Research Of Millimeter Wave Differentially Fed Antenna Based On Integrated Substrate Gap Waveguide

Currently,most of the 5G application frequency bands are the Sub-6G frequency band.The narrow bandwidth of this frequency band is crowded and cannot achieve ultrahigh transmission rates and ultra-low latency.Millimeter wave technology can lead 5G to achieve the required peak rate and ultra-low latency.To reduce the loss in the RF frontend system,differential-fed antenna can not only directly link to integrated circuits,but also suppress the crosstalk and electromagnetic interference produced in the transmission process.And it can easily be integrated with off-the-shelf differential equipment.Due to the introduction of differential signal,differential-fed antenna can offset the radiation leakage generated by single-end feed,reduce cross polarization,and improve the copolarization mode of the antenna.ISGW can suppress the radiation loss of microstrip lines in high frequency band,and has the advantages of self-encapsulation and structural stability.The combination of the differentially fed technology and ISGW in millimeter wave band provides a new idea in the antenna research field.The main contents are as follows:(1)A differentially fed network based on ISGW is designed.Firstly,the two-layer ISGW is designed,and the microstrip line width and insertion loss of the waveguide are calculated.Secondly,the rectangular slot coupling is proposed to open the rectangular gap on the metal floor to form a 180 degree phase difference.The proposed differentially fed network based on ISGW achieves deep matching from 20.5 GHz to 31.5 GHz below-15 d B,and its relative bandwidth reaches 44%.The phase difference does not exceed 3degrees,and the amplitude difference does not exceed 0.01 d B,which meets the design requirements of differential-fed antenna.(2)This paper proposes a differential-fed cross patch antenna based on ISGW.The equivalent circuit diagram of the cross patch is given by the three-port equivalent circuit model of the antenna.At the same time,the frequency point of the resonant antenna is obtained by calculating the input admittance of the equivalent circuit diagram.Some parameters are optimized by using electromagnetic simulation software.The antenna has a bandwidth of 23.88 to 28 GHz below-10 d B,with a relative bandwidth of 15.8%.The antenna radiation pattern is relatively good and the cross-polarization is relatively low.(3)This paper proposes a circularly polarized array antenna based on a ISGW differential-fed network.Using square tangential patch and square open resonant ring can expand the axial ratio bandwidth of the antenna.Firstly,the unit structure of ISGW differential-fed circularly polarized antenna is proposed.The impedance bandwidth below-10 d B of the proposed circularly polarized antenna reaches 18.5%(25.3 GHz-30.1GHz).The axial ratio bandwidth below-3d B reaches 6.7%(25.64 GHz-27.38 GHz),and the maximum gain in the band range is 7.1 d Bi.Secondly,the impedance bandwidth is from 23.9 to 29.25 GHz below-10 d B and the maximum gain in the range is 9 d Bi.The axial ratio bandwidth below-3d B can reach 12.8%(23.89 GHz-27.14 GHz).