On-site calibration of array antenna systems
AssigneeSRC, Inc.
InventorHarvey K. Schuman
Life of this patent
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Abstract
The present invention is directed to an antenna system and a method that is configured to compute calibration element voltage gain patterns as functions of a digital antenna model and a plurality of complex beamformer voltages, determine calibration through path transfer functions from the plurality of complex voltages, and remove the calibration element voltage gain patterns from the calibration through path transfer functions to determine a beamforming network transfer function. The beamforming network transfer function and the far-field element voltage gain patterns are combined to obtain a system transfer function used to revise a calibration table.
Claims41
A system comprising:
- a probe antenna configured to transmit or receive a calibration signal;
- an antenna including a plurality of antenna elements arranged in an antenna configuration, the plurality of antenna elements providing a plurality of antenna excitation signals in response to the calibration signal;
- a beamforming network including a beamformer port and a plurality of channels, each channel including a signal conditioning module coupled to a corresponding antenna element of the plurality of antenna elements, the signal conditioning module having a plurality of conditioning states specifying at least one phase state, the plurality of antenna excitation signals corresponding to a plurality of complex voltages at the beamformer port;
- a control system coupled to the beamforming network, the control system being configured to select a conditioning state of the plurality of conditioning states in accordance with a calibration control rule;
- a memory configured to store a digital antenna model and far-field element voltage gain patterns corresponding to the antenna configuration, the memory storing a calibration table configured to associate each steering angle in a set of steering angles to beamformer port complex voltages;
- and
- a processor configured to compute calibration element voltage gain patterns as functions of the digital antenna model and the plurality of complex voltages, determine calibration through path transfer functions from the plurality of complex voltages, and remove the calibration element voltage gain patterns from the calibration through path transfer functions to determine a beamforming network transfer function, the processor being configured to revise the calibration table based on the beamforming network transfer function.
The system of 16, wherein the control system is configured to select the conditioning state for the plurality of channels in accordance with a selected transmit steering angle in the set of steering angles.
A method comprising:
- providing a system comprising an antenna including a plurality of antenna elements arranged in an antenna configuration, the plurality of antenna elements providing a plurality of antenna excitation signals in response to the calibration signal, the system comprising a beamforming network including a beamformer port and a plurality of channels, each channel including a signal conditioning module coupled to a corresponding antenna element of the plurality of antenna elements, the signal conditioning module having a plurality of conditioning states specifying at least one phase state, the plurality of antenna excitation signals corresponding to a plurality of complex voltages at the beamformer port, the system further including a control system coupled to the beamforming network, the control system being configured to select a conditioning state of the plurality of conditioning states in accordance with a calibration control rule, and a memory being configured to store a calibration table configured to associate each steering angle in a set of steering angles to beamformer port complex voltages;
- storing a digital antenna model and far-field element voltage gain patterns corresponding to the antenna configuration in the memory;
- propagating a calibration signal;
- computing calibration element voltage gain patterns as functions of the digital antenna model and the plurality of complex voltages;
- determining calibration through path transfer functions from the plurality of complex voltages;
- determining a beamforming network transfer function as a function of the calibration element voltage gain patterns and the calibration through path transfer functions;
- and
- revising the calibration table based on the beamforming network transfer function such that a revised calibration table is stored in memory, the revised calibration table being configured to associate each steering angle in a set of steering angles to revised beamformer port complex voltages.
Dependencies are inferred from the claim text.