difference between current and wave
help me plz
Can you elaborate more your definition and the difference between them?
According to Antenna Theory and Design Stutzman 2nd p429, Surface current is your answer.
actually i have doubts regarding the differances between surface wave and surface currents so need ur help to get a clear defination of both.
what i came across is that when it comes to microwave frequency surface wave is nothing but surface current so the doubt is that is there any differance among them or is that both are same just they are known by different terms at different frequency range.
My understanding is that in uwave components both are the same. I usually refer to surface wave in uwave when I am referring to skin effect and surface current when I am discussing Method of Moment.
A surface current is just that, a current that flows on the surface of a conductor.
A surface wave is different. I have looked into this since the term is loosely thrown about and I have never found a concise definition. It is a guided wave that must have a boundary condition to propagate. Take for instance a 1/4 wave monopole on an infinite ground plane. It has a decent amount of gain at zero elevation (the pattern looks like a 1/2 toroid). This is because the gain at zero elevation is due to a surface wave; the infinite ground plane is the boundary along which it propagates. This seems odd since there is only one boundary unlike a waveguide with two walls, however it should still propagate just with only a single mode and no cut-off frequency.
If the plane is finite then the gain at zero elevation is reduced (to zero theoretically) and the pattern tilts upward; there is no surface wave to allow prorogation at zero elevation.
Most surface waves are unwanted. You can get a surface wave propagating along a circuit board or patch antenna, I believe even along an interface between two dielectrics.
Wikipedia calls it a ground wave but I don't agree with that. A surface wave propagates along the surface where a ground wave bounces between the surface (Earth) and ionosphere. It does mention a single conductor transmission line and that would be a true surface wave in my opinion.
http://en.wikipedia.org/wiki/Surface_waves
Surface current? Yes. Surface wave? Yes, if there is a media/waveguide that can carry it.