# US 2018/0020948 A1 · RF Attenuation Measurement System and Method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0020948 A1 - Document ID: US20180020948A1 - Status: Published application - Kind: A1 - Application number: 15/546,426 - Filed: 2016-02-04 - Published: 2018-01-25 - Earliest claimed: 2015-02-04 - Assignees: Massachusetts Institute of Technology - Applicants: Massachusetts Institute of Technology - Inventors: Ian Richard Butterworth; Luca Giancardo; Carlos Sanchez Mendoza - Web page: https://patentgrep.com/patent/US20180020948A1 ## CPC - A61B 5/0507: using microwaves or terahertz waves - A61B 5/4875: {Hydration status, fluid retention of the body} - A61B 5/681: {Wristwatch-type devices} - A61B 5/6824: {Arm or wrist} - G01N 22/04: Investigating moisture content - A61B 5/6823: {Trunk, e.g., chest, back, abdomen, hip} - A61B 5/6826: {Finger} - A61B 5/6829: {Foot or ankle} - A61B 2503/08: Elderly - A61B 2562/04: Arrangements of multiple sensors of the same type - A61B 2562/046: in a matrix array - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract In part, disclosure relates to a monitoring system for monitoring RF attenuation of a material. In one embodiment, the system includes a plurality of transmitting antennas; an RF generator having a first output terminal in electrical communication with each of the plurality of transmitting antennas and a second output terminal; a plurality of receiving antennas, each of the receiving antennas having an output terminal, and a processor having a first input terminal in electrical communication with the second output terminal of the RF generator, having a second input terminal in electrical communication with the output terminal of each of the plurality of receiving antennas, and having a first output in electrical communication with a display. In one embodiment, the processor calculates the attenuation of the RF signal in response to the RF signals received by the plurality of receiving antennas through the material. ## Claims ### Claim 1 An RF attenuation monitoring system for monitoring RF attenuation of a material, the system comprising: a plurality of transmitting antennas; a RF generator having a first output terminal in electrical communication with each of the plurality of transmitting antennas and a second output terminal; a plurality of receiving antennas, each of the receiving antennas having an output terminal, and a processor having a first input terminal in electrical communication with the second output terminal of the RF generator, having a second input terminal in electrical communication with the output terminal of each of the plurality of receiving antennas, and having a first output in electrical communication with a display, wherein each of the plurality of receiving antennas is positioned to receive RF signals transmitted by each of the plurality of transmitting antennas and the RF signals received by each of the plurality of RF receivers passing through the material along one of a plurality of measurement paths, and wherein the processor calculates the attenuation of the RF signal in response to the RF signals received by the plurality of receiving antennas. ### Claim 2 (depends on 1) The RF attenuation monitoring system of claim 1 wherein each of the plurality of transmitting antennas is also a receiving antenna and wherein each of the plurality of receiving antennas is also a transmitting antenna. ### Claim 3 (depends on 1) The RF attenuation monitoring system of claim 1 wherein the processor calculates a bulk RF attenuation value based on the plurality of measurement paths. ### Claim 4 (depends on 1) The RF attenuation monitoring system of claim 1, wherein the plurality of transmitters and receivers are arranged to surround the material. ### Claim 5 (depends on 1) The RF attenuation monitoring system of claim 1, where the plurality of transmitters and receivers are surrounded by an RF ground plane, providing partial bidirectional isolation between the material being monitored and the environment. ### Claim 6 (depends on 1) The RF attenuation monitoring system of claim 1, further comprising a multiplexer in electrical communication between the RF generator and each of the plurality of transmitters. ### Claim 7 (depends on 1) The RF attenuation monitoring system of claim 1, further comprising a multiplexer in electrical communication between the processor and each of the plurality of receivers. ### Claim 8 (depends on 1) The RF attenuation monitoring system of claim 1, wherein the display is in electrical communication with the processor through one of a wireless connection and a wired connection. ### Claim 9 (depends on 1) The RF attenuation monitoring system of claim 1, wherein the circuit is powered by one of near field communication with an external source, an external source connected to the circuit through a wired connection, and an internal battery source. ### Claim 10 (depends on 1) The RF attenuation monitoring system of claim 1, wherein the RF generator sweeps through a plurality of frequencies. ### Claim 11 The RF attenuation monitoring system of claim I, wherein the RF transmitting antenna is selected sequentially from the plurality of transmitting antennas. ### Claim 12 (depends on 1) The RF attenuation monitoring system of claim 1, wherein the RF receiving antenna is selected sequentially from the plurality of receiving antennas. ### Claim 13 (depends on 1) The RF attenuation monitoring system of claim 1, wherein the processor calculates hydration of a material in response to the attenuation of the RF signal received by the plurality of receiving antennas. ### Claim 14 (depends on 13) The RF attenuation monitoring system of claim 13, wherein the processor calculates changes in hydration of a material in response to the attenuation of the RF signal received by the plurality of receiving antennas. ### Claim 15 (depends on 1) The RF attenuation monitoring system of claim 1, wherein the RF attenuations for each sequentially selected pair of transmitting and receiving antennas are combined over all possible transmitting antennas. ### Claim 16 (depends on 1) The RF attenuation monitoring system of claim 1, wherein the RF attenuations at different RF frequencies, for different pairs of transmitting and receiving antennas, are combined according to a plurality of weighting values. ### Claim 17 (depends on 16) The RF attenuation monitoring system of claim 16, wherein the weighting values are determined using an ensemble of RF attenuations obtained from an ensemble of measurements. ### Claim 18 (depends on 17) The RF attenuation monitoring system of claim 17, wherein the weighted-combined RF attenuations at different RF frequencies and for different pairs of transmitting and receiving antennas are input to a function to output a number of dependent variables. ### Claim 19 (depends on 1) The RF attenuation monitoring system of claim 1, wherein the function is determined from an ensemble of RF attenuations and corresponding dependent variable values as measured by any means on an ensemble of material samples. ### Claim 20 (depends on 1) The RF attenuation monitoring system of claim 1, wherein the processor calculates hydration of a material in response to the attenuation of the RF signal received by the plurality of receiving antennas. ### Claim 21 (depends on 13) The RF attenuation monitoring system of claim 13, wherein the processor calculates changes in hydration of a material in response to the attenuation of the RF signal received by the plurality of receiving antennas.