Engineering topics

Gama, Eric

Publications and source records attributed to Gama, Eric.

5 records

NASA NTRS2012

Strut Shaping of 34m Beam Waveguide Antenna for Reductions in Near-Field RF and Noise Temperature

Strut shaping of NASA's Deep Space Network (DSN) 34m Beam Waveguide (BWG) antenna has been implemented to reduce near-field RF exposure while improving the antenna noise temperature. Strut shaping was achieved by introducing an RF shield that does not compromise the structural integrity of the existing antenna. Reduction in the RF near-field level will compensate for the planned transmit power increase of the antenna from 20 kW to 80 kW while satisfying safety requirements for RF exposure. Measured antenna noise temperature was also improved by as much as 1.5 K for the low elevation angles and 0.5 K in other areas.

near-field↗

NASA NTRS2012

Strut Shaping of 34m Beam Waveguide Antenna for Reductions in Near-Field RF and Noise Temeperature

Struts shaping of the NASA's Deep Space Network (DSN) 34m Beam Waveguide (BWG) antenna has been implemented to reduce near-field RF exposure while improving the antenna noise temperature. Strut shaping was achieved by introducing an RF shield that does not compromise the structural integrity of the existing structure. Reduction in the RF near-field exposure will compensate for the planned transmit power increase of the antenna from 20 kW to 80 kW while satisfying safety requirements for RF exposure. Antenna noise temperature was also improved by as much as 1.5 K for the low elevation angles and 0.5 K in other areas. Both reductions of RF near-field exposure and antenna noise temperature were verified through measurements and agree very well with calculated results.

reflector↗

NASA NTRS2006

Track Level Compensation Look-up Table Improves Antenna Pointing Precision

The pointing accuracy of the NASA Deep Space Network antennas is significantly impacted by the unevenness of the antenna azimuth track. The track unevenness causes repeatable antenna rotations, and repeatable pointing errors. The paper presents the improvement of the pointing accuracy of the antennas by implementing the track-level-compensation look-up table. The table consists of three axis rotations of the alidade as a function of the azimuth position. The paper presents the development of the table, based on the measurements of the inclinometer tilts, processing the measurement data, and determination of the three-axis alidade rotations from the tilt data. It also presents the determination of the elevation and cross-elevation errors of the antenna as a function of the alidade rotations. The pointing accuracy of the antenna with and without a table was measured using various radio beam pointing techniques. The pointing error decreased when the table was used, from 1.5 mdeg to 1.2 mdeg in elevation, and from 20.4 mdeg to 2.2 mdeg in cross-elevation.

Rotation↗

NASA NTRS2006

Thermal considerations for hydroformed reflectors

This paper discussed the thermal design and performance of the 6-meter hydroformed reflector antenna as well as projecting the performance of the Square Kilometer Array (SKA) 12-meter antenna.

thermal↗

NASA NTRS2005

Antennas for the array-based Deep Space Network: current status and future designs

Development of very large arrays1,2 of small antennas has been proposed as a way to increase the downlink capability of the NASA Deep Space Network DSN) by two or three orders of magnitude thereby enabling greatly increased science data from currently configured missions or enabling new mission concepts. The current concept is for an array of 400 x 12-m antennas at each of three longitudes. The DSN array will utilize radio astronomy sources for phase calibration and will have wide bandwidth correlation processing for this purpose. NASA has undertaken a technology program to prove the performance and cost of a very large DSN array. Central to that program is a 3-element interferometer to be completed in 2005. This paper describes current status of the low cost 6-meter breadboard antenna to be used as part of the interferometer and the RF design of the 12-meter antenna.

antennas↗