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WO-2026093780-A1 - A DEVICE AND METHOD FOR ELECTRONIC COMMUNICATION OR SENSING THROUGH DISSIPATIVE MEDIA USING RESONANT MAGNETIC COUPLING

WO2026093780A1WO 2026093780 A1WO2026093780 A1WO 2026093780A1WO-2026093780-A1

Abstract

The present Invention relates to methods and devices for sending and receiving electrical signals through "dissipative" media such as soil, mud, or sea/fresh water to distances extending to several tens of meters. Present methods for sending through such media use very high-power levels ranging to Mega-Watts and employ large equipment. Very Low Frequency (VLF) and Extremely Low Frequency (ELF) communication systems used to communicate with submarines are an example. In contrast, methods and devices disclosed here are powered by general purpose batteries (such as Lithium-Ion batteries) and can be used with consumable items as small as a mobile phone. The invention achieves this functionality by combining near field resonant magnetic coupling with symbol stretching at the transmitting end and matched filtering at the receiving end. While the range of near field magnetic coupling is limited to approximately 1' (30 cm), the combination disclosed in the invention enables to send/receive signals extending to several tens of meters. This new technology (the combination) opens several new applications. At present, there is no systematic methodology to detect victims of natural or man-made disasters such as landslides, earthquakes, and disasters where the victims are buried in media such as soil or mud. The invention can be used to add functionality to consumer devices such as mobile phones or similar so that they can be easily located. Alternatively, a novel device one can easily carry (smaller that the size of a mobile phone) can be introduced, which would be very useful for communities living in countries prone to natural disasters. Scanning for victims can be done fast by mounting the search device on a drone. The methods and devices disclosed can also be used for underwater communication between diver to diver and diver to vessel and the technology is especially suitable for freshwater applications. In addition, this technology can also be used for communication in mines in emergency situations. It is suggested to use in emergency situations due to low data rates.

Inventors

  • GUNAWARDENA, Aruna

Assignees

  • UNIVERSITY OF PERADENIYA: BLII-TTO

Dates

Publication Date
20260507
Application Date
20241030

Claims (13)

  1. A DEVICE AND METHOD FOR ELECTRONIC COMMUNICATION OR SENSING THROUGH DISSIPATIVE MEDIA USING RESONANT MAGNETIC COUPLING WHAT IS CLAIMED IS:
  2. 1. A method of Near-Field electromagnetic signal communication comprising weakly-magnetic coupled resonant coils connected to capacitors at transmitter and receiver ends, and with symbol -stretching in the time domain combined with matched filtering.
  3. 2. The method of claim 1, further comprising: a resonant circuit comprising a coil, inductor and a capacitor tuned to a fixed frequency f at the transmitter end which is excited by a signal stretched in time at the same frequency f representing a symbol; a series resonant circuit tuned to the same fixed frequency f at the receiver end whereby the voltage across the capacitor in the series resonant circuit is sensed and processed with a matched filter prior to detection.
  4. 3. The method of claim 1, further comprising a set of multiple resonant circuits tuned to a set of fixed frequencies f, f, ■■■f N at the transmitter end which are excited by signals at frequencies f, f, representing a symbol, stretched in time; a set of
  5. multiple series resonant circuits at the receiver tuned to the same fixed frequencies, ’ ’’ ' v whereb Y v °l ta g es across the capacitors in the series resonant circuits are sensed and processed with multiple matched filters and the summation of matched filter outputs is used for detection.
  6. 4. The method of claim 1, further comprising a set of multiple resonant circuits tuned to a set of fixed frequencies f, f, ■■■f N at the transmitter end which are excited by signals at frequencies f, f, •"f N , stretched in time representing a symbol; a set of multiple series resonant circuits at the receiver tuned to the same frequencies f, ’ '^N whereb Y voltages across the capacitors in the series resonant circuits are sensed, and first summed and then processed with a single matched filter prior to detection. 5. The method of claim 1, further comprising a set of multiple resonant circuits tuned to a set of fixed frequencies f, f, ■■■f N at the transmitter end wherein a signal of a frequency randomly picked from the set of fixed frequencies ^, f, "■f N , representing a symbol is stretched in time is used to excite one or all of the resonant circuits at a time; set of multiple series resonant circuits at the receiver tuned to the same fixed frequencies /, f, ■■■f N whereby the voltage across the capacitor in the series resonant circuit that is tuned to the randomly picked frequency from the set of frequencies /, f, '"f N ^ sensed and then processed with a matched filter prior to detection.
  7. 6. The method of claim 1, further comprising: a resonant circuit of which the resonant frequency is varied in synchronism with the frequency of the signal representing a symbol which varies either as a linear or a non-linear chirp is used to excite the said resonant circuit; a series resonant circuit tuned in synchronism to the said time varying frequency at the receiver end whereby the voltage across the capacitor in the series resonant circuit is sensed and processed with a matched filter prior to detection.
  8. 7. A device of Near-Field electromagnetic signal communication comprising weakly-magnetic coupled resonant coils connected to capacitors at transmitter and receiver ends, and with symbol -stretching in the time domain combined with matched filtering.
  9. 8. The device of claim 7, further comprising: a resonant circuit comprising a coil, inductor and a capacitor tuned to a fixed frequency f at the transmitter end which is excited by a signal stretched in time at the same frequency f representing a symbol; a series resonant circuit tuned to the same fixed frequency f at the receiver end whereby the voltage across the capacitor in the series resonant circuit is sensed and processed with a matched filter prior to detection.
  10. 9. The device of claim 7, further comprising a set of multiple resonant circuits tuned to a set of fixed frequencies /, f, ■■■f N at the transmitter end which are excited by signals at frequencies f, f, representing a symbol, stretched in time; a set of multiple series resonant circuits at the receiver tuned to the same fixed frequencies, ’ ’’ ' v whereb Y v °l ta g es across the capacitors in the series resonant circuits are sensed and processed with multiple matched filters and the summation of matched filter outputs is used for detection.
  11. 10. The device of claim 7, further comprising a set of multiple resonant circuits tuned to a set of fixed frequencies f, f, —f at the transmitter end which are excited by signals at frequencies f, f, •"f N , stretched in time representing a symbol; a set of multiple series resonant circuits at the receiver tuned to the same frequencies f, ’ '^N whereb Y voltages across the capacitors in the series resonant circuits are sensed, and first summed and then processed with a single matched filter prior to detection.
  12. 11. The device of claim 7, further comprising a set of multiple resonant circuits tuned to a set of fixed frequencies f, f, —f at the transmitter end wherein a signal of a frequency randomly picked from the set of fixed frequencies ^, /, '"f N > representing a symbol is stretched in time is used to excite one or all of the resonant circuits at a time; set of multiple series resonant circuits at the receiver tuned to the same fixed frequencies /, f, ■■■f N whereby the voltage across the capacitor in the series resonant circuit that is tuned to the randomly picked frequency from the set of frequencies /, f, '"f N ^ sensed and then processed with a matched filter prior to detection.
  13. 12. The device of claim 7, further comprising: a resonant circuit of which the resonant frequency is varied in synchronism with the frequency of the signal representing a symbol which varies either as a linear or a non-linear chirp is used to excite the said resonant circuit; a series resonant circuit tuned in synchronism to the said time varying frequency at the receiver end whereby the voltage across the capacitor in the series resonant circuit is sensed and processed with a matched filter prior to detection.

Description

A DEVICE AND METHOD FOR ELECTRONIC COMMUNICATION OR SENSING THROUGH DISSIPATIVE MEDIA USING RESONANT MAGNETIC COUPLING 1. FIELD OF THE INVENTION The methods and devices disclosed here (i.e., the “Invention”) relates to near-field, wireless, electronic communication devices and methods for sending and receiving electrical signals through “dissipative” (i.e., characterized by the dissipation of electromagnetic energy) media such as soil, mud, or sea/fresh water. The Invention also relates to methods and devices that exploit wireless resonant magnetic coupling of spatially separated coil systems, with each coil connected to a capacitor in series or parallel. The Invention utilizes resonant magnetic coupling combined with matched filtering to overcome severe energy losses normally observed when sending/receiving signals through a dissipative media using electromagnetic waves. Matched filtering is a linear technique that maximizes the signal-to-noise ratio (SNR) of a signal that is embedded in noise. The Invention also relates to Low Frequency (LF) Radio Frequency Identification (RFID) technology. A typical RFID system includes a “tag” comprising a tiny radio transponder, radio receiver, and transmitter. When triggered by an electromagnetic interrogation pulse from a nearby RFID reader device, the tag transmits a signal (i.e., digital data) back to the reader. Passive tags are powered by energy from the RFID reader’s interrogating radio waves. Passive tags utilize energy harvested from the environment and are limited to very small transmission distances. Active tags are powered by a battery and thereby transmit greater distances and thus can be read at a greater range from the RFID reader - up to hundreds of meters in air. Only Ultra High Frequency (UHF) RFIDs can transmit at this large a distance. However, UHF RFIDS are not useful for the dissipative media applications of the Invention due to the heavy signal loss when UHF signals propagate through dissipative media like soil or water. The Invention employs LF RFID technology, with some unique additions (introduced in this disclosure) to communicate through a conductive but energy-dissipative dissipative medium over a distance of several tens of meters. The Invention utilizes weakly-coupled, resonant magnetic coupling in a “Near Field”. The Near Field (as opposed to Far Field) is the region close to a radiating body such as an antenna dominated by either electric or magnetic mutual coupling. The invention is on a connectivity mode that enables short-range wireless connectivity/communication between devices keeping equipment size small and transmitted power levels low. Near Field connections enable communication (i.e., Near Field Communication or “NFC”) between two electronic devices over a typical distance of around 30 centimeters (12 in) or less in air. The applications of the Invention include detecting buried consumer devices (e.g., mobile phones, laptop computers), underwater communication, and emergency communication in mining. The term “communication” here refers to both analog and digital data transfer. The methods introduced are based on resonant magnetic coupling. Radio Frequency Identification (RFID) technologies use three frequency bands - Low Frequency (LF), High Frequency (HF) and Ultra High Frequency (UHF). Although RFID technology is typically used in through-air applications, in recent years it has been applied in underwater communications. In the Invention, Near Field resonant magnetic coupling combined with matched filtering counters energy losses due to eddy currents, while keeping equipment size small, and the transmitted power levels low. The technical field of the Invention can also be classified as NFC through a dissipative conductive medium. The Invention relates to electromagnetic resonators. Such resonators may be coil-based and connected in series or parallel with a capacitor. Radio signal reception with coil-based electromagnetic resonators (i.e., a coil connected to a capacitor) is not a new concept. Such coils connected to capacitors are sometimes referred to as “magnetic antennas” and used for AM (Amplitude Modulation) radio reception. However, in AM reception applications the coils are used in the “Far Field” - a mode of radio-frequency propagation in which the E and M components of an EM (electromagnetic) field are in-phase, and the radiation mode of energy dominates. This in-phase E to M propagation wave relation occurs at a far distance from the transmitter and the coil at the receiver should be placed such that the edge of the coil faces the direction of the incident wave. In contrast, the Invention utilizes axially coupled coils in the Near Field and therefore the coils should be placed such that their axes are in line. The Invention also relates to Wireless Power Transfer (WPT) technology. WPT is based on electromagnetic coupling that occurs when the electromagnetic field (E or H -field component) produced by an electric