| The integration of several systems with various purposes is one of the advancements in wireless technology.Antennas,an essential part of wireless systems,must be developed to meet the requirements of multi-function and multi-system integration.The term "multiband shared-aperture antenna" refers to the multi-band antenna with radiation aperture reuse.In contrast to the traditional single frequency array antenna,several antennas with multiple operating frequencies,polarizations,and feeds are combined into the same aperture.As a result,the occupied area of antennas is significantly reduced,and the utilization rate of system aperture is improved.On the other hand,millimeter wave has replaced the lower frequency bands as the primary one employed by the new generation of wireless communication and detection radar due to its greater available bandwidth,faster data throughput rate,and better system integration ability.Shared-aperture integration is also a need for many high-frequency antennas.As the frequencies and frequencies ratio of shared-aperture antennas rise,it becomes more difficult to implement the current shared-aperture methods.Delivering performance that satisfies application demands for bandwidth,channel isolation,and beam coverage is extremely difficult.It is extremely important and essential to study the technology of shared-aperture antenna at millimeter wave band.The improvement of millimeter wave shared-aperture antenna aperture reuse efficiency is taken as the research target in this study in order to address the mentioned problems.Increasing the reuse efficiency of aperture is not just about increasing the efficiency of the millimeter wave band shared-aperture antenna array;it also involves obtain more polarization,enhancing cross-band isolation of a shared-aperture array or element,and enhancing scanning performance using a variety of integration and decoupling techniques.The following is a summary of significant contributions and accomplishments in this thesis:The microwave-millimeter wave shared-aperture array with a large frequency ratio and high aperture reuse rate has been studied.The antenna forms are varied,the aperture utilization efficiency is not very great,and the integration is challenging among the existing shared-aperture antennas with a large frequency ratio.An antenna structure reusing design concept is put out in this thesis.The substrate integrated waveguide slots array,operating at a high frequency of 60 GHz,is reused into a radiation patch capable of handling 3.5 GHz.The edge field effect has been studyed to modify the low frequency operating frequency.At the same time,the cutoff characteristic of SIW at the low frequency band and the compact high frequency resonant structuret integrated on the low frequency feeder are used to realize the high isolations at high and low bands simultaneously.The antenna achieves a high reuse rate of 77% of the shared-aperture and isolations of 65 d B at high band.The related study has been published in a journal that is an ESI high-citation journal for 2020 in the IEEE Transactions on Antenna and Propagation(TAP).One Chinese invention patent and one US patent have so far been approved.The dual polarizations shared-aperture array with a large frequency ratio and high aperture reuse rate has been studied.In the microwave-millimeter wave joint communication,in order to overcome the communication multipath effect and improve the channel capacity,the dual-polarization shared-aperture based on the research of realizing single-polarization shared-aperture is realized in both frequency bands,and the aperture reuse efficiency is further improved.The research is based on the concepts of feed structure reusing and radiation structure reusing.The dual-frequency dualdegenerate mode composite feed is constructed.A five-port hybrid magic T is suggested based on the high-frequency circular waveguide with degenerate dominant mode,which is used to produce the 60 GHz dual-polarization dual-differential feed.Additionally,the magic T is multiplexed as the inner core of a 2.4 GHz half-mode coaxial cavity.The higher degeneracy mode of the half mode coaxial cavity serves as the foundation for the low frequency dual polarization feed.The coupling effect between orthogonal polarizations of the same frequency is minimal since their feed positions are the zero area of each other’s fields.60% of high caliber reuse and low high frequency dual-polarized radiation is realized.The related work has been published on the journal of IEEE TAP.The dual millimeter wave band shared-aperture array has been studied.Ka and W bands are the windows of millimeter wave atmospheric attenuation,which are commonly used in weather radar and cloud and rain detection.Due to the small wavelength at W band and the limited structure types of antennas and feed network,it is difficult to realize the shared-aperture with another antenna array at different band.There is no planar shared-aperture antenna in the existing works with the same frequency.Stacked continuous transverse long slot antennas are proposed for the first time in this thesis,as well as the composite functional waveguides with slow wave at Ka-band and imaginary characteristic impedance at W-band.The issue of high frequency leaking between stacked continuous transverse long slot plates is resolved via the study of a four-port equivalent network and the addition of an electromagnetic soft surface.The waveguide cutoff effect is produced simultaneously in both frequency bands,and the isolations at both bands are increased.The low-frequency radiation performance is enhanced further by reusing the high-frequency continuous transverse long slots structure as a low-frequency inductive impedance matching surface.The Ka-/W-band planarization of a shared-aperture antenna was realized for the first time in this work,with low and high frequency gain and aperture efficiency of 22 d Bi/57% and 28.5 d Bi/33%,and in-band isolation of better than 65/50 d B.The related work has been published on the journal of IEEE TAP.The dual millimeter wave band shared-aperture beam scanning array has been studied.The current K/Ka band shared-aperture antenna for low-orbit satellite communication has a higher channel density,so the strong element coupling,a small working bandwidth,a small beam scanning range,poor isolations will be generated.The research procedures for multi-stage embedded filter feed,induction current suppression,and topology optimization of a certain frequency ratio are provided in this work.Improvements are made to the working bandwidth,scanning range,isolation,and profile.The proposed antenna’s profile of 3 mm is 60% smaller than the existing filter antenna.The isolation has increased by nearly 20 d B in comparison to the existing low-profile antenna,and the in-band isolation of the high and low frequency unit is greater than 38/41 d B.Both high frequencies left-handed circular polarized beam and low frequency righthanded circular polarized beam have a ±60° scanning coverage.The related work has been accepted on the journal of IEEE TAP.One Chinese invention patent has been approved.Ulrich L.Rohde Conference Paper Innovation Award is obtained.The dual millimeter wave band shared-aperture array with an ultra-wide beam scanning range has been studied.Ka-/W-band has a shorter wavelength than centimeter wave,and the high gain,narrow beam and high resolution are easy to achieve.The planar wide-angle scanning antenna is widely used in automobile collision avoidance,shipborne and airborne radar.For the W-band phased array antenna,the main challenge is its still-restricted coverage range and difficulty of integrating another band array.the beam coverage is usually around ±60°.In this design,based on the idea of structural reuse,the combination of artificial magnetic conductor loaded magnetic dipole linear array and metal ground loaded dipole linear array is introduced in the same aperture.The high frequency antenna is reused as the surface element with zero reflecting phase at the low frequency band.The L-shaped LF antenna is employed in place of the traditional linear dipole to address the issue of changing mutual impedance and deteriorating HF antenna direction pattern.With patterns variations within 5 d B,both the HF and LF linear arrays have the beam coverage of 80°.The aperture multiplexing efficiency of millimeter wave ultra-wide beam angle is further improving.Related research has been submitted to IEEE TAP journal. |
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