Beam Waveguide Antenna Research Articles

Deep space debris—Detection of potentially hazardous asteroids and objects from the southern hemisphere

Space debris are composed of both natural and human made objects, some in near Earth orbits while others are passing through deep space. Asteroids may represent one form of near Earth and deep space debris. In this article we report on a set of asteroid observations from the southern hemisphere. We indicate that Apollo and Aten class asteroids represent another form of deep space debris of a potentially hazardous nature to orbiting spacecraft and/or Earth based locations. We also show some of the operational challenges, types of facilities and the importance of geographic diversity, that is, necessary for detecting, observing and characterising asteroids, especially PHA’s. For many years, space agencies and institutions have observed and monitored near Earth asteroids and objects (NEO’s) using high gain radio frequency antennas and optical telescopes in the northern hemisphere (GSSR, Arecibo, Catalina, Pan-STARRS, Atlas and Linear) 1) However a regular operational system to monitor the southern skies does not have the same level of maturity and is where a percentage of asteroids and various human made objects are not detected until they pass into northern skies. To fill that gap the Southern Hemisphere Asteroid Radar Program (SHARP) 2) located in Australia uses available antenna time on either a 70 or 34 m beam waveguide antenna located at the Canberra Deep Space Communication Complex (CDSCC) to transmit a Doppler compensated continuous radio wave at 2.114 GHz (14.2 cm) and 7.15945 GHz (4.2 cm) toward the NEO and receive its echoes at the 64 m Parkes or 6 m × 22 m Australia Telescope Compact Array (ATCA) antennas at Narrabri in Australia. This mode of NEO observation is termed a deep space bistatic radar. The southern hemisphere program has also recently been joined by the 12 m University of Tasmania antennas at Hobart (Tasmania) and Katherine (Northern Territory). Combining SHARPS bistatic radar with small optical apertures located at the University of New South Wales (UNSW) and University of Western Australia (UWA) allows combined optical/RF NEO detections. Whilst sub-metre class optical instruments have contributed independently to asteroid detection over decades, the use of coordinated small 0.3–0.5 m instruments synchronized to large asteroid radars offers an observational flexibility and adaptability when larger optical systems 3) are dedicated to other forms of professional optical astronomy. Since 2015, SHARP has illuminated and tracked over 30 NEO’s ranging in diameter from 7 to 5000 m at ranges of 0.1–18 lunar distances (LD) from Australia.

Solution and Design Technique for Beam Waveguide Antenna System by Using a Parallel Hybrid-Dimensional FDTD Method

This letter presents a novel technique to accurately solve the radiation problems of a beam waveguide (BWG) antenna system aiming to achieve high gain and low sidelobe level (SLL). In order to rapidly obtain the radiation field of the antenna system, a hybrid method using three-dimensional (3-D) nonuniform meshing finite-difference time domain (FDTD) with symmetric boundary condition and body-of-revolution FDTD has been employed. In this method, a parallel algorithm with MPI is applied to enhance computational efficiency, and several approaches are adopted to reduce the errors of simulation. Numerical examinations demonstrate that both the computer memory and run time can be greatly saved by performing this 3-D–2-D hybrid FDTD simulation instead of a complete 3-D one. Furthermore, the accuracy of this method has been validated with a scaled model. Finally, the hybrid method combined with an optimization algorithm has been applied to design an X-band BWG antenna system. Numerical results show a 2.02-dB gain improvement and a 3.46-dB SLL reduction after optimization.

Deep space

Beam waveguide antennas, each 34 m in diameter, lit up against the early-dawn sky at the Goldstone Deep Space Communications Complex in the Mojave Desert in California, US.

An Active Pointing Compensator for Large Beam Waveguide Antenna Under Wind Disturbance

With increasing interest in the application of large beam waveguide antenna operated at high frequencies, the requirement for pointing accuracy becomes more demanding. Owing to wind disturbance inevitably causing certain reflector surface distortions which lead to a pointing error, the overall antenna performance decreases. To decrease the pointing deviation, this study analyzes the pointing error caused by the structural deformation under wind disturbance and proposes a novel real-time pointing error correction system (RPECS) by designing the configuration of an active control beam waveguide with a real-time position adjustable plate mirror (APM). Through inverse displacement analysis, the pointing errors resulting from reflector surface distortions are compensated through properly adjusting the position of the APM. A displacement amplification factor is designed to ensure that the displacement of the APM should fall within the driving stroke range. Using a 65-m S/X band antenna, the simulation results show that the root-mean-square pointing error with RPECS is reduced by 92.6% compared with the traditional control method, the gain loss is only about 0.04 dB after compensation.

Design of Beam Waveguide Antenna Structure for TT&C Ship

According to the special working environment of TT&C ships, S/X/Ka frequency TT&C system needs to be developed by using beam waveguide antenna technology in order to ensure Goddess of the moon project. Antenna structure design is one of the key technologies in the TT&C system. This paper designs the antenna structure detailedly, in which features and design parameters of antenna reflector, antenna seat, shaft angle detection and safety protection devices are given. The load of antenna structure is simulated and calculated based on ANSYS and results show that the designed antenna structure is reasonable, antenna parameters and components configuration are correct, all that fully meets the requirement.

Ka-band high-rate telemetry system upgrade for the NASA deep space network

The NASA Deep Space Network (DSN) has a new requirement to support high-data-rate Category A (Cat A) missions (within 2 million kilometers of the Earth) with simultaneous S-band uplink, S-band downlink and Ka-band downlink. The S-band links are required for traditional telemetry, tracking & command (TT&C) support to the spacecraft, while the Ka-band link is intended for high-data-rate science returns. The new Ka-band system combines the use of proven DSN cryogenic designs, for low system temperature, and high-data-rate capability using commercial telemetry receivers. The initial Cat A support is required for the James Webb Space Telescope (JWST) in 2014 and possibly other missions. The upgrade has been implemented into 3 different 34-meter Beam Waveguide (BWG) antennas in the DSN, one at each of the complexes in Canberra (Australia), Goldstone (California) and Madrid (Spain). System test data are presented to show that the requirements were met and the DSN is ready for Cat A Ka-band operational support.

Pointing enhancement techniques for deep-space antennas

The present paper presents a very efficient technique for enhancing the pointing accuracy in beam-waveguide (BWG) antennas and its application to the deep space antenna DSA2 of the European Space Agency. The proposed technique permits to achieve a twofold result: on the one hand, it provides a solution to the beam aberration issue, arising when the antenna simultaneously receives from and transmits to a spacecraft moving in the transversal direction. On the other hand, it allows to perform a fast conical scan to enhance the pointing accuracy of the antenna. Both results are achieved by simple linear displacements of feeds and mirrors located in the lower part of the BWG, with a very limited deterioration of the antenna gain. The required displacements of feeds and mirrors are determined through a fast optimization algorithm, based on a top-down approach, which requires repeated physical–optics analyses of the lower part of the beam waveguide only, with a significant reduction in the computing time.

Observing the Moon at Microwave Frequencies Using a Large-Diameter Deep Space Network Antenna

The Moon radiates energy at infrared and microwave wavelengths, in addition to reflecting sunlight at optical wavelengths. As a result, an antenna pointed at or near the Moon will result in an increase in system operating noise temperature, which needs to be accounted for in RF telecommunications, radio science or radiometric link calculations. The NASA Deep Space Network (DSN) may use its large-diameter antennas in future lunar robotic or human missions, and thus it is important to understand the nature of this temperature increase as a function of observing frequency, lunar phase, and angular position of the antenna beam on the lunar disk. This paper reports on a comprehensive lunar noise temperature measurement campaign and associated theoretical treatment for a 34-m diameter Deep Space Network antenna observing an extended source such as the Moon. A set of measurements over a wide range of lunar phase angles was acquired at DSS-13, a 34-m diameter beam waveguide antenna (BWG) located at Goldstone, California at 2.3 GHz (S-band), 8.4 GHz (X-band) and 32 GHz (Ka-band). For validation purposes, independent predictions of noise temperature increase were derived using a physical optics characterization of the 34-m diameter antenna gain patterns and Apollo model-based brightness temperature maps of the Moon as input. The model-based predictions of noise temperature increase were compared with the measurements at all three frequencies. In addition, a methodology is presented that relates noise temperature increase due to the Moon to disk-centered or disk-averaged brightness temperature of the Moon at the microwave frequencies of interest. Comparisons were made between the measurements and models in the domain of lunar disk-centered and disk-averaged brightness temperatures. It is anticipated that the measurements and associated theoretical development will be useful in developing telecommunications strategies for future high-rate Ka-band communications where large diameter DSN antennas will be required.

Advances in Ground Transmitters for the NASA Deep Space Network

The Deep Space Network (DSN), managed by the Jet Propulsion Laboratory for NASA, is equipped with multiple microwave transmitters ranging in average radiated power from 200 W to 400 kW. The transmitters are used for routine or emergency communication with spacecraft, for navigation, and for radio science tasks. The latest advances in transmitter engineering were implemented in a new generation of 20-kW dual-band transmitters developed for the DSN 34-m beam waveguide antennas. Innovations include additional X-band communication capability for near Earth missions, new c, automated calibration, improved and expanded computerized monitoring and diagnostics, reduced cabling, and improved maintainability. The innovations were very beneficial for the DSN ldquooverloadrdquo during the Mars 2003/2004 missions and will benefit other missions throughout the next decade. This paper describes the current design of the new transmitters and possible future developments.

A Novel Technique for High-Performance Correction of Beam Aberration in Deep Space Antennas

This letter presents a high performance technique for beam aberration correction in beam-waveguide (BWG) antennas. Beam aberration arises when high-gain ground-station antennas target spacecrafts moving not only along the antenna boresight, but also in the transversal direction. In this case, the antenna receives and transmits in slightly different directions, and, therefore a separation of the transmission and reception beams is needed. The novel algorithm has been developed in the case of European Space Agency (ESA) deep-space antenna 2, and consists in moving part of the lower beam-waveguide feed system. In particular, an ellipsoidal solid mirror is translated along three axes, and a feed horn is translated along one axis. The proposed methodology is validated by comparing its performance with two other techniques found in the literature, in terms of physical optics simulation results. It will be shown how the novel approach allows for higher beam separation, while keeping very low antenna gain degradation. Moreover, the required movements can be achieved with simpler and cheaper servo-mechanisms.

A method and a GUI for the creation of azimuth-track level-pointing-error corrections

The JPL beam-waveguide (BWG) antennas are used for spacecraft tracking and for radio-astronomy observations. They are mounted on wheels that rotate around an uneven azimuth track, causing antenna deformations, and reducing pointing accuracy. The pointing errors affected by the track irregularities are repeatable, and can therefore be calibrated. The effects of the irregularities of the track can continually be corrected by using a lookup table, created by the interface presented. This paper is a continuation of previous work of Gawronski, Baher and Quintero (see ibid., vol.42, no.2, p.28-38, 2000). It describes the processing the inclinometer data, which includes the verification of repeatability, smoothing, slow-trend removal, re-sampling, and adjustment to a standard format. it also presents a user-friendly interface that process field data and creates a lookup table for pointing-error correction by clicking appropriate buttons on a computer screen. The GUI was tested with the JPL BWG antennas, and may be used with any antennas utilizing an azimuth track.

Noise temperature and gain loss due to paints and primers: a case study of DSN antennas

In achieving high performance for reflector antennas, it has been noted that it is essential to carefully assess the roles of surface paints and primers. A thorough literature search has revealed that not much has been reported on this very important engineering-implementation topic. It is one of the main objectives of this feature article to provide a detailed study on the effects of paints and primers on reflector-antenna performance. In particular, as a case study, this paper presents excess-noise-temperature and added-gain loss data at 32 GHz for various combinations of paints and primers currently being studied for use on DSN (Deep Space Network) antenna reflector surfaces. It is shown that 500FHR6 acrylic urethane-based paint has the lowest excess-noise-temperature contribution. Previously, it has been recommended that this paint be used for all new DSN beam-waveguide antennas being constructed, and for all those 34-m and 70-m antennas with reflector surfaces that need repainting. The results, methodologies, and observations presented in this article are also applicable to other reflector-antenna configurations.

The characterization of a 34-meter beam-waveguide antenna at Ka band (32.0 GHz) and X band (8.4 GHz)

New antennas for the NASA Deep Space Network (DSN) have been built to replace the aging antennas of older designs for deep-space communications. These new antennas incorporate a new dual-shape design as well as a beam waveguide (BWG), which utilize a series of additional secondary mirrors to relocate the focal point into a stationary room below the main reflector. The advantages of using such a design include increased isolation of the feed package from outside environmental factors, such as moisture, wind, and temperature changes; and ease of access to the equipment for maintenance, troubleshooting and repair purposes. This article reports on the performance of a beam waveguide antenna at X-band and Ka-band microwave frequencies. The Ka-band antenna performance experiment (KaAP) antenna-efficiency measurements presented in this article were acquired at the Goldstone DSS-13 research and development (R&D) beam-waveguide antenna between December, 1993, and November, 1995. The measured antenna efficiency and ground-station figure-of-merit (gain divided by operating system noise temperature) as a function of elevation angle and their uncertainties are presented. Also described are the station configuration, the measurement technique, the modeling used in the analysis processing, and the historical evolution of the DSS-13 Ka-band antenna-efficiency measurements as progressive improvements and configuration changes were implemented.

Novel solutions to low-frequency problems with geometrically designed beam-waveguide systems

The poor low-frequency performance of geometrically designed beam-waveguide antennas is shown to be caused by the diffraction phase centers being far from the geometrical optics mirror foci, resulting in substantial spillover and defocusing loss. Two novel solutions are proposed: (1) reposition the mirrors to focus low frequencies and redesign the high frequencies to utilize the new mirror positions and (2) redesign the input feed system to provide an optimum solution for the low frequency. A novel use of the conjugate phase-matching technique is utilized to design the optimum low-frequency feed system and the new feed system has been implemented in the Jet Propulsion Laboratory (JPL) Research and Development beam-waveguide (BWG) as part of a dual S/X-band feed system. The new S-band feed system is shown to perform significantly better than the original geometrically designed system.

Corrections to "The Fractional Frequency Stability of a 34-m-Diameter Beam Waveguide Antenna"

Corrections to "The Fractional Frequency Stability of a 34-m-Diameter Beam Waveguide Antenna"

The electrical conductivities of steel and other candidate materials for shrouds in a beam-waveguide antenna system

This article presents the results of electrical conductivity measurements made at 8.420 GHz on samples of the structural steel material used to fabricate shrouds on a Deep Space Network (DSN) 34-m-diameter beam-waveguide (BWG) antenna. Test results show that the structural steel samples at this microwave frequency had effective conductivities that were about 50 times worse than published dc values and also 230 times worse than the measured conductivities of aluminum test samples. Conductivity data are also presented for other candidate materials that could be used to fabricate BWG shrouds. Of interest are the improvements or degradations that were observed after some of the metal test samples were surface treated, plated, or painted.

Antenna servo design for tracking low-Earth-orbiting satellites

The upcoming NASA missions will require tracking of low-orbit satellites. As a consequence, NASA antennas will be required to track satellites at higher rates than for the current deep-space missions. This paper investigates servo design issues for the 34-m beam-waveguide antennas that track low-orbit satellites. This includes upgrading the servo with a feedforward loop, monopulse controller design, and tracking error reduction either through proper choice of elevation pinion location or through application of a notch filter or adjustment of the elevation drive amplifier gain. Finally, improvement of the signal-to-noise ratio through averaging of the oversampled monopulse signal is described. HE National Aeronautics and Space Administration (NASA) antenna network, called the Deep Space Network (DSN), is op- erated by the Jet Propulsion Laboratory. It consists of several antenna types located at three sites Goldstone, CA, Canberra, Australia, and Madrid, Spain and serves as a communication tool for space explo- ration. Future NASA missions will include low-orbiting satellites, which will require significantly higher antenna tracking rates. Thus the servos for the new-generation 34-m beam-waveguide (BWG) antennas should be upgraded to be able to follow commands at higher rates. These upgrades are illustrated in this paper, with the new DSS-13 BWG antenna controller design. The existing proportional and integral (PI) controllers of the antennas satisfy the requirements for deep-space X-band (8.4-GHz) tracking. For high-rate command following a simple and reliable choice is a feedforward controller, described in this paper. For track- ing, a monopulse controller is a fast-rate alternative to the existing conical scanning (conscan) technique. The design and performance of a monopulse controller is discussed. It is shown that its perfor- mance is improved through either proper choice of the location of the elevation pinion or the implementation of a notch filter or the ampli- fier gain adjustment. Finally, the improvement of the signal-to-noise ratio (SNR) of the monopulse signal is presented. By averaging the redundant monopulse samples, the SNR improvement ranges from 7 up to 17 dB.

Speed up of near-field physical optics scattering calculations by use of the sampling theorem

Physical optics scattering calculations performed on the NASA Deep Space Network (DSN) 34-meter beam-waveguide antennas at Ka-band requires approximately 12 hours CPU time on a Cray Y-MP2 computer-excessive in terms of resource utilization. The calculations are done two mirrors at a time. The sampling theorem is used to reduce the number of points on the second surface obtained by performing a physical optics integration over the first surface. The number of points required by subsequent physical optics integrations is obtained by interpolation. Time improvements on the order of 2 to 4 were obtained for typical scattering pairs.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Ground antennas in NASA's deep space telecommunications

Ground antennas are the major visible components of NASA's Deep Space Network (DSN). The role, key characteristics, and performance of these antennas in deep-space telecommunications are described. The system analyses and tradeoffs to optimize the overall ground-to-spacecraft link and to define future missions are elaborated from an antenna perspective. Overall performance of receiving systems is compared using the widely accepted G/T figure-of-merit, i.e., net antenna gain divided by the operating system noise temperature. Performance of past, present, and future antennas and receiving systems is discussed, including the planned development of a world-wide network of 34-m diameter beam-waveguide antennas. The need for multifrequency operation, presently in the S- and X-bands, and in the future in the Ka-band, is discussed. The resulting requirements placed on antenna technology are highlighted. Beam-waveguide antenna performance to further improve performance and operational advantages is discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The fractional frequency stability of a 34-m-diameter beam-waveguide antenna

Advances in fiber-optic technology have made it possible to develop a new technique to isolate and measure the frequency stability of a large beam-waveguide (BWG) antenna. Through the use of the technique described in the paper, at both 46.5/spl deg/ and 37/spl deg/ elevation angles, under good weather conditions, the degradation of the the fractional frequency stability of signals passing through the antenna path was measured to be between 1.3 and 2.2/spl times/10/sup -15/ for sampling intervals of 1024 s. These stability values apply to the portion of the antenna that includes the main reflector, subreflector, tripod legs, and six BWG mirrors. These test results are believed to be the first successful fractional frequency stability measurements made on the microwave optics portion of a large antenna to a level of 1 or 2 parts in 10/sup 15/. >