Microwave absorbing material test for ferrite of CAEP Fanbo Meng

Test method 𝜀=𝑒 𝑆11,𝑆21 𝜇=𝑢 𝑆11,𝑆21 TR theory: S21 S11 ferrite Coaxial line 𝜇=𝑢 𝑆11,𝑆21

Test scheme: DUT Remove the error of fixture Remove the error of cable and VNA （TRL calibration plane） DUT port （SOLT calibration plane） DUT Test port 转接夹具 Agilent矢量网络分析仪 Cable with N type connector Use two step calibration to get the accurate S parameter of DUT MATLAB code to compute ε & μ

𝑆 𝐷𝑈𝑇 𝑆 𝑚 𝑇 𝑚 = 𝑇 𝑓𝑖𝑥1 ∙ 𝑇 𝐷𝑈𝑇 ∙ 𝑇 𝑓𝑖𝑥2 Test scheme: 𝑆 𝑚 𝑇 𝑚 = 𝑇 𝑓𝑖𝑥1 ∙ 𝑇 𝐷𝑈𝑇 ∙ 𝑇 𝑓𝑖𝑥2 “S2T” code 𝑇 𝐷𝑈𝑇 = 𝑇 𝑓𝑖𝑥1 −1 ∙ 𝑇 𝑚 ∙ 𝑇 𝑓𝑖𝑥2 −1 “T2S” code 𝑆 𝐷𝑈𝑇 𝑇 𝑓𝑖𝑥 如何获得?? 即， 𝑆 𝑓𝑖𝑥 如何获得??

𝑆 𝑓𝑖𝑥 TRL calibration to get 𝑆 𝑓𝑖𝑥 ： “Thru”连接 转接夹具 转接夹具 测得T matrix T matrix、R matrix、L matrix 分别代表“T”“R”“L”三种状态下测得的S参数 “Reflect”连接 转接夹具 转接夹具 “TRL_Cal” code 测得R matrix 𝑆 𝑓𝑖𝑥 “Line”连接 转接夹具 转接夹具 测得L matrix

Test equipment (DUT + fixture): Ferrite sample (8mm)

Test data e & u of air: the first test

Probable reason: The data is not accurate in 0.02~03GHz. During the TRL calibration, the “Thru” connection is not a good electric connection.

e & u of air: the second test Solution: When “Thru” connection, binder plate is used to realize the good electric connection between the two fixture. e & u of air: the second test

e & u of ferrite:

(same to the test structure) Check the test accuracy of ferrite e & u Import the measurement data of ferrite to CST. Do simulation with the import data. Compare the simulation result with the measurement result. e curve (import and fit) u curve (import and fit) Simulation model (same to the test structure)

Simulation result

Test result

Compare the simulation result and test result