Re: [SI-LIST] : Parallel tracks on Flexible PCB without Ground Plane

Georg Ramsch (
Thu, 01 Jul 1999 15:46:14 +0200

Hello, Cai !

CAI ZhongPing wrote:
> Dear experts,
> Thanks for your reply. I am sorry that I did not explain my question clearly.
> Here the flexible PCB has not a ground plane. The transmission line is made from only two parallel traces, just like twisted pair wire.

Is your pair of TLs edge-side or broadside coupled ?
Reference: "Transmission Line Design Handbook" / Brian C. Wadell

1)If broadside coupled: here that is called a "Paired Strips" construction.
Wadell, p.71

2)If edge-side coupled:
a) if width of strips is equal: "Coplanar Strips" / Wadell, p. 83
b) if width of strips is different: "Asymetrical Coplanar Strips" / Wadell,

For the "Paired Strip" construction I have a test coupon with 4 different widths
as check for the calculation.

CU :-)


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