Investigations On Omnidirectional Dielectric Resonator Antennas

In recent years,as a kind of high efficiency,miniaturization,wideband antenna,dielectric resonator antennas?DRA?has been widely concerned and studied,and the performance of the wireless communication system has also put forward higher requirements to antennas.In this paper,the applications of the omnidirectional DRA in the existing wireless communication systems as the background,the theoretical analysis and design of vertically and horizontally polarized omnidirectional DRA mainly focus on widening their broadband and improving the omnidirectionality of the antennas in the horizontal plane.The main parts of this paper are shown as follow:In the first place,we summarize the research background and significance of the omnidirectional DRA.And we make a summary about the research status of DRA at home and abroad,and generalize the main advantages of DRA,omnidirectional antennas and omnidirectional DRA,which lead us to carry on the study about the omnidirectional DRA in this paper.In the second place,the working principle and analysis method of DRA are introduced in this paper,and the modes of cylindrical DRA are classified for pattern classification.And the empirical design formulas about resonant frequency and Q values of common modes are given.The effectiveness of the empirical formulas are verified by simulation.The TM₀₁?mode of the cylindrical DRA is excited by a central fed coaxial probe at the bottom.The designed DRA have a broadband by selecting an appropriate size of the fed probe.Physical processing and testing are carried out,and the experimental results are agreed well with the simulation ones.In the third place,we find out the modes that can produce horizontally polarized omnidirectional radiation pattern in cylindrical DRA,and a new excitement structure is designed to excite the TE₀₁?model.Then a ring DRA is designed an optimized,which works at WLAN band and can radiate horizontally polarized omnidirectional wave at the azimuthal plane.In order to verify the validity of the design method,the protype of the designed DRA is fabricated and measured.Finally,the basic design theory of the antenna array is expounded this paper,which provides the theoretical basis for the design of the lateral radiation array.The problem of vertical polarization omnidirectional antenna array is analyzed,and two ways to avoid the influence of the feed line on the radiation patterns of the antenna are designed.In order to verify the validity of the design methods,the protype are fabricated and measured.The measured results are basically consistent with the simulation ones.Then we study the effect of vertical feed lines on the dielectric ring loaded wideband horizontal polarization omnidirectional antenna array.