radial stub

1. Where should we use them (Uses)
2. Formulae used to dedign
3. Merits / demerits
4. Numerical modelling
5. Specific problem you faced

The models are implemented in practically every simulation software.
I usually proceed the following way. For example a radial stub to substitute a open stub in the bias network of an amplifier. I design the square stub and then it its a starting point for optimization.

These have the same properties as a quarter wave uniform width line only they have them over a wider bandwidth.

So the tradeoff on deciding to use them is the board area taken up and the need for a short over a wider frequency range.

Since you like to experiment, here is a utility program for stubs you can play with.

Thanks a lot for the program. BTW do you have the formulae?

I do not have any formuals.

I just want to add another query.

Can we use triangular stubs instade of radial one becaus trangular stubs are easier to optimize. What will I loose?

The radial stub comes from the radial transmission line investigations around 1940. It might be worh trying the triange to see what degrades. I suspect that the input impedance of a quarter wave stub will be finite and not infinite.

Hi,

what's the difference between radial stubs and butterfly stub?
Butterfly stub = 2 X radial stub?

It's known that radius of radial stub is around 1/4 wavelength. What about the butterfly?

Thanks!

this publication
https://www.edaboard.com/viewtopic.p...147&highlight=

Regards

Thanks Max!

The formula is real complex..... I'll find the stub length by tuning :)

When is it necessary to put a cap at the end of the 1/4wave line?

Also, it is known that the 1/4wave + radial stub arrangement suppresses even harmonics. How much suppression are we looking at here? Working at f0=6GHz (& without a cap), I got suppression of at 10.5GHz instead of 12GHz. Is this suppose to be the case?

use the software of flatulent or CAD (MWO...) , I did not work on the radial stub .

Regards

Hi,

I'm also interested on butterfly radial stub, when should we use it? What is its difference comparing to single radial stub? I searched on some webpages but most of them are just deriving the equations...

PS.: I clicked on the link mentioned by max ( https://www.edaboard.com/viewtopic.ph...147&highlight= ) expecting it is the explanation for butterfly stub but it turned out to be an invalid webpage.

Thanks,
Mario Young

Well people....
The sad thing is that the formula is not simple at all!, but the good one is that I 'm leaving here a pdf where you'll find it. Hope it helps you anyway .