ahmad said:
Hi,
My intension is more on studying how the electromagnetic field effect around a cable and how the magnetic field is changed when something come close to the cable. What parameter is changed and how to measure the changed.
A full electromagnetic study is studying evolution in time and space as part of electric engineering but there is another one called kinetic evolution surely is part of electromagnetic study but rather is chemical engineer area.
What you are asking is kinetic evolution. Engineers are lazy, all they need is the fact that wave hitting something will encounter an impedance discontinuity.
Did I say lazy? No I meant smart because electrical engineers have better rules than chemical engineers when problem comes to this point.
All you need to know is impedance discontinuity (i am calling with general term impedance discontinuity because sometimes can not simply be called so.), and just follow the rules and you in 99% of the cases will get a correct result.
What happens in this "impedance discontinuity"? Wave has intensity and its radiation beam/area and around the cable (is that what you want?), closer the better.
When a particle of the wave (foton in antennas, electron/ion if inside another wire) hits the cable something strange happens. No exactly strange because this wave has particles with higher energies they hit the wire and energy hitting the wire for this particle is higher than threshold energy atom in wire has in lattice (whenever is) causing atom to encounter a collision.
This collision depends on incoming particle but depends on kind of atom, crystalographic structure (as form, crystalographic direction, remember chemistry?), angle of collision, etc. DO not worry for these things. We are good friends with DuPont to tell us what we are expecting.
Defects happen in intestitials of atom, isiolated points of defects as vacancies etc. called Frenkel pairs. If energy is greater than 2.5Td threshhold energy than energy starts to get transmitted. Rate of energy is power. Power is bandwidth. Rate of information is also Bandwidth.
Normally, if this energy is some information data, some processing occurs later as filters, multiplication by a local oscillator etc. but if this energy can not be picked up then this will cause some other problems because it can be as an outsider local oscillator energizing things you do not want causing noise etc.
Electrical engineers have simple rules, which damn it they work pretty good without this nonsense. These rules are fruit of years and years of work. Now you want to start learn these rules, test them, prove them and re-invent the wheel or better accept as true?
Your call.