# US 2021/0333359 A1 · Interferometrics for mesa radar > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0333359 A1 - Document ID: US20210333359A1 - Status: Published application - Kind: A1 - Application number: 16/860,492 - Filed: 2020-04-28 - Published: 2021-10-28 - Earliest claimed: 2020-04-28 - Assignees: BAE Systems Information and Electronic Systems Integration Inc. - Applicants: BAE Systems Information and Electronic Systems Integration Inc. - Inventors: Will R. Grigsby; Joseph S. McGaughey; Eric A. Rundquist - Web page: https://patentgrep.com/patent/US20210333359A1 ## CPC - G01S 7/414: {Discriminating targets with respect to background clutter} - 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) - G01S 13/4454: {phase comparisons monopulse, i.e. comparing the echo signals received by an interferometric antenna arrangement} - G01S 13/4463: {using phased arrays} - G01S 13/58: Velocity or trajectory determination systems; Sense-of-movement determination systems - G01S 13/878: {Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector (G01S13/874 takes precedence)} - G01S 13/885: {for ground probing (prospecting or detecting using electromagnetic waves G01V3/12)} - H01Q 15/0086: {said selective devices having materials with a synthesized negative refractive index, e.g. metamaterials or left-handed materials} - H01Q 15/10: comprising three-dimensional [3D] array of impedance discontinuities, e.g. holes in conductive surfaces or conductive discs forming artificial dielectric - H01Q 21/065: {Patch antenna array} - G01S 7/025: {involving the transmission of linearly polarised waves} - 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 The present disclosure is a system comprising at least three electronically steered antennas arranged so that there is a baseline difference of a predetermined amount of wavelength between the centers of the antennas, typically configured as an obtuse or scalene triangle, where the distance between each antenna on an array is selected to provide the required accuracy and precision, the array having a timing circuit to ensure that the beam of each antenna is steered to the same azimuthal and elevation coordinates in space simultaneously. This enables the three electronically steered antennas to operate as an interferometer to determine a bearing to a target to ultimately determine the location thereof. The electronically steered antennas enable the system to be mounted on a platform in a small package that was previously difficult for traditional interferometers. ## Claims ### Claim 1 An electronically steered antenna system comprising: a plurality of Metamaterial Electronically Scanning Array (MESA) receivers that are arranged in an array; the plurality of MESA receivers operable to receive a plurality of reflected electromagnetic frequency signals; interferometer logic coupled to the plurality of MESA receivers and operable to: receive the reflected electromagnetic frequency signals from the plurality of antenna elements as they are moved with respect to a target location; determine a number and location of ambiguities received in the reflected electromagnetic frequency signals; and determine which of the ambiguities represents a real object at the target location. ### Claim 2 (depends on 1) The electronically steered antenna system of claim 1, further comprising: one of a two-dimensional configuration and a three-dimensional configuration of the MESA receivers arranged in the array. ### Claim 3 (depends on 2) The electronically steered antenna system of claim 2, further comprising: at least three antenna MESA receivers in the array that are each coupled with the interferometer logic. ### Claim 4 (depends on 3) The electronically steered antenna system of claim 3, further comprising: a fixed orientation of each MESA receiver relative to the other MESA receiver in the array. ### Claim 5 (depends on 4) The electronically steered antenna system of claim 4, further comprising: a linear configuration of the three MESA receivers. ### Claim 6 (depends on 4) The electronically steered antenna system of claim 4, further comprising: a modified linear configuration of the three MESA receivers. ### Claim 7 (depends on 4) The electronically steered antenna system of claim 4, further comprising: an obtuse triangular configuration of the three MESA receivers. ### Claim 8 (depends on 4) The electronically steered antenna system of claim 4, further comprising: a scalene triangular configuration of the three MESA receivers. ### Claim 9 (depends on 4) The electronically steered antenna system of claim 4, further comprising: a right triangular configuration of the three MESA receivers. ### Claim 10 (depends on 1) The electronically steered antenna system of claim 1, further comprising: wherein the plurality of MESA receivers are operable to receive electromagnetic frequency signal through a range of frequencies that are stepped or continuous. ### Claim 11 (depends on 10) The electronically steered antenna system of claim 10, wherein the range of frequencies extends from 5 Mega-Hertz to 130 Gigahertz. ### Claim 12 (depends on 10) The electronically steered antenna system of claim 10, wherein the plurality of MESA receivers are operable to repeatedly step the transmitted electromagnetic-frequency signals through the range of frequencies. ### Claim 13 (depends on 1) The electronically steered antenna system of claim 1, wherein the plurality of MESA receivers are configured on a moveable platform. ### Claim 14 (depends on 13) The electronically steered antenna system of claim 13, wherein the moveable platform is a land-based vehicle. ### Claim 15 (depends on 1) The electronically steered antenna system of claim 1, wherein the plurality of MESA receivers are operable to receive at least a portion of the reflected electromagnetic-frequency signals with a vertical spacing of one MESA receiver that differs from another MESA receiver. ### Claim 16 (depends on 1) The electronically steered antenna system of claim 1, further comprising: a target acquisition rate; wherein the antenna array is arranged so that the antenna array detects some number of ambiguities to be investigated; and wherein two antenna MESA receivers have respective centers that are positioned along a common axis and a MESA receiver having a center that is placed between and offset from the common axis. ### Claim 17 A method comprising: detecting, via a plurality of Metamaterial Electronically Scanning Array (MESA) receivers in an electronically steered antenna system, a signal representing the presence of an object at a target location; scanning an area around the target location; receiving data representing ambiguities and the object after scanning the area; comparing the received data; mapping the ambiguities; electronically steering the antenna system to scan an area around at least one ambiguity having been mapped; determining whether the ambiguity represents the object at the target location or is an ambiguity that is a result of phase wrapping ambiguity in the received data; determining that if there is not a valid target detection, then electronically steering the antenna system to the next ambiguity or potential target and repeat the determination for the next point; and determining that if there is a valid target detection, then starting one or more tracks and transmitting that data to a user or other computer system. ### Claim 18 (depends on 17) The method of claim 17, further comprising: acquiring and tracking the target with the electronically steered antenna system having a plurality of MESA receivers; estimating a range to the target; and estimating a range-rate of the target; compiling a database of the geographical area immediately surrounding the target; switching the antenna system from a monitoring mode into an interferometer mode after the signal crosses a signal-to-noise ratio (SNR) threshold; determining a number and location of ambiguities received in reflected electromagnetic frequency signals; determining which of the ambiguities represents the object at the target location; and acquiring angular information for the object at the target location using the electronically steered antenna system in the interferometer mode. ### Claim 19 (depends on 18) The method of claim 18, further comprising dynamically reconfiguring the electronically steered antenna system between the monitoring mode and the interferometer mode to update the range, range-rate, and the angular information.