Basics of Open and Short Circuited Stubs

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anu_pillai84

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I read from various literature that a short circuited quarter wave stub is open for AC and short for DC.

Can somebody explain the reason behind this?
 

Hi my friend!
we can draw an equivalent circuit for The quarter wave stub , it is a complex filter . and each filter has an impedance , this impedance , is not real , thus for DC , we have , not impedance , (short circuit) , and for AC we have complex impedance . for more information , refer to the Secrets of RF circuit design of joseph j carr ( incredible book at this area and simple)
Best Wishes
Goldsmith
 


Thank you so much Goldsmith.

Appreciate it so much.

---------- Post added at 01:37 ---------- Previous post was at 01:11 ----------
anu_pillai84 said:
Thank you so much Goldsmith.

Appreciate it so much.
Click to expand...

Hello Goldsmith,

One last question, why is it the opposite for open circuit quarter wave stub(short for AC and open for DC)?

Does it have only a real impedance?

Thanks.
 

hi.
if you know about smith chart then it is very simple.my suggestion is analyzing that in smith chart.
 

Hello my friend!
When you used a open circuit stub , in fact , DC can not go from that ( because it's frequency is zero ) . but for AC signals , because , they have very high frequency , for these applications , that stub , again can be considered as a filter ( high order)
. I'm agree with "young microwave engineer" . you should search for smith chart , and impedance matching with smith chart .
Best Wishes
Goldsmith
 

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