I am dealing with the transition from microstrip line to waveguide both are on substrate (PCB). I hv poblem assigning the excitation for my design. Actually I have three layers in my design one is the PCB substrate and the other two are copper layers sandwitching the substrate. How should I assign the excitaion should I select all three faces or just the substrate.
First, you should build the electromagneticl model with back-to-back transition (that is, microstrip-transition-waveguide-transition-microstrip). In addtion, air box should be used for the open structure.
Secondly, you use the waveport for the excitation of microstrip.
I am dealing with the transition from microstrip line to waveguide both are on substrate (PCB). I hv poblem assigning the excitation for my design. Actually I have three layers in my design one is the PCB substrate and the other two are copper layers sandwitching the substrate. How should I assign the excitaion should I select all three faces or just the substrate.
Microstrip port:
Can't you just put a layer of air above the PCB and set a waveport over the entire end of problem, which includes the air, PCB and the microstrip line? Then set your impedance line between microstrip and lower ground plane. Remember to set the waveport to include the face of PCB and air.
Waveguide port:
I would just set the waveport to cover the area of PCBs, from lower ground to upper ground. You might need to put small metal bodies on each end of your waveguide at the port face to connect the top and bottom ground planes. I think you could just put your impedance line to stretch from top to bottom ground plane near the middle of the waveguide.
I keep re-reading your question and your objective is not clear to me. Are you trying to transition from microstrip to rectangular waveguide? That is often done.
Or are you trying to transition from microstrip to strip line? This is also possible.
Part of my quandry is that when someone says waveguide they usually (but not always) are referring to rectangular waveguide. I am trying to understand how that fits with your comment about three conductors (usually the situation with stripline).
Or do you have something else in mind? Maybe microstrip to some kind of dielectric filled waveguide in the PCB? If that is the case you open the door to a discussion of via's (blind, buried, and through).
I am talking about microstrip to SIRW structure. Now I have a problem with HFSS simulation. When I run the validity check it gives me all ticks but when I start simulation it gives me error saying "Not enough triangular structers to model blah blah ...."
Secondly, I have designed the structure such as substrate (a box) is sandwitched b/w to conducs (rectangles) for micro strip operation I have to make the base conductor ground. Should I separate the microstrip base(ground) to the SIRW base?