Design and experimental investigation of a multibeam integrated reflector antenna of the millimeter wave band

A multibeam integrated reflector antenna operating in the millimeter wave band is considered. The antenna consists of a radiating array, a planar mirror, and a multichannel feed. The results of simulation of a radiating array of slots in a metal screen are presented. The array is manufactured on the basis of a medium with forced refraction, including a double-slot array, which can radiate along the normal to the array plane. Operation of the array in the multibeam mode is analyzed. It is shown that application of a medium with forced refraction increases the array aperture efficiency in this mode. The results of the design of a planar two-layer mirror are presented and the mirror’s quality indices are estimated. A multichannel radiator designed as an array of planar H-plane horns is studied. The results of simulation of such a radiator with the help of an approximate technique and numerical solution of an electromagnetic problem are considered. The design of the multibeam antenna and its experimental characteristics are presented.     

The dielectric-filled parabola: a new millimeter/submillimeterwavelength receiver/transmitter front end

A design is presented for a semi-integrated millimeter/submillimeter wavelength receiver/transmitter front end incorporating a planar antenna and a solid-state device in an efficient feed structure which can be matched directly to high f-number optical systems. The feed system combines the simplicity and robustness of a dielectric substrate lens with the high gain of a parabolic reflector in a single structure that is termed a dielectric-filled parabola. The same fundamental unit can be configured as either a heterodyne or direct detection mode receiver, a power transmitter or a frequency multiplier by changing out the solid-state device and/or the integrated antenna. The structure can also be used with a small integrated antenna array in a multibeam or imaging arrangement. Design and fabrication details for the feed system are given. These are followed by beam pattern and impedance measurements taken on a microwave model when dipole, bow-tie, log-periodic, and log-spiral antennas are used as the integrated feed elements     

Frequency-scanning grating-reflector antenna for multibeamsatellite communications

The analysis and design of a circularly polarized frequency-scanning grating-reflector antenna is presented. The antenna is intended for a multibeam satellite communication system, covering 3.1° north-south and 7.2° east-west with 25 spot beams. Frequency scanning is used for the north-south coverage, while the east-west coverage is obtained by the use of a cluster feed. The grating reflector consists of a planar frequency-scanned reflection grating with a quasi-periodic lattice geometry. The frequency-scanned grating reflects the incident field into a diffracted field composed of the first-order diffracted grating lobe. A focus-feed position for the diffracted field is obtained by a proper design of the quasi-periodic lattice geometry. Design principles for the planar grating-reflector antenna are presented together with an analysis method for predicting copolar and cross-polar radiation patterns. The analysis method is verified by experimental results     

A dielectric bifocal lens for multibeam antenna applications

An iteration technique is applied to the design of a bifocal dielectric lens antenna. A bifocal lens has two conjugate off-axis focal points and offers good off-axis scanning performance. A computer model was developed to aid in the design analysis and far-field performance evaluation of a bifocal lens. The computer simulation results demonstrate that the bifocal dielectric lens can provide a higher-gain radiation pattern for multibeam antenna (MBA) applications over a large field-of-view. The computer study also indicates that the quadratic phase error can be significantly reduced by constraining the feed along an optimized focal arc     

Planar three-dimensional constrained lenses

A new design for a beamforming lens is presented. Both faces are planar arrays of radiating elements interconnected by transmission lines whose length varies as a function of radius. While the front face elements are regularly spaced, the back face elements are displaced radially from their corresponding front face elements, the amount of displacement also being a function of radius. We show that such a lens is capable of forming low sidelobe beams over an angular sector 36 beamwidths across in all planes ofphiby switching between clusters of only seven feed elements. Because both faces are planar, construction of lightweight lenses for multibeam antennas should be feasible.     

Conformal four-beam antenna arrays with reduced sidelobes

Investigations on sidelobe reduction in multibeam conformal antenna arrays are presented. The recently presented concept of sidelobe reduction in planar multibeam antenna arrays in conjunction with the phase compensation technique has been applied for the design of reduced sidelobe multibeam conformal antenna arrays. Six- and eight-element antenna arrays fed by modified Butler matrices have been investigated and minimum radii have been found for which the sidelobe level is comparable to the respective planar multibeam arrays. A novel fully integrated six-element four-beam antenna array has been successfully designed in which sidelobes equal -14 dB for all four beams have been achieved.     

A coma-corrected multibeam shaped lens antenna, part II: Experiments

A dielectric lens based on the shaping technique described in Part I of this communication was fabricated and tested. This lens was shaped to control the sidelobes and zoned for improved scanning characteristics. Basic antenna measurements were conducted and excellent performance results have been observed. In the prototype lens system with unmatched surfaces, a 4 dB crossover between adjacent beams of -30 dB sidelobes was obtained. The beam was scanned up topm 12degwithout significant coma degradations. This coma-corrected zoned lens was developed for satellite multibeam applications. The multibeam antenna so designed not only reduces the total costs and the payload burden, but also enhances the system reliability and the overall gain compared to a conventional design because no complex feed network is required.     

Design and experimental investigation of stripline antennas

The results of development and experimental investigation of several centimeter-wave planar antennas are presented. The antennas contain a multichannel stripline power divider and a 2D periodic array of slot radiators excited by symmetric strip lines. A single-polarization antenna, an antenna with two linear polarizations, and an antenna with two circular polarizations are analyzed. The results of measuring the basic parameters of these antennas (the gain, the radiation pattern, and the cross-polarization level) are presented. Specific features of the design of such antennas and possible means of improvement of their performance characteristics are discussed.     

Beamforming network on the basis of unequal coupled waveguides

The theory and the results of the numerical simulation of a microwave beamforming network in the form of a system of unequal coupled waveguides are presented. The beamforming network is designed for a quasi-optical multibeam antenna. It is shown that the proposed N-channel network forms N flat-top patterns, which intersect each other at a level close to ?3 dB. The input channels are matched and are isolated. The theory of coupled waves is used to optimize the device. The theory of the systems of coupled EBG waveguides is developed on the basis of the method of compensating sources. The design version of a beamforming network on the basis of coupled EBG waveguides is considered. The results of the numerical calculation of the characteristics of this beamforming network are presented.     

Antenna with multibeam applications

The design of a dual-reflector antenna that focuses an inclined incident plane wave to a point away from the axis of symmetry of the reflector is discussed. A useful application of such a system would be as a multibeam antenna for use in communication via satellites. Curves of path-length errors are presented for the feed positioned on the axis of symmetry, and the effects of refocusing are shown.     

Design of Multibeam Dielectric Lens Antennas by Multiobjective Optimization

We propose an effective method for designing multibeam dielectric lens antennas. A genetic algorithm (GA) with multiobjective optimization is adopted to balance gain against sidelobe level. The lens shapes and the position of each feed are associated with chromosomes. The gain and sidelobe level are evaluated by a pareto ranking method. The method yields the distribution of the objective function values and the corresponding antenna structures.      

射电望远镜相控阵馈源技术

Phased array feed（PAF)is a small twodimensional phased array antenna as the multibeam feed.The most prominent merit of PAF is the capability of synthesizing closely overlapped beams,leading to continuous fieldofview coverage and faster survey speed.In this paper, the relationship between focal field matching and antenna efficiency is analyzed,radiation performance both in singlepixel and multibeam applications are compared between PAF and waveguide feeds,and the SNR model of phased array fed radio telescope is introduced.As an emerging feed technology,PAF exhibits more flexibility and better performance.     

基于均匀介质球透镜的二维扫描天线

在球透镜仅实现一维扫描的基础上,通过在另一维上平行放置多层馈源的方式,实现了二维同时扫描。基于坐标变换和GO/PO方法推导了馈源偏移量和波束指向角之间的关系式。该天线由一个均匀介质球透镜和多层平面馈源天线组成。通过同一层上的TSA(渐变缝隙天线)单元之间的切换实现水平面的扫描,而通过不同层上TSA单元之间的切换实现垂直面的扫描。作为在毫米波段的一个应用,研制了一个Ka波段用8×2的TSA单元阵馈电的天线实物。实测结果表明它可以在水平面和垂直面分别达到128°和30°的覆盖。     

A new planar grating-reflector antenna

A planar grating-reflector antenna with frequency-scanning properties is presented. The antenna system is composed of a point feed and a planar reflector consisting of a frequency-scanned reflection grating. The grating geometry must be selected such that the first higher-order diffracted wave propagates and serves as the frequency-scanned beam. A focus feed position for the diffracted field is obtained by allowing the lattice geometry to vary along the reflector surface. Methods for analyzing and designing the new antenna configuration are presented. The antenna concept is demonstrated theoretically and experimentally by the design, evaluation, and test of an experimental antenna operating over the frequency band 9.5-10.5 GHz     

Design and experimental investigation of radiators for antenna arrays based on EBG waveguides

Problems of the design of a centimeter-band antenna array containing a multichannel power divider based on EBG waveguides and helical radiators are considered. The general configuration of such an array is proposed. The properties of this array and the requirements on the array elements are analyzed. Features of the design of two-channel and four-channel elementary power dividers forming the multichannel power divider are studied. The structure and the parameters of these devices are determined. The array input part is designed in the form of a coaxial-to-waveguide transition (CWT) with equal power division. The CWT characteristics obtained with the use of numerical simulation are compared with experimental data. The results of the experimental investigation of a 16-element thinned antenna array in the frequency band 8–10 GHz are presented.     

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     

Design and Experimental investigation of an antenna array based on EBG waveguides

Problems of the design of a centimeter-band antenna array containing a multichannel power divider based on EBG waveguides and helical radiators are considered. The general configuration of such an array is proposed. The properties of this array and the requirements on the array elements are analyzed. Features of the design of two-channel and four-channel elementary power dividers forming the multichannel power divider are studied. The structure and the parameters of these devices are determined. The array input part is designed in the form of a coaxial-to-waveguide transition (CWT) with equal power division. The CWT characteristics obtained with the use of numerical simulation are compared with experimental data. The results of the experimental investigation of a 16-element thinned antenna array in the frequency band 8–10 GHz are presented.     

RF characterization of an inflatable parabolic torus reflectorantenna for space-borne applications

Space-borne satellite applications provide a vast array of services extending from global connectivity to Earth observation systems. The soil moisture radiation mission is a proposed space-borne passive microwave system complementary to the existing Earth observing system operating at low microwave frequencies and requiring an antenna with multibeam, high-beam efficiency, and dual polarization capabilities. To achieve both the large reflector size and the multibeam pattern at the operational frequencies an innovative multibeam reflector antenna design was needed. The advances in inflatable antenna technology has been proposed to overcome the launch vehicle size and weight restrictions. This paper describes a novel offset parabolic torus reflector antenna design that produces the desired multibeam pattern and is compatible with the inflatable antenna technology. Using the system requirements of this mission as an example, the design process for an inflatable parabolic torus reflector antenna is outlined, the development of suitable distortion models is given, and representative RF characteristics are presented. These RF characteristics include far-field patterns, beam contour patterns, beam efficiency, and other key performance parameters. The development of an advanced analytical modeling/numerical tool in support of the design effort is also detailed     

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.