Investigations On Millimeter-Wave Low-Profile Substrate Integrated Array Antennas

With the spectrum resources in millimeter-wave band become more scarce,many wireless applications have moved to the millimeter-wave band,such as communications,radar,electromagnetic imaging,etc..Serving as the key component of a wireless device,antenna plays an important role in the entire device.Among various kinds of antennas,the array antenna has been widely used in the fields of communications,radar,remote sensing,etc.,due to its advantages of high gain,beamforming,etc..This dissertation is dedicated to the research of low-cost,low-profile,high-performance millimeter-wave planar array antennas that can be directly integrated with the front-end circuits to meet the needs of different millimeter-wave bands and different applications.The main work of this dissertation is as follows:CHAPETER ONE introduces two Ka-band low-profile stacked-fed planar array antennas,including a wideband linear polarized?LP?array antenna fed by corporate stacked microstrip and substrate integrated waveguide?SIW?feeding structure,and a circularly polarized?CP?magneto-electric dipole?ME-dipole?array antenna with a low-profile microstrip feeding structure.These two designs have dealt with the problems exsited in some previously reported millimeter wave array antenna design techniques,i.e.using of over-thick feeding substrates,using of additional substrates to expand the radiating element into an array,insufficient bandwidth,etc..Design,analysis,and related experimental results of these two arry antennas are introduced,repectively.Both of these two array atennas possess a thin feeding network,and exihibit wide impedance bandwidth,stable pattern,easy expansion,and easy integration.One design has been published in IEEE Trans.on AP,while another has been published in IEEE AWPL,and two patent applications have been filed.CHAPETER TWO introduces a broadband LP substrate integrated ME-dipole element and corresponding array antennas.The ME-dipole element exhibits an impedance bandwidth of 42.78%and good in-band gain flatness.It can be easily expanded into a full-corporate fed array without bandwidth degradation and requiring additional dielectric substrates.Two arrays containing 4×4 and 8×8 ME-dipoles,respectively,were designed,fabricated and measured.The measured impedance bandwidth of both the array antennas are higher than 44%,and the in-band gain variation are less than 3dB.The proposed array antennas possess the superiority of compact structure,direct integration with the front-end circuits,easy expansion,etc.,thus they are suitable for various millimeter-wave applications.The designs have been submitted to IEEE Trans.on AP and a patent application is filed.CHAPETER THREE introduces the Q-band low-profile substrate integrated LP and dual CP array antennas.The dual CP is realized by sequentially rotating subarrays comprised LP SIW-fed patches.Firstly,the design methodology and operating principle of the LP sub-array are introduced,respectively.Then the design of dual CP feeding network based on SIW structure is introduced.The SIW dual CP feeding network is a three-dimensional structure distributed in both the top and the bottom dielectric substrates.The designed LP sub-array and dual CP array antenna are experimentally verified.The measured results show that the dual CP array antenna exhibits an available bandwidth of 8.9%,a polarization port isolation exceeds19dB,an orthogonal polarization discrimination higher than 25dB.The designs have been published in IEEE Trans.on AP,and two patent applications are filed.CHAPETER FOUR introduces three low-profile substrate integrated array antennas for W-band automotive radar applications,including a 1×10 series-fed microstrip patch array antenna,an 8×10 series-fed microstrip patch array antenna based on SIW feeding network,and a wideband 2×8 substrate integrated array antenna with a stable beam based on a multilayer PCB process.The first two array antennas can simultaneously serve as the transmitting antennas in the same radar system to balance the detection range and the field of view.With a symmetrically center-fed SIW feeding network,the third array antenna produces a stable beam within the operation band.The SIW feeding network is stacked beneath the patches,thereby ensures the compactness of the entire array antenna.All of the above array antennas were fabricated and measured.Partial array antennas have been successfully used in commercial automotive radar products.Part of these works has been published in IEEE Trans.on AP,part of the designs have been published in the international conferences procedings of UCMMT2017 and ISAP2019,two associated patents have been authorized,and two patent applications are filed.CHAPETER FIVE introduces an array antenna for both long-and medium-range 77GHz automotive radar applications.When a novel array antenna with a flat-shoulder shaped radiation pattern is proposed as the transmitting antenna in an automotive radar comprising one transmitter and multiple identical receivers,it can meet the demands of both long-range and medium-range detections without switching the operation mode back and forth between the long-range radar scenario and the medium-range radar scenario.The proposed antenna concept is fully introduced to explain its mechanism.An unconventional array was synthesized to achieve the desired flat-shoulder shaped radiation pattern.Prototype of the proposed array antenna was also designed according to the array synthesis result,which consists of several linear series-fed patch arrays and a SIW power and phase distributing network.Fabrication and measurement of the prototype array antenna were completed,showing a good agreement between the measured data and the synthesized as well as the simulation results,thereby validating the design.The proposed array antenna can realize the function which should be realized by two different conventional transmitting antennas with two different channels,thereby reducing the number of transmitting channels and improving the real-time performance of the automotive radar.Corresponding work has been published in IEEE Trans.on AP,and two associated patents have been authorized.CHAPETER SIX introduces a quasi-TM₂₁ mode slotted circular patch that produces boresight radiation and some corresponding array antennas.Firstly,the radiation principle is elaborated.Then,the proposed quasi-TM₂₁ mode slotted circular patch is used as the radiating element to form a one-dimensional array antenna and a two-dimensional substrate integrated array antenna for W-band automotive radar applications based on SIW feeding structure,and experimental verification of these two array antennas is completed;In order to broaden the impedance bandwidth of the quasi-TM₂₁ mode slotted circular patch,a vertically folded slotted circular patch operating at Ka-band has been proposed with a relative bandwidth of 23.24%.A low-profile microstrip feeding structure is used to feed the proposed vertically folded slotted circular patch forming a radiating element.A 2×2 LP array antenna,a 4×4 LP array antenna and a 4×4 CP array were designed based on it,respectively.Experimental verifications of all the three array antennas have been carried out,respectively.These designs have been published in?or submitted to?IEEE Trans.on AP,and one associated pattern is authorized,while two patent applications are filed.In the above works,7 first-author papers have been published in or sumitted to the international journals,i.e.IEEE Trans.on AP and IEEE AWPL,and 2 first-author paper has published in the proceedings of international conferences.Among them,4 papers have been indexed in SCI database,and 5 papers have been indexed in EI database.There are totally 7patents have been authorized,and 10 patents have been filed.