How to draw a curve of vivaldi antenna ?

[paow]

Hi to all,
I'd like to design a Vivaldi antenna in the 9 - 11 GHz frequency range on FR4 substrate (Er=4.4) with CST. So I can not draw a curve in CST. I drew a curve on AutoCAD but it could not import to CST. How can I do??

Thanks in advance
Paow

 

[GVVIN]

vivaldi antenna equation

You can draw curves in CST .

Select Curves> new curves>
use arc or circle to create an arc. make a line at its start for the width you need.
now select sweep curve option and click on the arc and line , you will get a solid 2D arc , now select face and extrude for thickness.

Regards
GV

 

[byteptr]

Re: curve of vivaldi

I also use a text file of precalculated table of points with my own made software, then I import this list to CST to select the curve points. Bezier is useful.

In CST may be you can make a simple VB script for doing this, please, read the help.

B.R

 

[shameemkabir]

Re: curve of vivaldi

As byteptr suggested, you can draw a line/curve using equation in Matlab and save that two column matrix as a text file. Then in CST, Curves > New curve and select Spline. Press Esc to have a window where you can import the .txt file. Select the .txt file and press OK. That's the curve you are looking for.

Regards,
Shameem

 

[paow]

Re: curve of vivaldi

Thanks a lot. I will try to do.

 

[radiohead]

Re: curve of vivaldi

Just one remark: I don't think it's a good idea to implement an antenna at 9-11 GHz on FR4. Tolerances on epsilonr and thickness are just too high to get good results, and moreover you'll get a lot of losses in the dielectric. Use some high frequency laminate which is designed for this.

 

[GVVIN]

Re: curve of vivaldi

check this, might be useful to you,

https://www.cst.com/Content/Applications/Article/Article.aspx?id=15

Regards
GV

 

[paow]

Re: curve of vivaldi

Dear raiohead,
What's the substrate that I should be use? Or how can I do, if I use the FR4. I know that FR4 is not suitable high frequency.

 

[shameemkabir]

Re: curve of vivaldi

Hi paow,

I guess Rogers RO5880 (ε_r = 2.2) would be a better substrate for your vivaldi. While designing an antenna, most of time try to use lower permittivity material since radiation from these kind of substrates are easier.

Regards,
Shameem

 

[paow]

Re: curve of vivaldi

Thanks shameemkabir,

I will design my antennas on RO5880. But the results are simulated from CST not from measured.