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My issue is that how to define those two side grounds of CPW ?
Since they(side grounds) are seperated by the signal line and will not have opportunity to contact each other, how to define they two to be grounds in the same time?
Nice to hear reply from you !
Actually, what I am wondering is that the "wave port" 's size is
somewhat hard to match two important criterion in the same time:
1. The port need to be large enough to reduce edge-effect.( >3(2g+w)
2. port's left & right edges need to contact the two side- grounds to
let them be connected together, to form the "lateral ground".
However, it is tough to meet above two requirements sometimes. For
instance, since the lateral metal trace have limited width, it is very
possible that the port had to be so wide (that all three metal traces are
included in the port) to meet requirement 1. Then, the edge of port
will bot contact lateral grounds. These two side-grounds are seperated
How to resolve this issue?
you have very narrow ground conductor... gorund width is comparable to center strip width. it is called finite-ground CPW (FGCPW)
port width> 3(2g+w) does NOT apply at all. you can forget the crit#1.
make the enclosure surface big enough to cover the whole line with some space between the CPW grounds and side wall (should be PML or packages). let port lying in the center cover the conductors and contacts grounds.
Make your enclosure walls conductors. Let your ground plane conductors contact the walls. They will then be grounded. One nice thing about EM simulators is you have to create a geometry that more or less reflects how you would do it in the real world with real conductors. Enough theory - give me results!