# US 2019/0377084 A1 · Single-frequency dynamic metasurface microwave imaging systems and methods of use > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0377084 A1 - Document ID: US20190377084A1 - Status: Published application - Kind: A1 - Application number: 16/436,037 - Filed: 2019-06-10 - Published: 2019-12-12 - Earliest claimed: 2016-12-13 - Assignees: Duke University - Applicants: Duke University - Inventors: Timothy Sleasman; Laura Pulido Mancera; Jonah Gollub; Michael Boyarsky; Thomas Fromenteze; Seyedmohammadreza Faghih Imani; David R. Smith - Web page: https://patentgrep.com/patent/US20190377084A1 ## CPC - G01S 13/42: Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S13/46) - G01S 7/03: Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver - G01S 7/032: {Constructional details for solid-state radar subsystems} - G01S 7/352: {Receivers} - G01S 13/34: using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal - G01S 13/36: with phase comparison between the received signal and the contemporaneously transmitted signal - G01S 13/888: {through wall detection} - G01S 13/89: for mapping or imaging - H01Q 3/26: varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture ({H01Q3/12,} H01Q3/22, H01Q3/24 take precedence) - H01Q 3/2611: {Means for null steering; Adaptive interference nulling} - H01Q 21/0018: {Space- fed arrays} - G01S 7/023: {Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques (auxiliary means for detecting or identifying radar signals or the like G01S7/021; means for anti-jamming G01S7/36)} - G01S 7/356: {involving particularities of FFT processing} - G01S 13/887: {for detection of concealed objects, e.g. contraband or weapons} - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72) ## Abstract A single frequency, or very narrow frequency band, microwave imaging system is described herein. A microwave imaging system can include an array transmitter; an array receiver; and a computing device that receives signals detected from the array receiver, transforms the signals received by the array receiver into independent spatial measurements, constructs an image using the independent spatial measurements, and outputs a reconstructed image. The array transmitter and the array receiver may each have a plurality of independently controllable metasurface resonant elements. ## Claims ### Claim at position 1 1-20. (canceled) ### Claim 21 A system comprising: an array transmitter comprising a plurality of subwavelength elements that are each tunable to transmit one or more transmit radiation patterns towards a region of interest from one or more feed signals within a narrow frequency band with respect to a fractional bandwidth of the array transmitter; an array receiver configured to receive one or more receive radiation patterns from the region of interest in response to the one or more transmit radiation patterns; and a computing device configured to generate one or more images of the region of interest based on the one or more receive radiation patterns. ### Claim 22 (depends on 21) The system of claim 21, wherein frequencies in the narrow frequency band are within at most 1% of an operating frequency of the array transmitter. ### Claim 23 (depends on 21) The system of claim 21, wherein the one or more feed signals are at a single frequency within the narrow frequency band. ### Claim 24 (depends on 21) The system of claim 21, wherein the one or more transmit radiation patterns include one or more spatially diverse radiation patterns. ### Claim 25 (depends on 21) The system of claim 21, wherein the array transmitter is configured to operate within a Fresnel zone of the array transmitter. ### Claim 26 (depends on 21) The system of claim 21, wherein the array transmitter is configured to transmit the one or more transmit radiation patterns towards the region of interest to image the entire region of interest at the same time. ### Claim 27 (depends on 21) The system of claim 21, wherein the one or more images of the region of interest include both range content and cross-range content of the region of interest. ### Claim 28 (depends on 27) The system of claim 27, wherein the one or more transmit radiation patterns include a plurality of spatially distinct radiation patterns and the cross-range content of the region of interest is multiplexed using the plurality of spatially distinct radiation patterns. ### Claim 29 (depends on 21) The system of claim 21, wherein the array receiver comprises a plurality of subwavelength elements that are each tunable to receive the one or more receive radiation patterns from the region of interest for generating the one or more images of the region of interest. ### Claim 30 (depends on 21) The system of claim 21, wherein at least a portion of the plurality of subwavelength elements are integrated along a microstrip waveguide configured to feed the one or more feed signals to the at least a portion of the plurality of subwavelength elements. ### Claim 31 (depends on 21) The system of claim 21, wherein the computing device is further configured to: receive, from detection circuitry, raw data of one or more characteristics of the one or more receive radiation patterns; and reconstruct the one or more images of the region of interest based on the raw data. ### Claim 32 (depends on 31) The system of claim 31, wherein the computing device is further configured to: sample the raw data to identify one or more phases and magnitudes of one or more signals corresponding to the one or more receive radiation patterns and included as part of the raw data; and reconstruct the one or more images of the region of interest based on the one or more phases and magnitudes of the one or more signals corresponding to the one or more receive radiation patterns. ### Claim 33 (depends on 31) The system of claim 31, wherein the computing device is further configured to: pre-process the raw data to generate pre-processed raw data; and reconstruct the one or more images of the region of interest using the pre-processed raw data. ### Claim 34 (depends on 33) The system of claim 33, wherein the computing device is further configured to: independently apply pre-processing to the raw data corresponding to each subwavelength element of the plurality of subwavelength element of the array transmitter and each subwavelength element of a plurality of subwavelength elements of the array receiver to generate a plurality of independent spatial measurements for the array transmitter and the array receiver; and reconstruct the one or more images of the region of interest based on plurality of independent spatial measurements. ### Claim 35 (depends on 34) The system of claim 34, wherein the plurality of independent spatial measurements are independent across the plurality of subwavelength elements of the array transmitter and the plurality of subwavelength elements of the array receiver and each spatial measurement of the plurality of independent spatial measurements corresponds to one of the plurality of subwavelength elements of the array transmitter or the plurality of subwavelength elements of the array receiver. ### Claim 36 (depends on 31) The system of claim 31, wherein the computing device is further configured to apply a range migration technique to reconstruct the one or more images of the region of interest based on the raw data. ### Claim 37 (depends on 36) The system of claim 36, wherein the computing device is further configured to: identify decoupled spatial contributions of the array transmitter and the array receiver based on the raw data; represent the decoupled spatial contributions in a spatial frequency domain; define k-space components for the decoupled spatial contributions from representations of the decoupled spatial contributions in the spatial frequency domain; and resample the k-space components onto a uniform grid to identify reflectivity in the region of interest and reconstruct the one or more images of the region of interest based on the reflectivity in the region of interest. ### Claim 38 (depends on 37) The system of claim 37, wherein the computing device is configured to apply Stolt interpolation to resample the k-space components onto the uniform grid. ### Claim 39 (depends on 37) The system of claim 37, wherein the decoupled spatial contributions are a plurality of independent spatial measurements identified by pre-processing the raw data. ### Claim 40 (depends on 31) The system of claim 31, wherein the computing device is further configured to reconstruct the one or more images of the region of interest directly from the raw data while omitting pre-processing of the raw data to reconstruct the one or more images. ### Claim 41 (depends on 40) The system of claim 40, wherein the computing device is further configured to identify reflectivity in the region of interest for reconstructing one or more images of the region of interest by applying a sensing matrix to the raw data. ### Claim 42 A method comprising: transmitting one or more transmit radiation patterns towards a region of interest from an array transmitter comprising a plurality of subwavelength elements that are each tunable to transmit the one or more transmit radiation patterns from one or more feed signals within a narrow frequency band with respect to a fractional bandwidth of the array transmitter; receiving one or more receive radiation parameters from the region of interest at an array receiver in response to the one or more transmit radiation patterns; and generating one or more images of the region of interest based on the one or more receive radiation patterns. ### Claim 43 (depends on 42) The method of claim 42, wherein frequencies in the narrow frequency band are within at most 1% of an operating frequency of the array transmitter. ### Claim 44 (depends on 42) The method of claim 42, wherein the one or more feed signals are at a single frequency within the narrow frequency band. ### Claim 45 (depends on 42) The method of claim 42, wherein the one or more transmit radiation patterns include one or more spatially diverse radiation patterns. ### Claim 46 (depends on 42) The method of claim 42, wherein the array transmitter is configured to operate within a Fresnel zone of the array transmitter. ### Claim 47 (depends on 42) The method of claim 42, wherein the array transmitter is configured to transmit the one or more transmit radiation patterns towards the region of interest to image the entire region of interest at the same time. ### Claim 48 (depends on 42) The method of claim 42, wherein the one or more images of the region of interest include both range content and cross-range content of the region of interest. ### Claim 49 (depends on 48) The method of claim 48, wherein the one or more transmit radiation patterns include a plurality of spatially distinct radiation patterns and the cross-range content of the region of interest is multiplexed using the plurality of spatially distinct radiation patterns. ### Claim 50 (depends on 42) The method of claim 42, wherein the array receiver comprises a plurality of subwavelength elements that are each tunable to receive the one or more receive radiation patterns from the region of interest for generating the one or more images of the region of interest. ### Claim 51 (depends on 42) The method of claim 42, further comprising: receiving raw data of one or more characteristics of the one or more receive radiation patterns; and reconstructing the one or more images of the region of interest based on the raw data. ### Claim 52 (depends on 51) The method of claim 51, further comprising: sampling the raw data to identify one or more phases and magnitudes of one or more signals corresponding to the one or more receive radiation patterns and included as part of the raw data; and reconstructing the one or more images of the region of interest based on the one or more phases and magnitudes of the one or more signals corresponding to the one or more receive radiation patterns. ### Claim 53 (depends on 51) The method of claim 51, further comprising: pre-processing the raw data to generate pre-processed raw data; and reconstructing the one or more images of the region of interest using the pre-processed raw data. ### Claim 54 (depends on 53) The method of claim 53, further comprising: independently applying pre-processing to the raw data corresponding to each subwavelength element of the plurality of subwavelength element of the array transmitter and each subwavelength element of a plurality of subwavelength elements of the array receiver to generate a plurality of independent spatial measurements for the array transmitter and the array receiver; and reconstructing the one or more images of the region of interest based on plurality of independent spatial measurements. ### Claim 55 (depends on 54) The method of claim 54, wherein the plurality of independent spatial measurements are independent across the plurality of subwavelength elements of the array transmitter and the plurality of subwavelength elements of the array receiver and each spatial measurement of the plurality of independent spatial measurements corresponds to one of the plurality of subwavelength elements of the array transmitter or the plurality of subwavelength elements of the array receiver. ### Claim 56 (depends on 51) The method of claim 51, further comprising applying a range migration technique to reconstruct the one or more images of the region of interest based on the raw data. ### Claim 57 (depends on 56) The method of claim 56, further comprising: identifying decoupled spatial contributions of the array transmitter and the array receiver based on the raw data; representing the decoupled spatial contributions in a spatial frequency domain; defining k-space components for the decoupled spatial contributions from representations of the decoupled spatial contributions in the spatial frequency domain; and resampling the k-space components onto a uniform grid to identify reflectivity in the region of interest and reconstruct the one or more images of the region of interest based on the reflectivity in the region of interest. ### Claim 58 (depends on 57) The method of claim 57, further comprising applying Stolt interpolation to resample the k-space components onto the uniform grid. ### Claim 59 (depends on 57) The method of claim 57, wherein the decoupled spatial contributions are a plurality of independent spatial measurements identified by pre-processing the raw data. ### Claim 60 (depends on 31) The method of claim 31, further comprising reconstructing the one or more images of the region of interest directly from the raw data while omitting pre-processing of the raw data to reconstruct the one or more images. ### Claim 61 (depends on 60) The method of claim 60, further comprising identifying reflectivity in the region of interest for reconstructing one or more images of the region of interest by applying a sensing matrix to the raw data.