共查询到20条相似文献,搜索用时 15 毫秒
1.
A new technique of synthesis of near-field (NF) amplitude and phase patterns of linear, planar, of volume arrays of finite size or arrays located on a planar contour of finite size is presented. The array could consist of point dipoles or directive elements. The criterion for prescribing the NF (amplitude and phase) pattern information in the synthesis problem for unique determination of array excitation currents is also stated. The proposed near-field synthesis technique is based on the potential integral solution of source currents, Nyquist sampling of the near-field data and the technique of linear least square approximation (LLSA). The NF pattern synthesis technique is illustrated to synthesize a variety of NF patterns with a number of array configurations. Application of the proposed NF pattern synthesis technique to minimize distortion in far-field patterns of arrays mounted on a conducting platform and to realize array antennas with low sidelobes in the near and far field is also presented. 相似文献
2.
A theory for analyzing the behavior of adaptive phased array antennas illuminated by a near-field interference test source is presented. Conventional phased array near-field focusing is used to produce an equivalent far-field antenna pattern at a range distance of one to two aperture diameters from the adaptive antenna under test. The antenna is assumed to be a linear array of isotropic receive elements. The interferer is assumed to be a bandlimited noise source radiating from an isotropic antenna. The theory is developed for both partially and fully adaptive arrays. Results are presented for the fully adaptive array case with single and multiple interferers. The results indicate that near-field and far-field adaptive nulling can be equivalent. The adaptive nulling characteristics studied in detail are the array radiation patterns, adaptive cancellation, covariance matrix eigenvalues, and adaptive array weights 相似文献
3.
4.
Mohammed Adnan Salhi Alireza Kazemipour Gennaro Gentille Marco Spirito Thomas Kleine-Ostmann Thorsten Schrader 《Journal of Infrared, Millimeter and Terahertz Waves》2016,37(9):857-873
We present the design and characterization of planar mm-wave patch antenna arrays with waveguide-to-microstrip transition using both near- and far-field methods. The arrays were designed for metrological assessment of error sources in antenna measurement. One antenna was designed for the automotive radar frequency range at 77 GHz, while another was designed for the frequency of 94 GHz, which is used, e.g., for imaging radar applications. In addition to the antennas, a simple transition from rectangular waveguide WR-10 to planar microstrip line on Rogers 3003? substrate has been designed based on probe coupling. For determination of the far-field radiation pattern of the antennas, we compare results from two different measurement methods to simulations. Both a far-field antenna measurement system and a planar near-field scanner with near-to-far-field transformation were used to determine the antenna diagrams. The fabricated antennas achieve a good matching and a good agreement between measured and simulated antenna diagrams. The results also show that the far-field scanner achieves more accurate measurement results with regard to simulations than the near-field scanner. The far-field antenna scanning system is built for metrological assessment and antenna calibration. The antennas are the first which were designed to be tested with the measurement system. 相似文献
5.
In this paper, we present the idea of using switching techniques in phased arrays in order to reduce the size and cost of the RF/IF circuitry on a smart array system with a given number of array elements. The principle is illustrated using a sectored phased array antenna working on the 5.2 GHz industrial, scientific and medical (ISM) band. The antenna is a four-element dipole array, with two active and two parasitic elements. The array uses a reflective 2P4T switch to route the RF signals to consecutive elements of the array and four pin diode SPST switches for short or open circuiting the antenna elements. The performance of the proposed antenna system surpasses the performance of traditional two-port phased array systems and is comparable to that of four-element planar arrays. Simulated results of the antenna performance and beam-forming capabilities are presented. 相似文献
6.
非对称单脊波导裂缝阵天线分析 总被引:5,自引:1,他引:4
将Elliott关于矩形波导缝阵理论推广运用到非对称单脊波导裂缝阵天线上,在考虑了裂缝外部互耦影响的情况下,给出相应的两个设计方程,同时给出8单元谐振裂缝线阵的具体计算和设计方法。加工样品的近场和远场测试结果证明了本文理论和设计方法是正确有效的。 相似文献
7.
The analysis of a Y-junction laser array is presented. It is shown that the lowest-order cavity mode of this array has the lowest threshold gain and is thus preferentially excited. This mode has a uniform near-field distribution. Compared with the sinusoidal near-field distribution of the supermodes of the evanescently coupled laser arrays, this uniformity not only can delay the onset of the spatial-hole burning, which is the source of unstable far-field characteristic at high power level, it also allows for higher total power output before catastrophic mirror damage. 相似文献
8.
An investigation is presented into the presence of spatial aliasing due to the operation of a linear array in the near-field. It shows that the standard half wavelength sensor spacings rule, which guarantees that no aliasing will occur in the operation of far-field arrays, is not sufficient to prevent aliasing in the near-field. This claim is justified by theoretical considerations and corroborated by simulation results 相似文献
9.
Yu N. Defreez R.K. Bossert D.J. Elliott R.A. Winful H.G. Welch D.F. 《Electronics letters》1988,24(19):1203-1204
The time evolution of the near-field radiation patterns of CW operated inphase locked flared `Y' coupled diode laser arrays has been observed with a streak camera. The arrays exhibit sustained self-pulsation at frequencies as high as 4 GHz 相似文献
10.
High resolution wideband direction finding arrays based on optimumsymmetrical number system encoding
A new interferometer direction finding (DF) array architecture based on the optimum symmetrical number system (OSNS) is presented. OSNS arrays are capable of unambiguous high resolution DF over a wide bandwidth and field of view with as few as three elements, with multiple baseline options. A three element array was designed, fabricated and tested at 8.5 GHz to verify the OSNS concepts experimentally 相似文献
11.
Hajimiri A. Komijani A. Natarajan A. Chunara R. Guan X. Hashemi H. 《Communications Magazine, IEEE》2004,42(8):122-130
Phased array systems, a special case of MIMO systems, take advantage of spatial directivity and array gain to increase spectral efficiency. Implementing a phased array system at high frequency in a commercial silicon process technology presents several challenges. This article focuses on the architectural and circuit-level trade-offs involved in the design of the first silicon-based fully integrated phased array system operating at 24 GHz. The details of some of the important circuit building blocks are also discussed. The measured results demonstrate the feasibility of using integrated phased arrays for wireless communication and vehicular radar applications at 24 GHz. 相似文献
12.
针对点目标扩展函数(PSF)不能有效分析复杂目标在毫米波近场多入多出(MIMO)雷达成像中的散射机理问题,研究了一种基于近场物理光学散射计算数据的毫米波MIMO雷达成像模拟方法。该方法利用近场物理光学方法,获得包含阵列构型和目标散射信息的近场计算数据,并通过近场MIMO成像处理器实现近场MIMO成像的全过程模拟。利用D波段“T”字型二维稀疏MIMO阵对复杂的三维目标开展了近场成像实验,仿真和实验结果表明,模拟结果与实际成像结果有很好的一致性。该方法能够分析近场MIMO成像系统的成像性能,为近场MIMO成像的阵型设计提供支撑,揭示复杂目标的近场散射特性与成像机理。 相似文献
13.
J. E. Sauvageau A. K. Jain J. E. Lukens 《Journal of Infrared, Millimeter and Terahertz Waves》1987,8(10):1281-1286
Voltage tunable oscillators operating at millimeter and submillimeter wavelengths can be designed and fabricated using series arrays of Josephson junctions. The coherent radiation obtained from such oscillators results from the mutual phase-locking of the junction through the high-frequency Josephson current generated in the array. A 40-junction array of Josephson junctions distributed over many wavelengths has been designed, fabricated and tested for operation at 100 GHz. This paper presents the experimental results obtained for this prototype array. A review of the theory for optimizing array design is presented along the implications for power generation at submillimeter wavelengths in future arrays. 相似文献
14.
《Antennas and Propagation, IEEE Transactions on》2009,57(12):3813-3820
15.
16.
17.
An improved technique is presented to scan a beam of a phased antenna array on a ferrite substrate through use of time delays instead of phase shifts provided by nonlinear transmission lines coupled to elements of the array. A coplanar transmission line loaded with a varactor diode when subjected to varied optical illumination offers bias dependent time delays to the elements of the arrays over a wide range of tunable operating frequencies at lower UHF without scan blindness effect. This method results in a broadband ferrite based phased antenna array with reduced weight, loss and complexity of the integrated system. This technique has proved to have a special application potential in case of beam steering by ferrite based microstrip antenna arrays at lower UHF (800 MHz-2 GHz) 相似文献
18.
An active millimetre-wave aperture-coupled microstrip patch and four element array are presented. The design methodology is discussed and experimental measurements between 41 and 42 GHz are presented. The results presented should have useful applications in phased arrays and communication systems at EHF frequencies 相似文献
19.
Microwave diagnosis of antennas is considered as a viable tool for the determination of reflector surface distortions and location of defective radiating elements of array antennas. A hybrid technique based on the combination of the spherical near-field measurements and holographic metrology reconstruction is presented. The measured spherical near-field data are first used to construct the far-field amplitude and phase patterns of the antenna on specified regularized u -v coordinates. These data are then utilized in the surface profile reconstruction of the holographic technique using a fast-Fourier-transform (FFT)/iterative approach. Results of an experiment using a 156-cm reflector antenna measured at 11.3 GHz are presented for both the original antenna and the antenna with four attached bumps. Several contour and gray-scaled plots are presented for the reconstructed surface profiles of the measured antennas. The recovery effectiveness of the attached bumps has been demonstrated. The hybrid procedure presented is used to assess the achieved accuracy of the holographic reconstruction technique because of its ability to determine very accurate far-field amplitude and phase data from the spherical near-field measurements 相似文献
20.
The mutual impedance method for determining the reflection from a loaded dipole array is extended to the case of two parallel planar dipole arrays. The dipole arrays are illuminated by a plane wave with arbitrary incidence angle in either theE - orH -plane. The specular reflection coefficient obtained is shown, with proper design, to have a more narrow stop band with steeper skirts and a flatter top than that for a single array. The near-field coupling is included in the analysis, and the criteria for the validity of a simple transmission line solution are given. For close spacings the near fields may cause the reflection coefficient curve to: 1) not reach unity reflection; 2) attain unity reflection at one frequency; or 3) attain unity reflection at two frequencies, with a shallow dip between. The type of resonance curve obtained depends on the spatial arrangement of the two arrays. The evaluation of the mutual impedance sums is greatly simplified by certain impedance relationships that are presented. Calculated and measured reflection curves for various array separations are included. 相似文献