Space-Filling Curve High-Impedance Ground Planes

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

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

9. 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.

10. High Impedance Surfaces

11. 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).

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

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

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

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

17. 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)

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

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

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

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

22. 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

25. Efficiency and Directivity • IE3D simulation code

26. 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.

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

28. Maxwell-Garnett formula

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

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