Why capacitance increases with frequency?

Hi!

When I simulate the capacitor example in sonnetlite and plot a capacitance vs frequency graph for 0.1 to 25 GHz frequency range, I have an increases curve from ≈1.5 pF @ 0.1 GHz to ≈6.5 pF @ 25 GHz. Why does this happen?

Does capacitance changes with frequency and does εr affect capacitance? If so, can you please elaborate about thi condition and tell me any reference so that I can convince my supervisor that sonnet is not wrong in giving such capacitance vs frequency graph...

He could not relate why capacitance increases with frequency (GHz) referring to these formula:

C=(εo*εr*A)/d, Xc=1/(j*ω*C), and C=-1/(2*Π*f*Z11)

Can anyone help me to make him clear? Thanks in advance.
(Please save my life !)

take a look at this document. it explains why capacitance increases with frequency till capacitor's self-resonance frequency. If you have trouble with downloading it, tell me your e-mail address so that i can send it to you.

regards.

Thanks for your help fiquran...:D

Iwill look into this and hpe it will convince him.