A Radio Telescope for High School Education Abe Reddy North Dakota State University, Department of Physics Advisor: Professor Brian Keating, UCSD CASS UCSD Physics REU, Sponsored by NSF

Outline  Radio Astronomy and Radio Telescopes  SRT Design  SRT Capabilities

Radio Astronomy  Radio vs. Optical  Less 1mm to several meters/ nm

Radio Telescopes  Larger than optical  Angular resolution proportional to λ/D  Prime Focus vs. Cassegrain Reflectors  Reflector, Subreflector, feed/horn, receiver

Overview  Made From Commercially Available Parts  Capable of receiving signals at 3 &12 GHz, simultaneously  Freeware Software Interface written in Java

Antenna

Antenna Mount  Motors for Azimuth and Elevation angles  0.1 degree pointing resolution  Reed Sensor  12 pole magnet  11.7 counts/degree  Counts are sent to Controller Box

Receiver Design  Orthomode Transducer  Splits EM waves into orthogonal components  Low Noise Block Downconverters  High Electron Mobility Transistor Amplifier  Increases the signal amplitude

 Mixer  HEMT output and reference signal  Heterodyne downconversion to reduce frequency  IF Amplifier  Amplifies signal again  Passes signal through shielded coax cable  Bias-T Circuit  Removes AC signal component

 Passed through total power detector then amplified again  Low-Pass Filter  Removes High-Frequency Interference  Voltage to Frequency Converter  Converts Voltage to pulses  Stamp Microcontroller  Determines frequency of pulses  Communicates with computer

Software Interface  Displays map of the sky  Displays power output for all 4 channels  Graphs power vs. time  Outputs contour plot for 25 point scans

Data Analysis  Azimuth Scans  Equivalent Blackbody Temp  Polarization

Outlook  Usage as a Polarimeter  Data Analysis  Pointing Corrections  Lab Courses