Microwave Magnetic Field Pattern Evaluation of Horn and Patch Antennas Using Cs Atomic Sensor

In this study, microwave (9.2 GHz) magnetic field radiation patterns of a horn antenna in the near-field (10 cm) and of a patch antenna in the near-field (3 mm, 2 cm) and far-field (10 cm) are measured using a Cs atomic sensor with <; 2 mm size, for the first time to the best of our knowledge. Radiation patterns measured using the atomic sensor are compared to radiation patterns measured in an anechoic chamber using traditional methods. Utilizing the atomic sensor, which is based on microwave-atom-laser interaction and works at the D
₂
transition of Cs-atoms, I observed 7π and 8 0 Zeeman double radio optical resonance (DROR) spectra at 6S
_1/2
(F=3,mf) - 6S
_1/2
(F=4, mf) - 6P
_3/2
(F=4) transition by applying a 6 Gauss external magnetic field. Radiation patterns of a horn antenna and a patch antenna are characterized by measuring the DROR amplitude, while rotating the antennas 360 degrees relative to the atomic sensor, and the results are compared to patterns measured in the anechoic chamber using traditional methods. Radiation patterns in both polarizations are measured in a single full rotation, by measuring the π and 0 Zeeman DROR fluorescence amplitudes at the same time. In addition, near-field microwave magnetic field radiation patterns of the patch antenna at orthogonal polarizations are measured at 3 mm distance by moving the antenna ±12.5 mm on the horizontal plane. Advantages and possible applications of small-sized atomic sensors in radiation pattern measurements at different polarizations and radiation analysis of complicated emitters such as circuit boards are discussed.