RadioTelescopeBasics Three Basic Questions: What do Radio Telescopes do? How do Radio Telescopes work? 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 down arrow to view animation Press up arrow to reset animation Some radio telescopes work like this Other radio telescopes work like this
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 used? • Name one fun fact about the telescope