Research Of Metamaterials And Its Applications In Antennas

Research of electromagnetic radiation and related issues is one of the mostimportant issues in the field of physics. Metamaterials consisting of artificial“electronic atom” and artificial “magnetic atom” with their flexible means ofelectromagnetic manipulation provide a new idea for the design of electromagneticradiation devices. This paper focuses on metamaterials and their applications in theantennas and carries out theoretical and experimental studies on the issues. First,around the special requirements of metamaterials for the antennas, we focus on theresearch and development of broadband, low loss and electromagnetic band-gapmetamaterials; Secondly, metamaterials and antennas integration method has beendiscussed after the research on the interaction between metamaterials and antennas,forming a kind of novel antennas with their performance improved. The maincontents and conclusion of this paper are as follows:(1) Research on the broadband, low-loss metamaterials and their applications inlens antennas. With the physical model of broadband, low-loss metamaterials, wehave achieved a broadband, low-loss metamaterial working in microwave band byperiodic metal columns which can control plasma frequency and intrinsic frequencyof metamaterials simultaneously. On this basis, a broadband slab lens has beenconstructed by using of the metamaterial with cross-shaped metal structure as a unit,which can work in whole Ku (12GHz–18GHz) band and bellow band. The slab lenscan convert spherical wavefront or cylindrical wavefront to a plane one throughphase manipulation, which will improve antennas’ gain. Experimental results showthat slab lens can increase the gain of antennas by1.3dB at least over the whole Kuband, which indicates that slab lens based on metamaterials can improve antennas’gain in a wide frequency band efficiently.(2) Research of artificial electromagnetic band-gap metamaterials and theirapplications in mutual coupling suppression. Modulation law of periodic groovestructure on quasi-surface wave has been proposed after deeply study ofquasi-surface wave on metal-air interface with periodic grooves. Then we acquire anelectromagnetic band-gap metamaterial based on periodic grooves, which can’tsupport surface wave propagation on it forming a band-gap. If the metamaterials isloaded on an antenna array surface, it will cut off surface wave transmission path, suppressing mutual coupling between antenna elements. Preliminary research resultsshow that mutual coupling of antenna units will reduce20dB using only cycles ofgroove structures.(3) Research on double-beam, co-aperture waveguide slot array antenna basedon electromagnetic band-gap metamaterials. When using a same aperture to producetwo or more different beams, the surface wave excitated by radiating elements in theconventional waveguide slot array will produce a serious crosstalk between thebeams, and the side lobe levels of all beams will deteriorate. By integratingelectromagnetic band-gap metamaterials into array surface, the transmission path ofsurface wave will be cut off. The mutual coupling between antenna units willdecrease and side lobe levels of the beams will reduce as a result. Based on thecomparison between waveguide slot array antenna with and without electromagneticband-gap metamaterial, the side lobe level is reduced by3.6dB and0.8dBindependently at least for two operation modes of designed antenna. Additionally, wealso focus on the structure design, parts fabrication, wielding technology andperformance testing, etc of the designed antenna, which make the double-beam,co-aperture waveguide slot array antenna based on electromagnetic band-gapmetamaterials more practical in multi-function radar and communication systems.