Showing papers on "Cassegrain antenna published in 2003"

Large antennas of the Deep Space Network

Abstract: Foreword.Preface.Acknowledgments.Chapter 1 : Introduction.1.1 Technology Drivers.1.1.1 Frequency Bands Allocated to the Deep Space Network.1.2 Analysis Techniques for Designing Reflector Antennas.1.2.1 Radiation-Pattern Analysis.1.2.2 Feed-Horn Analysis.1.2.3 Spherical-Wave Analysis.1.2.4 Dual-Reflector Shaping.1.2.5 Quasioptical Techniques.1.2.6 Dichroic Analysis.1.2.7 Antenna Noise-Temperature Determination.1.3 Measurement Techniques.1.3.1 Theodolite Measurements.1.3.2 Microwave Holography.1.3.3 Aperture Gain and Efficiency Measurements.1.3.4 Noise-Temperature Measurements.1.4 Techniques for Designing Beam-Waveguide Systems.1.4.1 Highpass Design.1.4.2 Focal-Plane Matching.1.4.3 Gaussian-Beam Design.1.4.4 High-Power Design.1.5 Summary.References.Chapter 2: Deep Space Station 11: Pioneer-The First Large Deep Space Network Cassegrain Antenna.2.1 Introduction to the Cassegrain Concept.2.2 Factors Influencing Cassegrain Geometry.2.3 The DSS-11, 26-Meter Cassegrain System.References.Chapter 3: Deep Space Station 12: Echo.3.1 The S-Band Cassegrain Monopulse Feed Horn.3.2 The 26-Meter S-/X-Band Conversion Project.3.2.1 Performance Predictions.3.2.2 Performance Measurements.3.3 The Goldstone-Apple Valley Radio Telescope.References.Chapter 4: Deep Space Station 13: Venus.4.1 The Dual-Mode Conical Feed Horn.4.2 Gain Calibration.References.Chapter 5: Deep Space Station 14: Mars.5.1 Antenna Structure.5.2 S.Band. 1966.5.3 Performance at X-Band.5.3.1 Surface Tolerance.5.3.2 Measured X-Band Performance.5.4 Tricone Multiple Cassegrain Feed System.5.4.1 Radio Frequency Performance.5.4.2 New Wideband Feed Horns.5.4.3 Dual-Hybrid-Mode Feed Horn.5.5 Reflex-Dichroic Feed System.5.6 L-Band.5.6.1 Design Approach.5.6.2 Performance Predictions and Measurements.5.6.3 L-Band System Modifications.5.7 The Upgrade from 64 Meters to 70 Meters.5.7.1 Design and Performance Predictions.5.7.2 S- and X-Band Performance.5.7.3 Ka-Band Performance.5.7.4 Adding X-Band Uplink.5.8 Distortion Compensation.5.8.1 Deformable Flat Plate.5.8.2 Array-Feed Compensation System.5.8.3 The Array-Feed Compensation System-Deformable Flat-Plate Experiment.5.8.4 Projected Ka-Band Performance.5.9 Future Interests and Challenges.References.Chapter 6: Deep Space Station 15: Uranus-The First 34-Meter High-Efficiency Antenna.6.1 The Common-Aperture Feed.6.2 Dual-Reflector Shaping.6.3 Computed versus Measured Performance.References.Chapter 7: The 34-Meter Research and Development Beam-Waveguide Antenna.7.1 New Analytical Techniques.7.2 Beam-Waveguide Test Facility.7.3 The New Antenna.7.3.1 Antenna Design Considerations.7.3.2 Upper-Mirror Optics Design.7.3.3 Pedestal Room Optics Design.7.3.4 Bypass Beam-Waveguide Design.7.3.5 Theoretical Performance.7.3.6 Dual-Shaped Reflector Design.7.3.7 The Effect of Using the DSS-I 5 Main Reflector Panel Molds for Fabricating DSS-13 Panels.7.4 Phase I Measured Results.7.4.1 The X- and Ka-Band Test Packages.7.4.2 Noise Temperature.7.4.3 Efficiency Calibration at 8.45 and 32 GHz.7.4.4 Optimizing the G/T Ratio of the Beam- Waveguide Antenna.7.4.5 Beam-Waveguide Antenna Performance in the Bypass Mode.7.5 Removal of the Bypass Beam Waveguide.7.6 Multifrequency Operation.7.6.1 X-IKa-Band System.7.6.2 S-Band Design.7.7 Bearn-Waveguide Versatility.References.Chapter 8: The 34-Meter Beam-Waveguide Operational Antennas.8.1 Bearn-Waveguide Design.8.2 Initial Testing.8.2.1 Microwave Holography Measurements.8.2.2 Efficiency Measurements.8.2.3 Noise-Temperature Results.8.2.4 Theshroud.8.3 Adding Ka-Band to the Operational 34-Meter Bearn-Waveguide Antennas.8.3.1 The Cassini Radio Science Ka-Band Ground System.8.3.2 Ka-Band Upgrades-Receive-Only System.References.Chapter 9: The Antenna Research System Task.9.1 Design of the Beam-Waveguide System.9.2 Design of the Transmit Feed Horn.9.3 Receive-System Design.9.4 Dual-Vane Polarizers.9.5 Uplink Arraying.9.6 Deep Space Station 27.References.Chapter 10: The Next-Generation Deep Space Network.10.1 The Study to Replace 70-Meter Antennas.10.1 . 1 Extending the Life of the Existing 70-Meter Antennas.10.1.2 Designing a New 70-Meter Single-Aperture Antenna.10.1.3 Arraying Four 34-Meter Aperture Antennas.10.1. 4 Arraying Small Antennas.10.1.5 Arraying Flat-Plate Antennas.10.1.6 Implementing a Spherical Pair of High-Efficiency Reflecting Elements Antenna Concept.10.2 Towards the Interplanetary Network.10.3 Final Thoughts.References.Acronyms and Abbreviations.

Random surface error effects on offset cylindrical reflector antennas

Abstract: The focus of this paper is to characterize the average power pattern of an offset cylindrical parabolic reflector antenna subject to random surface errors. A novel computational method is developed for studying the random surface error effects on the boresight gain loss and the sidelobe levels of the average power pattern. The particular antenna dimensions used for this study are similar to the specifications for the second generation precipitation radar (PR-2) mission. In keeping with the requirements in the PR-2 mission, both the Ku and Ka frequency bands are considered. Random surface error effects are also studied for different edge taper levels. In addition to analysis of a reflector with uniform random surface errors, a nonuniform surface error case is presented in this study. This is an important consideration for evaluating the suitability of large deployable membrane reflector antennas for the PR-2 mission.

Small reflector antenna with low sidelobes

Abstract: A prime focus low sidelobe parabolic reflector antenna with self-supported feed is designed for low sidelobe applications. The parabolic reflector diameter is between nine and twelve wavelengths. A simple design is achieved to satisfy the required first sidelobe level. The design is performed numerically using a computer code for bodies of revolutions (AKBOR2). The measured radiation patterns of 18 inch and 24 inch reflector systems at 5.75 GHz. are presented. Good agreement between computed and measured radiation patterns is obtained.

Multi-beam and multi-band antenna system for communication satellites

Abstract: An antenna system includes a reflector having a modified-paraboloid shape; and a multi-beam, multi-band feed array located at a focal point of the reflector so that the antenna system forms a multiple congruent beams that are contiguous. The system has a single reflector with non-frequency selective surface. The reflector is sized to produce a required beam size at K-band frequencies and is oversized at EHF-band frequencies. The synthesized reflector surface is moderately shaped and disproportionately broadens EHF-band and Ka-band beams compared to K-band beams. The synthesized reflector surface forms multiple beams each having a 0.5-degree diameter at K-band, Ka-band, and EHF band. The multi-beam, multi-band feed array includes a number of high-efficiency, multi-mode circular horns that operate in focused mode at K-band and defocused mode at Ka-band and EHF-band by employing “frequency-dependent” design for the horns.

Offset cylindrical reflector antenna fed by a parallel-plate Luneburg lens for automotive radar applications in millimeter-wave

Abstract: Using a single offset cylindrical parabolic reflector and a parallel-plate Luneburg lens, a novel high-gain and high-efficiency antenna is developed for automotive radar at mm-wave frequencies. Particularly, a pair of small corrugated extensions is added to the lens for a cylindrical wave. Thus, by feeding a cylindrical wave to the reflector, especially the performance in elevation is enhanced, keeping the complete antenna compact. For verification, a prototype antenna for an adaptive cruise control radar at 76.5 GHz is designed and measured. The theoretical results are verified with good agreement.

Comprehensive analysis and simulation of a 1-18 GHz broadband parabolic reflector horn antenna system

Abstract: A 1-18 GHz parabolic reflector horn antenna system featuring a broadband double ridged primary horn with a coaxial feed line is investigated. For the ridged horn antenna it is found that the radiation pattern, contrary to common belief, does not maintain a single main lobe in the direction of the horn axis over the whole frequency range. Instead, at frequencies above 12 GHz the main lobe in the radiation pattern starts to split into four lobes pointing in off-axis directions with a dip of up to 6 dB between them along the center axis. To investigate this phenomenon in detail, a combined method of moments and physical optics approach has been adopted to simulate the complete antenna system.

Displaced-axis-ellipse reflector antenna for spacecraft communications

Abstract: This work discusses the electrical characteristics of axially-symmetric dual-reflector antenna systems based on the axially displaced ellipse (ADE) configuration, with emphasis on its application in compact high-gain high-efficiency spacecraft communication antennas. Relevant ADE electrical properties are compared with the corresponding characteristics of the Cassegrain geometry (a configuration commonly used in high-gain spacecraft applications). It is shown that the ADE is capable of operating efficiently with electric apertures considerably smaller than the Cassegrain geometry, an important feature for small spacecraft. To demonstrate the outstanding electric performance that can be expected from the ADE, the predicted and measured results of an X-band 1250 mm aperture diameter prototype are presented.

Synthesis of the Inmarsat 4 multibeam mobile antenna

Abstract: The Inmarsat 4 Spacecraft user link or mobile antenna system consists of a 9m deployable reflector and a feed array with 120 helical elements. Over 220 simultaneous RF beams are created by applying vector weights to the feed elements under the control of the onboard digital signal processor (DSP). The simultaneous transmission and reception requires the achievement of very low levels of passive intermodulation (PIM). The mission requires continuous coverage over fixed ground cells for orbital inclinations of up to 3°. This is achieved by uploading modified beam weights on a daily basis. This requires a large number of beam weights to be presynthesized. In addition to the communication beams, a system of RF sensing beams are deployed in order to enhance the spacecraft pointing capability and hence overall communication performance.

Adjustable reflector system for fixed dipole antenna

Abstract: An adjustable reflector system for fixed dipole antenna comprising of reflector and several supporting devices is described. The beam direction of the antenna can be changed by rotating the reflector about the Y-axis and/or adjusting the reflector about X axis and Z-axis. Such adjustments allow the user to fine tune the antenna to meet new or unforeseen coverage issues. The plurality of the of the reflector's shapes is disclosed (flat, curved, etc.).

Conceptual reconfigurable antenna for 35 GHz high-resolution spaceborne synthetic aperture radar

Abstract: An innovative Cassegrain antenna for spaceborne synthetic aperture radar (SAR) utilizes a reconfigurable feed array for scene grazing angles from 15/spl deg/ to 70/spl deg/ to produce the largest antenna beam footprints that are circular and to maintain high efficiency or the transmitter. The antenna has a beam waveguide input and the feed array is located in this waveguide. The feed array of transmit-receive modules is reconfigured to vary the illumination shape and area of the radiating portion of the antenna. Each transmit device operates at its full power for maximum efficiency, and the number of devices is determined by the required power. Single-point design for a 35 GHz SAR in a 700 km altitude orbit is presented to detect terrain with 0.1 m resolution. The antenna is a 19.6 m/sup 2/ elliptical reflector, the power density at the aperture is 25.5 W/m/sup 2/, and 500 W maximum average power is required. Compared to X-band, 1) the 35 GHz design requires a much smaller antenna, 2) high resolution requires less percentage bandwidth, and 3) integration requirements are less demanding. For comparison, a 9 GHz SAR point design is included for grazing angles of 15/spl deg/ and 70/spl deg/.

Ultra-low profile airborne reflector antenna subsystem for broadband satellite communications

Abstract: An ultra-low profile airborne reflector antenna with an arbitrary polarization feed system and a wide-range scanning faculty has been proposed for the broadband satellite communication use. We have chosen a shaped elliptical dual reflector antenna with reflector shaping technique to realize both the ultra-low profile and high electric performances. A novel thin-type broadband OMT with pyramid-loaded waveguide turnstile junction has been presented to obtain the arbitrary polarization thin feed system.

Multi-band ring focus antenna system with co-located main reflectors

Abstract: A compact multi-band ring-focus antenna system. The antenna system includes a first and a second main reflector 304, 306, each having a shaped surface of revolution about a common boresight axis ( 322 ) of the antenna. A first backfire type RF feed system ( 302, 312 ) is provided for feeding the first main reflector ( 304 ) on a first frequency band. A second RF feed ( 301 ) coaxial with the first RF feed ( 300 ) is provided for feeding the second main reflector ( 306 ) on a second frequency band spectrally offset from the first frequency band. Further a portion of the second RF feed passes through a first sub-reflectors ( 302 ) of the backfire feed. The second RF feed is terminated a distance from the first sub-reflector to illuminate a second sub-reflector ( 303 ).

Antenna with reflector

Abstract: An antenna which includes a monoconical antenna feed assembly, where the feed assembly has a base and an apex, a ground plane adjacent to the monoconical antenna feed assembly near the apex, and an antenna reflector coupled to the ground plane, where the antenna reflector at least partially surrounds the monoconical antenna feed assembly. The monoconical feed point is used to drive a reflector antenna. The broadband characteristics of the monoconical image vertical antenna (typical ground plane geometry) are used as the feed point for the reflector to give modest amount of gain while maintaining larger than previously developed bandwidths.

Focal field analyses for front-fed and offset reflector antenna

Abstract: In this paper, we present results of focal field analyses carried out for front-fed and offset parabolic antennas. Such analyses are needed and especially important for hybrid antenna configurations with arrays in the focal zone. The front-fed configuration relates to work carried out for radio telescope applications within the FARADAY project. The offset geometry relates to potential applications for instance for Earth observation or telecommunication satellites. The focal field analysis is necessary as an intermediate step, before focal field matching procedures are applied, to derive suitable excitations for a focal array. But also such an analysis gives insight from another point of view for antenna operations in the generic sense.

Beam steering apparatus for a traveling wave antenna and associated method

Abstract: Steering of an electromagnetic beam of energy in the upper plate of a plate waveguide of a traveling wave antenna concurrently with the formation of a flat phase front and collimation of the electromagnetic beam is achieved by providing a second waveguide beneath the lower plate of the first waveguide and providing a 180% bend parabolic main reflector to reflect the energy beam to the upper plate of the upper waveguide. A feed horn is located in the lower waveguide and illuminates a pivotal subreflector which reflects the energy to the parabolic main reflector. By rotating the subreflector about its pivot point, the beam which is radiated to the upper waveguide is angularly shifted or steered.

Study of efficiencies and phase centers of broadband log-periodic feeds for large offset dual-reflector antennas using formulas for bodies of revolution (BOR/sub 1/ extraction)

Abstract: The Allen Telescope Array (ATA) is a new instrument being built by the SETI institute. It is an array of offset Gregorian reflector antennas with a very large bandwidth, covering 0.5 GHz to 11 GHz. The feed consists of four log-periodic arms, together forming a pyramid. In the center of the pyramid, a metallic pyramid is located, holding low noise amplifiers and cryogenics. We present a method for analyzing dual reflector systems based on BOR/sub 1/-extraction and use it to analyze the performance of the ATA feed in the offset Gregorian dual reflector. With a good corrugated feed in a paraboloid or Cassegrain antenna, the spillover efficiency is typically around -0.5 dB for the subtended angle giving the highest efficiency. The spillover efficiency for the ATA feed is around -1 dB, which is caused by high sidelobes. In order to increase the performance of the system, the sidelobes should be reduced. We have found that 0.5 dB gain can be accomplished by changing the shape of the ground pyramid in the center of the feed to a cone. This reduces the spillover and increases the BOR/sub 1/ efficiency. With optimized placement of the feed in the reflector, the reduction of phase efficiency due to phase center movement is better than -1 dB. Considering the bandwidth of the feed, this is very good.

Broadband waveguide horn antenna and method of feeding an antenna structure

Abstract: A waveguide horn antenna includes a horn-shaped body portion and one or more feed structures. Each feed structure includes feed locations positioned between spaced apart ends of the body portion according to short circuit locations of desired frequencies to facilitate propagation of electromagnetic energy at the desired frequencies. Multiple frequency bands can be supported with the antenna by employing more than one axially spaced apart feed structures having associated feed locations arranged along the body portion of the antenna.

An ultra-light large antenna reflector for communication satellites

Abstract: To lower the cost and increase the performance of commercial satellite systems, we are developing larger and lighter antenna reflectors than are currently available. To realize this new breed of reflector antennas, we propose a geodesic cable network system whose backbone is a tendon reinforced deployable frame structure. Two issues are fundamental to realizing a successful structure. One is to design a cable network system that keeps its shape even if the support structure is strongly deformed by in-orbit thermal and vibration disturbances. The other is to design an extremely light weight support structure whose structural behavior is non-linear and that can accept high levels of deformation. The results of a preliminary design consideration demonstrate the feasibility of a large deployable mesh antenna reflector whose aperture is 20m and weight is less than 80 kg.

In-band scattering of dipole array with edge loaded rectangular reflector

Abstract: The metallic reflector forms an important part of a practical dipole array. To study the contribution of the reflector edges to the overall scattering cross section, the edges of the reflector are loaded with resistance, and the back-scattering cross sections are compared to that of an array without edge-loading. Some preliminary results will be shown. Further investigation is in progress.

A novel leaky-wave retrodirective reflector using short/matched terminations

Abstract: A novel leaky-wave retrodirective reflector using short and matched terminations is presented. The principle of this reflector consists of terminating a backfire-to-endfire leaky-wave antenna by a short load at one end and by and matched load at the other end. In this manner, the incident field excites the antenna, is reflected by the short, and is reradiated toward the source, while it is absorbed by the matched load at the other end, avoiding a spurious beam a the "wrong" side of the normal to the antenna. While using a conventional antenna would lead a reflector working only in a 90 degrees space, using the recently developed backfire-to-endfire leaky wave antenna allows 180 degrees reflector operation.

Adaptive reflector antenna and method for implementing the same

Abstract: An adaptive reflector antenna includes an adaptive reflector and a mechanism for simultaneously effecting feed rotation and shape change for the adaptive reflector so as to maintain antenna performance with large scan angles while simultaneously reducing weight, complexity, and cost.

Multi-beam antenna system with shaped reflector for generating flat beams

Abstract: A side-fed dual reflector antenna system (10) of the present invention overcomes the size cost and complexity limitations associated with conventional single and multiple reflector antenna systems. The antenna system (10) includes a feed array (18) including separate feeds for generating separate respective antenna beams, a subreflector (20) for reflecting the separate respective antenna beams generated by the separate feeds of the feed array (18), and a reflector (22) having a shaped reflecting surface for reflecting the separate respective antenna beams received from the subreflector (20) toward a terrestrial target (16) to produce substantially contiguous flat beams, each of which provides substantially uniform coverage within a predetermined coverage area on the terrestrial target. The subreflector (20) and each of the separate feeds in the feed array (18) are arranged so that a center of each of the separate respective antenna beams illuminates a center of the reflector (22) subsequent to being reflected from the subreflector (20).

A double-layer microstrip reflectarray design to obtain Australia and New Zealand footprint

Abstract: A microstrip reflectarray, combining features of conventional reflector antennas and phased array technologies into one, is considered as an attractive replacement for either pencil or contoured beam reflector antennas in terrestrial and satellite communication applications. In this paper, we design Ku-band (12.25 GHz-12.75 GHz) dual linear polarized microstrip patch reflectarrays for Optus B1 geostationary satellites to generate a contoured beam for Australia and New Zealand.

Calculation of non-axisymmetrical parabolic reflector antennas

Abstract: An aperture method is used for calculation of non-axisymmetrical parabolic reflector antennas. The possibility of scanning of horizontal-plane pattern at rotation of reflector at fixed radiatorer is investigated. The results of numerical and measurement experiments are presented in the paper.

Receiving antenna for multibeam coverage

Abstract: The invention relates to a receiving antenna for satellite telecommunications. More specifically, the invention relates to an active antenna comprising a network of elementary sources which is positioned at the focal point of a focusing reflector. According to the invention, said network of sources is disposed on a more or less spherical, concave surface S. The aforementioned arrangement can be used to: (i) improve the efficiency of the optics and (ii) enable the use of polarisation duplexers behind surface S in order to increase the spectral efficiency of the antenna.

Dihedral corner reflector antenna excited by a probe inside rectangular ring

Abstract: This paper proposes a dihedral corner reflector excited by a probe inside rectangular ring. The antenna structure is simple. The radiation characteristics of the antenna for various spacing between a probe inside rectangular ring and the dihedral corner reflector are analyzed. The numerical results of the radiation pattern, elevational and azimuthal beam peak in E-plane and H-plane, beamwidth and maximum directivity are substantially investigated. In addition, these characteristics are also compared among the included angles of 30/spl deg/, 45/spl deg/, 60/spl deg/ and 90/spl deg/ of dihedral corner reflector. The result of the analysis is very useful to design the antenna of high directivity with unidirectional beam.

Analysis of the radiation characteristics of the reflector antenna with surface distortion and holes using PTD

Abstract: The reflector antenna distortion model is built by explosion test results The radiation characteristics of a kind of distorted shaped reflector antenna are computed by using PTD method, and the radiation characteristics of the reflector antenna with holes on the surface are also computed Good results are achieved, which can provide theoretical guidance for the radar attackers

Ku/Ka bands precipitation radar antenna: half-scale offset cylindrical reflector model [spaceborne]

Abstract: Precipitation radar provides new and exciting data on 3D rain structures, for a variety of scientific uses. The second generation spaceborne precipitation radar is a proposed profiling radar that will enhance the capabilities aboard the TRMM satellite. The proposed radar system antenna is a 5.3 m offset parabolic cylindrical reflector antenna which has dual frequency operation at 13.6 GHz and 35 GHz. In order to demonstrate the technological readiness of the concept, this paper focusses on a half-scale model of 2.65 m operating at Ku and Ka bands, with an evaluation of the antenna feed and reflector antenna system.

Correcting secondary mirror surface errors in Noto 32 m radiotelescope using the 'active' primary mirror

Abstract: Some results are presented of a successful attempt to correct the surface manufacturing errors on the secondary mirror of the Noto 32 m radiotelescope by means of a new primary mirror, the shape of which is controlled by 244 electromechanical actuators. During a 43 GHz Jupiter observation, the technique yielded a 22% gain increase.