G. De Michele BE-RF1

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 HOM dampers in CLIC accelerating structures G. De Michele BE-RF2 Motivations

Non-resonant method: Non-resonant method: – Reflection method: open-circuited reflection; short- circuited reflection (S 11 ) – Transmission/reflection methods: (S 11,S 12,S 21,S 22 ) Resonator method: – The sample forms a resonator or a key part of resonator Dielectric resonator Dielectric resonator Coaxial surface-wave resonator Coaxial surface-wave resonator Split resonator (dielectric sheet sample) Split resonator (dielectric sheet sample) G. De Michele BE-RF3 Different techniques for materials characterization

Resonant perturbation method: 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-RF4 Different technique for materials characterization

Non-resonant method : 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-RF5 Different technique for materials characterization

G. De Michele BE-RF6  S-parameters measurements for waveguides with material  Surface and contour plots  Resonant Cavity Method (as cross check at defined frequencies)  Agilent Dielectric High Performance Probe 85070E 1- 50GHz  EPFL-LEMA laboratory of electromagnetism can measure up to 50 GHz complex permittivity of solid materials with different set-ups Until the end of 2009… Courtesy R. Zennaro &T. Pieloni

G. De Michele BE-RF7 Waveguide method Imaginary S 21 at 10.5 GHz High frequency EM characterization: the intersection of the surfaces with the measured S 21 yields the possible solutions. Often one obtains the uniqueness of the solution with only two constrains furnished from the complex S 21. Courtesy C. Zannini, R. Zennaro, T. Pieloni ESK (Germany) typesample shape (mm) εr (10.5 GHz HFSS) εr (10.5 GHz CST) εr (28 GHz CST) EKASIC FSiC L49xW49xH 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-RF8 Coaxial method (in collaboration with C. Zannini) Pros Wide range of frequency Analytical model very simple and immediate (basic TL theory ) Hopefully one set-up for measurements Other applications (collimators (dielectrics), kickers (ferrites)) Cons Mechanical realization Possible air gap  conductive glue/paint

G. De Michele BE-RF9 Coaxial model validation via 3D EM simulations 1)Simulation to get the scattering parameter S 11 for a certain material 2)S 11 is the input for the model 3)The output of the model should fit with the input of simulations Simulations (measurements) Model

G. De Michele BE-RF10 Coaxial method Z_ DUT, k_ DUT Z 0, k 0 l O. C simulations j j j j j model j j j j j S. C simulations j j j j j model j j j j j

G. De Michele BE-RF11 Coaxial method (Teflon) Z_ DUT, k_ DUT Z 0, k 0 l O.C.18 GHz simulations j model j model(measurements) S.C.18 GHz simulations j model j model(measurements)

Conclusion and next steps Validation of the model via EM simulation (at least below cut-off of 1 st HOM) Acquisition of more points to check the repeatability of the method Check with the presence of HOM Fabrication of SiC samples Repeat measurements with waveguide method for comparison G. De Michele BE-RF12