Extreme sub-wavelength magneto-elastic electromagnetic antenna implemented with multiferroic nanomagnets

Antennas typically have emission/radiation efficiencies bounded byA/lambda(2)(A< lambda(2)) whereAis the emitting area and lambda is the emitted wavelength. That makes it challenging to miniaturize antennas to extreme subwavelength dimensions without severely compromising their efficiencies. To overcome this challenge, an electromagnetic (EM) antenna is actuated with a surface acoustic wave (SAW) whose wavelength is about five orders of magnitude smaller than the EM wavelength at the same frequency. This allows to implement an extreme subwavelength EM antenna, radiating an EM wave of wavelength lambda = 2 m, whose emitting area is approximate to 10(-8)m(2)(A/lambda(2)= 2.5 x 10(-9)), and whose measured radiation efficiency exceeds theA/lambda(2)limit by over 10(5). The antenna consists of magnetostrictive nanomagnets deposited on a piezoelectric substrate. A SAW launched in the substrate with an alternating electrical voltage periodically strains the nanomagnets and rotates their magnetizations owing to the Villari effect. The oscillating magnetizations emit EM waves at the frequency of the SAW. These extreme subwavelength antennas that radiate with efficiencies a few orders of magnitude larger than theA/lambda(2)limit allow drastic miniaturization of communication systems.