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# Reducing Side Lobes of a Parabolic Reflector

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#### GhS

##### Newbie level 4
Hey all,
I am a 5th year Engineer student and I choose "reducing side lobes of parabolic dish antenna" as my final year project. At the university, I have access to CST 2009, HFSS 11 and even ADS.

In the project I don't want to design a parabolic dish antenna, but use some techniques to reduce the side lobes only. My problem is that I don't how to model a parabolic reflector or dish to work on.

Can someone supply me a model that I can use or a way to draw my own model?'

The method I have used in CST is as follows.

Use Excel to create data point list of parabola. This allows you to choose how accurate a surface you want to model. Then save as a text file. Add data points to bring curve back to the origin. This way you have a closed shape.

Create a polygon and load data points.
Create a planar surface and make PEC
Rotate 360 degrees and you should have your reflector.

I can upload a model if need be

zuyngan

### zuyngan

Points: 2
Thanks, will try, if you can upload a model it would be nice

bconnor Hi!!

Sorry, been busy. Tell me what size reflector you want and what f/D ratio and I will upload CST model tomorrow

Dear GhS-88

I think there is a macro in cst for parabolic reflector.

pl

Here is a file for a 4 foot reflector with an 18 inch focus. f/D of 0.375
I could not find the macro for parabolic dish, I suppose you could create a curve for it.

Here is how I have done it.
1. calculate curve needed for parabola by entering equation in excel (Only half because you will be rotating it.
2. copy and paste to notepad for CST importing. I add data points here to make the curve a closed path and to give some depth.
3. Click the polygon icon in curve creation.
4. Import curve
5. Cover planar curve and make PEC
6. select face and click rotate. Push escape and put 1 where you are going to have axis of rotation.
7. click rotate again and enter 360 degrees and amount of segments you want to use. I chose 72.

There might be better ways to do this so that CST doesn't mesh the reflector past the surface, but I haven't found it yet and I haven't asked CST.

Here is a zip file of the dish.

Dderijken

### Dderijken

Points: 2
hi bconnor,

can i know how you define your waveguide guide for your dish antenna?
hope to hear from you soon.
tq

Hi,

you can use CST 2009: Macros - construct - curves - create 2D....

and edit - history list. So there is: execute macro:..... - edit it - write parabola equation

and after is it the same as "bconnor" answer , 2. point....

zuyngan

Points: 2