Design and Test of a Reconfigurable Broadband Very Low-Frequency Transmitting Antenna

The magneto-electric mechanical antenna (MEMA) does not depend on a servo motor. It offers the advantages of a high modulation rate, small size, and low power consumption, which can address the issue of the rotary mechanical antenna (MA) having a low modulation rate. However, the characteristic of the MEMA that can only operate at the point of resonance results in a narrow bandwidth, which is not conducive to through-the-earth communications. In this paper, a reconfigurable broadband VLF transmitter antenna is proposed with a bandwidth increase of 4 to 5 times. Firstly, we designed a MEMA with a resonance frequency of 5.6 kHz based on the requirements of deep-earth communication. Multi-array MEMA broadband is then investigated to increase the bandwidth by a factor of 5.5 through a three-array parallel connection approach. Finally, the influence factors of MEMA resonance frequency are analyzed based on the Modified Butterworth-Van Dyke (MBVD) model, and the problem of in-band flattening in the multi-array MEMA broadband method is solved. At the same time, we built a miniaturized prototype to test the antenna's performance and communication capabilities, and completed experiments on 140 m air information transmission.