Method and system for the sequential adaptive deterministic calibration of active phased arrays

A method of calibrating a phased array antenna having a plurality of active modules, and transmit, receive, and test manifolds, comprising the steps of:

• positioning the boresight of the array to be calibrated on a far field receiver/source of radiant energy;
• measuring a coherent steering vector of each individual module of the array in sequence both through a first path including the test manifold and a second path including the receive manifold;
• storing the measured amplitude and phase of each module for both the first and second paths;
• normalizing the stored data by dividing the steering vector of the second path by the steering vector of the first path;
• multiplying each normalized steering vector by conjugate transpose co-variance matrix to obtain corresponding weight vectors;
• determining a command amplitude and phase of each module;
• multiplying the weight vectors of each element by the commanded amplitude and phase of each module to obtain a weighted module command for each steering angle of the modules;
• adjusting the phase and amplitude of each module of the array in accordance with the weighted module command;
• injecting the weighted module command into the test manifold;
• measuring the output amplitude and phase of the injected module command;
• comparing the measured output of the test manifold with the weighted module command to obtain an error signal for each module;
• and
• combining the error signal with the weighted module command until the error signal is minimized.

An apparatus for calibrating a phased array antenna having a plurality of active modules and a test manifold, comprising:

• an RF antenna for positioning at a far field range from the antenna to be calibrated;
• a receiver having an input coupled to a far field source and the test manifold;
• a transmitter having an output coupled to the test manifold and to the modules of the antenna being calibrated for radiating RF energy to the far field range
• means for determining a command phase and amplitude for each steering angle of each module of the antenna being calibrated;
• means for comparing the phase and amplitude data from the test manifold with the phase and amplitude data of the far field range to obtain an error signal;
• and
• means for combining the error signal with the command amplitude and phase iteratively until the error signal is minimized for each module of the antenna.

An apparatus for calibrating a phased array antenna having a plurality of active modules and a test manifold, comprising

• a receiver and a source of RF energy for placing at a far field location on the boresight of the antenna to be calibrated;
• a receiver having an input connected to the far field receiver and the test manifold;
• a transmitter having an output for connection to the modules of the antenna being calibrated via a transmit manifold;
• a processor including a buffer coupled to the receiver for measuring and storing a coherent steering vector of each individual module of the array in sequence received both through a first path including the test manifold and a second path including the far field receiver,
• the processor including
• means for normalizing the stored data by dividing the steering vector of the second path by the steering vector of the first path,
• means for multiplying each normalized steering vector by a conjugate transpose co-variance matrix to obtain corresponding weight vectors,
• means for determining a command amplitude and phase for each module,
• means for multiplying the weight vectors of each module by the commanded amplitude and phase of each module to obtain a weighted module command for each steering angle of the modules;
• means for adjust the phase and amplitude of each module of the array in accordance with the weighted module command,
• means for injecting the weighted module command into the test manifold,
• means for measuring the output amplitude and phase of the injected module command;
• means for comparing the measured output of the test manifold with the weighted module command to obtain an error signal for each module;
• and
• means for combining the error signal with the weighted module command iteratively until the error signal is minimized.

An apparatus for calibrating a phased array antenna having a plurality of active modules and a test manifold, comprising

• a source of RF energy for placing at a far field location on the boresight of the antenna to be calibrated;
• a transmitter having an output for connection to the far field source for transmitting radar pulses to the antenna and connected to the test manifold,
• a receiver having an input connected to the antenna via the sum and difference manifold to receive radar pulses from the test manifold and return pulses from the far field source;
• a processor including a buffer coupled to the receiver for measuring and storing a coherent steering vector of each individual module of the array in sequence received both through a first path including the test manifold and a second path including the far field receiver,
• the processor including
• means for normalizing the stored data by dividing the steering vector of the second path by the steering vector of the first path,
• means for multiplying each normalized steering vector by a conjugate transpose co-variance matrix to obtain corresponding weight vectors,
• means for determining a command amplitude and phase for each module,
• means for multiplying the weight vectors of each module by the commanded amplitude and phase of each module to obtain a weighted module command for each steering angle of the modules;
• means for adjust the phase and amplitude of each module of the array in accordance with the weighted module command,
• means for injecting the weighted module command into the test manifold,
• means for measuring the output amplitude and phase of the injected module command;
• means for comparing the measured output of the test manifold with the weighted module command to obtain an error signal for each module;
• and
• means for combining the error signal with the weighted module command iteratively until the error signal is minimized.