People, I don't see in his original message anything that shows he is working with something "physical". His message says he's working with a "calculation". The raw answer for his question is - NO. When using calculations for Microstrip and Stripline, the value for the dielectric is the same. ______________________________ Reply Separator _________________________________ Subject: Controlled Impedance - Dielectric Constant Author: [log in to unmask] at internet-mail Date: 5/21/96 8:15 AM Subject: Controlled Impedance - Dielectric Constant I like to know if anyone found that Dielectric Constant, for the same material (e.g. FR-4), might be different when used for calculation of Microstrip or for calculation of Stripline. Avner Drory