Amplitude and intensity interferometry using satellite LNB receivers for innovative and low cost microwave and millimetre wave sensor development

Salmon, NA, Radiven, J and Wilkinson, PN (2012) Amplitude and intensity interferometry using satellite LNB receivers for innovative and low cost microwave and millimetre wave sensor development. [Conference or Workshop Item]

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Abstract

Satellite Low Noise Block-down convertors (LNBs) have been evaluated for use in amplitude and intensity interferometry. LNBs have been found to have a high performance to cost ratio which is beneficial for any sensor system. They are investigated here for a diversity of applications from the derisking of subsystems for next generation aperture synthesis imagers having hundreds of channels [1] to a platform for the investigation of phase recovery in intensity interferometry and experimentation in entangled photons. Measured noise temperatures of LNBs were found to lie between 170 K and 300 K which is higher than typical manufacturers’ specifications. A twin channel interferometer system was developed using satellite receiver feeds and LNBs at the front-end, other amplifiers, mixers, filters and local oscillators at intermediate stages, and 8-bit USB ADCs sampling synchronously at 100 MHz and a PC for data processing. LabVIEW was used to digitally demodulate the sampled data and process it into the first and second orders of coherence. Measurements of the first order of coherence from a standard low energy discharge lamp indicated interference fringes were commensurate with range and spacing of the two receivers and the source. The relationship between the measured first and second order of coherence agrees within the experimental error. Variations of the first and second orders of coherence with range, R, follow the relationship 1/R and 1/R2. The system has the potential for investigations into phase extraction for intensity interferometry and for the study of digital demodulation schemes for aperture synthesis amplitude interferometry with hundreds of receiver channels for next generation security screening systems. A twin, triple or quadruple channel polarimetric LNB interferometer could be used as basis for high precision investigations in to entangled photons and quantum communications.