1. EM characterization of SiC
G. De Michele BE-RF, C. Zannini BE-ABP
G. De Michele

2. G. De Michele BE-RF, C. Zannini BE-ABP
Outline
Why and where we need dispersive materials
Techniques for EM characterization of materials
Current status for CLIC accelerating structures
G. De Michele BE-RF, C. Zannini BE-ABP

3. G. De Michele BE-RF, C. Zannini BE-ABP
Outline
Why and where we need dispersive materials
Techniques for EM characterization of materials
Current status for CLIC accelerating structures
G. De Michele BE-RF, C. Zannini BE-ABP

4. Baseline structure and HOM damping
Iris radius  2.35mm
WG cross section 11x6.66mm
WG length 90mm
G. De Michele BE-RF, C. Zannini BE-ABP

5. Baseline structure and HOM damping
SiC cross section  1x1 to 5.6x5.5mm
SiC length  30mm+10mm flat
Distance tip_SiC-structure_axis  50mm
G. De Michele BE-RF, C. Zannini BE-ABP

6. Baseline structure and HOM damping
Double-feed coupler cell with a standard X-band WR-90 width
G. De Michele BE-RF, C. Zannini BE-ABP
G. De Michele

7. G. De Michele BE-RF, C. Zannini BE-ABP
Outline
Why and where we need dispersive materials
Techniques for EM characterization of materials
Current status for CLIC accelerating structures
G. De Michele BE-RF, C. Zannini BE-ABP

8. G. De Michele BE-RF, C. Zannini BE-ABP
Motivations
The study of EM properties at microwave (μw) frequencies is full of academic importance (materials property research)
μw communications and engineering (military, industrial, civil)
Clock speeds of electronic devices at μw frequencies require knowledge of permittivity and permeability
EM interference (EMI) and EM compatibility (EMC)
Various fields of science and technology could profit: agriculture, food engineering, medical treatment, bioengineering
High-quality design of the high order mode dampers in CLIC accelerating structures
G. De Michele BE-RF, C. Zannini BE-ABP

9. Different techniques for materials characterization
Non-resonant method:
Reflection method: open-circuited reflection; short-circuited reflection (S11)
Transmission/reflection methods: (S11,S12,S21,S22)
Resonator method:
The sample forms a resonator or a key part of resonator
Dielectric resonator
Coaxial surface-wave resonator
Split resonator (dielectric sheet sample)
G. De Michele BE-RF, C. Zannini BE-ABP

10. Different techniques for materials characterization
Resonant perturbation method:
The sample under test is introduced into the resonator and the EM properties are deduced from the changes in resonance frequency and quality factor of the cavity
Planar circuit methods (both resonant and non-resonant methods):
Stripline
Microstripe
Coplanar line
G. De Michele BE-RF, C. Zannini BE-ABP

11. Different technique for materials characterization
Non-resonant method :
possibility to measure EM properties in a wide range of frequencies
Resonator method:
Measurements possible at single or several discrete frequencies
Higher sensitivity and higher accuracy
G. De Michele BE-RF, C. Zannini BE-ABP

12. G. De Michele BE-RF, C. Zannini BE-ABP
Outline
Why and where we need dispersive materials
Techniques for EM characterization of materials
Current status for CLIC accelerating structures
G. De Michele BE-RF, C. Zannini BE-ABP

13. EM materials properties (T.Pieloni)
G. De Michele BE-RF, C. Zannini BE-ABP
G. De Michele

14. G. De Michele BE-RF, C. Zannini BE-ABP
Waveguide method
High frequency EM characterization:
the intersection of the surfaces with the measured S21 yields the possible solutions. Often one obtains the uniqueness of the solution with only two constrains furnished from the complex S21.
Imaginary S21 at 10.5 GHz
Courtesy C. Zannini, R. Zennaro, T. Pieloni
ESK (Germany)
type
sample shape
(mm) εr
(10.5 GHz HFSS)
(10.5 GHz CST)
(28 GHz CST)
EKASIC F
SiC
L49xW49xH10
11.2-j 1.06
(tanδ=0.095)
11.2-j 1.03
(tanδ=0.092)
11.0-j 0.88
(tanδ=0.080)
G. De Michele BE-RF, C. Zannini BE-ABP

15. G. De Michele BE-RF, C. Zannini BE-ABP
Coaxial method
Pros
Wide range of frequency
Analytical model very
simple and immediate
(basic TL theory )
Hopefully one set-up for measurements
Cons
Mechanical realization
Possible air gap
a=130μm
G. De Michele BE-RF, C. Zannini BE-ABP
G. De Michele

16. G. De Michele BE-RF, C. Zannini BE-ABP
Coaxial method
ESK (Germany)
type
sample shape
(mm) εr
(9 GHz CST)
EKASIC F
SiC
d=1.32
D=4.08
12.0-j 1.08
(tanδ=0.090)
G. De Michele BE-RF, C. Zannini BE-ABP

17. G. De Michele BE-RF, C. Zannini BE-ABP
Coax and WG methods
G. De Michele BE-RF, C. Zannini BE-ABP

18. TL model validation via 3D EM simulations
Simulation to get the scattering parameter S11 for a certain material
S11 is the input for the TL model
The output of the model should fit with the input of simulations
Simulations
(measurements)
Model
G. De Michele BE-RF, C. Zannini BE-ABP
G. De Michele

19. G. De Michele BE-RF, C. Zannini BE-ABP
Coaxial method
Z_DUT, k_DUT
Z0, k0 l
O. C. 8 9 10 11 12
simulations j j j j j
model j j j j j
S. C. 8 9 10 11 12
simulations j j j j j
model j j j j
G. De Michele BE-RF, C. Zannini BE-ABP
G. De Michele

20. Coaxial method (Teflon)
Z_DUT, k_DUT
Z0, k0 l
O.C.
18 GHz
simulations j
TL model j
TL model(measurements)
S.C.
18 GHz
simulations j
TL model j
TL model(measurements)
G. De Michele BE-RF, C. Zannini BE-ABP
G. De Michele

21. Coaxial method (CerasicB1)
WG method (MWS)
WG method (HFSS)
COAX method (TL model:airgap 2a=165um)
G. De Michele BE-RF, C. Zannini BE-ABP
G. De Michele

22. Cutoff limit and new geometry
Resonances found also at 11.5GHz,15.5GHz and 31.5GHz
New geometry has higher cutoff (around 25GHz)
Easy machining
Series production in order to evaluate chemical treatment and heat treatment
G. De Michele BE-RF, C. Zannini BE-ABP
G. De Michele

23. G. De Michele BE-RF, C. Zannini BE-ABP
Future work
Machining of the new samples/new geometry
Measurements (EkasicF, EkasicP, CerasicB1) until 30GHz: HOM-free up to  25GHz
Tolerances study on coaxial/sample variations on scattering parameters.
Investigation of influence of chemical and heating treatments on the properties of materials
G. De Michele BE-RF, C. Zannini BE-ABP
G. De Michele