I'm trying to run antenna using port 1, i picked up area then I calculate K parameter using solver. as you can see this port is shifted from substrate and ground plane. is this case normal or i need to do some thing for alignment
Dear Imran
In my opinion, for defining the waveguide port in CST MWS then consider the outer SMA connector maximum dimensions (which using for the hardware) and define the port accordingly or use the port excitation coefficient calculation tab and you will get the value of k. This k value is very high and adjust according to SMA connector dimension.
Hope you find the answer
Ali Adnan , yes i did. i used macro >> solver then i calculated K value and constructed the port . but as you can see in the fig , the port is shifted out of antenna dimension ? is this normal ( not effects on results ) or i must do some thing to correct it ?
Dear Alaa;
The problem is probably the value of the k parameter. So, a suitable value leads to the right result.
good luck
@Aounallah Naceur thank you for your answer. How can i find this suitable value?
Dear Alaa Imran Please show your port's settings - it will be helpfull to solve the problem!
Ussually I would recomend you to create a WVG port without picking up a face because if you use a optimisation sometimes it could "jump" somewhere else and you will get your model crushed. I do not pretend that it would be always this way but I asure you that I have encountered such a problem recently. Nevertheless creating a WVG port by picking up a face is a correct way - you would just want your model to be drawn in such a way that your ports would not "jump out". But drawing your port by giving it open position will help you to escape such problems so as problems that you encounter.
Anyway - it seems to me that you could made the port asymetrical due to a wrong deltas in port's assingment (in which you used the K extension coefficient).
P.S.
Show also your picked face please and total structure's screenshot please.
Alexander Plotnikov thank you for your answer . i hope this will help .
by way if the port in CST exceeds antenna dimension ( as in pic) is this will affect on my simulation results ?
Ali Adnan Thank you a lot.kindly , how can i choose the suitable value of K for my design ? is there any rules , book ,or paper ?
Ali Adnan . you mean i should choose K value using try and error ?
what about if the port still out off substrate dimensions , is this will give an error in my results ?
Dear Alaa! Everything seems to be correct - try to define your port as a free part or try to redefine your port using pick instrument but watch your steps.
You can send me a project file and I will look through it to find an error!
Alexander Plotnikov thank you very much really i appreciate you help.
your e_mail please?
Alaa Imran Please see the attached files! I have make it step by step:
1. Picked an end of a patch;
2. Put a WVG port;
3. Gave it it's delta's.
Now it's symmetrical. BUT, you as you can see on the second pic - the port has gone outside the model - it is wrong 'cause you just give part of energy into space. I would recomend to try discrete port - it is usefull in antenna aplications! Or you can model a RF connector and use the WVG port there.
As for your second qusetion in the letter - if I understood you right than your mistake is in absence of the diodes. I will give it a try next week and will tell you if I find any answer. As for me - I would recomend to watch for mistakes in defines.
Hello Alexander Plotnikov
yes. this is exactly what i did to build my port and this is exactly what i want to solve.
kindly, is there any reference or web site that i can learn from how to make discrete port in cst ?
about the second question , yes . i removed both diodes for ideal reconfiguration. the problem here is no match between simulation results and paper results ?
thank you
@Alaa Imran sure! The best way is the CST help - you can find it within the program! Just use the search there to find a discrete port. As for me - I prefer to draw a connector and to use the WVG port. But to get first result it is easier and much faster to use discrete port
Alexander Plotnikov i will check CST help. thank you a lot for your support ?
The port is where it should be. Your substrate and ground are too narrow to include all the fields around the microstrip. Make them wider - at least as wide as the port. You should have a wider margin around your component, too. Some of it is much to close to the edge of the board. Using a discrete port won't get the right impedance or S parameters. It will be ok for a rough idea, but not accurate. You can adjust the size of the port by ticking the "free port" option in the waveguide port definition window and then filling in the boxes with the dimensions you want.
Nada Al.Ani
return losses is high : this means there is high mismatch between antenna and feed.try to optimize your feed location.
coupling high: try to redirect your feed location to get different polarization.if this not work , you may need to implement such technique to reduce that coupling.
about SMA dimensions, different types and dimensions are available in market.try to choose one and google for its data sheet.
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