What is the optimum method/antenna structure to accomplish...
which antenna structure will work the best or how to optimize a dipole or other form of antenna for optimum performance in this very near field? assuming we have good control on alignment and orientation of antennas on either side.
Do we receive more signal on Rx-antenna when it is placed in the far-field of Tx-antenna rather than the near-field?
I apologize if my question sounds stupid, i am just trying to learn and clarify one of the doubts i have. No one talks clearly about what happens if we put the receive antenna in the near field... my common sense says the closer the better and you should receive more signal. if it is too much explain point me to the right references...
Thanks for the help guys.
It is a pity you do not mention the distance over which you want to communicate, and your wavelength.
In fact, these two quantities and their ratio are most important to answer your questions.
Take any textbook on electromagnetism to find out elmag field distribution as a function of distance from antenna. I would recommend Kraus, J.D.,:Antennas, McGraw-Hill, I think 1947.
You will see that in the near-field zone (determined by antenna size and wavelength) there are strong standing-wave oscillations of elmag field intensity, gradually decreasing to the sphere from which we name the field far-field zone.
The best solution would be to use the simplest antennas like quarter-wave stubs with a ground plane; with this antenna type, near-field zone oscillations would cease early with the distance, so receiving antenna location with respect to transmitting antenna would be not too sensitive. You can also try small loop antennas not requiring a ground plane.
Experiments will give you the best solution.
Small Loop antennas (circumference < λ/2) are the best for this very low range application.
They store in the near-field most of its energy in the magnetic H field.