[SOLVED] Transmission Line Theory Understanding

Hello all,

I am new to transmission line theory. I am reading Microwave Engineering by David M. Pozar. He mentions:

"The key difference between circuit theory and transmission line theory is the electrical size. Circuit analysis assumes that the physical dimensions of the network are much smaller that the electrical wavelength, while transmission lines may be a considerable fraction of a wavelength, or many wavelengths in size. Thus a transmission line is a distributed-parameter network, where voltages and currents can vary in magnitude and phase over its length, while ordinary circuit analysis deals with lumped elements, where voltage and current do not vary appreciably over the physical dimension of the elements"

My understanding: Does this mean that in transmission line theory, the voltage and current can vary in an element? For example, if we consider a resistor with 3 A flowing through it, does this mean that the current through the entire resistor may not exactly be 3 A?

Please explain.

Thanks

dzafar said:

Does this mean that in transmission line theory,
the voltage and current can vary in an element?

Click to expand...

No.
They can vary regarding location of element in line.

Electrons don't care what we call "element" and what we call "line". If element dimensions are not small compared to wavelength (not lumped element), the current will also vary for different locations inside a circuit element.