how to reduce sidelobe of Antenna waveguide using CST?
Hi everyone, i would like to ask about the sidelobe suppression.
I'm using CST and also an antenna waveguide 8 s a lot. Anyway, i have found the frequency of my Antenna around 9.4 GHz.
But, the sidelobe really spread off.
Im using EBG to reduce it, with Taconic TLY epsilon 3.2, and also with material EBG epsilon 3.2 and tangent loss = 0.003. And also i put the PEC as a patch for the EBG and PEC too for the Ground plane. But it's very difficult to find for reducing the sidelobe.
And, i have change any position with my EBG, but it's correctly wrong. And i haven't found until now.
Do you have any idea which way i could reduce that? i'm prefer to use EBG than the other.. thank you very much.
Corrugations usually do a good job on sidelobe level suppression, it still can be counted as "artificial" surface. I couldn't understand your antenna exactly but if it is OEW (open ended waveguide) you may try this.
thank you for your reply.
What do you mean a corrugations? actually i am using Artificial Magnetic Conductor. It's related with the EBG. but, anyway, i couldn't find the sidelobe reduce significantly. Do you know why?
thank you very much...
AMCs can be made of using different structures, and corrugated surfaces is one of them as well. AMC, EBG (electromagnetic band-gaps) are general terms used for surfaces which have high impedance behavior.
I couldn't figure exactly what kind is your EBG from your posts. Can you give the citation of the paper that you are using? Also, I still don't know what kind of antenna is your antenna.
In any case, you need to scale and recheck for the behavior of AMC at your own frequency. It is not like "one design works for all frequencies". It is very likely it only has some certain bandwidth that it is useful for.
You can use CST's built in corrugated wall materials (it uses homogenization) as a first trial. Go to materials, hit new material, there choose "corrugated walls". Make sure your corrugations depths are lambda/4 at the frequency of interest. You have to also set tooth and gap widths. You can start with lambda/10 for both. Don't forget that if you use corrugated walls, it uses some equivalent values, not the actual corrugated surface. So once you see your improvement, you can built the actual corrugated surface of yours...
Google corrugated horns, or corrugated surfaces, you will find plenty of references. Also you will have some insight about the shape, how to place it etc...
