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Radio Telescope Basics


									              Radio Telescope Basics

                          Three Basic Questions:
1.   What do Radio Telescopes do?
2.   How do Radio Telescopes work?
3.   How are Radio Telescopes similar or dissimilar to Optical Telescopes?
             What do Radio
            Telescopes Do?
• They “gather” Radio waves just like optical
  Telescopes “gather” light!
  – Concentrate radio waves that fall on the
    telescope “dish”
  – Bounce (reflect) waves from the dish to a
    radio receiver
  – Concentrating the waves gives information
    with more definition and resolution
How do Radio Telescopes work?
   Press radio telescopesviewlike this
    Some up arrow to to work animation
     Other radio arrow reset like this
   press downtelescopes workanimation
Once you get the raw signal
   from the antenna…

                   Learn more
            A few details:
        Receiver and Amplifier
• Receivers use cooled HFET
  (Heterostructure Field-Effect Transistors)
• These are very Low-noise input amplifiers.
• HFET Receivers are reliable and stable.
  They have an entire octave of bandwidth
  without unnecessary noise. What’s more,
  they’re cooled to keep the signal to noise
  ratio high.
    Why are receivers cooled?
• Cooling a receiver:
  – Reduces Thermal Noise. The electronics in
    the telescope emit radio waves themselves.
    Cooled electronics emit much less radiation,
    much less “noise”.
  – By reducing noise, the weak signal will be
    elevated in relative strength
  – The coolant used is typically either liquid
    Nitrogen or liquid Helium.
             LEARN MORE
• Visit this site and research several radio
  telescopes. For each telescope, answer the
  following questions:
• Where is it?
• What organization runs it?
• What is the telescope’s diameter (in meters)
• What wavelengths / frequencies does the
  telescope detect.
• For what investigations is the telescope being
• Name one fun fact about the telescope

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