The Research And Design Of The Novel High Gain Slot Antenna

Surface plasmon polaritons (SPPs), belong to a kind of electromagnetic waves existing on the interface between metal and dielectric. SPPs generate a strong localized electromagnetic field on metal surface. Nowadays, most of the researches about SPPs focus on the optical wavelengths. However, the characteristics of SPPs also can be applied to the microwave band, millimeter wave band and terahertz band. The research about SPPs in directional antenna is rare.This article includes two parts, the first part focuses on the generating, excitation and propagation characteristics of surface plasmons. The second part introduce two methods about devising high gain antenna. One is Yagi antenna. Another is based on the characteristics of SPPs.In the paper, firstly, we must demonstrate that surface plasmons are existing in microwave band (5-6GHz). Since the metal in the microwave band can be considered as a perfect metal, when considering only a single metal film, it does not support any kinds of surface plasmons, but if some structures carved on the metal, it is possible to support the surface plasmon plasmons. For the electromagnetic waves in microwave band, its frequency much less than the plasma’s frequency of the metal, which limits the application of SPPs in the microwave band. The plasma resonance frequency is determined by the density of free electrons in the metal, so it is possible to change the metal plasma frequency by adjusting the electron density. Such as digging periodic groove on the metal, by adjusting the slot making the plasma frequency is5-6GHz. Second, we will discuss how to excite SPPs. The study found that the electromagnetic wave vector in the horizontal direction is not matched with the wave vector of SPPs, so SPPs can’t be excited. To excite SPPs, we need to make the wave vector of SPPs and the electromagnetic wave vector in the horizontal direction matched. The results show that using periodic grid structure is the most typical way to realize wave vector matched.Afterwards, we will do some research about high gain antenna. In this section we will focuses on a high gain slot antenna with single-layer director. To further improve the antenna gain, we take measures to excite SPPs in surface of the director. When electromagnetic incident to the surface of the director, it will be coupled with SPPs, so that the electric field will be strength improved. In the case of the same size, the gain of antenna enhanced1.5dBi. Finally, we also study how to adjust the antenna radiation pattern by changing the structure of surface plasmons.