[Arm-netbook] HDMI High-Frequency Layout: Recommendations--Taper

[Luke Kenneth Casson Leighton]

On Mon, Dec 11, 2017 at 7:25 AM, mike.valk at gmail.com
<mike.valk at gmail.com> wrote:

> Just a small question. Why not deviate from the 45 degree angle? So
> you end up with converging lines, instead of the stepped approach?

 because the steps are a close approximation to the original 1956
paper which ensures that there is a smooth transition of the
impedance.

 if you think "microwave guide" and "lamina flow", if you just draw a
straight line the signal bounces about and comes straight back at you.

 however if you have these specially-arranged steps, it's a bit like a
parabolic mirror, the signal bounces in a mathematically very special
way that *focusses* the signal onto the (narrower) track, ensuring
that it doesn't bounce back at you.

 the ideal case would be to have hundreds of steps (not 45 degree
ones) and lots of small lines, i'm currently investigating the format
of the .ASC files, identifying where the heck you're supposed to put
traces.

l.