Re: Asymmetric Stripline / Microstrip online calculators for impedance and velocity

On 5/20/2025 1:59 PM, Bill Sloman wrote:

On 20/05/2025 11:53 pm, Mike Perkins wrote:

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I can find numerous calculators that provide impedance for the above structures, but are there any that give propagation velocity too?

 This is sort of nuts. Microstrip is on the surface of a printed circuit board. Half the field is located in the substrate and the other half in the air above the board. It's consequently dispersive - different frequency components propagate at different velocities.
 Strip-line is buried inside a printed circuit board and propagates in what can be a uniform environment. It's non-dispersive. A thicker layer of the insulating substrate above the strip line than below it could make it asymmetric, but I've no idea if this would mess up the propagation velocity. A different insulating substrate above the strip- line than below it presumably could make it dispersive.
 

Ya as I've been trying to explain, the propagation velocity has to be taken as a given to make finding either the symmetric or asymmetric stripline capacitance (and therefore Z_0) tractable to closed-form analysis. The simple online calculators don't do shit but take it as a constant for stripline, based on the relative permeability of the substrate, in either the symmetric or asymmetric case.
I didn't think this required a PhD to explain but maybe you or Dr. Hobbs or someone can explain it better than I can..