AIM Diffusion Field Resonance

AIM Diffusion Field Resonance is an AIM-related phenomena in which an esper's powers resonate with others.

Principles
Resonance occurs when two or more espers gather together; for example, Misaka Mikoto can resonate with other espers who has the same AIM field as hers. Normally, this phenomena is relatively harmless, in Mikoto's case she can detect other espers with the same ability as hers; however, when an overloaded esper in close proximity with other espers of the same AIM field, it can cause an occurence of RSPK Syndrome.

Poltergeist Arc
AIM Diffusion Field Resonance is referred by Konori Mii as the possible cause for the Poltergeist occurences happening all around the city. Later, Shirai Kuroko explains to Mikoto the relevance of the resonance of to the current poltergeist events happening all around the city.

It is later revealed in the final episode by Therestina, that exposing Haruue Erii (since she can exhibit power beyond her level class when exposed to a specific wavelength) to the Crystallized Esper Essence would cause a resonance with Kiyama Harumi's Child Error students, allowing her to achieve that specific wavelength, causing her to achieve level 6 at the cost of destroying the city.

Sisters Arc
Mikoto is introduced to a child who has a similar powers to her, the children asks if that one day they could form a 'radio' together (implying that if they could talk to each other with their powers), Mikoto tells them that it was impossible, but if they were in an open space with no obstruction, then they would be able to do detect each other. Mikoto then comments to herself that they could make a network if they have similar brainwaves, just like the Level Upper, then they could in theory make something similar to a radio.

Mikoto later detects a similar power to hers, and discovers the existence of Misaka 9982 and the clones.