board is realized on a FR4, 4-layers PCB. Substrate material is characterized by relative permittivity
εr = 4.6 ± 0.4 @ 1 GHz, TanD= 0.019 ÷ 0.026 @ 1 GHz.
A characteristic impedance of nearly 50 Ω is achieved using trace width = 1.1 mm, clearance from coplanar ground
plane = 0.3 mm each side. The line uses reference ground plane on layer 3, while copper is removed from layer 2
underneath the line. Height of trace above ground plane is 1.335 mm. Calculated characteristic impedance is 51.6
Ω, estimated line loss is less than 0.1 dB. The line geometry is shown below: