how do satellites send signals and receive signals through a vacuum?

Question: how do satellites send signals and receive signals through a vacuum?
- Keywords:
  earth,
  space,
  technology
Asked by to Anna, Elaine, Fiona, Kevin, Darren on 24 Jun 2014. This question was also asked by .
- Anna Bramwell-Dicks answered on 24 Jun 2014:
  
  Great question!
  
  This is because, the signals that are sent and received by the satellites are radio waves – which means they are electromagnetic waves, not mechanical waves. Radio waves have the longest wavelength and the lowest frequency of any wave type.
  
  On the other hand, mechanical waves, like sound waves, cannot travel through a vacuum – they need some sort of physical medium for them to propagate through. But, electromagnetic waves (like radio waves, or infrared) do not need this medium to travel through which is why they can travel through space’s vacuum!
- Zhiming Darren Tan answered on 25 Jun 2014:
  
  Electromagnetic waves, including light and x-rays and radio signals, wireless and bluetooth and all that, can travel through the vacuum. They set up electric and magnetic oscillations, which do not need matter. You can have these fields in a vacuum. This is not obvious – people spent a long time looking for the “aether” that allows electromagnetic waves to travel – but this was not found and we now understand that it is not necessary.
  
  Electromagnetism is very important in physics, as it helped in the foundations of Einstein’s relativity also.

Question: how do satellites send signals and receive signals through a vacuum?