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Innovative Surfaces for High-Impedance Applications

Discover the advantages of using space-filling curves in mathematical analysis for compact resonance structures. Learn about the applications and simulations of high-impedance surfaces, thin absorbing screens, and antenna improvements. Explore simulations of Peano and Hilbert surfaces, as well as the benefits of DNG bulk media in achieving effective permittivity and permeability. Uncover the experimental results and solutions to bandwidth limitations and polarization dependence in utilizing space-filling curves in high-impedance applications.

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Innovative Surfaces for High-Impedance Applications

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  1. Space-Filling Curve High-Impedance Ground Planes b96901128 王郁翔

  2. Outline • 1. Space-Filling Curve • 2. Resonance Property • 3. High-Impedance Surfaces

  3. Outline • 4. Applications Thin Absorbing Screens Antenna Application DNG bulk media • 5.Conclusions

  4. Space-Filling Curve • A problem in mathematical analysis. • Continuous mapping from line to plane for infinite iteration order.

  5. Why use space-filling curve? • This resonance structure is compacted within a small footprint.(microminiaturization) • The 2D structure is easy to fabricate.

  6. Resonances Simulation • Use method-of-moments(MoM) code to simulate. • Footprint = 30mm*30mm

  7. Resonance Property • The footprint is electrically small. However, the bandwidth is narrow.

  8. High Impedance Surfaces • Reflection coefficient about +1 • Artificial magnetic conductor • Utilizing resonance inclusions on a nonconducting host substrate layer in parallel with a conducting ground plane.

  9. High Impedance Surfaces

  10. Simulation of Peano Surface • Periodic MoM code • Measure reflection coefficient to frequency. • Condition: Normal incident plane wave. Infinite extent of ground plane and Peano surface of order 2. Perfect metal and dielectric(air).

  11. Simulation of Peano Surface Wire width = 0.5mm footprint = 30mm*30mm distance from ground = 15mm separation = 3.75mm

  12. Simulation of Peano Surface • Footprint and height are relatively small compare to wavelength.(0.153,0.063)(0.076,0.031) • Bandwidth: ±90°

  13. Simulation of Peano Surface • Change height and separation. • y-polarized is less pronounced.

  14. Simulation of Hilbert Surface • Hilbert curve of order 3. Footprint = 30mm*30mm Separation = 4.285mm Height = 15mm • Incident angle from 0 to 60.

  15. Experiment Results • Fabricate curve on 1.575-mm FR-4 substrate with dielectric constant 4.4 and loss tangent 0.02. • Scaled to match the frequency of WR-430 waveguide.(1.7~2.6 GHz)

  16. Experiment Results • Simulate by finite-element method and the measure data.

  17. Varying Loss Tangent • MoM-based IE3D simulation on Peano of order 2 and Hilbert of order 3 for x-polarized wave.

  18. Thin Absorbing Screens • Frequency-selective surfaces. • Thin absorber, application in absorbing material and low observables. • Much smaller than Salisbury screen.

  19. Antenna Application • Put a small dipole antenna above Hilbert surface. • Image current enhanced radiation. • High-performance, low-profile, conformal, flush-mounted antenna.

  20. Antenna Simulation • MoM software package IE3D and NEC-4 based Code GNEC. • Simulate impedance to frequency. • Additional height 15mm 11*11 Hilbert curves copper with conductivity 5.813*107S/m

  21. Efficiency and Directivity • IE3D simulation code

  22. DNG Bulk Media • Embedding many identical space-filling curve inclusions within a host medium. • Simulate electric and magnetic dipole moments to frequency, then use the Maxwell-Garnett mixing formula to analyze this polarizability tensor to obtain effective permittivity and permeability.

  23. Permittivity and Permeability • MoM based code. y-polarized Hilbert curve of order 3 wire radius = 0.125mm

  24. Maxwell-Garnett formula

  25. SNG media by Peano • Peano curve inclusions also has negative permittivity and permeability, but in different frequency. • Multifunction media

  26. Conclusions • There are two main problems have to solve. • 1.narrow bandwidth • 2.dependence of the response of space-filling curve on the polarization.

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