Recent content by xopek

Wow. Seriously? Active power is a textbook term. Active, reactive, apparent, and complex power. Active power: power is dissipated/transfer of energy occurs. It does work. https://en.wikipedia.org/wiki/AC_power I don't arbitrary assign words and meanings. Yeah I noticed that. Words can have...

I think it is a reading comprehension issue. I've never said there were "two types of resistances when power is transferred". I was referring to R in R + jX. R is called resistance. It is not "my real resistance". It is THE resistance when power is transferred. That's all. What I actually...

Active resistance, hmm sounds like something from criminal code. But I am sure you know that I meant "real" resistance R. "Active" is by an analogy with "active power" as opposed to reactive power, I guess. Can't you say that? The true or real, or actual or active power. Thanks. I may be...

Yes I understand that and that's helpful. Yes, makes sense, I am clear on that. As long as energy is absorbed, it then gets converted to another form of energy, thermal, or EM waves, or whatever. And for the energy to be absorbed, the resistance has to be active, otherwise some of it will be...

No, I don't know what that is. And no I don't have any doubts for that reason. I agree with what you said earlier that if some black box behaves like a resistance with U and I being in phase, that doesn't mean it is a resistor. I just thought of some other examples, for example JFET in a linear...

Funny that you mention Feynman. Some of the responses in this thread remind me of this video :)

The imaginary part wasn't really my question (pun unintended). Yes, that's what I asked about, the real part. About Radiation resistance and why it depends on frequency despite being a real active resistance. And if I understand you correctly, you are basically telling me "it just happens...

I didn't notice this post. Does that apply to both transmitting and receiving antennas? Can a receiving antenna be though of as a voltage source with a leaky transmission line attached to it so the load "sees" 73 ohm or whatever?

But that time delay in a transmission line is due to reactance since a transmission line is modeled as a bunch of repeating RLC segments? So it is not really "the real" resistance? What do you think about this explanation in wikipedia: Electromagnetic waves are radiated by electric charges when...

But it is not about a simple AC impedance. It is the resistance of an antenna that I am asking about. I understand simple AC impedance. It has a real and an imaginary part. The imaginary part is a simple reactance that depends on frequency. And the real part is a simple "conventional...

Found this in the wikipedia article: Radiation resistance is an effective resistance due to the power carried away from the antenna as radio waves.[1][2] Unlike conventional resistance, radiation resistance is not due to the opposition to current (resistivity) of the imperfect conducting...

Perhaps it is some kind of a lumped element that is "seen" as active resistance by the circuit at AC? I looked up the formula for radiation resistance and it is mind bogglingly complicated and seems to depend on the antenna geometry.

So that's actual real resistance, not reactance? So is this some kind of an "AC resistance"? Because if we push DC current through a resistor, there is also a loss of energy as it is dissipated as heat. I am just trying to wrap my mind around this magical "AC resistance" that cannot be...

So if I understand correctly, it is a high-pass filter and its transfer function is usually Vout/Vin, but we can think of it as impedance I/U which is R - j/wC. As frequency goes up, the reactive part diminishes and the phase approaches zero and the magnitude is approaching R. Strictly...

I am asking about a resistance of a half-wave radiating antenna as measured at the feed point. I am not asking how to make it resonant and how to get rid of reactance. What I am trying to ask is a really silly question, if the resistance is 73 ohm or whatever, why can't it be measured with a...