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

On 21/05/2025 7:39 am, john larkin wrote:

On Tue, 20 May 2025 14:09:46 -0400, bitrex <user@example.net> wrote:
 

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

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

<snip>

The simple equations, like from the Motorola ECL book, get stupid (as
in claim negative impedances) for some cases.

The simple equations in the Motorola Data book give good approximations to the characteristic impedance in the 50R to 75R range.
Back around 1990, when I needed to cover a wider range of impedances, I ended up buying Peter C.L. Yip's "High Frequency Circuit Design and Measurements" ISBN 0-412-34160-3. It had only just been published back then, and I'd found it in Heffer's in Cambridge U.K. which stocked that kind  of book for undergraduate and postgraduate students.
It offered slightly longer equations - including natural logarithm terms - which were claimed to stay valid for a slightly wider range of characteristic impedances.
Development being what it is, the project got cancelled before the relevant printed circuit boards got made or loaded. The precursor boards had worked well enough, after we'd tinkered with them, but we'd clearly needed to do better.
--
Bill Sloman, Sydney