NEO-5
-
Hardware
Integration
Manual
Preliminary
Design-In
GPS.G5-MS5-08003-A2
u-blox
proprietary
Page 22
your position is our focus
micro strip line
Optional active antenna supply
GNSS module
no crossing signal lines or
signal trace vias in this area
Figure 11: Recommended layout
As
seen
in
an
isolated
ground
area
is
created
around
and
below
the
RF
connection.
This
part
of
the
circuit
MUST
be
kept
as
far
from
potential
noise
sources
as
possible.
Make
certain
that
no
signal
lines
cross,
and
that
no
signal
trace
vias
appear
at
the
PCB
surface
within
the
area
of
the
red
rectangle.
The
ground
plane
should
also
be
free
of
digital
supply
return
currents
in
this
area.
On
a
multi
layer
board,
the
whole
layer
stack
below
the
RF
connection
should
be
kept
free
of
digital
lines.
This
is
because
even
solid
ground
planes
provide
only
limited
isolation.
The
impedance
of
the
antenna
connection
has
to
match
the
50
Ohm
impedance
of
the
receiver.
To
achieve
an
impedance
of
50
Ohms,
the
width
W
of
the
micro
strip
has
to
be
chosen
depending
on
the
dielectric
thickness
H,
the
dielectric
constant
ε
r
of
the
dielectric
material
of
the
PCB
and
on
the
build-up
of
the
PCB
(see
Section 2.7.5
).
shows
two
different
builds:
A
2
Layer
PCB
and
a
4
Layer
PCB.
The
reference
ground
plane
is
in
both
designs
on
layer
2
(red).
Therefore
the
effective
thickness
of
the
dielectric
is
different.
Module
micro strip line
Ground plane
Module
micro strip line
Ground plane
PCB
PCB
Either don't use these layers or fill with ground planes
H
H
Figure 12: PCB build-up for Micro strip line. Left: 2-layer PCB, right: 4-layer PCB
