Abstract: In a general aspect, data from a vapor cell sensor system is used to characterize radio frequency sources. In some aspects, a vapor cell sensor system generates output signals by operating one or more vapor cells at an array of locations in a radiating near-field region of an RF field produced by an RF source. Based on the output signals, a signal processing system generates measurement data that represents measured intensities of the RF field in the radiating near-field region. Based on the measurement data, the signal processing system generates a model of the RF field produced by the RF source. The model includes modeled intensities of the RF field in the radiating near-field region and a far-field region of the RF field.

Abstract: In a general aspect, vapor cells are used to characterize radio frequency sources. In some aspects, a system includes a vapor cell sensor system and a signal processing system. The vapor cell sensor system has one or more vapor cells that can be positioned at an array of locations. The vapor cell sensor system generates output signals based on operating the one or more vapor cells in a radiating near-field region of an RF field. The signal processing system is configured to generate measurement data based on the output signals; the measurement data represents measured intensities of the RF field in the radiating near-field region. The signal processing system is also configured to generate a model of the RF field based on the measurement data. The model includes modeled intensities of the RF field in the radiating near-field region and a far-field region of the RF field.

Abstract: In a general aspect, data from a vapor cell sensor system is used to characterize radio frequency sources. In some aspects, a vapor cell sensor system generates output signals by operating one or more vapor cells at an array of locations in a radiating near-field region of an RF field produced by an RF source. Based on the output signals, a signal processing system generates measurement data that represents measured intensities of the RF field in the radiating near-field region. Based on the measurement data, the signal processing system generates a model of the RF field produced by the RF source. The model includes modeled intensities of the RF field in the radiating near-field region and a far-field region of the RF field.

Abstract: In a general aspect, vapor cells are used to characterize radio frequency sources. In some aspects, a system includes a vapor cell sensor system and a signal processing system. The vapor cell sensor system has one or more vapor cells that can be positioned at an array of locations. The vapor cell sensor system generates output signals based on operating the one or more vapor cells in a radiating near-field region of an RF field. The signal processing system is configured to generate measurement data based on the output signals; the measurement data represents measured intensities of the RF field in the radiating near-field region. The signal processing system is also configured to generate a model of the RF field based on the measurement data. The model includes modeled intensities of the RF field in the radiating near-field region and a far-field region of the RF field.

Abstract: In a general aspect, a system is described for sensing radio frequency (RF) electromagnetic fields. The system includes a laser system that generates probe and coupling laser signals. The system also includes an RF source that generates a reference RF electromagnetic field. The reference RF electromagnetic field is part of a combined RF electromagnetic field that also includes a perturbing RF electromagnetic field. A vapor cell sensor of the system generates an optical signal in response to the probe laser signal, the coupling laser signal, and the combined RF electromagnetic field interacting with a vapor of the vapor cell sensor. The system additionally includes a control system that tunes the coupling laser signal and the reference RF electromagnetic field relative to respective transitions of the vapor. The control system generates, based on the optical signal, a value that represents a property of the perturbing RF electromagnetic field.

Abstract: In a general aspect, a radio frequency (RF) measurement device includes first and second mode converters, each configured to convert a mode of the RF electromagnetic wave between a first RF waveguide mode and a second RF waveguide mode. The RF measurement device also includes an internal cavity between the first and second mode converters that contains a vapor or a source of the vapor. The vapor includes Ryberg atoms or molecules. The RF measurement device additionally includes an RF waveguide extending between the first and second mode converters and configured to carry the second RF waveguide mode through the internal cavity. In some variations, the RF waveguide includes first and second longitudinal portions disposed on respective, opposite sides of the device and configured to establish a target RF profile in an interaction region of the internal cavity.

Abstract: In a general aspect, a system for measuring radio frequency (RF) electromagnetic waves includes a laser system configured to generate plurality of input optical signals. The system also includes an RF measurement device having first and second mode converters and an internal cavity therebetween. The internal cavity contains a vapor that is configured to produce an output optical signal based on the plurality of input optical signals. The RF measurement device also includes an RF waveguide that extends between the first and second mode converters and is configured to carry the second RF waveguide mode through the internal cavity. The system also includes an optical detector system configured to generate a detector signal in response to receiving the output optical signal. The system additionally includes a signal processing system configured to generate data in response to receiving the detector signal.

Abstract: In a general aspect, a radio frequency (RF) measurement device includes first and second mode converters, each configured to convert a mode of the RF electromagnetic wave between a first RF waveguide mode and a second RF waveguide mode. The RF measurement device also includes an internal cavity between the first and second mode converters that contains a vapor or a source of the vapor. The vapor includes Ryberg atoms or molecules. The RF measurement device additionally includes an RF waveguide extending between the first and second mode converters and configured to establish a circular polarization of the RF electromagnetic wave in the internal cavity.