Low-frequency metamaterial antenna based on magnetic field coupling effect

Low-frequency(LF) electromagnetic waves have high penetration and low attenuation characteristics in media,making them essential for cross-media communications. In LF communication systems, the loop antenna commonly functions as a receiver for detecting weak signals. However, traditional LF loop antennas typically require large structures to achieve high radiation efficiency, which poses challenges for portability and long-distance transmission. Here, a magnetic resonant coupling metamaterial(MRCM) antenna with high radiation capacity, frequency tunability, direction adjustability, and compact form is demonstrated. To elucidate its radiation mechanism and frequency modulation capabilities, the equivalent circuit model and electromagnetic simulations are carried out. Compared with conventional loop antennas, the MRCM antennas can realize the radiation magnetic flux density seven times and extend the effective magnetic transmission distance by three times. Besides, the MRCM antennas allow for adjustable radiation direction and operating frequency, enhancing its versatility in different application scenarios. This metamaterial antenna design allows a pocket-sized antenna to achieve an effective communication range of 180 m, presenting a promising solution for improving communication capabilities in changing environments such as underwater and underground settings.