This paper presents a novel microwave oscillator incorporating a simple microstrip ring-type resonant cell as its terminating resonance component. Reduced chip size, higher DC-AC power efficiency, and superior harmonic characteristics can be achieved from the introduction of this type of compact microstrip ring resonator cell. The oscillator provides a second harmonic suppression of 26.51 dB and an output power of 2.046 dBm, with 28% efficiency at an oscillation frequency of 2.11 GHz.