1：Experimental Design and Method Selection:

The microwave source consists of two parts: the reference oscillator and the frequency synthesis chain. A 5 MHz BVA type quartz oscillator is selected for the reference oscillator. A two-step phase-lock-loop (PLL) architecture was used in the frequency synthesis chain.

2：Sample Selection and Data Sources:

The output microwave signal benefits from both the ultra-high close-in spectral purity of the reference oscillator and the low phase noise level of the PLL at frequencies far from the carrier.

3：List of Experimental Equipment and Materials:

Includes a 5 MHz BVA type quartz oscillator, a low noise reference oscillator (LNRO), a power combiner, a frequency multiplier, a power splitter, a phase lock loop, an oven-controlled quartz oscillator, an amplifier, a coupler, a step recovery diode, a band pass filter, a direct digital synthesizer, a dielectric resonator oscillator, a switch, and an attenuator.

4：Experimental Procedures and Operational Workflow:

The 5 MHz signal of the reference oscillator is multiplied to 100 MHz, which is used to phase-lock a 100 MHz oven-controlled quartz oscillator. The 100 MHz signal is multiplied to 200 MHz, which is amplified and then sent to a 10 dB directional coupler. The coupled output is split into three signals. One signal is used to drive a direct digital synthesizer and the other two signals are sent to two mixers for frequency downconversion.

5：Data Analysis Methods:

The phase noise of the microwave source was characterized by comparing two identical devices using a phase noise test system.