To obtain the hyperfine transition spectrum of microwave 199Hg+ ion frequency standard there must be trapped 199Hg+ ions. 199Hg+ ion confinement is closely related to the stability of this frequency standard. The influence of radial confinement potential on the trapped 199Hg+ ion number in quadrupole linear ion trap was studied through experiments according to the stability condition of Mathieu equation. It is found that the influence is reflected in three aspects by spectrum scanning: fluorescence intensity, spectrum width and center frequency. As the radial confinement potential increases, the intensity of fluorescence becomes larger, the spectrum width becomes narrower, and the center frequency becomes smaller. Then, a miniaturized radio frequency (RF) source was designed based on the experiment. This RF source can provide the required radial confinement potential to guarantee the stability of the trapped 199Hg+ ion. The Amplitude stability of the RF source is 0.51 V expressed by standard deviation（SD）. The RF source volume of is only 0.1 L and the power consumption is about 3.5 W, which can meet the requirement of the frequency standards miniaturization.