hello everyone
i've been reading a book about Microstrip patch antenna, and in one chapter it explains the characteristics of microstrip patch antennas using cavity model. and it said "for the basic geometry of the microstrip patch antenna, a simplified physical model, known as the cavity model, can be developed to deduce the characteristics of the antenna. "
we know that In the patch antenna case, the side walls are not enclosed by conducting walls and the fields inside the cavity can leak out to space, leading to radiation. and finally it said that if the substrate is thin with respect to wavelength, the boundary condition on the side walls is Ht =0.
this is where i have problem. why Ht=0? i don't understand it. you will be a great help if you explain this to me.
thank you.
You can think of local magnetic field as representing the current, and the current on the edge is cut off (since the conductor is cut - approximation when the height is much smaller than wavelength - note the lateral dimensions do not have to be small). In the opposite situation - would edges be shorted together it would be Et=0 as representing the voltage.
Basically, one may think of it as end-open or end-shorted transmission line.
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