A novel near-field vector beam measurement system at 690GHz

A new near-field vector beam measurement system is developed for the characterization of the optics in a 600-696 GHz heterodyne receiver. This new method makes use of the difference between harmonic numbers in the RF and LO phase lock loops (PLL) with common reference sources, instead of using multiple PLL reference frequencies or independent LORF sources. The amplitude and phase stability of the measurement system is measured. With this new method, we can achieve amplitude and phase fluctuation within a ±0.2 dB and ±4 degree maximum in one-hour period, respectively. The amplitude dynamic range of the system is over 35 dB.