초록 ▼

Traditional airborne radar antennas are typically limited to placement above or below the aircraft, or in one or both of the wings, or in the nose. In the both-wing case, the fuselage prevents coherent array processing of both wing arrays without the introduction of grating lobes. Both wing arrays a

Traditional airborne radar antennas are typically limited to placement above or below the aircraft, or in one or both of the wings, or in the nose. In the both-wing case, the fuselage prevents coherent array processing of both wing arrays without the introduction of grating lobes. Both wing arrays are coherently combined without grating lobes through appropriate geometric configurations of the arrays and the use of MIMO processing techniques. A virtual array is formed by convolving the transmit and receive apertures to fill in the gap created by the fuselage, thereby allowing fully coherent array processing and greater angular resolution than previously achievable through a conformal array. The signal-to-noise ratios are potentially improved.

대표청구항 ▼

1. A radar system, comprising: first and second line arrays of receive antennas separated by a gap between an inside edge of the first line array and an inside edge of the second line array;first and second antenna point sources transmitting signal waveforms;wherein the first and second line arrays

1. A radar system, comprising: first and second line arrays of receive antennas separated by a gap between an inside edge of the first line array and an inside edge of the second line array;first and second antenna point sources transmitting signal waveforms;wherein the first and second line arrays of receive antennas receive radar return signals originating with said first and second antenna point sources; anda digital processor utilizing multiple-input multiple-output (MNO) techniques for cohering said first and second line arrays of receive antennas to form a virtual array that extends across said gap. 2. A radar system according to claim 1, wherein said signal waveforms transmitted by said first and second point sources are mutually orthogonal. 3. A radar system according to claim 2, wherein said first and second line arrays of receive antennas are mutually coaxial. 4. A radar system according to claim 2, in which the gap between said first and second line arrays of receive antennas is no larger than the length of one of said first and second line arrays of receive antennas. 5. A radar system according to claim 2, further comprising an aircraft including first and second wings and a fuselage separating said first and second wings, and wherein: said first and second line arrays of receive antennas lie generally along said first and second wings, respectively, with said fuselage occupying at least a portion of said gap. 6. The system of claim 1, wherein said first point source is proximate to the inside edge of the first line array and the second point source is proximate to the inside edge of the second line array. 7. The system of claim 6, wherein said first point source comprises a first transmission line array and said second point source comprises a second transmission line array. 8. The system of claim 7, wherein said first transmission line array and said second transmission line array are coaxial. 9. The system of claim 8, wherein said first line array and said second line array of receive antennas are coaxial along a first axis and wherein said first transmission line array and said second transmission line array are coaxial on a second axis that is parallel with the first axis. 10. A method for remote sensing, comprising the steps of: transmitting signal waveforms from first and second antenna point sources;receiving radar return signals originating with said point sources with first and second line arrays of receive antennas separated by a gap between an inside edge of the first line array and an inside edge of the second line array; anddigitally processing said radar return signals for cohering said first and second line arrays of receive antennas to form a virtual array that extends across said gap. 11. A method for remote sensing according to claim 10, wherein said step of transmitting waveforms from the first and second point sources includes the step of transmitting mutually orthogonal waveforms from said first and second point sources, and said step of digitally processing includes multiple-input-multiple-output (MIMO) processing. 12. The method of claim 11, wherein said step of transmitting mutually orthogonal waveforms from said first and second point sources comprises transmitting first and second mutually orthogonal signals; wherein said step of receiving radar return signals comprises receiving first and second return signals, each of said return signals including components attributable to said first and second mutually orthogonal signals; andwherein said step of digitally processing said radar return signals for cohering said arrays across said gap comprises:processing said radar return signals to separate said first and second components of said first and second mutually orthogonal radar return signals; andcoherently combining said first components of said first components of said first and second mutually orthogonal received signals with said second components of said first and second mutually orthogonal received signals to thereby define a first beam. 13. The method of claim 12, further comprising adjusting the weighting of said coherent combining to thereby shape said first beam. 14. A method for remote sensing according to claim 10, in which said step of receiving radar return signals originating with said point sources with first and second line arrays of receive antennas separated by a gap, includes the step of receiving radar return signals originating with said point sources with first and second line arrays of receive antennas separated by a gap which is no larger than the length of one of said first and second line arrays of receive antennas. 15. An airborne radar system, comprising: an airplane defining first and second spaced apart wings;a line receiving antenna array including a first portion and a second portion lying mutually coaxially along said wings, said first portion on said first wing and said second portion on said second wing, each of said first portion and said second portion of said receiving antenna array defining an inside edge, said space between the inside edge of each of the first portion and second portion defining a gap;a line transmitting antenna array including a first portion and a second portion lying along an axis parallel with the axis of the first portion and second portion of the receiving antenna array, the first portion of line transmitting array being proximate to the inside edge of the first portion of the line receiving antenna array, and the second portion of the line transmitting array being proximate to the inside edge of the second portion of the line receiving antenna array;a transmitter coupled to each of said antennas of said transmitting antenna array, for exciting said antennas of said transmitting array with mutually orthogonal signals; anda multiple-input multiple-output processor coupled to said transmitter and to said receiving antenna array, for processing received signals for forming an effective array including physical elements and also including virtual elements occupying positions along said gap. 16. A radar system, said radar system comprising: a first antenna array extending along a line, and having a first extent, at least in a horizontal plane;a second antenna array extending along said line, and having an extent, which need not be the same as said first extent;third and fourth antennas, said third antenna lying in a vertical plane passing through an inside end of said first array, and said fourth antenna lying in a vertical plane passing through an inside end of said second array, said third and fourth antennas lying at the same distance from said horizontal plane;first and second transmitters for generating mutually orthogonal RF signals, said first and second transmitters being connected to said third and fourth antennas, respectively, for transmitting both first and second mutually orthogonal electromagnetic signals from each of said third and fourth antennas;first and second receiver arrays coupled to said first and second antenna arrays and to said first and second transmitters, for processing reflected signals for generating first and second received signals from each of the elements of said first and second antenna arrays, respectively, each of said first and second received signals including first and second components of mutually orthogonal received signals attributable to said first and second mutually orthogonal electromagnetic signals;first and second processors coupled to said first and second receiver arrays, respectively, and to said first and second transmitters, for processing said first and second received signals to separate said first and second components of said mutually orthogonal received signals; and a beamforming processor coupled to said first and second processors for coherently combining said first components of said mutually orthogonal received signals with said second components of said mutually orthogonal received signals to thereby define at least a first beam. 17. A radar system according to claim 16, further comprising an airplane including left and right wings and a fuselage separating said left and right wings, and wherein: said first antenna array lies along said left wing and defines an inside edge and said second antenna array lies along said right wing and defines an inside edge, said inside edges of said first and second antenna arrays being separated by a gap at the location of said fuselage; andsaid vertical plane in which said third antenna lies passes through the inside end of said first array, and said vertical plane in which said fourth antenna lies passes through the inside end of said second array. 18. A radar system, said radar system comprising: a first antenna array extending along a line, and having a length, at least in a horizontal plane;a second antenna array extending along said line, and having said length, said second array being separated from said first array by a distance no greater than said length, thereby defining an inside end and an outside end of each of said first and second arrays; third and fourth antennas, said third antenna lying in a vertical plane passing through said inside end of said first array, and said fourth antenna lying in a vertical plane passing through said inside end of said second array, said third and fourth antennas lying at the same distance from said horizontal plane;first and second transmitters for generating mutually orthogonal RF signals, said first and second transmitters being connected to said third and fourth antennas, respectively, for transmitting first and second mutually orthogonal electromagnetic signals from said third and fourth antennas, respectively;first and second receiver arrays coupled to said first and second antenna arrays, for processing reflected signals for generating first and second received signals from each of said first and second antenna arrays, respectively, each of said first and second received signals including first and second components of mutually orthogonal received signals attributable to said first and second mutually orthogonal electromagnetic signals;first and second processor arrays coupled to said first and second receiver arrays, respectively, for processing said first and second received signals to separate said first and second components of said mutually orthogonal received signals;a second processor coupled to said first and second processor arrays for coherently combining said first components of said mutually orthogonal received signals with said second components of said mutually orthogonal received signals to thereby define a first beam. 19. A radar system according to claim 18, further comprising a radar control processor coupled to said second processor for adjusting the weighting of said coherent combining to thereby shape said first beam. 20. A radar system according to claim 19, wherein said second antenna array is separated from said first antenna array by a distance equal to said length, thereby defining the inside end and the outside end of each of said first and second antenna arrays.