Twisted Beams = Phase Modes = Old Stuff (Score 2, Insightful)

The concept of phase modes has been known for quite a while.
In the mid-thirties, Henri Chireix published [1] and patented [2] the application of phase
modes in antenna arrays. Since then, the concept has been widely used in
connection with circular arrays (e.g. [3]), multi-arm spiral antennas (e.g. [4]), radio
navigation systems (e.g. [5]), etc. The literature within the area is substantial, with
many papers published in various journals and conference proceedings.

Prior art search is an extinct art, indeed...

[1] H. Chireix, L'Onde Électrique, Vol. 15, pp. 440-456, 1936.
[2] H. Chireix, US Patent No. 2109835, Priority date 7 Jan. 1935, Granted 1 March 1938.
[3] H.L. Knudsen, IRE Trans. Antennas Propagat., Vol. AP-4, No.3, pp. 452-472, July 1956.
[4] J.E. Webb, US Patent No. 3344425, Priority date 13 June 1966, Granted 26 Sept. 1967.
[5] G. Höfgen, US Patent No. 4197542, Priority date 6 April 1977, Granted 8 April 1980.
[6] J.R.F. Guy and D.E.N. Davies, IEE Proc., Vol. 130, Pt. H, No.6, pp. 410-414, Oct. 1983.