Aperture has been employed on the ground plane in the hairpin resonator. Aperture has been fabricated by etching the part of the ground effected coupling coefficient and then quality factor of hairpin resonator has been increased. When the hairpin oscillator using aperture has been compared with the conventional hairpin oscillator using microstrip, it has been improved the phase noise about 19 ㏈c @100 ㎑. As a result of PBG connecting to the output of the employing aperture hairpin oscillator, the second and third harmonics are suppressed. In this paper, oscillator has been designed and fabricated in operating 5.8 ㎓ band. The output power has been obtained 0,67 ㏈m and the second harmonic has been suppressed about -53,67 ㏈c.