# US 8,786,489 B2 · Active target with height diversity > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,786,489 B2 - Document ID: US8786489B2 - Status: Granted - Kind: B2 - Application number: 13/070,109 - Filed: 2011-03-23 - Published: 2011-09-29 - Granted: 2014-07-22 - Earliest claimed: 2010-03-25 - Assignees: Guidance IP, Ltd. - Applicants: David E. Patrick - Inventors: David E. Patrick - Web page: https://patentgrep.com/patent/US8786489B2 ## CPC - G01S 3/14: Systems for determining direction or deviation from predetermined direction {(aerial arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00; combinations of different interacting aerial units for giving a desired directional characteristic H01Q21/29; aerials or aerial systems providing at least two radiation patterns H01Q25/00)} - G01S 5/0247: {Determining attitude} - G01S 7/025: {involving the transmission of linearly polarised waves} - G01S 13/825: {with exchange of information between interrogator and responder} - G01S 13/937: of marine craft - 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 ## Abstract An active radar target includes several receive antennas and several transmit antennas that are arrangeable into pairs of antennas. Each pair includes a transmit and a receive antenna. At least one antenna in a pair is at a different height relative to at least one other antenna in a different pair of antennas. ## Claims ### Claim 1 An active radar target comprising a plurality of antennas comprising a plurality of receive antennas and a plurality of transmit antennas arrangeable into pairs of transmit and receive antennas, each pair comprising a transmit antenna and a receive antenna the active radar target further comprising a first amplifier and a first modulator arranged to amplify and modulate an incoming signal prior to retransmitting it, wherein at least one antenna in one of the pairs of transmit and receive antennas is vertically displaced with respect to at least one antenna in a different one of the pairs of transmit and receive antennas and wherein the pairings are alterable in an automated manner. ### Claim 2 (depends on 1) An active radar target as claimed in claim 1, in which multiplexers responsive to a controller change the antenna pairings. ### Claim 3 (depends on 1) An active radar target as claimed in claim 1, where at least three antennas in the plurality of antennas are vertically displaced with respect to one another. ### Claim 4 (depends on 1) An active radar target as claimed in claim 1, where all of the antennas in the plurality of antennas are vertically displaced with respect to one another. ### Claim 5 (depends on 1) An active radar target as claimed in claim 1, in which the first amplifier and the first modulator are provided in a first channel, and a second amplifier and a second modulator are provided in a second channel, and the first channel processes a signal for a first receive antenna and transmit antenna pair, and the second channel processes a signal for a second receive antenna and transmit antenna pair. ### Claim 6 (depends on 1) An active radar target as claimed in claim 1, in which the first modulator is configured to frequency shift an output signal away from the input signal. ### Claim 7 (depends on 6) An active radar target as claimed in claim 6, in which the first modulator is configured to frequency or phase shift encode data onto the signal or some of the signals transmitted by each transmit antenna. ### Claim 8 (depends on 7) An active radar target as claimed in claim 7, in which the data includes one or more of: (i) an identity code, (ii) data provided by external equipment, and (iii) an estimate of relative direction of the incoming radar signal. ### Claim 9 (depends on 1) An active radar target as claimed in claim 1, in which the target has a detector for detecting when the target is illuminated by a radar signal above a predetermined intensity, and the target is adapted to energise the first amplifier and the first modulator in response to being illuminated by the radar signal above the predetermined intensity. ### Claim 10 (depends on 1) An active radar target as claimed in claim 1, further including a direction detector for detecting a direction of an illuminating radar signal with respect to the active target. ### Claim 11 (depends on 10) An active radar target as claimed in claim 10, in which the direction detector comprises first and second antennas and a phase detector for detecting the relative phases of signals arriving at the first and second antennas. ### Claim 12 (depends on 1) An active radar target as claimed in claim 1, in which the receive and transmit antennas are configured to receive and transmit, respectively, orthogonally polarised radar signals. ### Claim 13 (depends on 1) A radar system in combination with an active radar target as claimed in claim 1. ### Claim 14 (depends on 13) A radar system as claimed in claim 13, wherein the radar system further includes at least one of: (i) two or more receive antennas from the plurality of receive antennas, the two or more receive antennas being vertically displaced with respect to one another, and (ii) two or more transmit antennas from the plurality of transmit antennas, the two or more transmit antennas being vertically displaced with respect to one another.