1. Microwave absorbing material test for ferrite of CAEP
Fanbo Meng

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

3. 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

4. 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??

5. 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

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

7. Test data
e & u of air:
the first test

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

9. 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

11. e & u of ferrite:

13. (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)

14. Simulation result

15. Test result

16. Compare the simulation result and test result