Investigation Of Novel Wideband Dielectric Resonator Antennas

Dielectric resonator?DR?antenna?DRA?is widely used in modern wireless communication system because of its inherent advantages such as high degree of flexibility and versatility,low loss,high radiation efficiency,simple and diverse feed mechanisms,easy to be excited and so on.Moreover,DRA has great potential in millimeter wave?mm-wave?system by virtue of no conductor loss.On the other hand,with the rapid development of wireless communication,the number of wireless communication devices and users is increasing rapidly,and the data exchange rate is increasing,which requires the system to have wider bandwidth to ensure the system capacity and smooth link.Therefore,the antenna also needs wider bandwidth to meet the needs of the communication system.It can be seen that wideband DRA has great research value and application prospect.This thesis focuses on the design of singly-fed wideband DRA,investigating its circular polarization radiation characteristics and its application in mm-wave band.The main contents are as follows:?1?Four vertical metal plates are rotationally introduced to widen the axial ratio?AR?bandwidth of the rectangular DRA excited by the cross-slot.By choosing the size of metal plates properly and arranging the position of metal plates skillfully,orthogonal currents can be induced on the coupled metallic plates due to the interaction with DR.Additional AR passband can therefore be generated,and the AR bandwidth of the conventional cross-slot fed rectangular DRA can be substantially enhanced from?10%to?46.9%,without increasing either footprint or height of the antenna.?2?An mm-wave wideband CP substrate integrated DRA?SIDRA?which is based on high dielectric constant dielectric substrate is proposed.The fundamental HEM_11?mode of the inner DR and the higher order HEM_12?+1mode of the entire embedded DR are combined to enhance the operating bandwidth of the SIDRA.A cross-slot is employed as the excitation,which functions as a hybrid feeding circuit not only help to generate CP fields but also help to further increase the bandwidth.The DR is isolated from the surrounding substrate by two circles of hybrid holes?holes and metallic vias?.Moreover,the substrate integrated waveguide?SIW?cavity composed of metallic vias and the upper copper can improve the directivity of the antenna.For demonstration,a prototype at 26 GHz?the preseted 5G mm-wave band in China?was fabricated and tested,obtaining an impedance bandwidth of 34.6%and an AR bandwidth of about 30%.?3?An mm-wave wideband SIDRA which is based on low dielectric constant substrate is proposed.The SIDRA is realized by using the high dielectric constant substrate in the last work.However,the cost of the high dielectric constant substrate is relatively high and the higher dielectric constant substrate is difficult to obtain.By loading metallic vias on the substrate with low dielectric constant,it can be effectively equivalent to the substrate with high dielectric constant.This method is applied to a slot-fed stacked DRA.A wideband SIDRA is realized at 28 GHz,featuring a bandwidth of 34.1%and a peak gain of 11.2 d Bi.