Design Of Filtering Antennas Based On Dielectric Resonator

The rapid development of modern radio frequency communication system puts forward higher and higher requirements for the miniaturized,low loss and low cost of the system.As two key components,filters and antennas are generally designed independently and then cascaded.This will inevitably lead to disadvantages such as insertion loss and large size,which are unfavorable to improve the integration and performance of the system.Filtering antennas are designed to have both radiation and filtering characteristics.It can reduce insertion loss and improve system integration,attracting widespread attention from scholars at home and abroad.At present,the design methods of filtering antennas include:cascade design,comprehensive filter design,and fusion design.Compared with traditional metal antennas,the dielectric resonator antennas have high radiation efficiency,rich resonance modes,and low loss.Because of these advantages,the dielectric resonator antennas have the potential to be designed as high-performance filtering antennas.In this thesis,the literatures related to filtering antennas at home and abroad are investigated.Aiming at the research on filtering antennas based on dielectric resonators,two integrated dielectric resonator filtering antennas are designed.The main research and innovation contents are as follows:1.A dielectric resonator filtering antenna based on microstrip slot coupling feed is designed.The antenna is fed through the microstrip slot coupling,and the dielectric resonator is excited in the TE^x_11δmode.A radiation null is introduced by symmetrically grooving the dielectric resonator.In addition,the length of the microstrip line is extended and a short-circuit metalized vias is added at the end of the microstrip line,so that the current on the microstrip line is about zero near the slot at certain frequencies.Thus,a radiation null is obtained on each side of the passband.The microstrip line is bent into a special shape to reduce the size.Finally,an operating bandwidth of 15.8%（1.85-2.17GHz）,an average gain of 6.62d Bi,and an out-of-band rejection level below-15d B are achieved.The antenna is measured after processing,and the measured results are in good agreement with the simulation results.2.A dielectric resonator filtering antenna based on microstrip patch feeding is designed.The dielectric resonator is fed through a microstrip patch.The size of the microstrip patch coincides with the bottom surface of the dielectric resonator.The metal patch excites the TE^x_21δmode of the dielectric resonator.The electric field of the TE^x_21δmode is out of phase in all directions,thereby introducing a radiation null on the low-frequency side outside the passband.At high frequencies outside the passband,the electric fields of the metal patch and the dielectric resonator are equal in magnitude but opposite in phase.At this time,the dielectric resonator cannot be excited,and a radiation null is introduced.Then,in order to further suppress unwanted out-of-band resonant modes and improve the out-of-band suppression level,a folded U-shaped defect ground structure（DGS）is introduced to achieve good radiation and filter responses.The antenna operating bandwidth is 10%（2.92-3.23GHz）,the average gain of 8.82d Bi,and the out-of-band rejection level exceeds 15d B.The antenna is measured after processing,and the measured results are in good agreement with the simulation results.