Directional Magnetoelectric Dipole Resonator for Rydberg Atomic Sensors Using Characteristic Mode Analysis

This letter presents a pioneering magnetoelectric dipole (MED) resonator designed to enhance the directional sensitivity. Unlike traditional omnidirectional Rydberg atomic sensors (RASs) that struggle to selectively amplify signals from specific directions, this innovative resonator is directional and foregoes the need for a feed port, which is common in antenna designs. Instead, it boosts RAS sensitivity by intensifying local electric fields, thereby imparting the sensor with the directional properties of the MED and significantly reducing backlobe levels. Guided by the theory of characteristic mode, the resonator features an open cavity with a rectangular ring and two horizontal metal plates, creating magnetic and electric dipole resonator structures. It integrates a local oscillator port to support atomic heterodyne techniques, further improving sensitivity. The design impressively attains a peak electric field gain of 22 dB within a compact size while maintaining stable and directional patterns. These attributes render the resonator ideal for directional detection in RAS applications.