Design And Implementation Of Novel Wideband And Folded Reflectarray/Transmitarray Antennas

With the rapid development of modern wireless radio technology,various radios systems have increasingly higher requirements for the antenna performance.High gain antennas have always been one of the research hotspots.Modern radar,long-distance wireless communication and satellite communication systems have put forward more and more extensive requirements for high-gain antennas.However,traditional high gain antennas,such as parabolic antennas and array antennas,all have their own shortcomings.As a new type of high gain antennas,reflectarray/transmitarray antennas,which combine with the strengths of traditional parabolic antennas and array antennas,have many advantages such as simple structures,low cost,without complex feeding networks and with controllable beams,which can be widely used in long distance wireless communications,radar detection and satellite communications.Therefore,it is of great theoretical significance and engineering value to improve and innovate the design methods of different types of reflectarray/transmitarray antennas and constantly improve their performance indices to adapt to wider applications.In this dissertation,in-depth research has been carried out on the wideband circularly polarized(CP)orbital angular momentum(OAM)vortex electromagnetic wave reflectarray,wideband CP folded reflectarray antenna(CPFRA),reconfigurable CPFRA,wideband transmitarray and wideband folded transmitarray antenna(FTA).The main contributions of this dissertation are summarized as follows.1.Design and implementation of a reflectarray for generating wideband CP OAM vortex electromagnetic waves.Based on the in-depth study of the spatial phase distribution and physical generation mechanism of vortex electromagnetic wave,a wideband CP OAM reflectarray for generating vortex electromagnetic waves in X-band is proposed.First,a dual-linearly-polarized element consisting of two rhombus-shaped metal patches etched on two dielectric substrates is designed.The element has high isolations between two polarizations and preferable linear phase responses in wide frequency band.Then,the phase distribution of the reflectarray carrying the OAM vortex wave with mode l=1 is designed,and dimensions of the elements are determined by their reflective phases.The far-field radiation patterns and near-field phase distributions are simulated to verify the proposed design.Finally,prototype of a 313-element reflectarray with a linearly polarized(LP)Vivaldi feed,which converts an incident LP wave into a reflective CP wave,is fabricated and measured.The measurement results indicate that the reflectarray can generate CP OAM vortex wave with mode l=1 in 9-11 GHz band(a fractional bandwidth of 20%).Moreover,the reflectarray also achieves 20% 1 d B gain bandwidth and 40% 3 d B axial ratio(AR)bandwidth.2.Design and implementation of a wideband high-efficiency CPFRA.Based on the CP selective surface(CPSS),a wideband high-efficiency CPFRA is proposed.The proposed CPFRA antenna consists of a simple CPSS on the top layer,a wideband reflectarray plane on the bottom layer and a wideband planar CP antenna as the primary source.First,a simple CPSS based on the traditional Pierrot structure is designed,which can reflect one CP wave while transmit its orthogonal CP wave.Then,a wideband reflectarray based on the sub-wavelength element is proposed.To achieve a low-profile planar structure,a wideband planar CP antenna is chosen as the feed.Based on the ray tracing principle,the distance between the CPSS and the planar reflectarray is reduced to1/2 of the distance between the imaginary feed and the planar reflectarray approximately.Finally,a wideband high-efficiency CPFRA is designed,fabricated and measured.The measured results indicate that the proposed antenna achieves 15% 3 d B gain bandwidth and 23% 3 d B axial-ratio(AR)bandwidth,and its peak gain is 27.8 d Bic at 10 GHz.Its maximum radiation efficiency is 45.4%.Low profile characteristic of the proposed CPFRA makes it be an attractive candidate for some wireless applications.3.Design and implementation of the reconfigurable CPFRA.Two reconfigurable CPFRAs are proposed.The first antenna is a novel reconfigurable CPFRA based on the1-Bit polarization rotation reflection surface(PRRS).The proposed reconfigurable CPFRA mainly consists of four parts,a polarization grid(PG)and a linear-to-circular polarization converter(LCPC)on the top layer,a reflectarray plane with electronically reconfigurable ability on the bottom layer,a wideband plane stacked microstrip patch array antenna as the primary source and a direct current(DC)bias control circuit for controlling lower reflectarray to realize scanning function.Firstly,a novel reconfigurable element based on the 1-Bit PRRS is presented,which contains the square ring loading with two PIN diodes.The element can be used to rotate polarization of the transmission wave by 90° with respect to that of the incident wave by controlling the on-off of two diodes respectively.This unit cell can provide 0° and 180° phase shifts with 1-bit phase quantization in the 5-6 GHz band.Then,by using the proposed element,a 16x16-element reconfigurable CPFRA in the C-band is designed and fabricated.Measured results indicate that the beam scanning angle of the CPFRA achieves within the range of ±40°.Its peak radiation efficiency is about 14%.Measured results show consistency with the simulation ones,demonstrating effectiveness of the reconfigurable CPFRA design method.The second antenna is a novel reconfigurable CPFRA based on the CPSS.Based on the proposed CPFRA,a CPFRA with the scanning function is realized by improving performance of the lower reflectarray.Firstly,a single layer microstrip patch reflectarray element loading with one PIN diode is proposed.By controlling the on-off of the PIN diode,this unit cell can provide 0° and 180° phase shifts with 1-bit phase quantization.Then,a reconfigurable CPFRA in the X-band is designed and simulated.Simulated results indicate that the beam scanning angle of the CPFRA achieves within the range of ±40°.Its peak radiation efficiency is about 15%,which demonstrates effectiveness of the reconfigurable CPFRA design method.4.Design and implementation of the wideband 1-Bit transmitarray based on the polarization rotation transmission surface(PRTS).Three wideband 1-Bit transmitarrays based on the PRTS are proposed.The first antenna is a novel wideband transmitarray antenna based on the substrate integrated waveguide(SIW)PRTS.Firstly,a novel wideband transmitarray element based on the SIW PRTS is designed.The element consists of only one substrate layer sandwiched with two metallic layers,which can be used to rotate polarization of the transmission wave by 90° relative to that of the incident wave.The element and its mirror image can provide 0° and 180° phase shifts with 1-bit phase quantization and more than 80% polarization conversion rates in the 11.5-19.2 GHz band.Then,based on the proposed SIW PRTS element,a 21×21-element wideband SIW transmitarray antenna is designed,fabricated and measured.Tested results demonstrate that the proposed SIW transmitarray obtains 48% 3 d B gain bandwidth,and its peak gain at 15 GHz is 25 d Bi.The second antenna is a novel wideband four-layer metal-only transmitarray based on the metal-only PRTS.Firstly,a novel wideband metal-only polarization rotation element is designed,which consists of four metallic layers without any substrate layers.The element can also be used to rotate polarization of the transmission wave by 90° with respect to that of the incident wave.The element and its mirror image can provide 0° and 180° phase shifts with 1-bit phase quantization in the 9.2-11.2 GHz band with more than 80% polarization conversion rate.Then,by using the proposed element,a 21×21-element transmitarray with a standard pyramidal horn feed is designed and fabricated.The measured results show that the transmitarray achieves 16.8% 1 d B gain bandwidth with a peak gain of 21.6 d Bi.The third antenna is a novel wideband double-layer metal-only transmitarray based on the metal-only PRTS.Firstly,a novel ultrathin metal-only transmitarray element consists of only one metal cavity sandwiched with two metallic layers is designed.The element can also be used to rotate polarization of the transmission wave by 90° with respect to that of the incident wave.The element and its mirror image can provide 0° and 180° phase shifts with 1-bit phase quantization in the13-18 GHz band with more than 80% polarization conversion rate.Then,by using the proposed element,a 21×21-element transmitarray with a standard pyramidal horn feed is designed and fabricated.The measured results show that the transmitarray achieves 25% 1d B gain bandwidth and 36% 3 d B gain bandwidth with a peak gain of 25.4 d Bi at 15 GHz.Tested results agree consistently with the simulation ones,demonstrating effectiveness of the design methods of three wideband 1-Bit transmitarrays.5.Design and implementation of the wideband FTA based on the multilayer frequency selective surface(MFSS)and the PRTS.Three wideband FTAs based on the MFSS and the PRTS are proposed.The first antenna is a novel FTA based on the MFSS with loading PG.The FTA consists of a planar transmission array with PG,a wideband PRRS and a wideband stacked microstrip patch array as the primary source.First,a simple three-layer double-ring transmitarray element with the PG is designed,which can reflect one LP wave while transmit its orthogonal LP wave.Then,a wideband PRRS element is designed,by which one LP wave can be converted into its orthogonal LP wave.Due to the introduction of PG and PRRS,the distance between the transmitarray plane and the feed phase center can be reduced to about 1/3 of the original focal length.A wideband planar feed is also used to illuminate the transmitarray.Finally,a wideband FTA antenna is designed,fabricated and measured.Measured results indicate that the proposed FTA achieves 7% 1 d B gain bandwidth with 24.3 d Bi gain at 21.1 GHz.Its maximum radiation efficiency is about 42%.The second antenna is a novel wideband FTA based on the 2-Bit SIW PRTS.The difference between the second SIW FTA and the first FTA is that the triple-layer MFSS with the loading PG in the top layer is replaced with a double-layer SIW PRTS,which simplifies the antenna design while expanding the bandwidth and reducing the longitudinal height of the antenna.Firstly,based on the proposed 1-Bit SIW PRTS transmitarray element,a new 2-Bit SIW PRTS transmitarray element is proposed,which can be used to rotate polarization of the transmission wave by 90° relative to that of the incident wave.The element and its mirror image can provide 0°,90°,180° and 270° phase shifts with 2-bit phase quantization.Then a novel 441-element FTA in the K band is designed.The measured results show that the antenna achieves 12% 1 d B gain bandwidth with a peak gain of 22.9 d Bi at 21 GHz,and its maximum radiation efficiency is close to37%.The third antenna is a wideband metal-only FTA based on the metal-only PRTS.This metal-only FTA works on the same principle as the second SIW FTA.The proposed metal-only FTA consists of a planar metal-only PRTS,a wideband metal-only PRRS and a wideband circular waveguide as the primary source.Firstly,based on the proposed 1-Bit metal-only PRTS transmitarray element,a novel 2-Bit metal-only PRTS transmitarray element is proposed.Then,the bottom layer metal-only PRRS is simulated to meet the required performance of the array.To make the whole antenna adopt the metal-only structure,the standard circular waveguide is chosen as the feed antenna.Finally,a wideband metal-only FTA is designed,fabricated and measured.Measured results show that the proposed antenna achieves 25% 3 d B gain bandwidth with a peak gain of 27 d Bi at15.5 GHz.Its maximum radiation efficiency is about 36%.Tested results agree consistently with the simulation ones,demonstrating effectiveness of the design methods of three wideband FTAs.