Circularly Polarized Dielectric Resonator Antennas For The 5G Millimeter-wave Wireless Communication

With the development of communication technology,the millimeter-wave（mm-wave）communication has become the future development direction of wireless communication due to the broader bandwidth and lower latency.This advantages also make mm-wave antennas as a hot research area.However,the ohmic loss of metallic antennas increases when the frequency rises to mm-wave band,which seriously reduce the radiation efficiency of metallic antennas.Compared with the metallic antenna,the dielectric resonator（DR）antenna（DRA）has advantages of low ohmic loss and high degree of design freedom.Therefore,the DRA becomes a great candidate for 5G mm-wave wireless communication.In addition,compared with the linearly polarized（LP）antenna,the circularly polarized（CP）antenna has advantages of resisting the polarization mismatch and multipath fading.These advantages of the CP antenna can improve the communication quality of 5G mm-wave communication.Hence,this paper will carry out research on the CP DRA for 5G mm-wave communication.The contributions and innovations in this paper are as follows:（1）The design of a CP DRA for 5G mm-wave communication is proposed.We use a modified cross-slot to feed the rectangular DRA,so that the DRA achieves unidirectional CP radiation aound 26 GHz,and unidirectional LP radiation around 39GHz.The measured reflection coefficient bandwidths(S₁₁<-10 d B)of the antenna are 27.52%（23.5-31 GHz）at lower band and 11.31%（35.09-39.3 GHz）at upper band,respectively.The measured axial ratio（Axial Ratio,AR）bandwidth（AR<3 d B）is12.99%（25.2-28.7 GHz）at lower band.The DRA obtains the measured peak CP gain of 6.1 d Bic at lower band,and the measured peak LP gain of 5.7 d Bi.Then,we demonstrate the parasitic array with four antenna elements to improve the antenna gain.The results indicate the parasitic array obtains the measured peak CP gain of 8.2d Bic at lower band,and the measured peak LP gain of 6.1 d Bi at upper band,which can further meet the requirements of mm-wave communication.（2）The design of dual-band CP DRA for 5G mm-wave communication is proposed.We use a modified cross-flower（MCF）slot to excite a rectangular DRA and the DRA achieves dual-band wide CP radiation characteristics around 26 GHz and 39 GHz.Moreover,the lower and upper bands of the DRA can be controlled independently.The measured reflection coefficient bandwidths of the dual-band CP DRA are 29.3%（23.3-31.3 GHz）at lower band and 25.4%（34.36-44.36 GHz）at upper band.And the measured axial ratio bandwidths are 19.8%（24.75-30.18 GHz）and 7.8%（39.85-43.07 GHz）,respectively.The measured average CP gains are 4.98 d Bic at lower band and 5.76 d Bic at upper band.In order to improve the radiation gain of the dual-band CP DRA,we use the sequentially rotated feeding array technique to form the array of the dual-band CP DRA.The measured CP bandwidths of the sequential rotating feeding array are 31.3%（22.68-31.1 GHz）at lower band and 8.3%（39.45-42.86 GHz）at upper band.And the measured average CP gains are 9 d Bic at lower band and 10.93 d Bic at upper band.（3）The design method of dual-band CP DRA proposed in this paper requires neither precise machining on the structrue of the DR,nor tiny parasitic metallic structure to be loaded on the surface of the DR.Therefore,this method has the potential to realize the mm-wave dual-band CP DRA with higher operating frequency and smaller antenna size.This research contributes to the development of mm-wave CP DRA.