In the traditional wireless communication field, the application of long wave communication is limited in small and medium-sized platforms because it requires large size signal transmitting antennae. Based on the inverse piezoelectric effect, vibration theory, and Maxwell's equations, a three-degree-of-freedom cut-out beam structure of the vibration permanent magnet type mechanical antenna prototype was proposed, established its electric-mechanical-electromagnetic energy theory model and developed the mechanical antenna prototype, studied the radiation influence factors of the mechanical antenna and its frequency modulation technique. The experimental results proved that the electromagnetic wave signals can be frequency-modulated by exciting the different vibration modes of the mechanical antenna prototype, which provided novel ideas from theoretical and technical perspectives for communication of low-band signals.