RF characterization results

Current Results (frame v7)

The summary of the results of the characterization of the RF source v7 (2023) is shown below:

Power stability and band power

Original measurements: standing waves within the anechoic chamber are noticeable

Standing waves removed through spectral analysis. Estimated power at the waveguide output (considers free space path loss, mixer and cable losses, frequency extender feed horn gain).

Average Stability (standard deviation) of the RF source power throught the usable frequency range (130 to ~157 GHz ) is estimated at 0.106 dB.

Frequency stability

Average frequency stability (SD) of the RF source is ~0.1 ppm. Average frequency offset of the RF source is ~3.5 kHz.

Correlation matrix of all measurements within the band of 130 to 160 GHz. No statistically significant correlations were found.

RF Source beam pattern (Azimuth cut at Elevation = 0°)

The beam of the RF source (fnominal = 150 GHz ) is consistent with the simulation of an open wave guide at 150 GHz, with standing waves overlayed. The expected beamwidth (-3dB point) should be consistent with the simulation at ~47°.

Chopper performance

Oscilloscope FFT showing a peak at ~46.5 Hz for the frequency of the chopper when set at nominal 47 Hz.

Chopper waveform (from the Raspberry Pi pin)

Prior results (frame v6)

A summary of results obtained for the RF source v6 (2021-2022, thesis Felipe Carrero) are presented below:

Power stability and band power

Frequency stability

RF Source beam pattern (Azimuth cut at Elevation = 0°)

The beam of the RF source (fnominal = 144 GHz ) is consistent with the simulation of an open wave guide at 144 GHz, with standing waves overlayed. The expected beamwidth (-3dB point) should be consistent with the simulation at ~47°.

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