Study On Millimeter-wave Wide Band Integrated Antenna Based On GWG Technology

With the development of electronic information technology,the millimeter-wave frequency band has the advantages of wide absolute bandwidth,more available frequency bandwidth,and higher gain under the same physical size.Besides,the millimeter-wave has significant advantages in broadband communication,high resolution detection,radar imaging,and other fields.In the communication systems,it is necessary to improve the transmitting and receiving efficiency,signal isolation,and anti-interference ability.However,the increase of working frequency increased dielectric loss in substrate,and atmospheric absorptions affect the transmission efficiency of electromagnetic(EM)waves.The formation of arrays is an efficient way to compensate for the space loss to some extent,but dielectric losses and surface waves will increase as well.Meanwhile,the requirement of machining accuracy in millimeter-wave increases too.To realize the wideband antenna array in millimeter-wave with high gain,high integration and high reliability,the low-loss Gap Waveguide(GWG)transmission lines are combined with the high-performance magneto-electric dipole(ME)antennas.Based on different fabrication processes,some millimeter-wave antenna arrays are studied and designed.On the one hand,the GWG technology is studied as an important part of the low-loss millimeter-wave feeding network,and the wideband and high-gain ME antenna arrays are designed.On the other hand,the millimeter-wave high performance GWG based antennas are studied to reduce the transition loss and design antenna array with wideband and high integration performances.The GWG technology is combined with different kinds of fabrication processes to design the antenna arrays with high integration in millimeter-wave frequency.The advantages of GWG antennas in the millimeter-wave frequency band are shown clearly in this thesis.The main work of this thesis is as follows:1.Study and design of millimeter-wave dual-polarized array antenna with GWG-SL hybrid feeding: Taking advantage of Low Temperature Co-fired Ceramic(LTCC)multi-layer processing technology,the feeding networks of the dual polarized array antennas are arranged in different substrate layers.The wideband ME antennas are combined with the GWG feeding networks to realize the millimeter-wave array antennas.Firstly,the the working principle is shown based on the characteristic mode analysis to highlight the excellent performance of the ME antenna.Based on the LTCC multi-layer technology,the strip line(SL)located in different substrate layers and coupling slot feedings are combined to design the dual polarized ME antenna with wideband,high gain and high isolation performances.Secondly,the serialparallel hybrid feeding method arecombined with the main GWG transmission network to realize low loss GWG-SL hybrid feeding network in LTCC substrate.Finally,by cascading different layers of the structure,the 8×8 high integrated,wide band,dual polarized ME antenna arrays are designed and packaged in the LTCC substrate.The fabrication and measurement results indicate that the dual polarized highly integrated ME antenna array designed in this chapter has wide-band and high-integration performances in millimeter-wave frequency band.2.Research on millimeter-wave wideband circular polarized ME antenna array with GWG high order mode feeding: Based on the traditional machining and multi-layer PCB processing technology,a W-band circular polarized antenna array is designed by combining the circular polarized ME antenna element with metallic ridge GWG and groove GWG high order mode hybrid feeding network.Firstly,the ridge GWG is converted to the groove GWG,and a 1×2 resonate cavity is designed based on the short-ended terminal with periodic metal pins.The ME antenna is fed by coupling slot at an appropriate position with field analysis.A1×8 circular polarized linear array with wide bandwidth and high gain performances is designed based on the ridge GWG power divider.Secondly,the 1×2 resonate cavity is expanded by enlarge the terminal of groove GWG,and the highest mode cavity are designed under the guarantee of feeding efficiency.Besides,the structure and performances of the ME antenna are improved.A compact 4×8 array antenna is designed by combining the GWG checkboard slot coupling feeding networks with the improved ME antennas.Finally,the fabrication and measurement results indicate the low loss and wide band characteristics of GWG high order mode cavity feedings,and low cost,high gain,and wide band performances of the circular polarized ME plannar antennas in millimeter-wave band.3.Study and design of millimeter-wave wide band two-dimensional phase and frequency scanning GWG leaky wave antenna array: The 3D printing technology is explored to combining with the GWG structure in millimeter-wave frequency band.A twodimensional phase and frequency scanning antenna array is designed by combining the GWG frequency sweep leaky wave antennas with the GWG Butler matrix.Firstly,the controlling method of the metallic pins in the GWG leaky wave antenna is studied.By controlling the size and height of the metallic pins,the frequency scanning GWG leaky wave antenna is designed with low side lobe performances.Secondly,the devices include coupler and cross over are designed based on the interlayer slot coupling,and the Butler matrix for millimeterwave are designed based on these devices.Finally,a four-layer wide band GWG antenna with highly integrated structure is designed by combing the antennas with the Butler matrix,and some support pins with improved height are arranged around the array.The frequency scanning and phase scanning performances of the antenna array are measured after fabrication.The prospect of 3D printing process in application of millimeter-wave antenna array and the fusion between GWG structure and this process are verified in this chapter.4.Research and design of novel high-performance millimeter-wave antenna and array based on GWG technology: Based on GWG transmission line,two novel millimeter-wave antenna elements with wide band and high gain performances are explored in this chapter.Firstly,a novel antenna is designed based on the inverted microstrip GWG transmission line.A resonant cavity is designed at the transmission terminal,and the EM energy radiate from the corresponding apercture of this cavity.The high order mode of EM wave resonates in the cavity,and has great influence on the radiation performance of the antenna.Secondly,based on the research of metallic double-sided GWG transmission line,the energy is transimitted to the terminal with open circuit and radiates out in the end.Meanwhile,the working principle of the ME antenna are combined to design this novel wide band and high gain end-fired GWG antenna element in millimeter-wave.The metallic ridge is extended,and several pins are loaded on the ridge to improve the radiation performances of the antenna.Based on the above two antenna elements,the 1×4 linear arrays are designed and fabricated.The measured results verified the application prospect of GWG technology in high performance millimeter-wave antennas.