Design And Investigation Of Filtering Dielectric Resonator Antenna Arrays

With the rapid development of wireless communication technology,modern communication system requires communication devices that can be miniaturized,integrated and multi-functional.As two important devices of RF front-end,the integration of antenna and filter is of great significance.The proposed concept of filtering antenna can eliminate the transition between them and give a more compact size,a lower insertion loss,and a better overall performance than the traditional discrete design.On the other hand,antenna arrays with high gain and narrow beam are demanded for the long-distance point-to-point communication.As a result,the researches of filtering antenna arrays have also attracted broad attention in recent years.However,most of the filtering antenna arrays are concentrated in the field of metal antennas,such as patch antennas and slot antennas.In view of the advantages of dielectric resonator antenna(DRA)with low loss,flexible design and high efficiency,this thesis focuses on the fusion design method of filtering DRA arrays.In this paper,three filtering DRA arrays operating in microwave band and millimeter-wave band are designed and implemented.The main work of this paper is as follows.(1)A 1 × 3 filtering DRA array operating at 5.6 GHz with a simple feeding network is proposed.In this array,the central DRA is excited by slot coupling through a stepped metal microstrip feed line placed under the dielectric substrate,and the two side DRAs are excited by the dielectric bridges placed between the three elements.At the same time,a pair of vertical parasitic strips is introduced on the sidewalls of the central DRA.The array achieves a good filtering effect by resonating the vertical parasitic strips and setting the length of the stepped metal microstrip feed line reasonably so as to obtain two radiation nulls on both sides of the passband.The array obtains an impedance bandwidth of 13.7% with an average in-band gain of 11.4 dBi and an out-of-band rejection of more than 22 dB.(2)Based on the first work,a 3 × 3 filtering DRA array also operating at 5.6 GHz is proposed.The array utilizes the above 1 × 3 array as a subarray,and three subarrays are placed side-by-side to feed by a simple three-way power division network without any complex filtering circuit,and the array achieves good radiation and filtering effects.The measured results show that the proposed array has an impedance bandwidth of 11.4%,an in-band peak gain up to 14.7 dBi,and an out-of-band rejection of more than 24 dB.(3)A millimeter-wave filtering DRA array operating at 25.6 GHz is proposed.The array consists of six rectangular DRAs elements and a feeding network printed below the dielectric substrate.The feeding network consists of a main microstrip feed line and three pairs of microstrip feed lines with upper and lower branches.In addition,two transverse stubs of unequal lengths are introduced at the front of the feed line.Using the half-wavelength characteristics of the metallic microstrip feed line and the resonance of the two transverse stubs of unequal length,the array obtains three radiation nulls on both sides of the passband,and the whole array obtains a good bandpass filtering response.The final array has an impedance bandwidth of 6.2%,an in-band average gain of 11.9 dBi,and an out-of-band rejection of more than 24 dB.