1. AAE 450 – Senior Design J. Darcey Kuhn ERV Team – Communications January 23, 2001

2. Parameters High Gain Antenna Sizes – Beamwidth and antenna gain Capacity (i.e. number of channels of each type) – or bandwidths and frequencies Uplink & Downlink signal strength and quality to Deep Space Network (DSN) – support communications, science data, voice, video, engineering telemetry, and navigation http://deepspace.jpl.nasa.gov/dsn/

3. High Gain Antenna Beamwidth: from an antenna pattern, the angle between the half-power (3 dB) points of the main lobe, when referenced to the peak effective radiated power of the main lobe http://132.163.64.205/fs-1037/dir-004/_0572.htm

4. High Gain Antenna A useful rule of thumb for calculating beamwidth is 3 dB beamwidth = 70λ / D (degrees) where λ is wavelength and D the antenna diameter Surveyor: 0.56 deg Space Shuttle Uplinking: 0.56 deg Downlinking: 0.51 deg

5. High Gain Antenna Antenna Gain (Isotropic) – for a uniformly illuminated antenna with physical area A, the directive gain at the center of the main beam is given by: http://web.bham.ac.uk/eee1roj8/wbe/wbe031.htm

6. High Gain Antenna G = 4*  *A/λ 2 A=  d 2 /4 Gain is normally expressed in dBs by taking 10*log(G) Surveyor: 42.41 dB Space Shuttle: Uplinking: 42.39 dB Downlinking: 43.14 dB

7. Bandwidths & Frequencies Bandwidth: Amount of data that can be transferred in a fixed amount of time Space Shuttle uses S-band (1,700 to 2,300 MHz) & Ku-band (15,250 to 17,250 MHz) to transfer information Ku-band located in the payload bay Ku-band (12-18 GHz / λ = 2.5 to 1.67 cm) can handle higher quantities of data than the S-band systems (3 channels of data) All transmissions broadcasted by Surveyor utilized X- band radio signals near 8.4 GHz

8. Deep Space Network DSN is an international network of antennas that supports interplanetary spacecraft missions Currently consists of three deep-space communications facilities placed approximately 120 degrees apart around the world – CA, Spain, and Australia

9. Antenna Mounting High-gain antenna sits at the end of a long boom Two rotating joints, called gimbals, hold antenna to boom Gimbals will allow the antenna to automatically track and point at the Earth

10. Future Enhancements http://deepspace.jpl.nasa.gov/dsn/array/index.html

11. Future Enhancements Cost Analysis Power Consumption Signal Signal-to-Noise Ratio Weight Historically low Failure Probability Low Gain Antenna as back-up

12. Related Skills Matlab, Fortran 77, UNIX, AutoCAD, C Currently enrolled in 490E (Satellite Systems) Two co-op tours with United Space Alliance at Johnson Space Center – uplinking data from the MCC to ISS