Near field coupling and far field coupling: Comparative analysis of electromagnetic coupling effects

Near-field coupling refers to the electromagnetic coupling effect when objects or structures are very close to each other, usually less than half the wavelength. Different from far-field propagation, near-field coupling mainly transmits information and energy through electromagnetic induction and electrostatic interaction, allowing objects to exchange information or energy without direct contact, and has a wide range of application prospects.

The mechanism of near-field coupling involves the interaction of electromagnetic fields, which mainly includes the following forms:

1. Electric field coupling: When two objects are close to each other, the electric field interaction between them will produce a polarization effect of charges.

2. Magnetic field coupling: The magnetic fields between objects can couple with each other, resulting in the redistribution and transmission of the magnetic field. This coupling can play an important role in various physical systems.

3. Surface plasmon resonance: Near-field coupling can induce plasmon resonance on the surface of a medium or metal, thereby enhancing signal transmission and energy transmission efficiency.

Near-field coupling technology is widely used in the field of optical imaging, enabling super-resolution imaging and helping to reveal microstructure and surface morphology. In addition, using the near-field coupling effect, highly sensitive sensors can be designed to detect and monitor small objects, biomolecules, etc., which has important biomedical application potential. In quantum information science, near-field coupling can be used for interaction and information transmission between qubits, helping to build more stable and reliable quantum computing systems.

Near-field coupling and far-field coupling are two electromagnetic coupling effects in different ranges, which are of great significance in the fields of physics and engineering. Near-field coupling means that the distance between two objects is very close, usually less than half the wavelength. The propagation of electromagnetic fields mainly depends on electrostatic induction, electromagnetic induction and other effects. Far-field coupling means that when the distance between objects is relatively far, greater than half the wavelength, the electromagnetic field propagates in the form of radiation and obeys the law of far-field propagation. Near-field coupling mainly realizes information transmission and energy exchange through the interaction of electric fields and magnetic fields on or near the surface of objects, while far-field coupling realizes information transmission and energy exchange through the radiation propagation of electromagnetic waves. Near-field coupling technology is widely used in nanophotonics, nanoelectronics, sensor technology and other fields, and has important scientific research and application prospects.