Gaussian Profiled Horn Antenna for HISPASAT 1C Satellite

In this paper, the design and the measurements of a Gaussian profiled horn antenna for the 11.7-12.2 GHz frequency band for the HISPASAT 1C satellite are presented. The study shows the possibility of improving the electromagnetic and physical features of conventional horn antennas by using Gaussian techniques.     

Design and analysis of quasi-integrated horn antennas formillimeter and submillimeter-wave applications

The authors present a systematic process for the design of multimode quasi-integrated horn antennas, and provide a full range of practical antenna designs for millimeter- and submillimeter-wave applications. The design methodology is based on the Gaussian beam approach and the structures are optimized for achieving maximum fundamental Gaussian coupling efficiency. For this purpose, a hybrid technique is used in which the integrated part of the antennas is treated using full-wave analysis, whereas the machined part is treated using an approximate model. This results in a simple and efficient design process. The design procedure has been applied to the design of 20-, 23-, and 25-dB quasi-integrated horn antennas, all with a Gaussian coupling efficiency exceeding 97%. The designed antennas have been tested and characterized using both full-wave analysis and 91/370-GHz measurements. The quasi-integrated horn antennas are also examined as feed elements for Cassegrain antenna systems and are proved to be comparable to the traditional machined corrugated horn feeds     

Ultra-wide band corrugated gaussian profiled horn antenna design

Nowadays, an increasing number of applications need stable radiation patterns with low sidelobes and low crosspolar levels in a very wide bandwidth. Gaussian profiled horn antennas (GPRAs) have demonstrated their feasibility as one of the best solutions. A corrugated Gaussian horn antenna design with more than 40% bandwidth is proposed. The measured radiated far field patterns are in good agreement with the simulated ones. The measured results show a Gaussian antenna with extremely wide bandwidth, low sidelobes, and low crosspolar levels     

On the radiation of horn clusters including mutual coupling and theeffects of finite metal plates: application to the synthesis ofcontoured beam antennas

This work describes a model of the radiation of horn clusters for contoured beam antennas. The model includes internal mutual coupling (through a power divider network), modal conversions and reflections inside the horns, external mutual coupling and the effects of the edges of the metal plate that holds the cluster together. This model is applied to the synthesis of the direct broadcast satellite (DBS) antenna of the HISPASAT satellite, the computed immersed patterns of each horn being used in the optimization of the excitations. Results are given concerning model validation and optimization with immersed patterns     

Optimization of Broadband Smooth-Wall Circular Horn Antennas

This paper presents the optimization and characterization of broadband circular horn antennas with smooth walls. These antennas are simpler and easier to manufacture than corrugated horns. They work by converting the incoming fundamental mode to a mode mixture, whose total field corresponds to a Gaussian beam pattern at the aperture. The geometry of the horn is found by an optimization algorithm. While smooth-wall horn antennas have been designed for many years, they are inherently band limited because they rely on a correct multimode interference in the aperture to match the total field to a Gaussian distribution. The presented method achieves significantly larger bandwidths by allowing the Gaussian beam parameters, and thus the required mode spectrum in the aperture, to vary with the frequency. Together with an appropriate mirror optics, a receiver system with a bandwidth of more than 3 octaves could be realized.     

Gaussian beam mode analysis of the coupling of power between horn antennas

Gaussian beam mode analysis can be applied in an elegant way to study the coupling of power between two horn antennas. Coupling efficiencies are evaluated for a number of horn combinations and the results presented in a straightforward form useful in the design of submillimetre-wave interferometers and astronomical receiver systems. We show that there is a marked variation in efficiency (up to 30%) depending on the coupling optics, even for beams with well matched profiles.     

Linear array of woodpile EBG sectoral horn antennas

A technique is described for creating linear array antennas that conform to the natural stacking sequence of the woodpile electromagnetic bandgap (EBG) material. Each element in the linear array consists of a woodpile EBG sectoral horn antenna. The electromagnetic confinement mechanism within each horn antenna relies wholly on the 3-D EBG of the woodpile material. The array element has a typical sectoral horn pattern with a directional beam in one principal plane and a broader beam in the other. The bandwidth of the sectoral horn is almost equal to that of the defect EBG waveguide. Measured and theoretical results for radiation patterns, impedance bandwidth and gain of a sectoral horn antenna made from alumina are described, and theoretical results for a design made from silicon are presented. It is shown that the layer-by-layer nature of the woodpile EBG material enables sectoral horn antennas to be easily stacked together in the E-plane to create linear arrays. Analysis of the mutual coupling as a function of element separation and its effect on reflection coefficient are presented for a two-element linear array in silicon. Theoretical analyses for fixed and scanned beam linear arrays of silicon woodpile EBG sectoral horns are described and finite-difference time-domain results are compared with array theory. The fixed beam arrays are designed for high directivity while the scanned beam array enables wide angle beam steering through the use of parasitic array elements.     

Accurate analysis of TEM horn antennas for pulse radiation

In the past, various approximate theoretical models have been used to analyze TEM horn antennas. Because of the limitations of these approximate models, there has been, to date, only qualitative agreement of measurements for TEM horn antennas with the predictions of the theories. The finite-difference time-domain (FDTD) method is used to accurately analyze TEM horn antennas for pulse radiation. First, the metallic triangular-plate TEM horn antenna is considered. Computed results for the reflected voltage in the feeding transmission line and the time-varying radiated electric field are shown to be in very good agreement with new experimental measurements. Graphs of the electric field in the space surrounding the antenna (magnitude of field plotted on a color scale) are used to give a physical insight into the process of radiation. Next, the method is used to analyze two TEM horns that were previously designed for pulse radiation. The geometry and electrical properties of these antennas are more complicated than for the metallic, triangular-plate horn. One has shaped metallic plates with a resistive termination at the open end; the other has plates whose resistance varies continuously along their length. The computed results for these antennas are compared with previously made experimental measurements     

Gaussian beam techniques for illuminating reflector antennas

Simple design procedures are presented for use when a Gaussian beam is used to illuminate a classical reflector antenna. Displacement of the location of the beamwaist toward the focusing element in the case of electrically small antennas where the aperture is in the near field of the feed was calculated together with modification of the required beamwaist radius. Dual reflector antennas were discussed and design procedures appropriate for systems with large and small focal length to diameter ratio developed. Cases where a reflector or subreflector is electrically small, or in the near field of a feed, are readily treated. For elliptical beam antennas, a simple illumination system using only a scalar horn and a single cylindrical lens can generally be found; this has no ray optics analogue. A configuration of this type is discussed, with a practical case study of a 28-by-80-λ elliptical Cassegrain antenna operating at a wavelength of 3 mm. The design process for designing the feed system is discussed in detail. Despite the small size and relatively large aperture blockage, an aperture efficiency of 0.48 was measured, which compared quite well with the expected efficiency of 0.53, thus verifying the validity of the Gaussian beam design approach     

Integrated horn antennas for millimeter-wave applications

The development of integrated horn antennas since their introduction in 1987 is reviewed. The integrated horn is fabricated by suspending a dipole antenna, on a thin dielectric membrane, in a pyramidal cavity etched in silicon. Recent progress has resulted in optimized low- and high-gain designs, with single and double polarization for remote-sensing and communication applications. A full-wave analysis technique has resulted in an integrated antenna with performance comparable to that of waveguide-fed corrugated-horn antennas. The integrated horn design can be extended to large arrays, for imaging and phased-array applications, while leaving plenty of room for the RF and IF processing circuitry. Theoretical and experimental results at microwave frequencies and at 90 GHz, 240 GHz, and 802 GHz are presented     

Integrated horn antennas for millimeter-wave applications

This paper reviews the development of integrated horn antennas since their introduction in 1987. The integrated horn is fabricated by suspending a dipole antenna on a thin dielectric membrane in a pyramidal cavity etched in silicon. Recent progress resulted in optimized low and high-gain designs with single and double-polarizations for remote-sensing and communication applications. A fullwave analysis technique have resulted in an integrated antenna with performance comparable to that of waveguide-fed corrugated horn antennas. The integrated horn design can be easily extended to large arrays for imaging and phased array applications while still leaving plenty of room for the rf and w processing circuitry. Theoretical and experimental results at microwave frequencies and at 90, 240 and 802 GHz will be presented.     

Radiation pattern synthesis for circular aperture horn antennas

A set of radiation pattern functions, suitable for synthesis of radiation patterns from circular aperture horn antennas, is obtained by assuming an aperture distribution consisting of the fields of cylindrical waveguide modes. A technique is presented for using a linear combination of the radiation pattern functions to approximate a desired radiation pattern. Linear combinations of the radiation pattern functions resulting in maximum secondary gain, when used to illuminate a paraboloidal antenna, are obtained empirically. Using spherical wave theory, maximum performance theoretically obtainable from an antenna is derived as a function of the aperture size of the feed system; the feed efficiency resulting from these theoretical limits on performance is compared to the feed efficiency of patterns obtainable from circular aperture horn antennas, and to experimental results of attempts to realize optimum circular aperture horn patterns.     

Analysis of an octagonal micromachined horn antenna forsubmillimeter-wave applications

An analysis is presented of a new horn antenna, fabricated by a novel micromachining technique, that uses crystallographic etching of silicon and ultraviolet lithography of an ultra-thick photoresist (SU-8). The horn was found to have low cross-polarized field levels and a predicted Gaussian coupling efficiency of 92.5%. The horn shape is governed by the crystal planes of the silicon substrate and the thickness of the photoresist and has up to four independent design parameters that allow a wide range of antenna patterns. A design for the horn that yields symmetric beam patterns was investigated by computer analysis, microwave scale modeling, and measurements of a micromachined horn at 585 GHz. The major features of the 585-GHz beam patterns agree well with the computer-generated and scaled beam patterns. We have thus demonstrated a new micromachinable horn that has great potential for integration into array structures     

Design and simulation of metamaterial-based hybrid-mode horn antennas

The design and analysis of novel hybrid-mode soft and hard horn antennas with a low index metamaterial wall liner are presented. Metamaterial horn antennas have the potential for considerably larger bandwidth than the current state-of-the-art horns. The optimal or required metamaterial dispersion curve for these horns is qualitatively similar to the Drude dispersion, which indicates that the metamaterial horns are realisable.     

Low sidelobe precise beam aspect ratio scalar horns

A new design method for developing either linearly or circularly polarized low sidelobe corrugated sectoral horn antennas is described. These antennas may be designed to provide constant beam aspect ratios (BAR's) ranging from 2:1 to 5:1. Such performance is achieved over bandwidths of up to 21 percent for dual-linear polarization and 17 percent for circular polarization. Potential applications include use in communication satellite reflector systems where beam shaping, frequency reuse, or high adjacent beam isolation is required. Selecting aperture phase distribution rather than simply minimizing aperture phase error is the key to obtaining these results. Mechanical design and performance data are presented to facilitate fabrication of antennas that satisfy a wide range of performance requirements.     

Analysis of pyramidal horn antennas using moment methods

A hybrid numerical technique is developed for electrically large pyramidal horn antennas radiating in free space. A stepped-waveguide method is used to analyze the interior surfaces of the horn transition. The electric field integral equation (EFIE) is employed on the outer surfaces of the pyramidal horn including the radiating aperture. Meanwhile, the magnetic field integral equation (MFIE) is used on the aperture to relate the aperture fields and those in the horn transition The resultant hybrid field integral equation (HFIE) is solved numerically by the method of moments. This formulation is both accurate and numerically stable so that high-gain microwave pyramidal horns can be analyzed rigorously. Far-field radiation patterns, both computed and measured, are presented for three electrically-large X-band horn antennas. The comparisons demonstrate that this method is accurate enough to predict the fine pattern structure at wide angles and in the back region. Computed far-field patterns and aperture field distributions of two smaller X-band horns are also presented along with a discussion on the validity of the approximate aperture field distributions routinely used in the analysis and design of pyramidal horns     

Beam focusing using 60 GHz Fabry-Perot resonators with uniform and non-uniform metal grids

A new structure of millimetre-wave focusing antennas is presented. It consists of a plane-parallel Fabry-Perot resonator comprising two uniform and non-uniform inductive metal meshes excited by a horn antenna. The beam focusing is performed with the non-uniform mirror, the geometry of which is chosen so that it behaves as a spherical equiphase surface with a desired radius of curvature. The resulting radiation patterns are Gaussian; their directivity is controlled by the curvature of the synthesised wavefront. This concept is successfully validated in the 60 GHz band.