Generation of Multiple Nondiffracting Beams Based on Transmission Metasurface in Microwave-Frequency Region

In this letter, a method to generate multiple nondiffracting beams by a transmission metasurface is proposed. The unit cell consists of two layers of the same circular resonant patch and a medium layer in the middle. The unit cell is rotated by different angles to obtain a 360 $^\circ$ transmission phase shift. The method of generating multiple nondiffracting beams on the metasurface is realized by a multibeam shared-aperture method. Multiple subarrays are used to launch nondiffracting beams that propagate in different directions in a shared-aperture manner. Each subarray is independent and complementary to control the deflection of multiple nondiffracting beams more flexibly. In accordance with the method, three nondiffracting beams are generated by the same transmission metasurface. The metasurface is fabricated and measured and the results validate the proposed design method.