分类: 地球科学 >> 空间物理学 提交时间: 2017-03-10
摘要: A novel single-layer microstrip reflectarray element with fractal structure is proposed. Ansoft HFSS is used to analyze the reflect phase for the fractal element in honeycomb lattice. A 469-element prime focus microstrip reflectarray antenna composed of the proposed fractal elements is designed, manufactured, and measured. The measured gain level of 29.8 dB is obtained at the center frequency of 13.58 GHz with 1-dB gain bandwidth of 15.3%.
分类: 地球科学 >> 空间物理学 提交时间: 2017-03-10
摘要: This paper present a design for X/Ku dual-band reflectarray antennas with single layer which has two independent radiation patterns for X and Ku bands. In the design, a novel dual resonance structure has been used as the unit cell for both X and Ku band to achieve dual-band performance with a new approach. A 10�0 center-fed reflectarray operating at 9 GHz and 13.5 GHz with scattering angles of 12�and -30�respectively, is designed and the simulated results are presented to validate the approach.
分类: 地球科学 >> 空间物理学 提交时间: 2017-03-10
摘要: A novel X-band unit cell structure with improved bandwidth performance for single-layer microstrip reflectarray antenna is proposed. The new element structure consists of two circular rings, each with a pair of gaps, and two phase-delay lines are attached to the outer ring to provide the required phase shift. A 9� center-fed reflectarray antenna operating at 10 GHz is designed to validate the broadband performance of the proposed unit cell. Simulated results show 20% 1-dB gain bandwidth and 38.5% 3-dB gain bandwidth. The maximum gain at 10 GHz is 20.1 dB, which is equivalent to 40 % efficiency.
分类: 地球科学 >> 空间物理学 提交时间: 2017-03-10
摘要: The W-band full-polarization radar detection system is in need of a new type of antenna feed with good performance. The waveguide slot array antenna, has the advantages of low profile, high radiation efficiency, easy access to high gain. It has been become the research emphasis in the field of millimeter wave detection. In order to satisfy the need of developing complete polarization radar detection system, a W-band four-channel dual-polarization waveguide slot antenna is designed. The results of the simulation and optimization tests show that, the antenna has outstanding technical characteristics in double polarization. The antenna gain is higher than 13dB, and the cross-polarization level lower than -34dB. The bandwidth below VSWR 1.5 is better than 2.8GHz. High isolation of over 50dB is achieved between different polarization input ports.
分类: 地球科学 >> 空间物理学 提交时间: 2017-03-10
摘要: In this paper, a novel X-band broadband single-layer unit cell with attached phase-delay lines for reflectarray antennas is proposed to surmount the limitation of the reflectarray bandwidth. The unit cell is composed of three circular rings, each with a pair of gaps which are mutually placed orthogonally, and two identical circular phase-delay lines are attached to the outer ring to provide the required reflection phase. After the simulation for the unit cell carried out, a large reflecting phase range of about 600�and almost linear phase curve are achieved at the center frequency of 10 GHz. Parallel phase curves of different frequencies ranging from 9 GHz to 12 GHz are also obtained. To validate the broadband performance of the proposed unit cell, a 9 �9 center-fed reflectarray antenna operating at X band is designed and simulated. Simulation results show that the designed antenna has 34% 1-dB gain bandwidth, which demonstrates that an obvious improvement on the bandwidth has been achieved compared to the previous works. Besides, the cross-polarization level is decreased to -40 dB by a mirror symmetric element arrangement.
分类: 地球科学 >> 空间物理学 提交时间: 2016-05-12
摘要: In this paper, we propose a method based on signal processing techniques to improve the performance of aperture antennas, such as a parabolic reflector, used to estimate the Direction of Arrival (DOA) of a signal. Three signal processing algorithms are investigated, including the correlation method, which is used to make an initial estimate of the incidence angle within a certain range. Then inverse matrix method and singular value decomposition method are subsequently utilized to refine the estimate within this range.
分类: 地球科学 >> 空间物理学 提交时间: 2016-05-03
摘要: A KB-band beam-steering leaky-wave antenna (LWA) based on composite right/left-handed (CRLH) rectangular waveguide is proposed and investigated in this paper. The CRLH waveguide is composed of a traditional rectangular waveguide with short-circuited double ridge corrugations periodically mounted on one broadtail. The CRLH structure is air-filled to avoid dielectric loss. A straight long slot is cut on the other broadtail of the rectangular waveguide acting as the radiation aperture to realize a LWA. A balanced condition has been optimized for the LWA to acquire a continuous beam-steering capability from backward to forward quadrants. This capability is verified and high-gain performance is realized by simulations. Compared with other planar CRLH LWAs, the LWA proposed in this paper has the advantages of high power capacity, low loss and consistent high gain, which is very suitable for applications in practical radar systems.