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 45between 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.

This paper presents the generation of orbital angular momentum (OAM) vortex waves with mode +1 using dielectric resonator antenna (DRA) array. The proposed antenna was designed and fabricated using FR-4 substrate to generate OAM mode +1 at 3.56 GHz (5G new radio band). The proposed antenna consists of 2 × 2 rectangular DRA array, a feeding network, and four cross slots etched on the ground plane. The proposed antenna succeeded in generating OAM waves; this was confirmed by the measured radiation pattern (2D polar form), simulated phase distribution, and intensity distribution. Moreover, mode purity analysis was carried out to verify the generation of OAM mode +1, and the purity obtained was 53.87%. The antenna operates from 3.2 to 3.66 GHz with a maximum gain of 7.3 dBi. Compared with previous designs, this proposed antenna is low-profile and easy to fabricate. In addition, the proposed antenna has a compact structure, wide bandwidth, high gain, and low losses, thus meeting the requirements of 5G NR applications.

Reconfigurable Intelligent Surfaces (RIS) have recently attracted significant attention as a means to control the propagation environment, enabling improved signal coverage, interference management, and more efficient spectrum utilization. This work presents a 1-bit RIS operating at 5.8 GHz, designed for wide-angle beam steering and real-time software-defined radio (SDR) validation. While many earlier 1-bit RIS designs demonstrated steering angles up to about 45°, the proposed design extends the range to 60°, with a realized gain of 22.60 dBi at 10° and 14.62 dBi at 60°. The unit cell, fabricated on a RO4350B substrate, features a tailored RF choke structure that suppresses mutual coupling and limits RF leakage, thereby improving phase stability, a key aspect rarely emphasized in prior RIS studies. Experimental validation using an SDR-based testbed confirms significant signal quality improvements, including a 57.4% reduction in error vector magnitude (EVM), from 57.30% to 24.39%, and a 7.42 dB increase in signal-to-noise ratio (SNR), resulting in better QPSK video transmission. Additionally, orbital angular momentum (OAM) beamforming capabilities were explored via full-wave simulations, demonstrating feasible generation of modes 1, 2, and 3 for potential multiplexing. This RIS offers a scalable, energy-conscious, and cost-effective solution by integrating low-cost PIN diodes (SMP1320-079LF) and an efficient biasing network. The presented RIS architecture aligns with emerging 5G/6G network requirements and can support applications including adaptive indoor coverage, UAV-assisted links, and holographic MIMO.