Implementing orbital angular momentum modes using single‐fed rectangular patch antenna

Abstract

Wireless transmission based on orbital angular momentum (OAM) can improve spectrum utilization, but it requires effective OAM mode generation. Using the characteristic mode analysis, it is easy to obtain degenerate mode distributions of the symmetric rectangular patch. The coupling phase difference of 90° between two degenerate modes can be implemented by disrupting the symmetry. In that case, a single feed structure located at the common position of equal mode current amplitudes can excite two degenerate modes to synthesize OAM modes. When the fundamental degenerate modes of the rectangular patch antenna are used, only the field component along the beam direction has the characteristics of the first order OAM. To achieve higher order OAM modes, the patch structure should be further adjusted. By introducing slots in the patch edges and grounding the patch at its center, the single‐fed rectangular patch antenna can radiate the vortex wave carrying the second order OAM. Furthermore, the OAM mode performance such as mode purity can be analyzed by the modal excitation coefficients.

Two Patch Antennas for Two- or Four-OAM-Mode Generation

“…In 2007, OAM waves in EM field have been realized by simulation for the first time in [5]. Since then many approaches have been proposed to generate OAM waves, such as: reflecting surface approach [6]- [8], transmission surface approach [9]- [11], dielectric resonator [12], [13], cavity [14]- [16], single patch antenna [17], [18] and antenna array [19]- [22].…”

An orbital angular momentum vortex wave antenna with low in‐band radar cross section and reduced divergence angle

“…Quite recently, a unique electromagnetic wave carrying orbital angular momentum (OAM), which is called OAM vortex wave, has attracted a lot of interests. [1][2][3][4] Different from the plane wave or spherical wave, the OAM vortex wave owns helical wave front. The structure of the wave front is denoted by topological charge l and the phase variation in a circle around the beam axis equals to 2πl.…”

“…Besides wireless communication, the OAM vortex wave can also be applied to military use such as radar imaging. [8][9][10] At present, the generation of OAM vortex wave includes single patch antenna, 4,11 uniform circular array antenna, [12][13][14][15] metasurface antenna [16][17][18][19][20] and so on.…”

Converged OAM vortex wave generation using EBG‐loaded patch array antenna

“…13 Afterward, the microwave bands were also explored to generate OAM vortex wave. These methods include the spiral phase plate, 14 single patch antenna, 15 holographic plate, 16 circular traveling-wave antenna 17 and uniform circular array antenna, 18 and so forth. It is worth mentioning that the metamaterial technique paves a new way to generate OAM radio vortex wave.…”