Capacitor

At RF, a capacitor may be modelled as shown below;

en-20130214-p1_img0002

where:
            C = capacitance
            ESR=equivalent series resistance due to heat dissipation loss expressed either as power factor or dissipation factor
            ESL= some parasitic inductance (ESL) due to electrodes


Losses in capacitor may be expressed as capacitor Q which is defined as;

en-20130214-p1_img0003
According to above figure, capacitor works as a capacitor before self-resonant frequency.
Capacitor will not work as a function of capacitor after self-resonant frequency and it behave as an Inductor.
Therefore the capacitor should be chose as per below criteria.
Freq (srf) >> Freq(rf)
where:
            Freq(srf) = self-resonant frequency
            Freq(rf) = the radio frequency used in design