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MURI Progress Review: Electromagnetic Simulation of Antennas and Arrays with Accurate Modeling of Antenna Feeds and Fe

MURI Progress Review: Electromagnetic Simulation of Antennas and Arrays with Accurate Modeling of Antenna Feeds and Feed Networks. PI: J.-M. Jin Co-PIs: A. Cangellaris, W. C. Chew, E. Michielssen Center for Computational Electromagnetics Department of Electrical and Computer Engineering

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MURI Progress Review: Electromagnetic Simulation of Antennas and Arrays with Accurate Modeling of Antenna Feeds and Fe

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  1. MURI Progress Review:Electromagnetic Simulation of Antennas and Arrays with Accurate Modeling of AntennaFeeds and Feed Networks PI: J.-M. Jin Co-PIs: A. Cangellaris, W. C. Chew, E. Michielssen Center for Computational Electromagnetics Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign Urbana, Illinois 61801-2991 Program Manager: Dr. Arje Nachman (AFOSR) May 17, 2005

  2. Problem Description Problem configuration Problem characteristics • Very large structures • Space/surface waves • Conformal mounting Antenna/platform interactions • Complex structures • Complex materials • Active/nonlinear devices • Antenna feeds Antenna array elements • Complex structures • Complex materials • Multi-layers • Passive/active circuit elements Distributed feed network

  3. Solution Strategy Problem configuration Simulation techniques Antenna/platform interactions MLFMA/PWTD coupled with ray tracing FE-BI coupling Antenna array elements Time/frequency- domain FEM & IE Broadband macromodel Distributed feed network Time/frequency- domain FEM

  4. Accurate Antenna Feed Modeling Using the Time-Domain Finite Element Method Z. Lou and J.-M. Jin Center for Computational Electromagnetics Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign Urbana, Illinois 61801-2991 j-jin1@uiuc.edu

  5. Typical Feed Structures • Antenna element (opened for visualization of interior structures) • Details showing coaxial cable, microstrip line and radial stub.

  6. Feed Modeling 1. Probe model (Simple & approximate) 2. Coaxial model (Accurate) At the port: Mixed boundary condition:

  7. Feed Modeling Waveguide Port Boundary Condition By mode decomposition:

  8. Conversion to Time Domain Frequency-domain operators: Time-domain operators: Inverse Laplacian Transform

  9. Time-Domain WPBC Time-Domain Formulation: Assume dominant mode incidence:

  10. Monopole Antennas Measured data: J. Maloney, G. Smith, and W. Scott, “Accurate computation of the radiation from simple antennas using the finite difference time-domain method,” IEEE Trans. A.P., vol. 38, July 1990.

  11. Five-Monopole Array (Geometry) • Finite Ground Plane: • 12’’ X 12’’ • Thickness: 0.125’’ • SMA Connector: • Inner radius: 0.025’’ • Outer Radius: 0.081’’ • Permittivity: 2.0 unit: inch

  12. Monopole Array (Impedance Matrix) 1 2 3 4 5 5 4 3 2 1

  13. Monopole Array (Gain Pattern) Feeding mode: Port V excited, Ports I-IV terminated. Freq: 4.7GHz f = 0o (x-z plane) f = 45o f = 135o f = 90o (y-z plane)

  14. 2 X 2 Microstrip Patch Array • Substrate: • 12’’ X 12’’ • Thickness: 0.06’’ • Permittivity: 3.38 • SMA Connector: • Inner radius: 0.025’’ • Outer Radius: 0.081’’ • Permittivity: 2.0 unit: inch

  15. Patch Array (Impedance Matrix) 1 2 3 4 4 3 2 1

  16. Impedance Matrix (FETD vs FE-BI)

  17. _ + _ + Patch Array (Gain Pattern at 3.0GHz) x-z plane Feeding mode: y-z plane Phasing Pattern:

  18. Antipodal Vivaldi Antenna Reflection at the TEM port “The 2000 CAD benchmark unveiled,” Microwave Engineering Online, July 2001

  19. Antipodal Vivaldi Antenna E-plane Radiation patterns at 10 GHz H-plane

  20. Layer-by-Layer Finite Element Modeling of Multi-Layered Planar Circuits H. Wu and A. C. Cangellaris Center for Computational Electromagnetics Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign Urbana, Illinois 61801-2991 cangella@uiuc.edu

  21. Layer-by-Layer Decomposition • 3D global meshing replaced by much simpler layer-by-layer meshing • 2D-meshing used as footprintfor 3D mesh in each layer • 3D mesh developed from its 2D footprint through verticalextrusion • If ground planes are present, they serve as physical boundaries between the layers • Otherwise mathematical planar surfaces are used to define boundaries between adjacent layers

  22. Example of Layer-by-Layer Mesh Generation

  23. Layer-by-Layer FEM Solution • FEM models developed for each layer • Overall solution obtained is developed through enforcement of tangential electromagnetic field continuity at layer boundaries • Assuming solid ground plane boundaries, layers interact through via holes and any other apertures present in the model • Direct Domain Decomposition-Assisted Model Order Reduction (D3AMORe) • Reduced-order multi-port” macromodels developed for each layer with tangential electric and magnetic fields at the via holes and apertures in the ground planes as “port parameters” • On-the-fly Krylov subspace-based broadband multi-port reduced-order macromodel generation • Overall multi-port macromodel constructed through the interconnection of the individual multi-ports

  24. Absorbing boundary box 50-Ohm microstrip Surface-mount cap gap 50-Ohm stripline Demonstration Tunable bandpass filter with surface-mounted caps: Via hole

  25. Two Signal Layers Pins used to strap together top and bottom ground planes Input/output ports Connecting ports Connecting ports microstrip layer (top) stripline layer (bottom) The filter is decomposed into amicrostrip layerandstripline layer. Ground planes are solid; hence, coupling between layers occurs through the via holes.

  26. Tunable band-pass filter (cont.) D3AMORe FEM Solution(w/o surface-mounted cap) Reference Solution: Transmission line model with ideal 10 fF caps for modeling the gaps. Impact of vias is neglected.

  27. Tunable band-pass filter (cont.) Use of surface-mounted caps help alter the pass-band characteristics of the filter

  28. Hybrid Antenna/Platform Modeling Using Fast TDIE Techniques E. Michielssen, J.-M. Jin, A. Cangellaris, H. Bagci, A. Yilmaz Center for Computational Electromagnetics Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign Urbana, Illinois 61801-2991 emichiel@uiuc.edu

  29. Progress in TDIE SchemesResulting from this MURI Effort • Higher-order TDIE solvers • TDIE solvers for material scatterers • TDIE solvers for surface-impedance scatterers • TDIE solvers for periodic applications • TDIE solvers for low-frequency applications • Parallel TDIE solvers • PWTD based accelerators • TD-AIM based accelerators • More accurate (nonlinear) antenna feed models • More complex nonlinear feeds • More accurate S- / Z- parameter extraction schemes • Symmetric coupling schemes between different solvers (including cable – EM interactions) Previous code Added

  30. Code Characteristics A higher-order MOT algorithm for solving a hybrid surface/volumetime domain integral equation pertinent to the analysis of conducting/inhomogeneous dielectric bodies has been developed This solver is stable when applied to the study of mixed-scale geometries/low frequency phenomena This algorithm was accelerated using PWTD and TDAIM technology that rigorously reduces the computational complexity of the MOT solver from to H1: Linear/Nonlinearcircuits/feeds in the system are modeled by coupling modified nodal analysisequations of circuits to MOT equations H2: A ROM capability was added to model small feed details H3: Cable feeds are modeled in a fully consistent fashion by wires (outside) and 1-D IE or FDTD solvers (inside)

  31. Nonlinear Feed: Active Patch Antennas *B. Toland, J. Lin, B. Houshmand, and T. Itoh, “Electromagnetic simulation of mode control of a two element active antenna,” IEEE MTT-S Symp. Dig. pp. 883-886, 1994.

  32. Nonlinear Feed: Reflection-Grid Amplifier Amplifier built at University of Hawaii, supported through ARO Quasi-Optic MURI program. Pictures from A. Guyette, et. al. “A 16-element reflection grid amplifier with improved heat sinking,” IEEE MTT-S Int. Microwave Symp., pp. 1839-1842, May 2001.

  33. RF Output & Bias RF input Bias RF input Bias Bias & RF Output Nonlinear Feed: Reflection-Grid Amplifier *A. Guyette, et. al. “A 16-element reflection grid amplifier with improved heat sinking,” IEEE MTT-S Int. Microwave Symp., pp. 1839-1842, May 2001. Each chip is a 6-terminal differential-amplifier that is 0.4 mm on a side

  34. Interfacing with ROMs:Mixed Signal PCB with Antenna 1 3 2 4 4 mm 6 7 9 10 12 cm 8.0 cm 11 5 8

  35. Interfacing with ROMs:Mixed Signal PCB with Antenna • Full-wave solution only at the top layer • Dimension of the 11-port macro-model: 623 • Bandwidth of macro-model validity: 8 GHz • Plane wave incidence & digital switching currents

  36. Interfacing with ROMs:Mixed Signal PCB with Antenna 3 m 8 cm 1.5 m 1.3 m 12 cm

  37. Interfacing with ROMs:Mixed Signal PCB with Antenna Received at port 8

  38. Cable Feeds: TD LPMA Analysis King Air 200 13.3 m 3.4 m 16.6 m

  39. Cable Feeds: TD LPMA Analysis Antenna feed-point Antenna feed-network

  40. 25 MHz 52 MHz 61 MHz 88 MHz Cable Feeds: TD LPMA Analysis * Dielectrics not shown

  41. Using Loop Basis to Solve VIE, Wide-Band FMA for Modeling Fine Details, and a Novel Higher-Order Nystrom Method W. C. Chew Center for Computational Electromagnetics Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign Urbana, Illinois 61801-2991 w-chew@uiuc.edu

  42. Volume Loop Basis • Advantages: • Divergence free • Less number of unknowns (A reduction of 30-40%) • Reduction in computation time • Easier to construct and use than other solenoidal basis, e.g. surface loop basis; no special search algorithm is needed. • Stable in convergence of iterative solvers even with the existence of a null space RWG Basis Loop Basis

  43. Volume Loop Basis Example:

  44. Volume Loop Basis Bistatic RCS: Incident Wave: 1 GHz, –z to +z Relative permittivity: 4.0 No of tetrahedrons: 3331 No of RWG basis: 7356 (11.5) No of loop basis: 4965 (10.05) Basis reduction: 32.5% No of iterations: RWG: 159; Loop: 390

  45. Full-Band MLFMA Incident Wave: 1 MHz θ = 45deg, Φ = 45deg No of triangles: 487,354 No of unknowns: 731,031 7 x 7 fork structure

  46. Z d t O a X Y Novel Nystrom Method Scattering by a pencil target: a=0.1 m d=3 m t=0.173 m f=1.0 GHz

  47. Z d a O X Y Novel Nystrom Method Scattering by an ogive: a=1 inch d=5 inchs f=1.18 GHz

  48. Z h O Y a a X Novel Nystrom Method Scattering by a very thin diamond:

  49. Novel Nystrom Method Higher-order convergence for ogive scattering:

  50. Novel Nystrom Method Higher-order convergence for pencil scattering:

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