A Radio TelescopeA Radio Telescopefor High School for High School

EducationEducationAbe ReddyAbe Reddy

North Dakota State University, Department of PhysicsNorth Dakota State University, Department of Physics

Advisor: Professor Brian Keating, UCSD CASSAdvisor: Professor Brian Keating, UCSD CASSUCSD Physics REU, Sponsored by NSFUCSD Physics REU, Sponsored by NSF

OutlineOutline

Radio Astronomy and Radio TelescopesRadio Astronomy and Radio Telescopes

SRT DesignSRT Design

SRT CapabilitiesSRT Capabilities

Radio Astronomy Radio Astronomy

Radio vs. OpticalRadio vs. Optical

Less 1mm to several meters/400-700nmLess 1mm to several meters/400-700nm

Radio TelescopesRadio Telescopes

Larger than opticalLarger than optical Angular resolution Angular resolution

proportional to proportional to λλ/D/D

Prime Focus vs. Prime Focus vs. Cassegrain Cassegrain ReflectorsReflectors

Reflector, Reflector, Subreflector, Subreflector, feed/horn, receiverfeed/horn, receiver

OverviewOverview

Made From Commercially Available PartsMade From Commercially Available Parts

Capable of receiving signals at 3 &12 Capable of receiving signals at 3 &12 GHz, simultaneouslyGHz, simultaneously

Freeware Software Interface written in Freeware Software Interface written in JavaJava

AntennaAntenna

Antenna MountAntenna Mount

Motors for Azimuth and Elevation anglesMotors for Azimuth and Elevation angles 0.1 degree pointing resolution0.1 degree pointing resolution Reed SensorReed Sensor

12 pole magnet12 pole magnet 11.7 counts/degree11.7 counts/degree Counts are sent to Controller BoxCounts are sent to Controller Box

Receiver DesignReceiver Design

Orthomode TransducerOrthomode Transducer Splits EM waves into orthogonal Splits EM waves into orthogonal

componentscomponents

Low Noise Block DownconvertersLow Noise Block Downconverters High Electron Mobility Transistor High Electron Mobility Transistor

AmplifierAmplifier Increases the signal amplitudeIncreases the signal amplitude

MixerMixer HEMT output and reference signalHEMT output and reference signal Heterodyne downconversion to reduce Heterodyne downconversion to reduce

frequencyfrequency

IF AmplifierIF Amplifier Amplifies signal againAmplifies signal again Passes signal through shielded coax cablePasses signal through shielded coax cable

Bias-T CircuitBias-T Circuit Removes AC signal componentRemoves AC signal component

Passed through total power detector then Passed through total power detector then amplified againamplified again

Low-Pass FilterLow-Pass Filter Removes High-Frequency InterferenceRemoves High-Frequency Interference

Voltage to Frequency ConverterVoltage to Frequency Converter Converts Voltage to pulsesConverts Voltage to pulses

Stamp MicrocontrollerStamp Microcontroller Determines frequency of pulsesDetermines frequency of pulses Communicates with computerCommunicates with computer

Software InterfaceSoftware Interface

Displays map of the skyDisplays map of the sky

Displays power output for all 4 channelsDisplays power output for all 4 channels

Graphs power vs. timeGraphs power vs. time

Outputs contour plot for 25 point scansOutputs contour plot for 25 point scans

Data AnalysisData Analysis

Azimuth ScansAzimuth Scans

Equivalent Blackbody Equivalent Blackbody TempTemp

PolarizationPolarization

OutlookOutlook

Usage as a PolarimeterUsage as a Polarimeter Data AnalysisData Analysis

Pointing CorrectionsPointing Corrections

Lab CoursesLab Courses