[SI-LIST] Re: Coax vs. Microstrip

Siva,

Depending on the frequency range,
I don't think the 50 ohm microstrip
launch is realistic. If you are using
a 3D tool, why not model the SMA
as 50 ohm coax leading to the launch point.

If you a using a planar tool, you might
get a better approximation using vias
from the bottom of the box to approximate
the coax launch into the board. Might
have to flip the board over and put the
top surface near the bottom of the simulation
box.

Dan

Dan Swanson             EMAIL:  d.swanson@xxxxxxxx
Forem USA                       PHONE:          978-834-4085
37 South Hunt Road      FAX:    978-388-7077
Amesbury, MA  01913

> -----Original Message-----
> From: SS [mailto:cacofonix98@xxxxxxxxx]
> Sent: Tuesday, March 25, 2003 4:27 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Coax vs. Microstrip
> 
> 
> 
> Hello,
> 
> I am trying to model the SMA to PCB launch interface
> in a "popular tool". 
> I am making a couple of simplifications 
> 1) modeling only the part of the SMA that is embedded
> in the PCB. 
> 2) Launch into the center conductor through a 50 ohm
> microstrip structure.
> 
> Are these simplifications realistic or valid? If not,
> how far off from reality is it compared to a coaxial
> launch? 
> 
> Thanks
> Siva 
> 
> 
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