Research Of Holographic Surface-wave Antennas

In recent years,the concept of holography is very popular.Although the concept of holography belong to the optics region,but in essence,microwave and light waves are the same things.They are two kinds of electromagnetic waves.So,some of the classic ideas and applications in optics,can be extended in the microwave frequency band.In this paper,a surface-wave launcher is implemented to excite cylindrical surface-waves,which are bound to a grounded dielectric slab.By the addition of circular metallic strip gratings,a partially reflecting surface is realized,providing appropriate conditions for 2-D leaky-wave radiation.I write this paper hoping to provide some help for the later researchers.In this paper,we select the SWL as the surface-wave source for the holographic antenna.At first step,we discuss the theoretical foundation.Then a general modeling approach for leaky-wave antennas(LWAs)has been investigated where the radiating aperture is represented as a scalar transfer impedance.This allows antenna engineers to represent LWAs with an equivalent circuit model which is defined by the guiding surface and the employed antenna source configuration.The relationship between dielectric substrates and the efficiency of surface wave are explained.Then,the theory of how to change the surface wave into the leaky wave is discussed.The equivalent circuit model of the antenna structure is established.Then,series of planar leaky-wave antenna based on a grating of concentric annular micro-strip rings fed by a non-directive TM surface-wave launcher are presented.Second,we discuss a useful procedure to design a sin modulated reactance surface which can radiate at any arbitrary angle.In this procedure,the antenna is allowed to nearly independent control of the leakage constants and phase constants above the surface.Then we print an array of metallic strips over a grounded dielectric substrate to practically make the theoretical SMRS come true.A method of mapping these gaps between metallic strips to make sin surface impedance is presented as an much more efficient way compared with the way before.Finally,in the design process,we discuss the idea of lens surface wave antennas,first we analyze several traditional lens surface wave antenna,and then use the method of the decreasing dielectric constant substrate to antenna design,and then use high impedance surface to design a special kind surface lens.