measuring dielectric constant pcb
Hi y'all,
one method that I have found to be quite effective in characterizing the properties of some given PCB material is the following:
1. design a ring resonator (length should be an integer multiple of the wavelength that you're designing for, transmission line coupled in parallel with the ring) using some approximate value for εr
2. fabricate the ring resonator and measure S21 with a VNA.
3. resimulate the ring resonator design with same simulator that you're intending to use for your antenna design
4. adjust εr and tanδ of the substrate model in the simulator until the dips and the slope of S21 matches the measured one.
I used this method in characterizing FR4 material at 10 GHz for patch antennas and got good results.
Hope this helps...