This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: 10-11 THE IONOSPHERE THE IONOSPHERE Discovery of the Ionosphere 1820 Hans Christian Oersted discovers that electricity and magnetism are related 1864 - 73 James Clerk Maxwell describes theory of electromagnetic radiation and predicts existence of radiowaves 1882 Balfour Stewart suggests winds drive electric currents in the upper atmosphere 1887 Heinrich Hertz proves existence of radiowaves 1895 Guglielmo Marconi demonstrates wireless (radio) communication in Bologna, Italy 1899 Marconi transmits radio signal across English Channel Dec. 12, 1901 Marconi transmits radio signal across Atlantic Ocean from Cornwall, England to St. John's, Newfoundland 1902 Oliver Heaviside; Arthur Kennelly propose existence of conducting layer in upper atmosphere 1909 Marconi awarded Nobel Prize 1924 Edward Appleton and others develop the ionosonde and begin ground-based soundings ; prove existence of ionosphere 1925 Appleton discovers second layer (the F region) 1926 Robert Watson-Watt (later developer of radar) coins word "ionosphere" 1927 Sydney Chapman describes theory for formation of ionosphere 1947 Appleton awarded Nobel Prize 1948 Rocket probes begin 1950's Riometer (R elative I onospheric O pacity M eter using E xtra T errestrial E lectromagnetic R adiation) developed 1958 Incoherent Scatter Radar developed 1962 Alouette 1 satellite makes first topside soundings Radio Communication Spaceweather presented by The Windows to the Universe has a section on radio wave propagation and wave modulation (AM vs FM) The howstuffworks.com page on the radio spectrum Even more detail on the allocated uses of the radio and microwave spectrum from 9 kHz to 275 GHz Radio Reception • Amplitude Modulated (AM) radio (540 - 1600 kHz) o ground wave - received (local reception) o sky wave - DAY: absorbed in D-region of ionosphere NIGHT: reflected by E-region interference from distant transmitters fading in/out of long distance reception • Short Wave (SW) radio (2 - 26 MHz) o ground wave - received (local reception) o sky wave - reflected by F-region (enables long distance reception) • Frequency Modulated (FM) radio (88 - 108 MHz) o ground wave - received (local reception) o sky wave - transmitted through ionosphere into space Some Milestones in the History of Radio Feb 1892 William Crookes publishes idea of wireless (radio) communication May 7, 1895 Alexander Popov demonstrates lightning produces radiowaves March 24, 1896 Popov demonstrates wireless communication in Russia . June 2, 1896 Marconi files patent in England for wireless communication March 3, 1899 Earliest reported use of wireless to report naval accident when the Steamship Matthews collides with East Goodwin Lightship Dec 12, 1901 Marconi transmits and receives radio signal (the Morse code for letter S) across the Atlantic 1902 U.S. Navy installs radio telephones aboard ships 1906 Lee DeForest invents radio amplifier and radio tube triode 1906 Reginald Fessenden first broadcast of voice and music 1906...
View Full Document
- Spring '09
- Solar Wind, Magnetic Field