Research On Millimeter-wave/terahertz Antennas Based On Empty Waveguide Structure

In recent years,with the development of information technology,the millimeter-wave/terahertz frequency band has received extensive attention from academia and industry.The millimeter-wave/terahertz band has abundant frequency resources,which can greatly increase the bandwidth of wireless communication and largely solve the shortage of electromagnetic spectrum.As the key component of the wireless communication system,the performance of the antenna is directly related to the quality of the communication.The millimeter-wave/terahertz antenna design faces many challenges such as high gain,wide bandwidth,low cost,etc.In this frequency band,the substrate integrated waveguide(SIW)and the empty waveguide have attracted much attention due to low radiation loss.However,the dielectric loss of the SIW in the millimeter-wave band directly reduces the radiation efficiency of the antenna,and the use of low-loss dielectric materials leads to high manufacturing costs.The empty substrate integrated waveguide(ESIW)structure can achieve low-loss transmission of electromagnetic waves by removing the dielectric in SIW,and has broad application prospects in the millimeter-wave band.This thesis focuses on the application of empty waveguide technology in millimeter wave/terahertz antenna.The main research contents and innovations are as follows:1.Coaxially-fed ESIW transmission line is realized by FR-4 dielectric substrate.Through modeling analysis and calibration test,the ESIW's low-loss performance of 0.045 dB/cm is obtained in the Ka band.The transmission line structure can be applied to millimeter-wave antennas and antenna arrays,which can greatly reduce the manufacturing cost and improve the performance of the antenna simultaneously.2.For the disadvantages of low gain and narrow bandwidth of the H-plane horn antenna,gain and bandwidth improvement techniques are proposed.The dielectric and the coupling line dual-loading technique is proposed.The realized gain is increased by 4.1 dB in the Ka band,the relative impedance bandwidth is 32.9%,the measured maximum realized gain is 11.3 dBi,and the total efficiency is 79.4%.The rectangular groove dielectric loading structure is proposed in the W band.The realized gain is increased by 4 dB,the measured impedance bandwidth is 19.6%,the maximum realized gain is 14.5 dBi,and the total efficiency is 70.7%.3.Based on the proposed ESIW H-plane horn antenna element,a H-plane horn array is realized in the millimeter-wave band through a 3D printing support structure in the E-plane,which avoids the narrow beam width and the generation of the grating lobes.The measured impedance bandwidth is 31.9%,the maximum realized gain is 17.2 dBi,and the total efficiency is 68%.4.High-gain ESIW slot arrays with cavity loading structure are proposed.ESIW-1×6 and 8×6 slot arrays are realized.The measured impedance bandwidth of the 1×6 slot array is 12.7%,the measured maximum realized gain is 15.5 dBi,and the total efficiency is 90.7%.The 8×6 slot array measured impedance bandwidth is 12.1%,the maximum realized gain is 24 dBi,and the total efficiency is 86.5%.The bandwidths satisfy the application requirements of the 5G millimeter-wave n260 band(37-40 GHz)proposed by 3GPP.5.In order to solve the shortcomings of the high-profile and unsuitable integration of the reflector antenna in the terahertz communication system,a multi-layer coupled wideband,high-gain 140 GHz planar terahertz slot array is designed based on the metal-only empty waveguide structure with a maximum measured gain of 30.4 dBi.