User's Manual
GE/GC864-QUAD V2 and GE864-GPS Hardware User Guide
1vv0300915 Rev.2 – 2011-06-15
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights
Reserved. Page 48 of 97
• Place EM noisy devices as far as possible from GE864-QUAD
V2 antenna line;
• Keep the antenna line far away from the GE864-QUAD V2 or
GE864-GPS power supply lines;
• If you have EM noisy devices around the PCB hosting the
GE864-QUAD V2 or GE864-GPS, such as fast switching ICs,
take care of the shielding of the antenna line by burying
it inside the layers of PCB and surround it with Ground
planes, or shield it with a metal frame cover.
• If you don't have EM noisy devices around the PCB of
GE864-QUAD V2 or GE864-GPS, by using a strip-line on the
superficial copper layer for the antenna line, the line
attenuation will be lower than a buried one;
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: