However, space-time coding can alter the direction, frequency, and amplitude of the electromagnetic waves from the new-generation antenna, known as a "sideband-free (STC) metasurface antenna."Successful combination of two research advancesProfessor Chan Chi-Hou, Chair Professor of Electronic Engineering and an Acting Provost at CityU, confirmed that the antenna is a successful collaboration of space-time coding techniques and amplitude-modulated (AM) leaky wave antennas.In 2020, the AM leaky-wave antennas concept was first proposed by Dr. Wu Geng at CityU, a postdoctoral fellow in the State Key Laboratory of Terahertz.This breakthrough eliminated unwanted harmonic frequencies, referred to as 'spectrum pollution', while increasing the antenna's directivity beam for secure communication.Professor Chan's amazing innovation harnesses the power of a RADAR-like STC metasurface antenna, allowing it to focus its energy into a single point with adjustable or fixed focal lengths."