Figure 3
From: Remote sensing of soil moisture using Rydberg atoms and satellite signals of opportunity
A horn antenna is connected to a low noise amplifier (LNA), then a filter, and a long coaxial cable (50 m long) to drive the atomic system via the TEM cell. (a) The horn is pointed towards the XM satellite (see Methods) to detect XM satellite signals. (b) A classical system with the same horn, LNA, filter, and coax cable is used to drive an RF mixer, IF (intermediate) filter and amplifier. Both quantum and classical readouts are digitized with an analog-to-digital converter (ADC) and correlated to compute the envelop by sweeping local oscillator frequencies (c) Continuos readout of the XM satellite band using the correlations between (a, b). Both satellite and terrestrial repeaters are sensed. (d) The quantum systems (antenna) is directed downward towards the specular reflection to sense reflections off the soil sample (see Methods).
