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Antenna Beam Steering and Beam Forming at Mm-Wave and Thz Frequencies

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Antenna Beam Steering and Beam Forming at Mm-Wave and Thz Frequencies Antenna beam steering and beam forming at mm-Wave and THz frequencies Master Thesis submitted to the Faculty of the Escola T`ecnicad'Enginyeria de Telecomunicaci´ode Barcelona Universitat Polit`ecnicade Catalunya by Sara Vega Pi~na In partial fulfillment of the requirements for the master in TELECOMMUNICATIONS ENGINEERING Advisor: Mar´ıaConcepci´onSantos Co-Advisor: Daniel Nu~no Barcelona, January 20th, 2021 Contents List of Figures4 List of Tables6 1 Introduction8 2 Photonic Antenna Control 10 2.1 Phased Array Antennas Beam forming...................... 10 2.2 Photoconductive Antennas for THz Radiation.................. 11 3 Optical TTD Network 14 3.1 Multiwavelength Beam Steering Network.................... 14 3.1.1 Effect of compensating delays...................... 15 3.1.2 Geometrical Delays............................ 16 3.1.3 Dispersive Delays............................ 18 3.1.4 Maximum beam steered angle...................... 19 3.2 CD-fading control................................. 20 3.3 OTTDN Simulations............................... 23 4 TeraHertz Systems 26 4.1 Definition of THz systems simulation methodology............... 26 4.1.1 Time-Domain simulation of PCAs (Primary fields)........... 26 4.1.2 Time-Domain simulation of Lens-coupled PCAs (Secondary fields).. 32 4.2 Validation of THz Simulation Methodology................... 35 4.2.1 PCAs modeling.............................. 35 4.2.2 Lens approach.............................. 36 4.2.3 Primary fields............................... 38 4.2.4 Secondary fields............................. 38 4.3 Simulation and measurement of THz systems.................. 40 4.3.1 Fractal structures characteristics..................... 40 4.3.2 Modeling of Sierpinski Fractal structures for THz radiation....... 40 4.3.3 Simulation of THz Far Fields with Sierpinski structures......... 44 4.4 Terahertz Beam Steering............................. 49 5 Conclusions and future development 52 References 54 Appendices 59 A Matlab Codes 59 A.1 VPI Radiation Pattern .mat file.......................... 59 A.2 VPI Radiation Pattern Polar Plot......................... 59 A.3 Radiation Pattern Projection........................... 60 A.4 Radiation Pattern Cuts.............................. 61 2 B PCAs dimensions 63 B.1 Dipole dimensions list.............................. 63 B.2 Bow-Tie dimensions list............................. 64 C Sierpinski PCAs Secondary Fields 65 C.1 Bow-Tie Secondary Fields............................ 65 C.2 Sierpinski 1st-Order Secondary Fields...................... 66 C.3 Sierpinski 2nd-Order Secondary Fields...................... 67 C.4 Sierpinski 3rd-Order Secondary Fields...................... 68 C.5 Sierpinski 4th-Order Secondary Fields...................... 69 3 List of Figures 1 Vision of a future communication network architecture integrating THz wireless links into optical-fiber infrastructures.......................8 2 Currents distribution for an N elements PAA................... 10 3 Block scheme of PAA feeding network for beam steering............. 11 4 PCA parts. Biasing Voltage (1), Electrodes or antenna metalization (2), Sub- strate of photoconductive material, optical pulse (3) and the correspondent input Optical Pump (4) and output THz radiation (5)[10]................ 12 5 Radiated rays refraction with a single dielectric substrate (a) and a dielectric lens coupled (b)................................... 13 6 PCA coupled to an Hyperhemispherical lens................... 13 7 OTTDN setup with DE-MZM........................... 14 8 Group delay distribution against wavelength at the PAAEs: red line, right after the AWG (see Figure7) and green line, right before photodetection (see Figure 7).......................................... 15 9 Geometrical delays for each PAAE and a beam direction q............ 17 10 Relative delays and beam direction for MW tuning................ 18 11 Maximum wavelength shift for dl0 < 0 (a) and dl0 > 0 (b)........... 19 12 Sketch of the typical options for external RF modulation at optical frequencies: DE-MZM configured for SSB modulation (a), Conventional PP-MZM (b), and DE-MZM for CD RF-amplitude free band control using the bias voltage (c)... 20 13 Comparison of fading function between a PP-MZM at Quadrature Point (blue) and a DE-MZM biased by condition (22) (red).................. 21 14 VPI setup of the MW-OTTDN........................... 23 15 Array Factor diagram for a relative progressive wavelength shift dl0 > 0 (a) and dl0 < 0 (b)................................... 25 16 Array Factor diagrams for qB = p=2 (a) and qB = 1:35p (b)........... 25 17 Primary fields (a) and Secondary fields (b) radiation scenarios.......... 26 18 Back (a) and perspective (b) view of a PCA structure in CST........... 27 19 CST background configuration section...................... 27 20 CST boundary conditions section......................... 28 21 Discrete port connected to the electrodes (a) and excitation signal (b)...... 29 22 CST decoupling plane settings in the far field plot properties menu........ 29 23 Example of far field 2D plots without decoupling plane (a)-(c) and with a de- coupling plane at Z = −20 (b)-(d). The Copolar components of the field are represented in (a)-(b) while the Crosspolar ones are plotted in (c)-(d)...... 30 24 Example of far field 3D plots without decoupling plane (a)-(c) and with a de- coupling plane at Z = −20 (b)-(d). The Copolar components of the field are represented in (a)-(b) while the Crosspolar ones are plotted in (c)-(d)...... 31 25 Back (a), perspective (b) and left (c) view of a lens-coupled PCA structure in CST......................................... 32 26 Excitation signal for a frequency range 0:45 − 0:55 THz............. 32 4 27 Co-polar and Cross-polar far fields cuts for a mesh of 4 lines per wavelength (a), 8 lines per wavelength (b), 12 lines per wavelength (c) and 14 lines per wavelength (d) at f = 0:5 THz........................... 33 28 Reference PCAs models for simulation methodology validation: H-shape Dipole (a) and Bow-Tie (b)................................ 35 29 Dipole PCA schematic............................... 35 30 Bow-Tie PCA schematic.............................. 36 31 Parameters setup of the Lens figure........................ 36 32 Maximum lens angle................................ 37 33 Co-polar and Cross-polar Primary fields projections comparison between the previous work [5] (left) and simulations (right) for a frequency f = 0:5 THz.. 38 34 Co-polar and Cross-polar Secondary fields cuts comparison between the previ- ous work [5] (left) and simulations (right) for a frequency f = 0:5 THz..... 39 35 Schematic of bow-tie (a), sierpinski’s first-order (b), sierpinski’s second-order (c), and sierpinski’s third-order (d) structure.................... 40 36 Example of sierpinski PCA schematic with La = 1200 mm and it = 4...... 41 37 Reflection coefficient of Bow-tie and sierpinski antennas of dimensions La = 400 mm (a) and La = 1200 mm (b)......................... 44 38 Co-polar and Cross-polar Primary fields projections comparison between the Bow-Tie structure and different sierpinski orders at f = 0:5 THz......... 45 39 Secondary far field cuts of sierpinski PCAs: Co-polar component cut at f = 90º (a) and Cross-polar component cut at f = 45º (b) at f = 0:5 THz........ 46 40 Secondary far field cuts of a 3rd-Order sierpinski PCA of dimensions La = 400 mm: laboratory measurements (a) versus simulations (b) at f = 0:5 THz.. 47 41 Design of the optically steerable array with the dielectric lens [6]: Perspective view with dielectric lens and beam switching (a) and Back view with optical switch and fiber connections (b).......................... 49 42 Rays direction representation when the PCA is positioned at x = 0 (a) and at x = Dx (b)...................................... 49 43 CST setup of the lens-coupled PCA with an off-axis of Dx = 1000mm (a), Dx = 0mm (b) and Dx = −1000mm (c).......................... 50 44 Simulated radiation patterns for different off-axis displacements at f = 0:5 THz. 51 45 Co-polar and Cross-polar Secondary Fields projections comparison between Bow-Tie of dimensions La = 400 mm (a) and La = 1200 mm (b) at f = 0:5 THz. 65 46 Co-polar and Cross-polar Secondary Fields projections comparison between 1st-order Sierpinski of dimensions La = 400 mm (a) and La = 1200 mm (b) at f = 0:5 THz................................... 66 47 Co-polar and Cross-polar Secondary Fields projections comparison between 2nd-order Sierpinski of dimensions La = 400 mm (a) and La = 1200 mm (b) at f = 0:5 THz................................... 67 48 Co-polar and Cross-polar Secondary Fields projections comparison between 3rd-order Sierpinski of dimensions La = 400 mm (a) and La = 1200 mm (b) at f = 0:5 THz................................... 68 5 49 Co-polar and Cross-polar Secondary Fields projections comparison between 4th-order Sierpinski of dimensions La = 400 mm (a) and La = 1200 mm (b) at f = 0:5 THz................................... 69 Listings 1 Sierpinski Macro - Main Script.......................... 42 2 Sierpinski Macro - Iteration Script......................... 42 3 Matlab Function to generate a .mat file from VPI output............. 59 4 Matlab Code to plot the polar radiation pattern from the .mat file......... 59 5 Matlab Code to plot radiation pattern circular projections from ASCII files ex- ported from CST.................................. 60 6 Matlab Script to plot radiation pattern cuts from ASCII files exported from CST. 61 List of Tables 1 Summary of delays and wavelengths expressions
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