https://www.dhs.gov/publication/st-pointer-factsheet
In 2014, the U.S. Department of Homeland Security partnered with the NASA Jet Propulsion Laboratory (JPL) to develop the Precision Outdoor & Indoor Navigation & Tracking for Emergency Responders (POINTER) technology. "POINTER is a precision positioning sensor that locates first responders via" "low-frequency magnetoquasistatic fields that can transmit signals through any building materials."
"That differentiates it from Ultra-Wide Band, GPS, radio frequency identification systems and sensor fusion methods, all of which rely on radio position location and suffer reduced performance in non-line-of-sight and indoor environments."
Excerpts below from https://www.dhs.gov/science-and-technology/how-pointer-works
"What are Magnetoquasistatic (MQS) fields?"
"MQS fields are magnetic fields with very slow temporal variations that appear static and can penetrate through most natural materials just like the Earth’s magnetic field. As a result, they can be used in a broad array of sensor applications."
"What are some examples of how MQS fields are currently used?"
"MQS fields can be beneficial in applications where information or sensing is needed when a clear line-of-sight (LoS) is not available. This includes position sensing in buildings or homes—like with POINTER—as well as in wireless communications and power transfer technologies currently being used to power smart phones in similar environments."
https://engineering.purdue.edu/~shreyas/SparcLab/static/pdfs/j/MN_TBME_Magnetic.pdf
(Note: Please refer to Figure 1).
"There are three categories of Wireless Power Transfer (WPT) technologies: inductive coupling, magnetic resonant coupling, and electromagnetic radiation." (https://arxiv.org/pdf/1502.04727.pdf)
Here is an example of magnetic resonance coupling using "Quasistatic cavity resonance (QSCR):
"Wireless power transmission safely charges devices anywhere within a room" by Disney Research
https://phys.org/news/2017-02-wireless-power-transmission-safely-devices.html
The resonant frequencies of the cavity (room) and receiver are tuned to be identical*. Upon this condition, power is transmitted to the receiver.
*equal to 1.32 MHz
Magnetic resonance coupling is also termed "resonant inductive coupling" and "electrodynamic Induction". (https://en.wikipedia.org/wiki/Resonant_inductive_coupling).
A proposed classification for the wireless transmission of electrical power based on http://ijcee.org/papers/480-N015.pdf is the following:
1) Induction (cf. electromagnetic induction and the example of the "transformer").
2) Electrodynamic induction, also known as "resonant inductive coupling" or "magnetic resonance coupling".
3) Electrostatic induction, also known as "capacitative coupling".
4) Electromagnetic transmission - radio, microwave, laser power beaming (cf. use of rectennas).
5) Evanescent Wave Coupling
Efficient Communication and Powering for Smart Contact Lens with Resonant Magneto-Quasistatic Coupling
https://arxiv.org/abs/2406.08220