A high-gain 58-GHz box-horn array antenna with suppressed gratinglobes

A low-profile high-gain antenna array of box horns for the frequency band 57.2-58.2 GHz is presented. The antenna consists of 256 radiating elements divided into two subgroups of 128 elements fed by a rectangular waveguide feed network. The radiating elements are fed in parallel and the waveguides are connected with T-junctions. The matching of the T-junctions is improved with a matching pin and a splitter. Because of the waveguide feed network, the element spacing is larger than one wavelength, which causes grating lobes. The grating lobes and sidelobes in the H-plane have been suppressed by the use of a combination of subarrays, a special characteristic of the box horn, and an array amplitude tapering. The measured sidelobe levels in the H-plane are below -30 dB at angles larger than 8° from boresight. A gain higher than 35.7 dBi and a return loss higher than 14.4 dB have been measured for the antenna over the band 57.2-58.2 GHz     

Circularly polarized dielectric-loaded planar antenna excited bythe parallel feeding waveguide network

A new receiving planar array antenna for DBS (direct broadcasting satellite) is proposed. The element antenna is a short waveguide aperture mounted in the ground plane, loaded with a dielectric and polarizers, and excited through its side wall by another feeding rectangular waveguide. The gain of the element antenna loaded with a dielectric is so high that the grating lobes can be reduced sufficiently even if the element spacing in the array is wider than the wavelength in free space. Therefore we can reduce the number of the array elements, and parallel feeding by the low loss waveguide network can be feasible to provide a planar array antenna. This paper describes the experimental results of several kinds of the circularly polarized dielectric-loaded element antennas and the planar antennas fed by the waveguide network. In the 12 GHz band the planar antenna with 64-element radiators has a maximum gain of 31.9 dBi with an aperture efficiency of 94.7%, the 1 dB-down frequency bandwidth of the gain is about 800 MHz (6.7% for a center frequency of 11.85 GHz), and the frequency bandwidth of the axial ratio is less than 1 dB of 850 MHz (7.2%)     

Development of a compact transverse slot array antenna using corrugation in groove gap waveguide technology

We present the proof of concept of a compact slot array antenna with proper side lobe level in groove gap waveguide (GGW) technology. Four transverse slots are etched at the GGW broad wall along with the nulls of standing TE₁₀ wave existing inside the shorted GGW. To decrease the sidelobes and antenna size, corrugations are applied through the wave path inside the GGW. Proper use of corrugations can reduce the wavelength inside the GGW leading to reduction of the distance between adjacent transverse slots, which can help to suppress the grating lobe problem and consequently enhance the radiation efficiency, which is a challenge in transvers slot array antennas. The designed antenna is optimized to achieve maximum gain, lowest grating lobe level, and return loss at 15 GHz using HFSS simulator. The achieved gain is about 13 dBi, and the SLL is better than 15 dB. To confirm the simulation results, the designed antenna was fabricated and tested. Both simulation and measurement results confirm that the grating lobes are well suppressed at the antenna operating frequency.     

A large planar 39-GHz antenna array of waveguide-fed horns

A planar antenna in which box horns are used as radiating elements is described. The feed network is built by connecting rectangular waveguides with T-junctions. The matching of the T-junctions is improved by using rounded splitters and matching pins in the junctions. The radiating element has been designed to cancel out the grating lobe. The grating lobe is due to an element spacing larger than one wavelength. The highest sidelobes are at least 31 dB below the main beam in the H-plane and 16 dB in the E-plane. A gain of 37 dBi has been achieved at 39.2 GHz. These results demonstrate the feasibility of this antenna for applications requiring high gain at millimeter wavelengths     

Phased-array radiator reflection coefficient extraction fromcomputer waveguide simulator data when grating lobes are present

Commercially available finite-element software that solves Maxwell's equations for arbitrary three-dimensional bounded structures has enabled phase-array radiator designers to perform waveguide simulator modeling of phased-array radiating elements on the computer very efficiently. Published work on waveguide simulator design has concentrated on array performance in the absence of grating lobes, a requirement for many radar applications. For such simulators, the reflection coefficient of each propagating mode at the waveguide simulator port gives the radiator reflection coefficient at a discrete scan angle. However, the design of limited scan arrays can lead to selection of an array element spacing that allows grating lobes in real space. When a waveguide simulator is modeled on the computer, and a grating lobe is present, the two waveguide modes representing the main lobe and the grating lobe will propagate in the waveguide simulator and they will be coupled together. The simulator port-reflection coefficient of either mode is not the true reflection coefficient seen by the radiating element. We describe a method for extracting the reflection coefficient of the radiating element from the waveguide simulator data when one or more grating lobes are present     

利用双载频方向图相乘的稀疏均匀阵栅瓣抑制方法

针对稀疏阵列天线间距远大于信号波长导致阵列方向图出现大量栅瓣的问题,该文基于不同载频阵列方向图主瓣与栅瓣相对位置关系存在差异的特性提出一种新型的栅瓣抑制算法。该算法充分利用不同载频回波信息,避免了大规模搜索,有效降低了计算量。首先根据算法原理确定了影响该栅瓣抑制算法性能的因素,然后进一步对影响栅瓣抑制性能的关键参数进行了定量分析,推导得出了栅瓣抑制后峰值旁瓣比(PSLR)与频率差的关系表达式。该表达式为栅瓣抑制快速选择最优频率差提供了理论依据。最后,通过计算机仿真验证了该算法对栅瓣抑制的有效性以及该文所推导的峰值旁瓣比与频率差关系表达式的正确性。     

Grating lobes caused by parallel-plate polariser

An unexpected high-level sidelobe was encountered when a parallel-plate polariser was fitted to a slotted waveguide array. The phenomenon is explained using grating lobe theory and linear near-field measurements. A technique to suppress the grating lobe is proposed.     

94 GHz dielectric slab-line leaky-wave antenna

A leaky-wave planar antenna for millimetre-wave frequencies is described using a dielectric slab line, fed by a slotted waveguide array. The radiation of the planar antenna is induced by line discontinuities such as metallic discs on the guide surface.     

Simulation of a phased-array antenna in waveguide

A method has been developed for simulating a large planar phased-array antenna in order to determine the performance of its radiating elements. By simple measurements of a few elements inside of waveguides, their performance in the antenna array as a function of frequency, scan angle, and polarization may be determined. The number of elements that need to be constructed is small, and the method is well-suited to economical, empirical design of an element for an array having a very large number of elements. For this purpose, such an array is well represented by the infinite array which results from imaging by the waveguide walls. Five waveguide simulators, sampling five significant combinations of scan angle and polarization, have been developed for a particular array comprising circular elements in a square arrangement. The array impedance has been measured in the simulators, and from these measurements the reflection loss of the array has been calculated. An equivalent circuit for the element in the array has been obtained from two simple waveguide-impedance measurements, and the active impedance of the elements has been determined therefrom. Finally, these results have been employed to determine the behavior of the elements when the array is excited for circular polarization; the departure from circularity of the radiated polarization, as well as the reflection in both senses of circular polarization, have been obtained.     

Leaky NRD guide fed microwave planar antenna

A novel and unique application of leaky waveguides as feeding systems for microwave planar antennas is presented. A new leaky nonradiative dielectric (NRD) guide based on a grating structure is proposed, and a planar array slot antenna using this leaky waveguide is constructed and measured at 23 GHz.<>     

High-gain and high-efficiency single-layer slotted waveguide arrayfor use in 22 GHz band

A slotted waveguide planar array using a single-layer feed circuit is proposed for high-frequency and high-gain antennas. The high efficiency of 75.6% and the gain of 35.9 dBi are obtained in the 22 GHz band, which confirms the potential of this type of antenna. The antenna consists of only two components, a slotted plate and a groove feed structure, and can be mass produced     

基于FSS 覆层的高增益稀疏阵列天线设计*

设计了一种基于FSS 覆层的高增益EBG 谐振天线。设计了一种在预定频段内谐振的FSS 单元,作为覆层加载到微带贴片天线上方。仿真结果显示,在5GHz 频点,加载覆层的天线增益为11.43dB。接着,还研究了FSS 覆层在稀疏阵列中的应用,在这个结构中,采用一个2×2 的阵元间距较大的天线阵作为馈源。对该结构进行加工和测试,结果显示天线阵增益为18. 54dB。同时,阵列在E 面和H 面的副瓣分别为-9.17dB 和-12.04dB,避免了栅瓣的产生。     

Trifocal Three-Layer Slotted Waveguide Antenna Array

Journal of Communications Technology and Electronics - A trifocal planar slotted waveguide antenna array consisting of three layers, the first two of which are planar waveguides and the third is an...     

The Millimeter Wave Radiation of a Dielectric Leaky-Wave Antenna Coupled with a Diffraction Grating: Broad-Face Interaction

The millimeter wave radiation of a dielectric leaky-wave antenna (DLWA) coupled with a metallic diffraction grating with a sinusoidal height profile is experimentally investigated. The interaction between dielectric and grating is contactless and it is from the broad-face of the dielectric line. The measured field patterns are compared with the simulated HFSS patterns. Antenna parameters such as polarization, HPBW, cross-polarization and side lobe levels are measured. The effects of the geometrical parameters of the grating to the radiation are also investigated. Some results are compared with a DLWA which has another diffraction grating profile shape (rectangular). The investigated antenna can be used as a frequency scanning antenna in mm-wave radars because it has low cross and side lobe levels and narrow beam width.     

Transverse slot antenna array in the broad wall of a rectangular waveguide partially filled with a dielectric slab

A compact and wide-band transverse slot antenna array in the broad wall of a rectangular waveguide partially filled with an H-plane -dielectric slab is presented in this paper. By partially filling an H-plane dielectric slab in the waveguide, the inter-element spacing between slots is reduced to be about 0.8 free-space wavelengths to avoid grating lobes. In addition, the partially filled material provides extra flexibility to adjust the slot impedance as desired within a relatively wide frequency range. A new feeding network is designed for this antenna array, which can prevent the shift in the pointing angle of the array's main radiation beam with the change of frequency. Experimental data for a 2/spl times/4 antenna array operating at X-band show that stable radiation pattern over a wide frequency range can be obtained. The measured gain is 16.9 dB at 10 GHz and the fluctuation is less than 2 dB over a frequency band of 1.5 GHz. The slot array's 10-dB return loss bandwidth is 13% and the cross-polarization level is better than -25 dB.     

相控阵天线栅瓣效应与规避

相控阵天线由许多阵元排列组成。根据不同的阵元间距和波长的关系,给出了栅瓣出现的位置。搭建了一个试验平台,通过控制扫描角度可以看到栅瓣出现的位置。采用相控阵天线技术结合传统天伺系统的方法,可以扩大天线的扫描范围,并且起到了规避栅瓣的作用。简述了多波束形成过程,论述了阵列天线的空间功率合成,并仿真出天线多波束方向图的理论值,与实验得到的结果相吻合。对工程起到指导作用。     

InP‐Based Polarization‐Insensitive Planar Waveguide Concave Grating Demultiplexer with Flattened Spectral Response

InP‐based planar waveguide 48‐channel concave grating demultiplexers with a channel spacing of 0.8 nm (100 GHz) are described and demonstrated. Polarization insensitivity and flattened spectral response are successfully achieved by the introduction of a polarization compensator and a two‐focus grating, respectively. The fabricated device shows a polarization‐dependent wavelength shift of less than 20 pm and a ?3 dB spectral width of about 0.55 nm (68.75 GHz) over all channels.     

Design of an Efficient X-Band Waveguide-Fed Microstrip Patch Array

The design and fabrication of a 10.5 GHz microstrip patch array fed by a waveguide is presented. The gain of this antenna is 29 dB and its efficiency is 65%. Commonly, the efficiency of conventional microstrip arrays at X-band is not more than 50%. This antenna demonstrates the ability to accomplish a very high efficiency at X-band in a simple structure. This is achieved by using a slotted waveguide to feed the planar array. To allow symmetrical feed of this antenna, the waveguide is a center-fed slotted waveguide, the two ends of which are shorted. The design procedure is expatiated, which contains the study and design of the waveguide-fed subarray structure and of the coax-to- waveguide transition structure. For designing this entire antenna, a three-dimensional electromagnetic field simulation software CST Microwave Studio is applied. Good agreement is achieved between measurement and simulation results.     

平面相控阵天线极限扫描空域分析

基于平面相控阵天线单元间距由设定的扫描空域中不出现栅瓣条件确定，分析了在选定矩形栅格和三角形栅格的阵列单元间距后，平面相控阵天线的极限扫描空域，揭示了相控阵天线尚未被充分利用的扫描资源。     

A compact two-dimensional grating coupler used as a polarization splitter

We demonstrate a novel polarization splitter based on a two-dimensional grating etched in a silicon-on-insulator waveguide. The device couples orthogonal modes from a single-mode optical fiber into identical modes of two planar ridge waveguides. The extinction ratio is better than 18 dB in the wavelength range of 1530-1560 nm and the coupling efficiency is approximately 20%. The device is very compact and couples light only to transverse-electric modes of the planar waveguides. Therefore, it may be used in a polarization diversity configuration to implement a polarization insensitive photonic integrated circuit based on photonic crystal waveguides.