Research On Broadband And High-gain Millimeter-wave,THz Antennas Based On Different Processes

Millimeter-wave(MMW)and terahertz(THz)spectrum have exten-sive application prospect in the fields such as radar,imaging,high-speed communication due to their advantages of small wavelength and broad bandwidth.Thus,MMW and THz technologies have attracted much at-tention of the researchers from academia and industry.The main focuses of this dissertation include broadband,high gain,high efficiency,low cost,and high integration MMW and THz planar antenna arrays with different fabrication process.The main contents of the thesis are summarized as follows:1.Broadband and high-gain MMW antenna arrays based on the low-loss air-filled rectangular coaxial transmission line in microm-achining technologyThe 60-GHz low loss feeding network based on the rectangular coax-ial transmission line(RCTL)is proposed.SU8 is used to support the in-ner signal line of the RCTL.The RCTL features the advantages of low loss in the MMW bands due to its hollow structure.Then,two 60-GHz high gain antenna arrays are designed based on the low loss feeding net-works.The first design is a 60-GHz probe-coupled-fed circular patch lin-ear polarization antenna array.The parallel dual-probe feeding method is proposed to improve the bandwidth of the single-probe-fed antenna ele-ment.A 2×2 antenna array is designed for high-gain applications.The bandwidth of the 2×2 antenna array is 10.6%(57.9-64.4 GHz).The maximum gain and radiation efficiency of the 2×2 array are 14.6 dBi and 91.4%,respectively.The second design is a 60-GHz circularly polarized(CP)patch antenna array based on the dual-probe feeding method.The two probes in the CP design are placed perpendicular to each other to achieve CP radiation.The phase difference between the two probes is 90°.A sequential rotation feeding structure is adopted to enhance the axial ra-tio(AR)bandwidth of the 2×2 CP array.The 3-dB AR bandwidth of the 2×2 CP array is 15.8%(54.8-64.2 GHz).The maximum gain and radia-tion efficiency of the 2×2 CP array are 14.62 dBic and 91%,respectively.2.Broadband and high-gain MMW substrate integrated wave-guide(SIW)antenna arrays based on the broadband and high effi-ciency radiating structures loading in PCB technologyTwo antenna arrays are designed based on the multilayer SIW slot coupling feeding network which reduces the antenna area.In the first de-sign,a broadband and high-gain SIW-fed magneto-electric(ME)dipole antenna array is proposed.Two pairs of metallic posts act as dipoles and are surrounded by an air-filled cavity.The height of the cavity is designed to be higher than that of the posts to broaden the bandwidth of the anten-na element.The measured impedance bandwidth of the proposed 8×8 an-tenna array is 16.3%from 35.4 to 41.7 GHz for |S11|?-10 dB,and the measured peak gain is 26.7 dBi.The measured radiation efficiency is 83.2%.In the second design,it is proposed to improve the impedance matching and gain of the antenna element simultaneously by stacking a metallic cross-shaped radiating slot atop of a cross-shaped coupling slot.The maximum gain can be enhanced by 2.4 dB compared with con-ventional SIW slot antenna element.For proof of concept,a 4×4 antenna array with a low-loss SIW feeding network is further designed and meas-ured.The measured impedance bandwidth of the proposed 4×4 antenna array is 20.5%from 42.4 to 52.1 GHz for |S11|?-10 dB.The measured peak gain is 19.4 dBi at 50 GHz.The measured radiation efficiency is 81.7%.3.High gain and high integration THz silicon-based on-chip an-tennas based on the cavity-backed dual-resonance structuresTwo THz silicon-based high gain on-chip antennas based on SIW cavity-backed structures are proposed.The SIW backed cavities are de-signed to reduce the surface wave and improve the radiation efficiency in two designs.Firstly,a 260-GHz SIW cavity-backed slot antenna is pro-posed.By adopting dual-slot and cross-shaped feeding line,the band-width is significantly enhanced by 196%compared with the single slot antenna with straight feeding line.The proposed dual-slot antenna shows a measured impedance bandwidth of 15.2 GHz from 248.2 to 263.4 GHz for |S11| less than-10 dB.The measured peak gain of the cavity-backed dual-slot antenna is-2.1 dBi.The simulated radiation efficiency is 31.1%.Secondly,a 340-GHz SIW cavity-backed patch antenna is proposed.The antenna is excited by a strip line.The feeding strip line feeds the patch and the SIW cavity simultaneously to generate two resonant frequencies to broaden the bandwidth.The proposed antenna shows a simulated im-pedance bandwidth of 9.2 GHz from 335.6 to 344.8 GHz for |S11| less than-10 dB.The simulated gain of the antenna at 340 GHz is 3.2 dBi.The simulated radiation efficiency is 56.7%.4.Broadband and high-gain THz LTCC antenna array based on the high order mode substrate integrated cavity feeding networkThe multilayer LTCC SIW feeding network based on high-order mode(TE340 mode)substrate integrated cavity(SIC)is proposed firstly.The proposed feeding network based on TE340-mode SICs uses less vias compared with the conventional TE10/TE20-mode design.The proposed simplified and miniaturized antenna design reduces the fabrication cost and the loss caused by feeding network.The TE210-mode SICs are loaded atop of the radiating slots to improve the impedance matching.The measured impedance bandwidth of the proposed 8×8 antenna array is 10.7%from 130.3 to 145 GHz for |S11|?-10 dB,and the measured peak gain is 20.5 dBi.The measured radiation efficiency is 59.2%.