The problem with leaky resonator characteristic modes? How?

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The problem with leaky resonator characteristic modes? How?

Post by Hale_812 » Wed 05 Feb 2020, 06:42

It is known that FDTD is hard to analyze closed cavities where the signal does not decay well.
But there is an opposite problem.
Lets consider a resonator with PEC on the top and bottom, but PMC on the sides!
When loaded with 2 perfectly matched ports, it works more or less as a filter (if there is a magnetized ferrite inside, it is called a circulator)

But the moment you remove the port load, it starts radiating the energy to 377 Ohm load of the free space. A perfect patch antenna.

I tried analyzing the spectrum of decaying oscillation close to exciting Gauss pulse (E-field created by driving H-field probe)
But it radiates the energy to space too fast to see anything. So the only option seems to be loading it with ports. But it is a problem because port matching is a problem with unknowns.

So a topic of characteristic mode analysis came up in my mind. It is available in HFSS, a full-wave simulator,

But can we do a close to that thing in OpenEMS?

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