Ray tracing on extended hemispherical and elliptical silicon dielectric lenses

In this paper, extended hemispherical and elliptical silicon dielectric lenses are compared by means of ray tracing. It is shown that the optical focuses of two lenses are not at same position though the elliptical lens is synthesized from an extended hemispherical lens by carefully choosing a particular extension length as stated in ref[1]. It may be used to explain why the best compromise between alignment, directivity and Gaussian-coupling effciency will be obtained if the feed antenna is placed at the region between 2.2 mm and 2.4 mm of extension length (for 13.7 mm diameter lens, dielectric contant = 11.7).     

An improved solution for integrated array optics in quasi-opticalmm and submm receivers: the hybrid antenna

A dielectric lens antenna that is a special case of an extended hemispherical dielectric lens and is operated in the diffraction-limited regime is considered. The dielectric lens antenna is fed by a planar antenna that is mounted on the flat side of the dielectric lens antenna, using it as a substrate, and the combination is termed a hybrid antenna. Beam pattern and aperture efficiency measurements were made at millimeter and submillimeter wavelengths as a function of the extension of the hemispherical lens and of lens size. An optimum extension distance for which excellent beam patterns and simultaneously high aperture efficiencies can be achieved is found experimentally and numerically. At 115 GHz the aperture efficiency was measured to be (76±6)% for a diffraction-limited beam with sidelobes below -17 dB. Results for a single hybrid antenna with an integrated superconductor-insulator-superconductor (SIS) detector and a broadband matching structure at submillimeter wavelengths are presented. The hybrid antenna is space efficient in an array due to its high aperture efficiency, and is easily mass produced, thus being well suited for focal plane heterodyne receiver arrays     

Compound Fresnel Zone Lens Conformal to Truncated Cone: Antenna Application

A millimeter wave antenna consisting of two Fresnel zone plate lenses, plane and conical, is examined numerically by use of the vector diffraction theory. The lenses are of Wood-Wiltse (double-dielectric) or Soret (half-open) type, and are designed for the frequency of 117 GHz. The lenses are made conformal to a truncated circular cone with a base diameter of 500 mm and a plateau diameter of 250 mm. Designs for two opening semi-angles, 45° and 75° each of them with a particular lens thickness are presented. For the angle of 90° the cone lens becomes a plane ring lens, which in combination with the plateau zone lens forms a plane lens of size equal to the cone base diameter. Illuminated by directive feeds set at a focal distance of 525 mm from the cone apex, the double-dielectric and half-open compound and plane lenses, form three pairs of Fresnel zone lens antennas, the co-polar and cross-polar radiation characteristics of which have been compared numerically. The double-dielectric lens antennas examined are about 5 dB superior in gain to the half-open lens antennas, which has a gain of approximately 45 dBi. Because all lenses are of equal transverse aperture, the corresponding lens antennas exhibit the same ?3 dB beamwidth of about 0.33 degrees. The plane zone lens antenna is very thin and simple. Instead, the antenna comprising a 3-D compound Fresnel zone lens is thicker but can be made conformal to a specific surface shape and possesses more levels of design and optimization freedom.     

A low sidelobe asymmetric beam antenna for high altitude platform communications

In a communications network served by a high altitude platform, the antenna beams illuminating each cell require minimized sidelobe powers. Asymmetric beams are advantageous so that cell footprints remain circular. At millimeter wavelengths a lens antenna can have the desired properties. We have chosen a 6 km diameter cell at 32/spl deg/ elevation angle and shown how the required beam asymmetry can be implemented using an optimized polynomial for describing the lens profile. The measured average sidelobe level is below -42 dB.     

A variable beamwidth millimetric wave antenna

A preliminary investigation of a millimeter wavelength antenna based upon the optical zoom lens system is presented. The antenna consists of an axial lens system of four elements and possesses a beamwidth that can be continuously varied over a range of 7.7 to 1 at 140 Gc and 5.3 to 1 to 70 Gc by the proper axial motion of its lens elements. An analysis based upon both visible and microwave optics is presented which provides approximate expressions for the beamwidth and gain variations in terms of the positions of the lenses of the system.     

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     

Synklysmotron lenses—A new electron-optical correcting system

This electron-lens system, working in an inverse principle of multicavity-klystron operation at centimeter wavelengths, exhibits diverging lens properties. It can, therefore, be very advantageously used in tandem with the conventional electron lenses of a high-resolution electron microscope in order to correct the spherical abberation of the objective lens (particularly), which is inherently a converging lens. It would, then, be possible to substantially improve the present limitation in the resolving powers of the electron microscopes.     

Resolution of Near-Field Microwave Target Detection and Imaging by Using Flat LHM Lens

It is demonstrated in this paper that higher focusing resolution will be provided by flat left-handed metamaterial (LHM) lens if compared to convex dielectric lens and elliptical reflector focusing system. High-resolution near-field microwave target detection and imaging with flat LHM lens can be implemented by scanning the focal point of the flat LHM lens in the region under detection and screening directly the field intensity distribution of backscattered microwave refocused by the flat LHM lens. Numerical simulations demonstrate that sub-wavelength imaging resolution can be obtained by the proposed approach due to the sub-wavelength focusing resolution of flat LHM lens. Moreover, almost unique imaging resolution for the detection and imaging of target at different depths is also demonstrated. For practical LHM lenses, it is shown that the losses of LHM up to the order as reported in some LHM experiments will limit the sub-wavelength resolution of the proposed approach to an acceptable level.     

Lens design for surface wave applications

A new type of lens is proposed which is effective for surface waves on dielectric slabs at millimetre wavelengths. The lens consists of two identical metallic plates of double convex shape which sandwlch the dielectric slab between them. It is demonstrated that a periodic sequence of the lenses can guide surface beam waves efficiently.     

Small Hemielliptic Dielectric Lens Antenna Analysis in 2-D: Boundary Integral Equations Versus Geometrical and Physical Optics

We assess the accuracy and relevance of the numerical algorithms based on the principles of geometrical optics (GO) and physical optics (PO) in the analysis of reduced-size homogeneous dielectric lenses prone to behave as open resonators. As a benchmark solution, we use the Muller boundary integral equations (MBIEs) discretized with trigonometric Galerkin scheme that has guaranteed and fast convergence as well as controllable accuracy. The lens cross-section is chosen typical for practical applications, namely an extended hemiellipse whose eccentricity satisfies the GO focusing condition. The analysis concerns homogeneous lenses made of rexolite, fused quartz, and silicon with the size varying between 3 and 20 wavelengths in free space. We consider the 2D case with both - and -polarized plane waves under normal and oblique incidence, and compare characteristics of the near fields.     

一种高集成高空间分辨率220 GHz检波器

本文设计了一种高集成检波器,其包含贴片天线、匹配电路、肖特基二极管和透镜。在中芯国际130nm工艺下将天线、匹配电路、肖特基二极管集成到一个芯片上,检波器的集成度相比于分离式有了明显的提高。为增强片上天线的方向性,进行了带有空气腔的尼龙透镜的设计和优化。透镜上的空气腔不但提供了组装空间而且减小了透镜体积。通过测试,天线在220 GHz辐射增益为22 dB,其中透镜贡献约为20dB。检波器测试得到的响应率可达到130-150V/W,对应的等效噪声功率（NEP）估算为400-460 。     

A Luneberg-lens update

Some proposed satellite-based mobile communication systems require multibeam systems at millimeter-wave frequencies. This is a primary factor in the renewed interest in Luneberg lenses. Luneberg (1944) lenses prove useful in a variety of antenna and scattering applications. In antenna applications, their chief advantages are an ability to form multiple beams that may point in arbitrary directions, and their broadband behavior. Lens weight, and complexities involved in manufacturing such lenses, remain their primary drawbacks. Unfortunately, no significant advances in the fabrication techniques have come to pass in forty years. However, operation at millimeter-wave frequencies makes the lens weight inconsequential. The vast majority of the research on spherical lenses took place before computers were commonplace in antenna design. The author reviews some of the applications of Luneberg lenses, and adds some more recent data, generated using a numerical model     

面向毫米波透镜阵列的FNN天线选择算法

为了减少毫米波大规模多输入多输出( Multiple-Input Multiple-Output,MIMO)系统在数据传输过程中所使用的射频链数目,解决高硬件成本和高功耗的问题,可以将透镜天线阵列作为一个实际有效的解决方案部署在毫米波MIMO系统的基站端.利用透镜天线阵列具有基于方向的能量聚焦特性,对透镜阵列进行天线选...     

Planar Log-Periodic Antennas on Extended Hemishperical Silicon Lenses for Millimeter/Submillimeter Wave Detection Applications

In this paper, the radiation properties of log-periodic (LP) antennas on extended hemispherical dielectric lenses are investigated. The starting point is the far field pattern for the log-periodic antenna on a semi-infinite silicon substrate obtained from numerical simulation. Then the effects of extended hemispherical silicon dielectric lenses on this far field pattern are evaluated using ray tracing and field integration techniques. The far fields patterns out of the lenses are derived as a function of the extension length (L), from which the optimum L can be determined. The coupling efficiencies of the pattern to Gaussian beams are also calculated. The computation results show that the log-periodic antennas have good performance in terms of impedance and pattern and can be used in many submillimeter/THz systems. The simulation methods are verified by comparing the simulation results with experimental data from literature. The utilized approach represents an effective method for log periodic antenna-lens system design at millimeter/submillimeter wavelengths.     

Double-slot antennas on extended hemispherical and ellipticalsilicon dielectric lenses

Far-field patterns and Gaussian-beam coupling efficiencies are investigated for a double-slot antenna placed on hemispherical lenses with varying extension lengths. The radiation patterns of a double-slot antenna on a silicon dielectric lens are computed using ray-tracing inside the dielectric lens and electric and magnetic field integration on the spherical dielectric surface. The measured radiation patterns at 246 GHz and Gaussian-beam coupling efficiencies show good agreement with theory. The theoretical results are presented in terms of extension-length/radius and radius/λ, and therefore result in universal design curves for silicon lenses of different diameters and at different frequencies. The theoretical and experimental results indicate that for single units, there exists a wide range of extension lengths which result in high Gaussian-coupling efficiencies (50-60%) to moderately high f 's. These Gaussian-coupling efficiencies can be increased to 80-90°% with the use of a λ_m/4 matching-cap layer. For imaging array applications with high packing densities, an extension-length/radius of 0.38 to 0.39 (depending on frequency) will result in peak directivity and a corresponding Gaussian-coupling efficiency 15-20% lower than for single units     

Shaped dielectric lenses for wireless millimeter-wavecommunications

Dielectric-lens antennas are effective at producing highly shaped beams that can enhance the performance of wireless broadband communication systems. Beam shaping is used to reduce multipath interference, which causes fading and decay spread, and to enhance gain, so that the received power level is compatible with the requirements of high-data-rate transmission. This paper presents an overview of the design and measured performance of some examples of dielectric lenses that can be used in typical scenarios of wireless broadband communication systems. The paper also addresses the radio coverage produced by these antennas. The lenses are based on a single basic configuration where the feed is embedded in the lens body. This antenna configuration is flexible enough to accommodate different target beam-shaping specifications     

基于新型泡沫材料的龙伯透镜天线设计

该文利用新型泡沫材料聚甲基丙烯酰亚胺(PMI),设计了一种适用于复杂太空环境探测的毫米波龙伯透镜天线,通过将泡沫材料的密度与介电常数相关联,结合传统龙伯透镜天线的工作原理进行仿真优化,实现了小型化高增益多波束的功能。仿真结果表明:该天线工作于33.7 GHz,增益可以达到25.65 dBi,波束宽度4.17°。该设计方法为将来小型化高增益的龙伯透镜的实现提供了新的思路。     

On the modeling of metal strip antennas contiguous with the edge ofelectrically thick finite size dielectric substrates

A solution to the problem of radiation by a narrow metal strip antenna contiguous with the edge of a dielectric substrate is presented where the substrate has parameters such that its electrical thickness is appreciable. Such an antenna may be useful at millimeter wavelengths as an integrated phased array element forming a part of a monolithic microwave integrated circuit (MMIC). A suitable geometry for this application is illustrated and an efficient computational procedure developed. Comparisons with experimental results for the input impedance and far-field radiation patterns show excellent agreement. The influence of the dielectric substrate on the performance of an antenna designed to operate at approximately 60 GHz is discussed. Two examples, the first involving the analysis of a coplanar strip transmission line fed antenna and the second involving impedance matching and control of cross-polarized radiation using a folded strip dipole, are given to illustrate practical applications of the analytical method to design problems     

Extending the R-2R lens to 360°

The R.2R lens is a remarkable microwave device that provides perfect focusing, giving multiple simultaneous antenna beams from a circular or cylindrical array. However, the perfect focusing of the R-2R brings with it a serious limitation on angular coverage as a result of the angular doubling that enters when the array elements in the antenna are connected to the launcher elements on the lens periphery. We have now found a way to modify the R-2R concept so that a full circle of array elements can be mapped onto a full circle of beam ports. The new mapping makes use of hybrid junctions and either four or six physical lenses. The interconnections result in360degof simultaneous antenna beams, each of which can be used both for transmission and for reception.     

High-power constant-index lens antennas

The results of a study to develop a high temperature dielectric lens antenna for use in the microwave frequency range are presented. The design and fabrication of spherical and hemispherical constant-index lenses are described. Radiation patterns, gain, polarization, and VSWR characteristics of spherical and hemispherical constant-index dielectric lens antennas over the frequency range from 2 to 11 GHz are presented. The results from high-power testing of both spherical and hemispherical constant-index lenses at a 2 kW average power level indicate that this power level causes no degradation in the performance of the lenses.