Electromagnetic Vortices

9 Chapter 9Figure 9.1 The schematic of OAM waves: (a) Plane spiral OAM (PS–OAM) wave; (...Figure 9.2 Distributions of PS–OAM wave ( l = 9): (a) radiation pattern; (b) ...Figure 9.3 Schematic of structured radio beam constructed by PS–OAM modes.Figure 9.4 Normalized beam pattern for 4 PS–OAM modes of l = {1, 2} (solid l...Figure 9.5 Structured radio beams with 8 PS–OAM modes. (a) Normalized beam p...Figure 9.6 The section view of the ring dielectric resonator antenna (DRA)....Figure 9.7 Electric far‐field radiation patterns of the ring DRA. (a) The si...Figure 9.8 (a) An antenna prototype for generation of PS–OAM waves of l = ±...Figure 9.9 Far‐field radiation of ring horn loaded traveling wave circular s...Figure 9.10 The cross‐section of the antenna.Figure 9.11 Simulated patterns at E ‐plane with or without RPR.Figure 9.12 Gain and phase distributions of the PS–OAM modes at the H ‐plane ...Figure 9.13 Normalized theoretical (solid line) and measured (dash line) pat...Figure 9.14 Structure of the proposed antenna: (a) multi‐mode SIW antenna; (...Figure 9.15 OAM spectra of the different modes.Figure 9.16 Beam scanning schematic provided by the manipulation of eight PS...Figure 9.17 Configuration of the partial slotted curved waveguide leaky‐wave...Figure 9.18 The directivities and phase distributions within the mainlobe fo...Figure 9.19 The OAM spectrum analysis of the simulated results (bar graph) a...Figure 9.20 Beam steering of structured radio beam for radar detection.Figure 9.21 Spatial spectrum of the imaging system under different topologic...Figure 9.22 System configuration of the MIMO system. d mn: the propagation di...Figure 9.23 Capacity gain over SISO system for existing MIMO system, PS–OAM–...Figure 9.24 The BER curves and the receiving constellations with EVM.Figure 9.25 The architecture of the SFDM system based on OAM mode group.Figure 9.26 SER vs SNR with different number of receivers N , given the numbe...

10 Chapter 10Figure 10.1 OAM multiplexing system using coaxial UCAs and DFT/IDFT beamform...Figure 10.2 Coaxial UCA configuration; (a) Tx UCA; (b) Rx UCA; (c) Tx/Rx UCA...Figure 10.3 Various types of coaxial UCA configurations: (a) single‐polarize...Figure 10.4 Examples of circular‐polarized MSAs: (a) LHCP; (b) RHCP.Figure 10.5 Achievable rates of different configurations versus (a) transmis...Figure 10.6 Antenna rotation: (a) m th Tx antenna; (b) n th Rx antenna.Figure 10.7 Optimal radius versus transmission distance for (a) N = 2, (b) N Figure 10.8 Schematic of a 180° hybrid coupler: (a) symbol; (b) circuit conf...Figure 10.9 Third‐order Butler matrix: (a) circuit configuration; (b) phase ...Figure 10.10 Fourth-order Butler matrix: (a) circuit configuration; (b) phas...Figure 10.11 Reflection and coupling of the fourth-order Butler matrix: (a) ...Figure 10.12 Transmission amplitude of the fourth-order Butler matrix: (a) I...Figure 10.13 Transmission phase of the fourth-order Butler matrix: (a) In 1;...Figure 10.14 Achievable rate characteristics versus (a) misalignment, Δ x ; (b...

11 Chapter 11Figure 11.1 Illustration of path loss, shadowing, and multipath versus propa...Figure 11.2 MIMO system.Figure 11.3 Architecture of the PASR‐based OAM multiplexing system. RA: rece...Figure 11.4 The measured (a) inter‐channel interference; (b) constellations;...Figure 11.5 Architecture of (a) the CAL‐based OAM multiplexing system and (b...Figure 11.6 A 4 × 4 PSOAM‐based MIMO system [7].Figure 11.7 Eigenvalues of H of the PSOAM‐based and conventional MIMO system...Figure 11.8 Equivalent MIMO systems of the PSOAM‐based MIMO systems with Δ L ...Figure 11.9 Simulated and measured BER of the PSOAM‐based and conventional M...Figure 11.10 Architecture of the system combining the OAM multiplexing with ...Figure 11.11 Measurement setup of the multiplexing system where each transmi...Figure 11.12 Measured BERs as functions of SNR of different cases: (a) BERs ...Figure 11.13 Constellations of received 1 Gbaud 16‐QAM signals for channel l ...Figure 11.14 (a) Draft and (b) practical measurement setups to the analysis ...Figure 11.15 Intensity, phase, and OAM spectrum of the LoS OAM wave, the ref...Figure 11.16 Normalized received power of the signal for different l 1(i.e. Figure 11.17 Simulation results of the intra‐channel interference for OAM wa...Figure 11.18 Measured BER and SNR as functions of the reflector distance for...Figure 11.19 Received power from different OAM channels (i.e. l 2= ±1, ±3) a...Figure 11.20 Measured BER as functions of the reflector distance for (a) l 2...Figure 11.21 Measured BERs as functions of SNR at different reflector distan...Figure 11.22 Measurement setup to investigate the frequency‐selective OAM ch...Figure 11.23 Impulse response of OAM channels when l = 0, +1, and +3 [28]....Figure 11.24 EVM and BER of the QPSK signal as a function of baud rate when Figure 11.25 Spectra of the OAM channels l = 0, +1, and +3 when 2 Gbaud QPSK...Figure 11.26 Measured (a) EVM and (b) BER of three scenarios (i.e. a single ...Figure 11.27 Measured (a) EVM and (b) BER of three scenarios (i.e. a single ...Figure 11.28 Measurement configurations in a lecture room [30].Figure 11.29 Measurement configurations in a corridor [30].Figure 11.30 An illustration of the reverberation chamber.Figure 11.31 Measurement setup of the OAM‐based 2 × 2 MIMO system in the RC ...Figure 11.32 Ergodic capacities of the 2 × 2 OAM‐based and nonOAM MIMO syste...Figure 11.33 Uncoded BER performances of the 2 × 2 OAM‐based and nonOAM MIMO...Figure 11.34 Correlation magnitudes between the transmitted signals of the 2...

12 Chapter 12Figure 12.1 Concept of a building‐to‐building communications employing OAM m...Figure 12.2 Conceptual schematic of a communication system employing OAM mul...Figure 12.3 Potential challenges for an OAM multiplexing FSO communication l...Figure 12.4 (a) Simulation model of the free‐space OAM multiplexing communic...Figure 12.5 Simulation results. (a) Simulated spot size (diameter) of differ...Figure 12.6 (a) Two different cases of alignment between the transmitter and...Figure 12.7 (a, b) Simulated power distribution among different OAM modes as...Figure 12.8 (a) A rotating phase plate is used as an atmospheric turbulence ...Figure 12.9 Concept of obstruction in an OAM communication link.Figure 12.10 Concept of (a) generation of an information‐carrying OAM beam w...Figure 12.11 Experimental results of 16‐QAM signals over pol‐muxed OAM beams...Figure 12.12 (a1–a3) Three steps to produce 24 multiplexed OAM beams using t...Figure 12.13 (a) The intensity profiles and phase fronts of LG beams with di...Figure 12.14 Experimental setup of a 120‐m OAM‐multiplexed link on a buildin...Figure 12.15 (a) Sketch of the experimental setup; (b–e) examples of superpo...Figure 12.16 Different crosstalk mitigation approaches in an OAM‐multiplexed...Figure 12.17 Concept of using the AO to mitigate turbulence‐induced crosstal...Figure 12.18 Concept of AO turbulence mitigation using a Gaussian beam as a ...Figure 12.19 Far‐field intensity images of the Gaussian probe beam and OAM b...Figure 12.20 The performance of AO mitigation in an OAM‐multiplexed FSO comm...Figure 12.21 Concept of OAM‐based quantum data encoding. Within each symbol ...Figure 12.22 The performance of AO mitigation in OAM‐based quantum link (Upp...Figure 12.23 The performance of AO mitigation in an OAM‐encoded, bidirection...Figure 12.24 Concept of the phase correction for a distorted OAM beam using ...Figure 12.25 (a) Far‐field intensity profiles for various OAM beams (OAM ℓ ...Figure 12.26 Concept of the LG mode decomposition and the complex OAM spectr...Figure 12.27 (a) The concept of the turbulence compensation utilizing invers...Figure 12.28 (a1–a2) The normalized transmission intensity matrices and (b) ...Figure 12.29 (a) Concept diagram of transmitting each data channel on a comb...Figure 12.30 Displacement‐induced channel crosstalk under various horizontal...Figure 12.31 The concept of using MIMO DSP equalization for crosstalk mitiga...Figure 12.32 Recovered constellations of 20 Gbit/s QPSK signal in each of th...Figure 12.33 The concept of receiving signal and pilot tone using a free spa...Figure 12.34 Concept of mixing OAM pilot tones and signal beams to achieve t...Figure 12.35 EVM performance for two multiplexed OAM channels under differen...Figure 12.36 Challenges of different scenarios in OAM‐multiplexed FSO airbor...Figure 12.37 (a) Scheme of displacement tracking using Gaussian/OAM beam‐bas...Figure 12.38 Concept of a free-space optical communication link between an u...Figure 12.39 (a) Schematic diagram of different locations where the UAV hove...Figure 12.40 Concept of an OAM‐multiplexed FSO link between a ground transmi...Figure 12.41 (a) Recovered QPSK constellations at transmitted power of 10 dB...Figure 12.42 Challenges of different scenarios in underwater FSO communicati...Figure 12.43 (a) Intensity profiles of OAM beams under various channel condi...Figure 12.44 Experimental setup of a 40‐Gbit/s OAM multiplexed underwater li...Figure 12.45 (a) Concept of on–off‐keying (OOK) modulation. Eye diagram for...Figure 12.46 Measured BER curves of OAM channel ℓ = +1 and ℓ = +...