Post subject: Gap between the Microstip trace
and ground trace
Unread postPosted: Fri Jan 14, 2005 5:27 am
If 'W' is the width of the microstrip line, maintaining
a gap of 'W' between the microstrip line and ground trace/plane
next to it on the same layer is considered as good RF practice.
Am I right on this thumb rule?
If anyone has opinion on this
, pl let me know. Let me know even if you agree on it. I am following
this thumb rule in the RF board I am making. It will greatly aid
in coming out with good board with your valuable opinions.
Post subject: Microstrip Line
Unread postPosted: Fri Jan 14, 2005 11:09 am
rule of thumb is correct but remember it is a rule of thunb. The
width is what determines the impedance of the line so I would recommend
going on the Microsoft Office Website and downloading there "free"
transmission line calculator. I am sure Kirt has a link to the sight.
In this way you will know for a fact that you have the proper impedance.
Keeping the ground trace a W away from the ground trace is usually
adequate but I usually keep it 2W away.
Unread postPosted: Fri Jan 14, 2005
Yes it is a good practice. I did it in my latest
board design and will be doing it in the next too.
Post subject: Re: Microstrip
Unread postPosted: Fri Jan 14, 2005 12:16 pm
Joined: Sun Aug 03, 2003 2:02 pm
Location: Erie, PA
recommend going on the Microsoft Office Website and downloading
there "free" transmission line calculator. I am sure Kirt has a
link to the sight.
Right you are. There is a link
to it (Tx-Line is the applet name) on the Software page (1) and
the Calculators page (2), and the direct link to the MWO site is
here (3). It is quite a nice program for free!
Kirt Blattenberger :smt024
Unread postPosted: Mon Jan 17, 2005 3:55 am
Please make sure that GND away from the Transmission Line
(At least 3 to 4 times of the width due to the GND coupling effects
if it is filter / high power applications).
Or make use
of Coplanar Waveguide with GND plane, which is very similar to the
Microstrip but it has lots of advantages.
Microstrip Vs Coplanar Waveguides (with GND plane)