Edit: I was interested how is voltage gap maintained across an antenna. It seemed to me that an antenna might be like a wire where if there's a voltage at the top, the same voltage would be at the bottom, and hence no gradient and no current flow.
Several individuals explained to me that antenna is not a simple circuit element and goes beyond basic circuit analysis, and so there is no contradiction in it having different voltage at the top and bottom, which would lead to current flow.
One question that still bothers me:
Let's say that at one moment there's a positive voltage at the top of the antenna (10V relative to bottom, say), and current flows from top to bottom. But at the bottom where the antenna is actually connected, voltage is 0. That seems like the end of the journey, and it's unclear to me how the presence of a gradient in the antenna, also creates a voltage gradient in the circuit that drives the circuit elements?
On the other hand in the pic below it makes sense to me as the circuit is connected at 2 points in the antenna and there's a voltage differential between the 2 points that drives current to the radio circuit:
Old question: In circuit sims and in theory, ground always maintains zero volts.
Thus if the point to which the ground is connected has more than 0V, some current will flow into the ground, while ground still maintains 0V despite incoming current.
But it looks like that in most real cases ground is merely a theoretical construct, and unless the circuit is earthed, the point labeled as "ground" can't actually maintain 0V, if the point to which the "ground" is connected in the circuit is above 0V, and current flows into the "ground".
Is there an element or some way to get "real" grounding, such that when the "ground" is connected to say a 1V point in a circuit, the "ground" will maintain 0V, despite current flowing from the 1V point to the "ground"? Otherwise the point labeled "ground" is just a loose wire that will quickly acquire the 1V of the point it is connected to, and not maintain zero volts.
My motivation is radio antennas where I'd like to have one end of the antenna connected to a permanent zero volts, so that when the top end of the antenna gets 1V, currently will flow from top to ground, while the ground maintains zero volts despite current flow.
- on the left almost no current flows (just tiny bit to get other end of wire to match voltage of source), while on the right current flows steadily. If this was a real circuit, what can I do to make it behave like the one on the right, and not like one on left? I have antennas in mind, so that's why the simple solution of having 2 sided AC voltage source (i.e. like an AC 'battery') that maintains the voltage gap, like in the pic. below, won't help..
Thanks for your help!