With continuous development of the science and technologies, the electromagnetic wave technologies have penetrated into various aspects of people's life gradually. An important property of electromagnetic waves is that they can propagate in any media or even in a vacuum. During propagation of an electromagnetic wave from a transmitting terminal to a receiving terminal, the energy loss has a direct impact on the propagation distance of the electromagnetic wave and on the signal transmission quality.
The electromagnetic wave suffers substantially no energy loss when propagating through a same medium. However, when the electromagnetic wave propagates through an interface between different media, partial reflection of the electromagnetic wave will occur. Usually, the larger the difference in electromagnetic parameters (e.g., the dielectric permittivity or the magnetic permeability) between the different media at two sides of the interface is, the more the reflection will be. Due to partial reflection of the electromagnetic wave, the electromagnetic wave will suffer an electromagnetic energy loss in the propagation direction, which has a serious impact on the propagation distance of the electromagnetic wave and on the signal transmission quality.
Accordingly, researches have been made on impedance matching in order to reduce signal reflection when the electromagnetic wave propagates through an interface between different Media. However, currently the researches on impedance matching during the electromagnetic wave transmission are still limited to be within circuits, and there is still no sophisticated technology directed to impedance matching during propagation of the electromagnetic wave in space.