Yiling Chen

Multiplexed Millimeter Wave Communication with Dual Orbital Angular Momentum (OAM) Mode Antennas

Communications using the orbital angular momentum (OAM) of radio waves have attracted much attention in recent years. In this paper, a novel millimeter-wave dual OAM mode antenna is cleverly designed, using which a 60 GHz wireless communication link with two separate OAM channels is experimentally demonstrated. The main body of the dual OAM antenna is a traveling-wave ring resonator using two feeding ports fed by a 90° hybrid coupler. A parabolic reflector is used to focus the beams. All the antenna components are fabricated by 3D printing technique and the electro-less copper plating surface treatment process. The performances of the antenna, such as S-parameters, near-fields, directivity, and isolation between the two OAM modes are measured. Experimental results show that this antenna can radiate two coaxially propagating OAM modes beams simultaneously. The multiplexing and de-multiplexing are easily realized in the antennas themselves. The two OAM mode channels have good isolation of more than 20 dB, thus ensuring the reliable transmission links at the same time.

The Capacity Gain of Orbital Angular Momentum Based Multiple-Input-Multiple-Output System

Wireless communication using electromagnetic wave carrying orbital angular momentum (OAM) has attracted increasing interest in recent years, and its potential to increase channel capacity has been explored widely. In this paper, we compare the technique of using uniform linear array consist of circular traveling-wave OAM antennas for multiplexing with the conventional multiple-in-multiple-out (MIMO) communication method, and numerical results show that the OAM based MIMO system can increase channel capacity while communication distance is long enough. An equivalent model is proposed to illustrate that the OAM multiplexing system is equivalent to a conventional MIMO system with a larger element spacing, which means OAM waves could decrease the spatial correlation of MIMO channel. In addition, the effects of some system parameters, such as OAM state interval and element spacing, on the capacity advantage of OAM based MIMO are also investigated. Our results reveal that OAM waves are complementary with MIMO method. OAM waves multiplexing is suitable for long-distance line-of-sight (LoS) communications or communications in open area where the multi-path effect is weak and can be used in massive MIMO systems as well.

A Flat-Lensed Spiral Phase Plate Based on Phase-Shifting Surface for Generation of Millimeter-Wave OAM Beam

A multilayer phase-shifting-surface-based flat plate is designed to offer a combination of lens and spiral phase plate (SPP) for orbital angular momentum (OAM) beam generation and convergence at 60 GHz. The proposed design consists of a series of phase-shift unit cells to control the emergent phase and form a flat lens for the purpose of beam focusing. The results of simulation and experiment verify that the OAM beam with small divergence angle can be achieved.

Orbital Angular Momentum-Based Communications With Partial Arc Sampling Receiving

A generalized signal model for multiple orbital angular momentum (OAM) mode-based radio communication combined with a novel partial arc sampling receiving (PASR) scheme for compactly receiving is proposed and mathematically analyzed. Furthermore, a near-field line-of-sight PASR radio data link using four OAM modes is experimentally demonstrated to quadruple the spectral efficiency without adding signal processing complexity at the receiving end. Experiment results show that all the four OAM channels are recovered with bit-error rates below 3.8 × 10-3, indicating the robustness of the four-OAM-mode-PASR data link.

Free-Space Radio Communication Employing OAM Multiplexing Based on Rotman Lens

The design of a radio communication system employing orbital angular momentum (OAM) mode multiplexing is described. Rotman lenses followed by circular antenna arrays are used to transmit and receive radio frequency beams carrying OAM. In our experiment, two 3 × 3 Rotman lenses are fabricated to feed the three-element circular arrays with certain phase gradients for OAM modes multiplexing and demultiplexing. The OAM-carrying beams of mode number l = +1, 0, and -1 are generated at 9.7 GHz, with each channel carrying an independent data stream of 40 Mbit s-1 quadrature phase shift keying signal in a bandwidth of 20 MHz. And all three channels are recovered with bit error rates below the forward error correction limit of 3.8 × 10 -3.

Single-frequency computational imaging using OAM-carrying electromagnetic wave

A concept for single-frequency microwave imaging using orbital angular momentum (OAM) carrying wave is introduced. The orthogonality of OAM waves, which is well suited for compressed sensing, enables the reconstruction of a sparse scene with limited measurements. A traveling wave circular slot antenna is demonstrated to generate the OAM carrying wave theoretically and experimentally. Using a set of illumination patterns radiated from the designed OAM antennas as the measurement modes, the echo signals versus OAM modes are acquired and the scene is reconstructed based on computational imaging methods. This microwave imaging scheme is verified by a proof-of-principle experiment at a single frequency without mechanical scanning or beam-forming technologies.

Realization of Beam Steering Based on Plane Spiral Orbital Angular Momentum Wave

A new form of plane spiral orbital angular momentum (PS-OAM) carrying wave with the spiral harmonics of exp(−

Experimental Demonstration of Radio Frequency Orbital Angular Momentum Multiplexed Communication System Using Microwave Photonic Demultiplexer

jl\varphi

Four-OAM-Mode Antenna With Traveling-Wave Ring-Slot Structure

) as a complete set of eigenmodes is proposed to realize beam steering. Such a wave possesses the fundamental characteristics of an OAM-carrying wave, i.e., a spiral phase distribution, yet propagates along transverse directions. Hence, it owes unique advantages for use in realizing desired radiation beams, while avoids the puzzles encountered by traditional OAM-carrying beams. Various OAM mode grouping using the superposition of PS-OAM waves are demonstrated here via theoretical calculations as well as experimental verifications. The generation methods for PS-OAM waves are also proposed and experimentally validated to authenticate the feasibility. Both the calculated and experimental results show that the PS-OAM grouping is capable of providing a practical realization of eigenmode beamforming.

Half-mode substrate integrated waveguide antenna for generating multiple orbital angular momentum modes

A two-channel RF OAM multiplexed communication system using microwave photonic demultiplexer is experimentally demonstrated. Both of the two OAM-multiplexed OFDM-QPSK signals have been successfully recovered in the experiment.