Researches On Reconfigurable High-gain Wide-angle Antenna

With the rapid development of wireless communication and new radarsystem, the antenna systems are required to possess long range with highprecision, large spatial coverage and flexible beam scanning, thus theantenna unit is required to own wide-angle and high-gain features, whichchallenge the traditional antennas and arrays a lot. Reconfigurable antennaconcepts have been proposed and studied, which release new designfreedom and enhance the performance of the antennas and arrays. Thispaper focuses on the research of the reconfigurable high-gain wide-angleantenna and the application of RF switch on this antenna unit, making asort of innovative achievements.In this paper, a new antenna structure like Chinese character “大”with high gain and wide angle easily realized by direction reconfigurationis presented under the demand of realizing high gain and wide anglesimultaneously, which is based on the theoretical analysis ofhalf-wavelength dipole and corner antenna. The antenna contains fivemetal rods and earth plane to realize three antenna models, thusreconstructing three different radiation patterns. The synthesis ofhalf-power beam width is about124°in E plane and117.2°in H planewhile keeping the antenna low side-lobe level and high gain at7dBi, whichsatisfies the wide beam feature of antenna unit in wide-angle scanningphased array antenna. S-parameter curves and E-plane、H-plane patterns of2.4GHz antenna model are basically consistent with the simulation values,demonstrating the effectiveness and feasibility of the antenna structure. Based on the antenna unit, reconfigurable high-gain wide-angleantennas based on PIN diode switch and MESFET switch relatively arefurther developed. Since RF switches and the controlling circuit have beendifficult problems in the design of reconfigurable antenna for long, PINdiode switch and controlling circuit have been deeply studied during theresearch of the pattern reconfigurable antenna based on PIN diode switch.The paper gives the relationship among the insertion loss、isolation and theinternal equivalent electrical parameters in PIN diode switch, summarizesthe design ideas and topology of controlling circuit used in commonantenna unit integrated with RF switches and presents the propercontrolling circuit used in the pattern reconfigurable antenna based on PINdiode switch. The significance of isolation of PIN diode switch has beenconfirmed after the analysis of experimental results of reconfigurablehigh-gain wide-angle antenna based on PIN diode switch. PIN diodeswitch of less than20dB isolation can’t satisfy the design demand ofpattern reconfigurable antenna based on PIN diode switch, providing asignificant value for the subsequent experimental work and properguidance.This paper is focusing on the isolation of RF switch during thedevelopment of reconfigurable high-gain wide-angle antenna based onMESFET switch. The paper has a deep marketing investigation in highisolation and simple controlling MESFET switches and gives thecomparison of performance, especially analyzes the influence ofapplication environment of MESFET switch to the isolation of MESFETswitch, including the external circuit design, PCB layout and routing.Taking into account that MESFET switch in this paper is applied in thefinite ground, how to ensure the effective transmission of RF signals andkeep the isolation between different RF signals becomes the focus anddifficulty of this antenna design. In order to solve the difficulties, the paperproposes a series of controlling circuit designs and RF PCB layout designs,comprising the effects of short RF lines and the use of high-frequency lumped elements. Consequently, the measured synthesis of half-powerbeam width is about105°in both E plane and H plane while keeping theantenna low side-lobe level and high gain at6dBi, in good agreement withthe simulated results.In summary, this paper presents a novel three-dimensionalreconfigurable antenna, breaking the limitation of traditional printedreconfigurable antenna, achieving the wide-angle coverage in both E planeand H plane while keeping a high gain through reconstructing threedifferent radiation patterns and solving many critical problems incontrolling circuit. It provides a new idea for reconfigurable antenna and aseries of solutions for many key issues of controlling circuit, winning highresearch value.