Welcome to WIFI Antennas

Register now to gain access to all of our features. Once registered and logged in, you will be able to contribute to this site by submitting your own content or replying to existing content. You'll be able to customize your profile, receive reputation points as a reward for submitting content, while also communicating with other members via your own private inbox, plus much more! This message will be removed once you have signed in.

Sign in to follow this  
Followers 0
a.ndiaye@

Mysterious s21 coplanar waguide

28 posts in this topic

Hi everyone,

I have design a coplanar waguide with this parameters : w=3.3mm, h=1.6 and gap=2mm, er = 3.66, via espacing = 2mm and via size =0.3mm.

sma ref : Cinch :142-0791-821

in HFS. CST and measure i get invalid results near 12GHz, it's look like low pass filter.

Can someone help me please

Any suggestions are welcomed.

Thank 

board.png

board_measure.s2p

stack.png

s11.png

s21.png

1 person likes this

Share this post


Link to post
Share on other sites

,,,hi buddy...!!!

,,, dimensions are incomplete, you can post a * CST file...!!!

,,,and that's what it is...??

"board_measure.s2p"

 

1 person likes this

Share this post


Link to post
Share on other sites

Thank you for your reply

Please find the cst file

,,and that's what it is...??

"board_measure.s2p"

 

that is s parameter measure  of the board

coplanar_board.cst

Share this post


Link to post
Share on other sites

I think the problem come from :

- via espacing : 2mm is too large

- internal gnd plane : can make resonnance

- sma transition can make capacitive effects as the picture show i reduce the trace at the sma contact

board_modificated.jpg

Share this post


Link to post
Share on other sites

Posted (edited)

What about the REST of the BOARD you know is COUPLED right...?

and there are missing components , there...a cap maybe...

Edited by clanon
1 person likes this

Share this post


Link to post
Share on other sites

Posted (edited)

OK , this is what i got (low precision so take it with a grain of salt)

tell if i'm close or far away from goal...

 

S111221.JPG

Captura.JPG

it seems there's ASSYMETRY from 2:2 (and its okay from 1:1

Edited by clanon
1 person likes this

Share this post


Link to post
Share on other sites
10 minutes ago, clanon said:

OK , this is what i got (low precision so take it with a grain of salt)

tell if i'm close or far away from goal...

 

S111221.JPG

Captura.JPG

it seems there's ASSYMETRY from 2:2 (and its okay from 1:1

goal_measure.s2p

Thank you for your help clanon, i send you attached the s parameters measurement, 

the goal is to get S11<-20DB and not resonnance at S21..

 

Share this post


Link to post
Share on other sites

Posted (edited)

28 minutes ago, a.ndiaye@ said:

the goal is to get S11<-20DB and not resonnance at S21..

 

S11 is high Q (more than okay)@13ghz

S22  (@17ghz) not so high Q 

What's the function of this MIXER...getting and S1 + S2  , S1 - S2...

Sorry it isn't clear for me...

besides the card you show on the first post seems to TAKE SIGNAL out...(and is incomplete)

Captura.JPG

Edited by clanon
1 person likes this

Share this post


Link to post
Share on other sites
34 minutes ago, clanon said:

S11 is high Q (more than okay)@13ghz

S22  (@17ghz) not so high Q 

What's the function of this MIXER...getting and S1 + S2  , S1 - S2...

Sorry it isn't clear for me...

besides the card you show on the first post seems to TAKE SIGNAL out...(and is incomplete)

Captura.JPG

 

This is used for switching signal, the idea is to pass a maximum power and not loss in the transmission line

but as you see, i lost signal in the insersion loss

Share this post


Link to post
Share on other sites

Posted (edited)

is it a DUPLEXER...?

and WHAT about the REST of the BOARD...?

Edited by clanon
1 person likes this

Share this post


Link to post
Share on other sites

screenshot_561.png

,,,see this...

 

2 people like this

Share this post


Link to post
Share on other sites
40 minutes ago, clanon said:

is it a DUPLEXER...?

and WHAT about the REST of the BOARD...?

No it's a RF SWITCH

and this trace line is used for calibration 

1 person likes this

Share this post


Link to post
Share on other sites

 I have change the design and now the gap between the connector and the pcb is 0.1mm

The result is similar to the measure but it's not enougth, i must get s11<-20dB (0GHZ to 15GHZ)

s21.png

s11.png

Share this post


Link to post
Share on other sites

 

There are internal GND plane, the electronic technician who makes the layout forgot to remove it.

there are some via in the layout

 

Stackup_AX70.png

3D.png

via.png

Share this post


Link to post
Share on other sites

screenshot_567.png

1 person likes this

Share this post


Link to post
Share on other sites
1 minute ago, Admin said:

screenshot_567.png

 

Without gap, there may be a short circuit

i put a litle gap of 0.1mm and the result is here

s21.png

s11.png

Share this post


Link to post
Share on other sites

,,,it must to be without gap...!!!

1 person likes this

Share this post


Link to post
Share on other sites
15 minutes ago, Admin said:

,,,it must to be without gap...!!!

Have you some idea to remove the gap in fabrication or special sma connector to minimize the gap?

Share this post


Link to post
Share on other sites

,,, by translation...!!!

1 person likes this

Share this post


Link to post
Share on other sites
7 minutes ago, Admin said:

,,, by translation...!!!

can you explain please?

 

Share this post


Link to post
Share on other sites
2 minutes ago, Admin said:

screenshot_568.png

I have try different scenario

But physically to  mount the SMA it's will impossible to translate less than 0.1mm, and when i do this the result is not ok for at 15Ghz

translated_sma.png

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0