aperture coupled antenna

Hello.I am a new user fo CST MWS and trying to design an aperture coupled rectangular patch antenna.When I design it according to papers, program gives warning "paralell symmetry planes, no farfield calculation" and aborts transient analyses " steady state eneygy crietion ..." . What can be the problem?

any web sites, papers or suggestions that how can I build a aperture coupled antenna? In fact I built it but as I said it gives warning and error.
Thanks a lot.

It seems that your background/boundary definitions are wrong.

If u built your antenna by the book then try this :

1. Background materials -> Choose "Normal" background
2. Boundaries -> set all boundaries to "expanded open" ( I assume you're interested in radiation pattern ).
3. Boundaries -> Symmetry planes -> set all planes to "none".

Run the Solver.

Tell me if it works,

Good luck,
P.

Unfortunately it didnt work again.the same problem.Let me explain briefly how I formed it.
I did a substrate with a rectangular patch and below the substrate, extrude ground with a thickness of 1 or 2 mm.Then open a rectangular small slot in the center of the ground with a 1 mm to 10 mm dimensions.And did a feed line.Below the feed line again another substrate.Boundries are open except the feed substrate (ground).And symmetry planes are "None". For me it all stands true but simulator does not agree with me.And i should add that I use waveguide port with free coordinates.

Thanks for your interest...

I am not sure if this helps correct the CST messages but I think you have not got the design alright. After the ground plane ( with a slot ) you should do the feed substrate and then do the feed line. How can you have the feed line above the feed line substrate in an aperture coupled feed. ? Also please look up in the CST online help as to how to define the wave port for a microstrip line.

-svarun

By the way here is a review paper by the inventor of Aperture coupled feed, David Pozar and another paper on the design of an aperture coupled p@tch antenna.

I tried to simulate again according to your suggestions and could not operate it.Here I send my work and maybe the problem is a little thing that I can not notice.If you look up and suggest me something you will be very helpful to me.

For your frequency of interest ( 2.45 GHz ), I think your ground plane size is too small. Make it at least λ0 x λ0 and try to simulate again. Also your port should be from the ground and should be about five times the height of the feed substrate in the -z direction.

I made ground plane and port larger as you say but still have problem.Program reports that again no farfield calculation unfortunately.If you have any aperture coupled antenna examples with CST, can u pm me or another suggestions? I really want to realize what the problem is.
Thanks...