# microstrip radial stub

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#### spide

##### Member level 3

hi can anyone,provided me based concept on radial stub?i am using ADS to simulate.i have tried to search a lot of book in library but still couldnt find relevent topic.

#### sergio mariotti

##### Advanced Member level 1
Radial stub is born to realize a "short circuit" at the point where it's placed.
Because in planar circuits a true short require an extra work (i.e. metalizzed via hole), a way that not require via hole is preferred.
A λ/4 open stub realize a short, but it's narrowband.
The Radial stub is a λ/4 open stub with wider bandwidth.
Keywords:
- at connection point, Width shoud be small
- At the open end, Width shoud be wide
- At open end, corners should be avoided (reduce charge accumulation due to point effect), so here's why it's rounded.

For references, look on IEEE web site

matherman

### matherman

Points: 2

#### footprint

##### Member level 5

but how to design the R0 of Radial stub ?I find it not well with λ/4!

#### flatulent

##### Advanced Member level 5

The length of the stub includes the pointed end which overlaps the main transmission line. Here is a very old free program to get you in the right ballpark.

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### gyzuestc

Points: 2

#### footprint

##### Member level 5

thanks a lot

Added after 13 minutes:

But I still don't know how it calculate? Do you have a paper about design Radial stub ?

#### snmeciut

##### Member level 4

I found one paper and one book on this topics with this below title:

H. Atwater, “The design of the Radial Line Stub: A
Useful Microstrip Circuit Element”, Microwave Journal,
November 1985, p. 149-156.

and

B. Wadell, “Transmission Line Design Handbook”,
1991 Artech house Boston.London, p. 300-305.

but i have not none of the abow.
have you?

macunix

### macunix

Points: 2

#### rautio

##### Full Member level 5

A radial stub is analyzed on the basis of radial transmission line theory. This is performed in cylindrical coordinates. I seem to recall reading it in Jordan and Balmain (EM Theory text book). It should also be in Harrington (Time Harmonic Fields text book, look in the chapter on cylindrical coordinates). The radial transmission line modes are writen in terms of Bessel functions. If you are comfortable with Bessel functions, the theory is very easy to understand.

#### aizudean

##### Newbie level 1

hello,

some say that the radial stub`s radius is not λ/4 but λ/5.

#### smallcat

##### Newbie level 4
the design of radial line stub + mw journal

could you tell me how to design a radial stub, for example, how to choose the angle, how to get the length?

#### dianhuaqq

##### Newbie level 1
design microstrip & stub radial

could you tell me how to design a radial stub, for example, how to choose the angle, how to get the length?

#### akedar

##### Full Member level 5

see paper by
1. March et.al in IEEE MTT..
2. Sorrentino et.al

They are good paper and you will know the procedure of designing

On eda board already ppl have posted these papers you can find them

#### ghribi

##### Newbie level 6
radial line stub design

Hello
I am also interested in designing microstrip radial stubs to replace via hole.
The probleme is that I don't have access to the articles mentioned before of sorrentino and march and I didn't find it on edabord. If anyone has the papers or a link I would be thankful.
Here are the references I am searching for

A new simple and accurate formula for microstrip radial stub, Sorrentino et al
Planar circuit analysis of microstrip radial stub, Giannini et al

Many thanks

#### parthong

##### Newbie level 1

hi

my project use radial stub. but i don't know in mean

i need a basic of radial stub

ex. introduction

thank you

#### dseye

##### Newbie level 1

Why don't you just simulate on your substrate:

input, short 50 Ohms-Line, T, same 50 ohms-line, output

on the T you put your radial Stub and vary angle and length.

Watch S11 or S21 and watch what angle, radius is best.

If you vary the angle, then length has to be altered, too.
the wider the angle, the more broad your bandwidth.

Also, you can put several smaller angle-radStubs for even broader bandwidth.

Try and error !

#### bless_fooling

##### Member level 2
anyone can supply this paper?
H. Atwater, “The design of the Radial Line Stub: A Useful Microstrip Circuit Element”, Microwave Journal, November 1985, p. 149-156

thanks
I can't find it with internet.
Thanks very much

#### pejal

##### Newbie level 4
how about the angle of the radial stub?? what the suitable angle for f0=2.4GHz?? Is there any formula/equation to calculate it??

#### gata_peter

##### Newbie level 3
Hy there,
i' working on a amplifier, and the biasing networks I have chose are radial stubs.. I use these web page to design the stub " **broken link removed** ". I work's grate on the simulation, but i still can't find the equation for Zi. If i find it i'll post it. :evil:

#### tony_lth

##### Advanced Member level 5
Zi is the trace impedance of Ri, using TXLINE to calculate it.

#### gata_peter

##### Newbie level 3
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.

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macunix and sushia

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