PCB saturn conductor impedance

[rayhh27]

Hi,

I have been using pcb saturn for calculating my trace impedance. This time I want to calculate impedance 50 ohm for the RF signal.
My question is, in the frequency tab, the frequency that i should put is 1575.42 MHz (GPS freq) or is it something else?

Thank you.

Best regards,

RH

 

[marce]

Yes. More importantly change the Er to match what your dielectric will be at 1575.42MHz. The frequency got added recently I will have to read the notes and see what its fuction is in the calculations, because it has a minor effect on the results. But materials Er does change with frequency so double check as this will have a bigger effect.

 

[rayhh27]

Yes. More importantly change the Er to match what your dielectric will be at 1575.42MHz. The frequency got added recently I will have to read the notes and see what its fuction is in the calculations, because it has a minor effect on the results. But materials Er does change with frequency so double check as this will have a bigger effect.

So basically, if I use FR4 which has dielectric constant of 4.6, this value will change due to the frequency?

 

[marce]

Yes check with your PCB manufacturer if its 4.6 at 1MHz its going to be nearer 4.2 at 1GHz... Data sheets may show just 1MHz or a variety of frequencies.