Method and apparatus for phased antenna array calibration
First Claim
1. A method for calibrating an antenna array comprising a plurality of antennas in a two-dimensional arrangement, each of the antennas operatively coupled to a respective controllable phase shifter, the method comprising:
- exciting the antennas according to a sequence of excitation patterns, each of the excitation patterns defining a plurality of phases to be applied by the phase shifters during concurrent excitation of the antennas, wherein the plurality of phases correspond to phase values of a basis function of a two-dimensional discrete Fourier transform, and wherein each of the excitation patterns is associated with a different basis function of the two-dimensional discrete Fourier transform;
monitoring output of a calibration antenna to provide a sequence of measurements, each measurement of the sequence of measurements indicative of response of the calibration antenna due to a superposition of radiated fields of the antennas excited according to a corresponding one of the excitation patterns;
obtaining indications of radiated fields of the antennas based on the sequence of measurements, the indications corresponding to values of an inverse two-dimensional discrete Fourier transform applied to the measurements; and
calibrating the antenna array based on the indications of radiated fields of the antennas.
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Abstract
A method and apparatus for calibrating a phased antenna array. The antennas are excited using several excitation patterns, each changing the state of the antennas by a specific amplitude and phase. The phases correspond to phase values of a basis function of a two-dimensional discrete Fourier transform, and each excitation pattern corresponds to a different basis function. Using a calibration antenna, e.g. at a fixed point inside the system, the phase and amplitude of the radiated field due to each excitation patterns is measured sequentially. From this data, the phase and amplitude of the radiated field for each element at the location of the calibration antenna is obtained and used to adjust the phase shifters and amplifiers. For calibrated systems, the spectral domain representation of radiated fields can be sparse. Taking advantage of this property and a spectrally compressed sensing technique, recalibration can involve fewer measurements to mitigate service interruptions.
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Citations
21 Claims
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1. A method for calibrating an antenna array comprising a plurality of antennas in a two-dimensional arrangement, each of the antennas operatively coupled to a respective controllable phase shifter, the method comprising:
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exciting the antennas according to a sequence of excitation patterns, each of the excitation patterns defining a plurality of phases to be applied by the phase shifters during concurrent excitation of the antennas, wherein the plurality of phases correspond to phase values of a basis function of a two-dimensional discrete Fourier transform, and wherein each of the excitation patterns is associated with a different basis function of the two-dimensional discrete Fourier transform; monitoring output of a calibration antenna to provide a sequence of measurements, each measurement of the sequence of measurements indicative of response of the calibration antenna due to a superposition of radiated fields of the antennas excited according to a corresponding one of the excitation patterns; obtaining indications of radiated fields of the antennas based on the sequence of measurements, the indications corresponding to values of an inverse two-dimensional discrete Fourier transform applied to the measurements; and calibrating the antenna array based on the indications of radiated fields of the antennas. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A calibration apparatus for an antenna array having a plurality of antennas in a two-dimensional arrangement, each of the antennas operatively coupled to a respective controllable phase shifter, the calibration apparatus comprising:
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a calibration antenna configured to generate an electrical signal in response to radiated fields generated by the antennas; a calibration controller configured to; cause excitation of the antennas according to a sequence of excitation patterns, each of the excitation patterns defining a plurality of phases to be applied by the phase shifters during concurrent excitation of the antennas, wherein the plurality of phases correspond to phase values of a basis function of a two-dimensional discrete Fourier transform, and wherein each of the excitation patterns is associated with a different basis function of the two-dimensional discrete Fourier transform; monitor output of the calibration antenna to provide a sequence of measurements, each measurement of the sequence of measurements indicative of response of the calibration antenna due to a superposition of the radiated fields of the antennas excited according to a corresponding one of the excitation patterns; obtain indications of radiated fields of the antennas based on the sequence of measurements, the indications corresponding to values of an inverse two-dimensional discrete Fourier transform applied to the measurements; and calibrate the antenna array based on the indications of radiated fields of the antennas. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification