Study On Key Technology Of The Ultra-widevabd Endfire Antenna And Its Applications

Antenna is an indispensable key part of wireless communication systems, itsperformance plays a decisive role in whole systems. Similarly, the endfire antennaelement or array on the surface of missile, which is responsible for sending andaccepting the electromagnetic signals, determines the battlefield performance when theanti-radiation missile acquires and tracks the target, and launch directional attack on theradiating source. With the rapid development of modern anti-radiation missile, thetechnological requirement of antenna is becoming higher and higher. For example, theantenna is expected to work at high gain, wide3dB beamwidth, low sidelobe level, verywide bandwidth, small size, simple install configuration, and so on. Meanwhile, theantenna also suffers from the effects of metal surface and dielectric antenna radome,which further increase the design difficulty. If we use conventional antenna-designtechnique to design an antenna which meets the engineering requirements andovercomes the difficulty, it is a very highly challenging. Thus, it is necessary to researchon the key technique of endfire antenna, and break through the technical difficulty byusing other correlative electromagnetic subject. Under the support of the State KeyLaboratory Foundation (Research of Endfire Conformal Direction-Finding AntennaArray), this dissertation, based on original Vivaldi antenna and log-periodic antennaarray, explores or develops compact ultra-wideband endfire antenna structure andworking mechanism, and researches and resolves the key techniques of ultra-widebandendfire antenna which is suitable for the surface of missile, such as, theory, design,measurement, and so on. The main research workings are as follow:1. A wideband high gain balanced Vivaldi antenna is proposed: because originalbalanced Vivaldi antenna has very low gain value in endfire direction when it isworking in high frequency ranges (>11GHz), and the main beam direction of that willdeviate from endfire direction largely, this chapter adopts a novel technique ofelongating of the supporting substrate of an original balanced antipodal Vivaldi antennabeyond its aperture, and shaping of triangular configuration, which lead to the mainbeam direction close to the endfire direction. And then, the antenna will be modified byonly cutting triangular patch along the terminal of two dual exponential curves, andloading three I-shaped notched slots on the edge of every copper layer, which further enhances the front-end ratio of radiation field. Finally, the chapter also analyzes theeffect of metallic surface on the radiation field when the proposed antenna is placednear a metallic surface.2. The section first analyzes the radiation characteristic of endfire antenna placedon surface of metal cylinder: the chapter uses the balanced Vivaldi antenna as theelement of direction-finding antenna array, and analyzes the radiation field of thehorizontally polarizated antenna placed on metal surface, aiming to find the variation ofthe radiation pattern.3. A compact ultra-wideband monopole antenna with vertically polarizedcharacteristic is proposed: Firstly, by using designed theory of conventional uniplanarVivaldi antenna, a monopole configuration is proposed, then selecting anexponent–shaped exterior edge configuration and integrating with a resistance of100in the end of the proposed antenna, which lead to further add resonant frequencybandwidth. On this basis, a parametric study is presented for knowing the variation ofthe radiation pattern, aiming to obtain optimal dimension.4. Effect of dielectric antenna radome on radiation pattern of the endfire antennamounted on a large conducting cylinder is presented: There are few literatures whichdiscuss the effect of antenna radome when the proposed endfire antenna is placed on theexterior of dielectric antenna radome, so the chapter firstly presents some physicsperformance and deduces the expression of power transmission coefficient when amodel simulating slanting the incidence of the TE waves or TM waves into thedielectric slab is adopted, and uses the graph curve attribute to show the effect ofdielectric board on the radiation field. Subsequently, by using theoretical analysis thesection shows the comparison between effects of dielectric antenna radome onhorizontally polarizated antenna and vertically polarizated antenna, and summarizes theeffect of dielectric antenna radome on radiation field of different polarization antenna.Finally, a parametric study showing the impact of the various parameters of dielectricantenna radome on the vertical-polarization antenna performance is presented.5. It puts forward the constant radiation condition of monopole log-periodicantenna, and designs a monopole log-periodic antenna array which is suitable forplacing on the surface of missile. The section, based on the design theory of classicallog-periodic antenna array, analyzes and studies the constant radiation condition ofmonopole log-periodic antenna array, then designs a wideband monopole log-periodic antenna array placed on the surface of missile, which possess practical engineeringapplication.