measuring dielectric constant in high frequency?

[guo-hai]

using capacitor just can be used in low frequency measurement , anyone can teach me how to measure dielectric in high frequency? maybe microstrip line?

 

[jiripolivka]

There are many methods to measure material permittivity at RF and microwaves. You can use capacitive sensors as well as microstrip lines, resonators and other devices. Check "www.damaskos.com" and "www.agilent.com" for white papers and methods.
Maybe I can help if you indicate what is your frequency of interest and material type. In general, the "dielectric constant" is not a constant, but a rather complex permittivity, often a function of frequency and other effects.

 

[guo-hai]

i will check the web, thank you jiripolivka,.

I am studying about IPD capacitor, and my first step is searching for the High K material, I'm using BSTZ ceramic as my material.
Can you explain to me how to measure with the microstrip line?
As I know microstrip lines can measure broaden frequency, and I have searched a lot a paper, my conclusion is using VNA to get S21 and then convert it to dielectric constant.
But I still dont know how it can s21 convert to dielectric constant?

 

[jiripolivka]

A microstrip line can be loaded with a known-value capacitor, then replaced with an equal-size one made of BSTZ.
I do not know how to convert S21 into permittivity but the Agilent white paper describes how to use S11 an how to get the permittivity from sample holders Agilent recommend.
For high-K ceramic samples I used a resonator-perturbation method. Small ceramic samples were inserted in a 9 GHz cavity resonator, and frequency shift was used to measure permittivity. The K was ~600 and measurement accuracy was better than 1%. My work was not finished ~25 years ago. In the IEEE Trans. on Material Measurement and elsewhere you can find more contributions as many people are ow interested in high-K materials.