Measurement of the Near Field Distribution of a Microwave Horn Using a Resonant Atomic Probe

Jingxu Bai,Yuechun Jiao,Liping Hao,Jianming Zhao,Jiabei Fan,Nicholas L R Spong

doi:10.3390/app9224895

Abstract

We measure the near field distribution of a microwave horn with a resonant atomic probe. The microwave field emitted by a standard microwave horn is investigated utilizing Rydberg electromagnetically inducted transparency (EIT), an all-optical Rydberg detection, in a room temperature caesium vapor cell. The ground 6 S 1 / 2 , excited 6 P 3 / 2 , and Rydberg 56 D 5 / 2 states constitute a three-level system, used as an atomic probe to detect microwave electric fields by analyzing microwave dressed Autler–Townes (AT) splitting. We present a measurement of the electric field distribution of the microwave horn operating at 3.99 GHz in the near field, coupling the transition 56 D 5 / 2 → 57 P 3 / 2 . The microwave dressed AT spectrum reveals information on both the strength and polarization of the field emitted from the microwave horn simultaneously. The measurements are compared with field measurements obtained using a dipole metal probe, and with simulations of the electromagnetic simulated software (EMSS). The atomic probe measurement is in better agreement with the simulations than the metal probe. The deviation from the simulation of measurements taken with the atomic probe is smaller than the metal probe, improving by 1.6 dB. The symmetry of the amplitude distribution of the measured field is studied by comparing the measurements taken on either side of the field maxima.

Highlights

Precise measurements of the strength, phase, polarity, etc. of electromagnetic (EM) fields are of great importance for science, communications, and biomedicine, having prominent roles in everyday life
As AT splitting is proportional to the the Rabi frequency [9], the microwave dressed AT splitting is proportional to the microwave coupling, 2πγ AT = Ω MW
Using a room temperature caesium vapor cell as an atomic probe, we have measured the near field of a microwave horn emitting microwaves at 3.99 GHz by analyzing microwave dressed electromagnetically inducted transparency (EIT)-AT

Summary

Introduction

Precise measurements of the strength, phase, polarity, etc. of electromagnetic (EM) fields are of great importance for science, communications, and biomedicine, having prominent roles in everyday life. The radiation field of such a horn can be divided into three parts: the induction near field, the radiation far field, and an intermediate zone. Measurement of the induction near field is advantageous, as these measurements are convenient, have high fidelity, and can provide a large amount of characteristic information. The electric field distribution of a microwave horn can be used to understand the propagation of the microwaves as well as the electric field distribution in the far field, which can be difficult to measure. Measurements of the microwave electric field are made using a dipole antenna as a probe. Probes are calibrated prior to measurement [1,2,3]. With the development of atomic physics and detection technology, one can improve

Methods

Results

Conclusion