Antenna Reactive Field: Capacitance, Inductance & Energy

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An antenna functions as an RCL circuit, where R represents radiation resistance from the energy radiated, while L and C relate to the reactive fields surrounding the antenna. The capacitive field stores energy in the electric field, and the inductive field does so in the magnetic field, with their energy contributions not necessarily being equal. It is possible for some antennas to have a predominance of either capacitive or inductive reactive energy, and structures like real capacitors and inductors can also act as antennas. The reactive fields are time-varying and closely aligned with the source, resembling electrostatic and magnetostatic fields. Understanding the distribution of capacitive and inductive parameters in antennas, such as the Hertzian dipole, can be complex and is essential for analyzing their performance.
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An antenna behaves like an RCL circuit.
The R is the radiation resistance corresponding to energy actually radiate. Half come from the E field and half from the B field.

The L and C are responsible for the reactive field close to the antenna. the C tells about the energy stored in the E field attached to the antenna.
The L about the B field.

Do the capacitative and inductive reactive fields store energy in the amount?
Do some antennas have more energy in one or the other? Any example? Can we have an antenna with only inductive reactive field and no C field?
Is it correct to say that the reactive field is time-varying (almost in phase with the source since it is so close) and looks like the electrostatic+magnetostatic field?
thanks
 
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Any structure that radiates electromagnetic energy can be considered an antenna in the context of your question. Therefore a (real, not ideal) capacitor is antenna, because any such structure can be made radiate to some degree; a real inductor is similarly a radiator.

So clearly, for a given structure the capacitive and inductive fields do not have to be equal in terms of stored energy.

Time varying charge densities and current densities give rise to time varying electrostatic and magnetostatic fields in addition to electromagnetic radiation.
 
ak7948 you are very clear. But how about the simple Hertian dipole? It current is time changing (sinusoidally). Does its reactive field have more C reactive energy or L reactive energy? I guess the C and the L are distributed parameters and it is not easy to det. how much each one is.
 
Hello! Let's say I have a cavity resonant at 10 GHz with a Q factor of 1000. Given the Lorentzian shape of the cavity, I can also drive the cavity at, say 100 MHz. Of course the response will be very very weak, but non-zero given that the Loretzian shape never really reaches zero. I am trying to understand how are the magnetic and electric field distributions of the field at 100 MHz relative to the ones at 10 GHz? In particular, if inside the cavity I have some structure, such as 2 plates...
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