Quote:
Originally Posted by Gravdigr
Radar is a radio wave, correct? RAdio Detection And Ranging? How is it I can receive a radio station from Nashville? That is beyond line of sight. Is it that the returning signal doesn't have the same properties as the outgoing?
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Frequencies below about 30Mhz will bounce off the ionosphere hence the ability to receive a station beyond the horizon, the AM broadcast band being the band most people are probably familiar with.
International broadcasters, VoA, BBC etc will use higher frequencies (but below 30Mhz) for global coverage from a limited number of transmitter sites.
When you get up into the FM broadcast band, 88-108Mhz in the UK and probably the US, VHF radio waves travel, save for unusual circumstances, straight through the ionosphere.
It's therefore possible to have several different stations on the same frequency simply by well planned geographic separation.
Air Traffic Control radar of the long range variety tends to operate at about 1300Mhz. A radar sited on high ground will 'see' further than one mounted at sea level.
A good example of this is the radar on Mt Gabriel in Southern Ireland which is operated by the Irish aviation authorities but is also 'piped in' to UK Air Traffic Control.
It allows early identification of trans Atlantic arrivals.
That's a bit of a broad brush approach but I think it lays out the general principles.
Have to go and water some plants now on instructions from the manager in residence.
Back later.
ETA If you'd like clarification of any of the above points, please do ask.
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