Methods and apparatus for determining parameters of an array
Methods and apparatus for determining parameters for an array are described. An exemplary embodiment of a method determines a set of parameters for an antenna array including multiple array elements, the array being fed by a feed array including a plurality of feed elements. The embodiment of the method includes measuring a plurality of bistatic ranges Rijk through different signal path combinations, each signal path combination from a feed element “i,” to an array element “j,” and to a feed element “k”. The measuring includes radiating energy from feed element “i”, and reflecting some of the radiated energy from array element “j” back to feed element k of the feed array. The measured bistatic ranges are processed to solve for the set of parameters. Another embodiment of a method is for measurement of multiple array elements of an array, and includes radiating energy from one or more array elements, reflecting some of the radiated energy from a set of reflector elements back to the array elements each reflector element having a variable phase shifter associated therewith, cycling each reflector element phase shifter through a range of phase shifter settings at a unique rate, processing the received signals to extract a phase of the reflected energy as received at each element; and using the extracted phase for each element to determine a relative location of each array element.
1. An antenna array, comprising:
a first array of radiator elements;
an excitation source connected to at least a first set of the first array radiator elements;
a receiver connected to at least a second set of the first array radiator elements;
a second array of radiator elements spaced from the first array of radiator elements, the second array comprising a variable phase shifter connected to each of said radiator elements and a switch arranged to connect the phase shifter to either a reflective termination or a load device, so that in a first mode, the phase shifter is connected to the reflective termination and in a second mode the phase shifter is connected to the load device;
an array controller configured in a measurement mode to set the phase shifters to the first mode, control the excitation source to radiate energy from said at least a first set of the first array radiator elements so that some of the radiated energy is reflected from said second array of radiator elements back to at least said second set of first array radiator elements, and to process signals from said receiver as a result of said excitation to measure bistatic ranges R ijk through a signal path from a first array radiator “i,” to second array radiator “j,” and to first array radiator “k”.
2. The array of claim 1 , wherein said array controller is operable in an operating mode to set the phase shifters to the second mode.
3. The array of claim 1 , wherein the first array is a feed array, and the second array is part of a lens array in which the load device is a radiating element.
4. The array of claim 1 , wherein the first array is a feed array, the second array is a set of retro reflectors arranged on a reflector surface of the array in a distributed configuration, and the load device is an absorptive load.
5. The array of claim 1 , wherein the array is an electronically scanned antenna (ESA), the first array is an ESA radiator set, the second array is a measurement array used in a measurement mode, and the load device is an absorptive load.