  We describe the design of a low-phase-modulated (PM) noise, 40 GHz oscillator
that uses a conventional air-dielectric cavity resonator as a frequency
discriminator to improve the PM noise of a commercial 10 GHz dielectric
resonator oscillator (DRO) frequency multiplied by four. The main features of
this design incorporate (1) unloaded cavity quality factor (Q) of 30,000, (2)
high coupling coefficient, (3) large carrier suppression by use of
interferometric signal processing, (4) large operating signal power of
approximately 1 watt (W), and (5) relatively small size. In addition, we report
the PM noise of several Ka-band components.
