Abstract
Designing planar antenna with orbital angular momentum (OAM) radiation beam is quite challenging. Adding mode configurability in the OAM antenna further increases the complexity for practical realization. This article presents a novel modified single-fed uniform circular array (UCA) antenna capable of generating three OAM modes (l = −1, +1, and 0). These modes can be controlled electronically using three p-i-n diodes in real-time. A series-fed network with eight circularly polarized (CP) patches generates −1 and +1 OAM modes depending on two possible ways of excitation (i.e., clockwise or counterclockwise). Two-element linearly polarized (LP) array placed at the center of the UCA antenna generates l = 0 OAM mode. The CP elements are rotated sequentially along a circle maintaining 45◦ between two consecutive elements to obtain the desired phase excitation. The final optimized antenna was fabricated on an FR4 substrate with the p-i-n diode switches. The experimental results show that the proposed UCA antenna successfully generates the desired OAM modes at 6 GHz. The proposed concept offers simple OAM mode reconfigurability and can be scaled to operate at other frequencies, making it advantageous for various vehicular and wireless communication applications.