34-m Beam Waveguide Antennas Research Articles

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.

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.

Precision DSN radiometer systems: impact on microwave calibrations

The NASA Deep Space Network (DSN) has a long history of providing large parabolic dish antennas with precision surfaces, low-loss feeds, and ultra-low noise amplifiers for deep-space telecommunications. To realize the benefits of high sensitivity, it is important that receiving systems are accurately calibrated and monitored to maintain peak performance. A method is described to measure system performance and to calibrate the receiving system using procedures, software, and commercial instruments that are easy to implement and efficient to use. The utility of the measurement procedures and the precision of the receiver calibration technique were demonstrated by performing tests at Ka-band (32 and 33.68 GHz) frequencies at Goldstone on a 34-m beam-waveguide antenna. Observations of multiple calibration radio sources are used to measure the dependence of antenna gain and system noise temperature on source elevation and derive the performance parameters. The experimental results described illustrate some of the ways that receiving system nonlinearity can negatively impact system performance. A simple radiometer calibration technique and analysis provide quantitative information that enables the system engineer to adjust and linearize the receiving system. When that is not practical, the experimenter or the operator can apply connection coefficients to the measured values of system noise temperature and thereby compensate for the receiving system nonlinearity. >

Microwave antenna holography

The application of the holography technique to the newly constructed NASA/JPL Deep Space Network (DSN) 34-m beam-waveguide antenna, resulting in 4.1-dB performance improvement at 32 GHz by reducing the main reflector RMS surface error at 0.43 mm, is described. The improved antenna performance was verified by additional holographic measurements and efficiency measurements at X-band (8.45 GHz). Microwave holography has been demonstrated to be a required tool for achieving antenna aperture efficiency of 52% at Ka-band (32 GHz) and is probably necessary for maintaining an operational DSN Ka-band ground antenna capability.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>