comsol/capacitor simulation

Discussion in 'The Projects Forum' started by alienator, Feb 20, 2009.

  1. alienator

    Thread Starter New Member

    Feb 20, 2009
    hi all ,

    am working with annular capacitors ,
    made a simulated annular plates capacitor in Comsol

    but my experimental results are not matching with the experimental results
    experimental capacitances are far smaller than the simulated ones

    ex: actual capacitance for 3 mm distance is 1.4 pf
    by simulation we am getting around 14pf

    in Comsol i used : electrostatics module in AC/DC -3D module

    i made 2 annular plates and 2 guard rings around them , and one more big box surrounding all of them
    (guard rings are just 2 grounded rings surrounding both the capacitor plates , one with +ve potential other with -ve potential to reduce the effect of external disturbances on capacitance )

    in subdomain settings i have deactived all except the big box in which i have put field and other stuff active , have put ε(relative) as 1 .

    now for boundary settings i gave zero charge or symmetry for the bigger box , ground for both guard rings , -1V for one plate , and set port as input for other plate ,

    when i simulate this i am getting results which are not matching with experimental values

    so somebody plzz help me out
    Last edited: Feb 21, 2009
  2. KL7AJ

    Senior Member

    Nov 4, 2008
    What is your dielectric material made out of? This can DRASTICALLY affect capacitance.

  3. alienator

    Thread Starter New Member

    Feb 20, 2009
    i didnt use any dielectric either in simulation or in the experiment