Study On High Gain Antenna Based On Space Feed Method

With the development of science and technology,more and more demands on long-distance communication and detection are needed.The long-distance transmission of electromagnetic waves has a large space attenuation,which usually needs to be compensated by a large-aperture antenna with high-gain.The reflector antenna,reflectarray antenna(RA)and transmitarray antenna(TA)have the advantages of high efficiency and simple structure.These types of antennas can achieve strong directivity and high gain by simply increasing the aperture size.The ring-focus reflector antennas are widely used,because they have no sub-reflector blockage,compact structure and high efficiency.How to design ring-focus reflector antennas with higher aperture efficiency working in wide frequency band or multiple frequency bands is more significance.New type of planar array antennas(RA and TA)not only could obtain lower profile and lighter weight than traditional reflector antennas,but also has higher gain and efficiency than microstrip array antennas.They have been paid more and more attention in recent years.However,the existing planar array antenna still has some shortcomings such as narrow bandwidth,multiple layers and low efficiency.It is necessary to carry out research on high-performance ring-focus reflector antennas and new type of planar array antennas.The ring-focus reflector antennas and the new type of planar array antennas are studied in this dissertation.The details of the innovative content are as follows:1?Researching on high-performance ring-focus reflector antenna.A new phase efficiency calculation model(PECM)for the ring-focus reflector is proposed to accurately calculate the phase efficiency for a back-fire feed with arbitrary radius of ring-shaped phase center(RSPC).Based on the new PECM,and by using the co-simulation method of HFSS-MATLAB-API,three types of ring-focus reflector antennas are designed,manufactured,and tested.These three antennas use the same ring-focus paraboloid.The first one is a dual-band dual linearly polarized(LP)hat-fed reflector antenna working in 12.25-12.75 GHz and 14-14.5 GHz.The second one is a circularly polarized(CP)hat-fed reflector antenna working in 14.5-16.5 GHz.The corrugated structure is used to expand the beam-width,and hence to increase the illumination efficiency of the feed.The third one is a dual-band dual CP ring-focus reflector antenna working in 19.6-21.2 GHz and 29.4-31 GHz.The dielectric self-supporting axially displaced elliptical(ADE)construction is used in feed design.The measured results indicate that the aperture efficiency of the three antennas is higher than 67.4%,66.58% and 47.6% within the band,respectively.2?Researching on broadband RA.A windmill unit is designed to achieve broadband characteristics by combining the polynomial technology with the co-simulation method of HFSS-MATLAB-API.Based on the element,a broadband RA is designed and manufactured.The measured results indicate that the proposed RA has a 1 d B gain bandwidth of 35%(11.4-15.6 GHz),and has a maximum aperture efficiency of 62% at 12 GHz.Based on subwavelength technology,a meander-line ring element is designed.An offset-fed RA composed of these elements is designed to achieve broadband characteristics.The measured results indicate that the RA has an aperture efficiency of 63.3% at 12.5 GHz and a 1 d B gain bandwidth of 32.8%(11.9-16.1 GHz).3?The design of the metal-only RA.Two types of elements are combined to achieve desire phase distribution of RA.A high-efficiency metal-only RA with dual polarization characteristics is designed and manufactured.The measured results indicate that the metal-only RA achieves a peak gain of 33.8 d Bi at 20 GHz corresponding to aperture efficiency of 58.4%.4?Researching on low-profile RA.Rectangular meander-line rings which has high polarization independence is studied.A low-profile folded RA with a F/D of 0.43 is designed by using folding structure and polarization technology.The measured results indicate that the maximum gain of 30.5 d Bi is achieved at 14.25 GHz corresponding to aperture efficiency of 43.97%,and the 1 d B gain bandwidth is 10.5%(13.5-15 GHz).Another low-profile RA with a F/D of 0.28 is designed by using square patch subwavelength elements loaded with Jerusalem slots,and fed by a hat feed.The measured results indicate that the RA achieves an APERTURE EFFICIENCY of 45.9% at 12.5 GHz and a 1 d B gain bandwidth of 14.4%(11.8-13.6 GHz).The third one low-profile dual-band RA with a F/D of 0.28 is designed by using the elements with high polarization independence,and fed by a hat-fed with wide beam.The measured results indicate that that the RA achieves an aperture efficiency of 41.8% and 37.8% at 12.5 GHz and 14.25 GHz,respectively,and the 1 d B gain bandwidth is 7.2%(12.1-12.9 GHz),6.3%(13.8-14.7 GHz)in the two bands.5?Researching on double-layer TA.A novel double-layer 45° LP element loaded with metal vias structure is presented.The element has broadband characteristics,and could obtain 360° phase shift range without more transmission attenuating.Based on the proposed element,a broadband TA with high efficiency is designed and manufactured.Measurement results indicate that the TA has a maximum gain of 26.9 d Bi at 20 GHz,an aperture efficiency of 53.5%,and a 1 d B gain bandwidth of 12%(18.8–21.2 GHz).A dual-band TA is designed by using two types of multi-resonant dipoles with orthogonal arrangement.The measurement results indicate that maximum gains of 25.2 d Bi,and 27.4 d Bi corresponding to aperture efficiencies of 55% and 49% are obtained at 13.75 GHz and 20 GHz,respectively.Moreover,the 1 d B gain bandwidths of 10% and 6% are also achieved in the Ku and K frequency bands,respectively.A dual polarized TA is designed by using the cross-dipole elements loaded with parasitic L-shaped stubs.The measured results indicate that the proposed TA achieves an aperture efficiency of 56.7% at 20 GHz,and the 1 d B gain bandwidth of 12.5%(19-21.5 GHz).6?Researching on multiple orbital angular momentum(OAM).Superposition of aperture field is used to obtain the desired phase distribution,and a double-layer TA is designed by using two types of elements.Dual-mode OAM vortex beams are produced by the proposed TA.The measured results indicate that the TA could simultaneously generate vortex electromagnetic waves with beam pointing to(0°,15°)and(0°,-15°)corresponding to modes of l = 1 and l =-1,respectively.Another dual polarization TA is designed by using the element with high polarization independence.Multiple OAM vortex waves are produced by reasonable control the phase distribution of the TA.The measured results indicate that the proposed TA could generate vortex electromagnetic waves with beam pointing to(0°,20°)and(0°,-20°)corresponding to modes of l = 1 and l =-1 respectively,when the TA is working at 45° LP.The proposed TA could simultaneously generate vortex electromagnetic waves with beam pointing to(90°,20°)and(90°,-20°)corresponding to modes of l = 2 and l =-2 at the same time,respectively,when the TA is working at-45° LP.