A Low Phase-Noise SIW Reflection Oscillator with Hexagonal Resonator

A low phase noise reflection oscillator using a hexagonal substrate integrated waveguide (SIW) resonator is proposed in this paper. The hexagonal SIW resonator, which can combine flexibility of a rectangular cavity and performance of a circular cavity, is convenient for oscillator design. Since any of the six sides of a hexagonal resonator can be utilized for coupling, the oscillator configuration is flexible and adaptable. A simplified generalised phase noise condition and its optimization approach are proposed for the low-phase noise oscillator design. Furthermore, a 10.4 GHz oscillator prototype was designed, fabricated and measured to validate the proposed optimization approach. The measured results show that this oscillator provides 11.3 dBm output power and possesses low phase noise of -127.2 dBc/Hz at 1 MHz offset from 10.37 GHz carrier frequency, which is suitable for low-cost application in microwave and millimeter-wave band.