A matrix-fed circular array for continuous scanning

The Butler-matrix-fed circular array will form a focussed radiation pattern when the proper current distribution is established on the inputs to the matrix. Further, this beam can be scanned through 360° by changing only the phases of the matrix input currents, just as with a linear array scanning is accomplished by varying the phases of the element currents. This operation was experimentally demonstrated with a 32-dipole circular array and reasonable agreement was obtained between the measured and calculated patterns. Finally, a synthesis procedure is described for determining the matrix input currents required to attain a prescribed current distribution on the array.