[SOLVED] extra circuit board tracing as waveguide, any info?

[newbusofborg]

I heard you can do rf stuff cheaply on a circuit board by running extra traces along each side of a signal line that act as a waveguide. It does not make any sense to me. I was always taught that wave guides had to surround the signal line. Does anyone know anything about this? Does it work fairly well, or is it just something that helps out when you can't do anything better?

 

[FvM]

Sounds like you are talking about coplanar waveguides. https://en.wikipedia.org/wiki/Coplanar_waveguide

In contrast to usual pipe-like waveguides they are transmission lines with a center conductor, operating in TEM (transverse electro magnetic mode). My suggestion is to study the basic stuff about transmission lines and conducted electromagnetic waves.

 

[jiripolivka]

There are many waveguide types with various modes of propagation.
You possibly mention parallel-plate waveguide which is similar to twin-line. Such "open" structures also can carry waves but often are lossy as part of energy is radiated.
Find a textbook on transmission lines and study the possibilities.