GE/GC864-QUAD V2 and GE864-GPS Hardware User Guide
1vv0300915 Rev.5 – 2011-10-03
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved.
Page 47 of 94
7.2.
PCB Guidelines in case of FCC certification
In the case FCC certification is required for an application using GE864-QUAD V2 or GE864-GPS,
according to FCC KDB 996369 for modular approval requirements, the transmission line has to be
similar to that implemented on GE864-QUAD V2 or GE864-GPS interface board and described in
the following chapter.
7.2.1.
Transmission line design
During the design of the GE864-QUAD V2 or GE864-GPS 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
ε
r
= 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:
0.3 mm
0
.0
3
5
m
m
0.3 mm
6.
2
m
m
FR4
0
.0
3
5
m
m
0
.0
3
5
m
m
1
.3
3
5
m
m
0
.2
m
m
1
.1
m
m
L3
L2
L1
1.1 mm
