High-Efficiency Angled-Dipole Antennas for Millimeter-Wave Phased Array Applications

A high-efficiency microstrip-fed endfire angled-dipole antenna has been developed for millimeter-wave phased array applications. The antenna is built on both sides of a Teflon substrate (epsiv_r = 2.2) and this allows a wideband feed from the single-ended microstrip line to the differential dipole. The design results in wide radiation patterns for scanning purposes with a gain of around 2.5 dB at 20-26 GHz and a cross-polarization level of < -15 dB at 24 GHz. A mutual coupling of < -23 dB is measured between adjacent elements with 6.8 mm center-to center spacing (0.50-0.54 lambda₀ at 22-24 GHz). A variant of the angled-dipole antenna with a magnetic ground plane edge was also developed, and shows a measured gain of > 6 dB at 23.2-24.6 GHz and very low mutual coupling between elements (<-23 dB for a 6.8 mm spacing). Both antennas result in a radiation efficiency of > 93% when referenced to the microstrip line feed (including mismatch loss). The usefulness of these antennas as phased array radiators is demonstrated by several eight-element linear arrays at 22-24 GHz with scan angle up to 50 degrees. The application areas are in automotive radars and high data-rate communication systems.     

A 94-GHz aperture-coupled micromachined microstrip antenna

This paper presents an aperture-coupled micromachined microstrip antenna operating at 94 GHz. The design consists of two stacked silicon substrates: (1) the top substrate, which carries the microstrip antenna, is micromachined to improve the radiation performance of the antenna and (2) the bottom substrate, which carries the microstrip feed line and the coupling slot. The measured return loss is -18 dB at 94 GHz for a 10-dB bandwidth of 10%. A maximum efficiency of 58±5% has been measured and the radiation patterns show a measured front-to-back ratio of -10 dB at 94 GHz. The measured mutual coupling is below -20 dB in both E- and H-plane directions due to the integration of small 50-μm silicon beams between the antennas. The micromachined microstrip antenna is an efficient solution to the vertical integration of antenna arrays at millimeter-wave frequencies     

Design and characterization of single- and multiple-beam mm-wavecircularly polarized substrate lens antennas for wireless communications

Single- and multiple-beam circularly polarized ellipsoidal substrate lenses suitable for millimeter-wave wireless communications have been designed, implemented, and experimentally characterized at 30 GHz. The lenses are made out of low-cost low-permittivity Rexolite material. The single-beam lens achieves a directivity of 25.9 dB, a front-to-back ratio of 30 dB, and an axial ratio of 0.5 dB is maintained within the main lobe. The measured impedance bandwidth is 12.5% within a SWR⩽1.8:1. The single-beam antenna is well suited for broad-band wireless point-to-point links. On the other hand, the multiple-beam lens launches 31 beams with a minimum 3-dB overlapping level among adjacent beams. The coverage of the lens antenna system has been optimized through the utilization of a hexagonal patch arrangement leading to a scan coverage of 45.4° with a maximum loss in directivity of 1.8 dB due to multiple reflections. The multiple-beam lens antenna is suitable for indoor point-to-multipoint wireless communications such as a broad-band local area network or as a switched beam smart antenna. During the proposed design process, some fundamental issues pertaining to substrate lens antennas are discussed and clarified. This includes the depolarization properties of the lenses, the effect of multiple internal reflections on the far-field patterns and the directivity, the nature of the far-field patterns, the estimation of the lens system F/B ratio, and the off-axis characteristics of ellipsoidal lenses     

Design of 45-degree Linearly Polarized Substrate Integrated Waveguide-fed Slot Array Antennas

This paper presents a method of designing substrate integrated waveguide-fed (SIW-fed) slot array antennas. The design theory is based on the circuit model of slot and via as well as the reflection canceling. To prove the feasibility of this method, a 10-element K-band SIW-fed 45-degree linearly polarized slot array antenna with uniform power distribution is designed. By full-wave simulation, the antenna has a good impedance bandwidth of 7.5% and uniform power distribution. Besides, a maximum gain of 15.3dBi is obtained in the broadside and the cross polarization is suppressed below -23.5dB in the boresight. This type of SIW-fed slot array antennas can be a good candidate for microwave and millimeter-wave applications, especially for auto-motive collision-avoidance radar systems.     

An affordable millimeter-wave beam-steerable antenna using interleaved planar subarrays

Design and fabrication aspects of an affordable planar beam steerable antenna array with a simple architecture are considered in this paper. Grouping the elements of a phased array into a number of partially overlapped subarrays and using a single phase shifter for each subarray, generally results in a considerable reduction in array size and manufacturing costs. However, overlapped subarrays require complicated corporate feed networks and array architectures that cannot be easily implemented using planar technologies. In this paper a novel feed network and array architecture for implementing a planar phased array of microstrip antennas is presented that enables the fabrication of low-sidelobe, compact, beam-steerable millimeter-wave arrays and facilitates integration of the RF front-end electronics with the antenna structure. This design uses a combination of series and parallel feeding schemes to achieve the desired array coefficients. The proposed approach is used to design a three-state switched-beam phased array with a scanning width of /spl plusmn/10/spl deg/. This phased array which is composed of 80 microstrip elements, achieves a gain of >20 dB, a sidelobe level of <-19 dB and a 10-dB bandwidth of >6.3% for all states of the beam. The antenna efficiency is measured at 33-36% in X band. It is shown that the proposed feeding scheme is insensitive to the mutual coupling among the elements.     

一种新型圆极化可重构天线

本文利用最大功率传输效率法(MMPTE),通过4个相同左旋圆极化贴片单元作为子阵来实现阵列天线圆极化可重构.通过在被设计阵列(作为发射阵列)远场区引入极化控制接收天线,可以将整个收发系统看作一个无线功率传输系统,这样就可以把阵列天线的设计问题转换为一个天线之间的传输效率最优化的问题.通过调节接收天线的极化方式和接收位置...     

Full-Wave Analysis of Monopulse Dielectric Lens Antennas at W-band

Lens antenna is a good substitute for the Cassegrain antenna at millimeter-wave frequencies, especially at W-band. On one hand, the antenna design, which is bulky and heavy at low frequencies, becomes compact and light-weighted at W-band. On the other hand, without the blockage caused by the sub-reflector and the feed horns which are unavoidable in a Cassegrain antenna, the lens antennas show better radiation characteristics. In this paper, several lens antennas fed by metal horns are analyzed using a full-wave method-finite element method based on the weak form of the Helmholtz equation (WF-FEM). Numerical results show that the lens antennas presented have low side lobe level (SLL), and good sum and difference performances.     

A variable-coverage satellite antenna system

A multibeam antenna system and-combiner switch capable of producing a variable-coverage radiation pattern are described. The antenna consists of a waveguide lens illuminated by a 19-element feedhorn array. The combiner switch consists of a corporate arrangement of variable power dividers; the latter is made up of two phase shifters and two conventional hybrid power-dividers. An earth-coverage radiation pattern with less than 2-dB ripple and an antenna gain ≈ 20 dB is obtained by equally exciting all beams of the muItibeam antenna simultaneously. Excitation of a single feedhorn results in a narrow beam with an antenna gain ≈ 30 dB and a near-in sidelobe level less -20 dB. The side|obe level can be reduced appreciably by appropriately exciting the adjacent feedhorns. The frequency bandwidth corresponding to 0.5-dB decrease in antenna gain is 10 percent. A technique for computing the radiation properties of the antenna is described; the agreement with measured data is shown to be excellent.     

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%)     

A multielement high power monopulse feed with low sidelobe and high aperture efficiency

A multielement high power monopulse feed was investigated for excitation of a phased array. This feed has the advantages of high antenna efficiency, effective independent sidelobe control for the sum and difference patterns, and high power handling capability. A 32-element device has been designed which yields theoretical sidelobe levels less than -31 dB for both the sum and difference patterns over the 2800 to 3200 MHz frequency band. The aperture efficiency is 69.5 percent which includes 0.1 dB spillover loss and 1.40 dB tapering loss. The difference slope efficiency defined as the actual slope gain over the maximum possible value is 50 percent at midband. An experimental feed was constructed to verify the predicted performance characteristics. Measured data on both the radiation patterns and the antenna gain agreed very Well with the analytical results. The measured sidelobe level is below -30 dB for all sum and difference beams over the 2800 to 3200 MHz. In addition, this feed can be designed for low power intensity at the feed aperture so that very high power operation can be attained.     

A survey of possible passive antenna applications ofhigh-temperature superconductors

A survey of possible applications of high-temperature superconductors (HTSs) to antennas and antenna feed networks is presented. The frequency range considered is 1 MHz for 100 GHz. Three antenna application areas seem appropriate for HTS material: electrically small antennas and their matching networks; feed and matching networks for compact arrays with enhanced directive gain (superdirective arrays); and feed networks for millimeter-wave arrays. Preliminary experimental results are presented on YBaCuO and TlBaCaCuO 500 MHz half-loop antennas that show an increase in radiation efficiency (compared with a copper antenna at the same temperature) by a factor of 5 for the HTS antennas     

A retrodirective antenna array using a spatially fed localoscillator

This work investigates a spatially fed local oscillator (LO) for a retrodirective antenna array. Compared to conventional planar transmission-line feed networks, the spatial feed offers a more flexible array layout and easier implementation, especially in large two-dimensional (2-D) arrays. This method of delivery involves radiating the LO through free space to the back-side of the array where it is received by slot-coupled patch antennas and delivered to the mixing elements. A four-element linear retrodirective array utilizing this approach is demonstrated at an LO frequency of 10.7 GHz. Retrodirectivity is observed at scan angles from -40° to +40°     

低耗低剖面单层波导阵列天线研究

新型单层波导阵列天线具有低耗、低剖面、结构紧凑、实用性强等诸多优点, 在毫米波甚至太赫兹无线通信领域具有巨大应用潜力, 是当前的研究热点。 文章首先介绍了用于构建波导阵列天线的几类波导馈电网络的特点, 指出E 面波导馈电网络在毫米波应用领域的优势,接着针对E 面波导在单层并馈波导阵列天线和Butler矩阵多波束阵列天线方面的研究展开叙述,最后给出了可应用在单层波导阵列天线中的开口波导辐射单元在实现多频和圆极化等不同功能上的最新研究进展。 文章对于低耗低剖面单层波导阵列天线的发展及其应用具有参考价值。     

A high aperture efficiency, wide-angle scanning offset reflectorantenna

A unique single offset reflector antenna has been designed which provides as much as ±30° of scanning in azimuth while maintaining a much higher aperture efficiency than a torus antenna. Like a torus antenna, different portions of the reflector are illuminated for each scanned beam. The reflector profile curve in the plane of scan is found by least squares to minimize the error for the beams with the greatest scan angle, and then polynomial terms of up to sixth order which minimize nonplanar phase errors are added to produce a three-dimensional reflector surface. Numerical simulation indicates very good results for all 0.5° beams in the ±30° azimuth field of view, with peak gain no more than 0.3 dB below ideal and highest side-lobe levels no worse than 13.3 dB below the peak gain. Additionally, comparable performance can be extended to the elevation plane out to 15°/-30°, although full azimuth performance becomes compromised at extreme elevation scan angles. By using an offset design, there is no blockage of the outgoing beam by the feed array assembly for azimuth scanning. With better feed performance than comparably sized paraboloids, and being more compact than similar torus reflectors, this novel antenna should find numerous uses in spacecraft and terrestrial applications     

毫米波车地通信的小型化波导螺旋阵列天线设计

高速磁浮列车毫米波车地通信系统要求其车载天线具有小型化、宽频带、圆极化和辐射扇形波束等特点。为更好地满足这些要求,设计一种中心馈电的小型化波导螺旋阵列天线。该天线馈电系统采用同轴波导中心馈电、4路矩形波导并馈的形式,通过改变馈电波导尺寸、耦合探针长度以及末端采用波导同轴转换器等形式,实现了所有单元的等幅馈电;天线单元由低剖面螺旋天线构成,采用顺序旋转技术改善天线的圆极化性能。利用全波电磁仿真软件设计了一款中心频率为38 GHz的28单元波导螺旋阵列天线,并进行了实验测试。测试结果表明：在37~39 GHz频带范围内,天线驻波比小于1.41,增益大于21.7 dB,轴比小于3.6 dB,俯仰面波瓣宽度为4.5°~4.7°,方位面波瓣宽度为29°~29.7°,满足毫米波车地通信系统车载天线的设计需求。     

Submillimeter-wave antennas on thin membranes

Submillimeter-wave antennas have been fabricated on 1-μm thick silicon-oxynitride membranes. This approach results in better patterns than previous lens-coupled antennas, and eliminates the dielectric loss associated with the substrate lens. Measurements on a wideband log-periodic antenna at 700 GHz, 370 GHz and 167 GHz show no sidelobes and 3-dB beamwidths between 40° and 60°. A linear imaging array has similar patterns at 700 GHz. Possible applications for membrane antennas include wideband superconducting tunnel-junction receivers for radio astronomy and imaging arrays for radiometry and plasma diagnostics.     

5G毫米波有源阵列封装天线技术研究

提出了一种5G毫米波有源阵列封装天线.该阵列由8×16个微带天线单元组成,通过耦合式差分馈电,天线实现了宽带匹配和方向图高度对称特性.通过对天线与芯片进行合理布局,减小了芯片射频端口到天线子阵的馈电线损,提高了有源阵列天线的整体效率.测试结果表明,该阵列天线在工作频段为24.25～27.5 GHz的等效全向辐射功率(E...     

Combination dielectric resonator, power combiner, and antenna

A rectangular dielectric resonator housed in a cutoff parallel-plate waveguide is used both as a radiating element and microwave power combiner. The resonator is excited by using tuned electrically short monopole antennas to induce a longitudinal electric operating mode. The resonator is then used in conjunction with free-running oscillators in order to provide, via mutual injection locking, stable in-phase power combining. Furthermore, the resonator is arranged such that one of its faces radiates a portion of the power-combined signal. Since the resonator is housed in a cutoff waveguide, the cross-polarization radiation from the antenna is suppressed. It was found that, for a single element, a gain in the azimuthal plane of 5 dB could be achieved and, for a two-element array, a gain of 7 dB was obtained with better than -25-dB cross polarization for each case. The oscillator power-combining efficiency for a single-element antenna (two oscillators) was 91%, and the spatial power-combining efficiency for a two-element antenna array, (four oscillators) was found to be 90%. In addition, it is shown that the presence of the dielectric inserts in conjunction with coupled oscillator dynamics provides moderate overall oscillator phase noise improvement     

一种Ka频段高效率圆极化宽角扫描波导缝隙相控阵天线

该文提出一种新型小尺寸、低剖面、“f”字型波导缝隙圆极化器,高度仅1/6波长,宽度约2/5波长。基于该圆极化器,设计了一种高效率、低剖面、圆极化脊波导缝隙线阵天线。为满足空间应用中对轻质、高效率、圆极化、±60°宽角扫描相控阵天线的需求,采用该线阵天线作为阵元设计、仿真并实现了16阵元Ka频段脊波导缝隙相控阵天线。仿真和实测结果表明,该相控阵天线可实现1维±60°宽角扫描。在扫描角范围内,相控阵天线的轴比小于4.1 dB,增益下降小于4.3 dB。在0°扫描角工作时,天线的实测增益为35.9 dBi,辐射效率接近85%。     

A microstrip array feed for land mobile satellite reflectorantennas

A circularly polarized feed array for a spacecraft reflector antenna is described that was constructed by using linearly polarized microstrip elements. The array has seven subarrays which form a single cluster as part of a large overlapping cluster reflector feed array. Each of the seven subarrays consists of four linearly polarized microstrip elements. The array achieved a better than 0.8-dB axial ratio at the array pattern peak and better then 3 dB antenna gain to 20° from the peak, across a 7.5% frequency bandwidth. A teardrop-shaped feed probe was used to achieve wideband input impedance matching for the relatively thick microstrip substrate. The low impedance and axial ratio bandwidths were achieved using a relatively thick honeycomb substrate with the impedance-matching feed probes