Does kirchoffs law apply to RF? RF does some funny things. The only way for RF to appear on the braid is for the driven element to radiate into the counterpoise or braid instead of working against it. Or do I have it all wrong? RF is not like DC, it doesn't need a return. Like static electricity, it goes from a place where there is more to a place where there is less. Like cold is the absence of heat, heat seeks cold. Dark is the absence of light. No RF is the absence of RF? Or not? Not trying to badger, just trying to learn.
Chris
Some very good questions and observations. My own thoughts about the Kirchoff's laws and antennas.
My first thought is every problem I have seen that involves using Kirchoff's laws to calculate and solve for what is happening electrically uses DC circuits. I have never seen AC circuits used in such problems, even in engineering level books. If someone has a reputable link that shows otherwise, I would very much like to see it.
My next thought is AC is different than DC. You hook up a DC circuit, and assuming the values of the components don't change, the readings don't change. With AC, and by extension RF, that is not the case. If you could freeze time and look at the currents going in and out of the nodes, the inputs will always have a different amount of current than the outputs. This is due to the nature of AC.
Building on my last thought, if the currents in an AC circuit are averaged over time, and assuming a steady sine wave (or whatever waveform you are using), the average current going into each node will necessarily equal the current going out of each node, and as we are talking about equal amounts of positive and negative currents over time, this will necessarily balance out to a current of 0.
Taking that a step further, if you modulate the AC signal, and it doesn't matter how, unless that modulation is a consistent steady pattern, will the currents flowing in and out of the nodes always be the same? I want to say no, but I don't have anything to back that up.
Another line of thinking.
Whenever Kirchoff's current law is mentioned when it comes to antennas, it is in referencing the feed point as a single node. This is objectively false. Each wire of the feed line is attached to one and only one wire (or element) at the feed point of the antenna. These connections are never connected directly to each other. Each of these connections is a node, therefore the feed point of an antenna is made up of two separate nodes.
Are these two nodes flowing the same amount of current? For example, if one wire is attached to a 1/2 wavelength element, and the other is attached to one or more 1/4 wavelength elements (lets say four radials for this). One side of the feed point will be presented with high voltage and low current, the other side is presented with high current and low voltage. Can Kirchoff's laws account for this difference on both sides of the feed point?
Can the feed line cause the currents in the two nodes at the feed point of the antenna to be different. I would expect that with a balanced feed line such as ladder line both nodes will have nearly the same amount of current supplied by the feed line, but what about an unbalanced feed line like coax? Again, I want to say no but as of yet I have found nothing to back that up...
The DB
