Design of patch antenna

[aman7]

I am working on design of patch antenna that consist of air gap between patch and ground plane. I am filling a material in the gap to find its dielectric constant. However, I am getting number of resonance peaks. How to select the frequency to find the dielectric constant of material?

 

[vfone]

https://cdn.rohde-schwarz.com/pws/dl_downloads/dl_application/00aps_undefined/RAC-0607-0019_1_5E.pdf

https://academy.cba.mit.edu/classes/input_devices/meas.pdf

 

[aman7]

Thank you for your reply. I have studied these methods. However I want to know that the method i am using can be effective or not??

 

[vfone]

According to the two metal plates capacitance equations, the capacitance varies pretty linear with the value of the dielectric constant filled between plates.
For example, if for a plate area of 10^2 mm and distance between plates of 0.088mm you get 1pF capacitance for air dielectric (Er=1), get 2pF for Er=2, get 3pF for Er=3, and so on..
The above statement is valid only for one frequency, because dielectric constant vary slightly with frequency. How much vary with frequency, this depends by many factors including by manufacturer to manufacturer when speaking about the same material.