WAVEGUIDE EXPERIMENTS TO CHARACTERIZE PROPERTIES OF SNG AND DNG METAMATERIALS

1. WAVEGUIDE EXPERIMENTS TO CHARACTERIZE PROPERTIES OF SNG AND DNG METAMATERIALS 學生 電機三 許宗堯 指導教授 吳瑞北

2. OUTLINE • review—rods , rings, rectangular waveguide… • rectangular waveguide of 2D uniaxial MNG • Subwavelength resonator • Refraction experiment

3. REVIEW • Thin-wire epsilon-negative metamaterials

4. REVIEW • SRR Array MNG metamaterials

5. REVIEW • Rectangular waveguide analysis

6. INVESTIGATION OF RECTANGULAR WAVEGUIDE FILLED WITH 2D UNIAXIAL MNG • 2D uniaxial MNG • Structure : • Below cutoff frequency, backward-wave propagation occurs.

7. In backward-wave propagation • due to energy conservation • so one concludes that any passive metamaterial can exhibit negative permeability only within the limited frequency band

8. Nine double rings were placed along the line of symmetry of a 60-mm-long section of a standard J-band waveguide (d = 35 mm) • Solid line, resonance frequency located below cutoff (a = 12 mm) dash line, resonance frequency located above cutoff (a = 35 mm)

9. WAVEGUIDE MINIATURIZATION • The classical constraint on the minimum transverse dimension of a waveguide does not hold in this case, that is, the waveguide width can be arbitrarily smaller than half of the wavelength in the filling material • The transverse dimension of this waveguide was approximately only 3.7 percent of half of the wavelength

10. SUBWAVELENGTH RESONATOR • combination of a DPS slab and a DNG slab sandwiched between two infinite conducting planes • The phase delay of the forward-wave can be completely compensated by the phase advance of backward-wave.

11. The conventional case: overall phase shift = π d>=0.5λ • With metamaterial, overall phase shift = 0 • Zin1 = Zin2

12. If d1 and d2 are much shorter than a wavelength • d1 and d2 can arbitrarily be shorter than the wavelength, provided that their ratio satisfies the above equation • Modeled by equivalent circuit

13. The resonance frequency

14. Solid line: measured phase distribution of H field • Dashed line: phase of standing wave • The length of the structure: approximately 0.1λ

15. REFRACITON EXPERIMENTS IN WAVEGUIDE ENVIRONMENTS • negative refraction • left-handed media are also referred to as negative refractive index or negative refractive media

16. ENG DNG MNG DPS

17. ENG DNG MNG DPS

18. REFRACTION EXPERIMENTS IN WAVEGUIDE ENVIRONMENTS • In this chapter, we consider transverse electric (TE) incident waves polarized in the y direction, so that the relevant parameters are (εy , µx , µz) in the dispersion relation: • First consider normal incident (transmission) • n2 is real, wave number is also real • n2 is pure imaginary, wave number is also pure imaginary → the wave is strongly attenuated inside the slab

19. REFRACTION

20. Example : …… hyperbola when ω ↑ k0 ↑ ,so the radius of blue circle ↑ (εyμz) ↓ (εyμx) ↑ εy μx μz