Method for synthesizing vortex electromagnetic wave carrying high orbital angular momentum (OAM) mode

A synthetic uniform circular array (SUCA) method for generating vortex electromagnetic (EM) wave, characterized in that the method is to form a radially placed uniform circular antenna array (UCA) with N elements, where N is a positive integer, and then by rotating the array elements to various spatial locations, modifying their feeding phases, and superimposing the generated fields at various spatial locations, vortex electromagnetic (EM) waves can be generated;

• the method includes the following steps:
• (1) N antenna elements are arranged on a circular ring to form an UCA;
• (2) N antenna elements are fed at the initial position to emit EM waves with the initial phase;
• (3) By rotating the array elements to various spatial locations and modifying their feeding phases, the phase-controlled EM waves are emitted;
• (4) The EM waves emitted in step (2) and step (3) are superimposed to generate vortex EM waves;
• said step (1) also includes determining the OAM mode number α′ of the synthesized vortex EM wave, and determining the elements number Ns of the virtual synthesized antenna array;
• where Ns=kN, k>0, and k is an integer;
• in said step (2), the phase of the EM wave emitted by the nth element is:
• α
• ′
• *
• 2
• ⁢
• π
• ⁡
• (
• n
• -
• 1
• )
• N
• ,
• where 1≤n≤N, and n is an integer;
• the specific operation method of step (3) is:
• rotating the antenna array around the central axis of the ring in a set direction, and feeding the N antenna elements for emitting the EM waves from the position after rotation;
• the antenna array is rotated a total of s times, and the angle of each rotation is
• 2
• ⁢
• π
• N
• s
• ;
• after the antenna array is rotated for the ith time, the phase of the EM wave emitted by the nth antenna elements is:
• α
• ′
• *
• 2
• ⁢
• π
• ⁡
• (
• n
• -
• 1
• )
• N
• +
• α
• ′
• *
• 2
• ⁢
• π
• N
• s
• *
• i
• ;
• wherein, s=k−1;
• 1≤i≤s, and the rotation direction is clockwise or counterclockwise.