This letter presents a novel water spiral dielectric resonator antenna (DRA) to generate multimode orbital angular momentum (OAM) waves. The shell of the spiral DRA filled with distilled water is designed as a cylinder with a spiral paraboloid on one side produced by a 3-D printer, and fed with two orthogonal signals at the other (bottom) side to excite higher order modes. By changing the radius, height, and notch height of the spiral DRA, l = ±1 OAM modes can be generated at 4.8 and 5.6 GHz, and l = ±3 OAM modes can be generated at 5.11, 5.66, and 6.36 GHz, respectively. The measurement results show that the 10 dB frequency bandwidth of the spiral DRA from 5.07 to 5.14 GHz and isolation excess of 20 dB can be achieved. The proposed spiral DRA with low cost, compact construction, and easy processing has the potential in a short-range OAM wireless communication.

中文翻译：

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用于产生多模 OAM 的水螺旋介质谐振天线

这封信提出了一种新颖的水螺旋介质谐振器天线 (DRA)，用于生成多模轨道角动量 (OAM) 波。充满蒸馏水的螺旋 DRA 的外壳被设计为一个圆柱体，一侧有一个螺旋抛物面，由 3D 打印机产生，并在另一侧（底部）输入两个正交信号以激发高阶模式。通过改变螺旋 DRA 的半径、高度和凹口高度，可以在 4.8 和 5.6 GHz 下产生 l = ±1 OAM 模式，在 5.11、5.66 和 6.36 GHz 下可以分别产生 l = ±3 OAM 模式. 测量结果表明，螺旋DRA从5.07到5.14 GHz的频率带宽可以达到10 dB，隔离度超过20 dB。建议的螺旋 DRA 成本低，结构紧凑，