What is a stub column

What is a stub on the circuit board?

What is a stub on the PCB and what is it used for? Stubs exist with PCB traces and also vias, why?


They are used for impedance matching and filtering.

The image from Wikipedia below shows various stripline features used to create various elements etched into a circuit board with the descriptions below.

In the first column some simple planar filter structures are shown. The second column shows the open-wire equivalent circuit diagram for these structures. The third column is a semi-lump element approximation where the elements labeled K or J are impedance and admittance transformers, respectively. The fourth column shows an approximation with lumped elements, the further assumption being made that the impedance transformers are λ / 4 transformers.

(a) A short-circuit stub parallel to the main line.

(b) An interruption parallel to the main line.

(c) A short-circuit line coupled to the main line.

(d) Coupled short-circuited lines.

(e) Open circuit coupled lines.

Stripline vias (the little silver connections at the ends) create a strap through the board that connects to the baseplate below

Once you become familiar with transmission lines, you will understand the purpose of these elements. If you're not familiar, it's a scary but fascinating subject that I want to learn more about. It's the weird stuff about electricity. Know your enemy.

There is a little more explanation in a previous answer I gave to your previous question about reflections.

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