1. FORTH
- Modelling
Heraklion, July 2004

2. Issues addressed in the last 4 months
SRR study: The background dielectric constant influence; the board influence
Square vs non-square LHM unit cells
Examination of alternative SRR systems, with aim to improve the LH peak
SRR study: The electric cut-wire response (SRR vs cut-wires, and influence of SRR orientation)
THz SRR structures study

3. Role of the dielectric constant of the board (b)
2m 1/b
20 1/b

4. Square vs. non-square unit cells (1)
Unit cells reduced in size along E direction give higher LH peaks.
Possible reasons:
1) Change of impedance through decrease of ’p
(larger cut-wire (SRR) length  reduced 0  reduced ’p) E
Square
akxaE=5x5 mm2
Non-square (reduced) akxaE=5x3.63 mm2

5. Square vs. non-square unit cells (2)
Unit cells reduced in size along E direction give higher LH peaks.
Possible reasons:
2) Stronger interaction between SRRs?
(wider <0 regimes  possibility for higher peak?) E
Square
akxaE=5x5 mm2
Non-square (reduced) akxaE=5x3.63 mm2

6. Square vs. non-square unit cells (3)k
Reduction of ak does not influence the LH peak

7. SRRs of different dimensions
We studied metamaterials of SRRs (of the conventional design) with different linear size, different rings width, different rings distance and different cuts-size with aim to improve the LH transmission, through impedance improvement.
Unit cell: 5x5, 5x4.6
SRR size: 4x4
Rings width (w): 0.4
Rings distance (s): 0.2, 0.4
Gaps (g): 0.2, 0.4
No any considerable improvement compared to our experimental design

8. SRRs of different dimensions
We studied metamaterials of double unit cell size, to see if going to lower frequencies reduces the losses in the board at the LH peak
No any significant improvement compared to our experimental design

9. SRR vs cut-wires: Why lower 0 for the SRR?Ek EE E k + - E k - + + - - - E k + + 0

10. 0 is in most of the cases higher in A
SRR rotation and 0
0 is in most of the cases higher in A Ek EE - + A E k - - B E k + + 0

11. SRR rotation and 0 (FDTD)- + + - E k
Bilkent
FORTH E k - - + +

12. THz structure Unit cell: 7x7x5 m3 SRR size: 5x5 m2 All other: 1 m
Board’s =2.8 (polyamide)

13. THz structure, FDTD & MWS, in-plane incidencek
6 uc
1 uc

14. THz structure, FDTD & MWS, in-plane incidencek
FDTD
MWS

15. THz structure, FDTD & MWS, in-plane incidencek E k

16. THz structure, vertical incidencek
FDTD
MWS

17. THz structure, inversion, in-plane incidencek

18. THz structure, inversion, vertical incidencek

19. Summarizing…..
Board influences “differently” the characteristic SRR frequencies (m, 0)
Unit cells reduced along the wires direction give higher LH transmission peaks
0 (SRR-FORTH) < 0 (cut-wires) < 0 (SRR-Bilkent)
THz SRR structure:
Magnetic response at ~6 THz
Good agreement between theory and experiment
Good agreement between FDTD and MWS