Ionosfero

Ionosfero esas la parto ionizita dil atmosfero, jacanta de cirkume 48 km til cirkume 965 km super la marala nivelo, inkluzanta tale nomizita "termosfero" e parti de la "mezosfero" ed "exosfero". Ionosfero ionizesas da sunala radiaco. Ol esas importanta por atmosferala eletktrozeso ed influas la propago di ondi di radiofrequeso til 30 MHz a longa disti.

Historio di la deskovro[redaktar | redaktar fonto]

Ja en 1839, Germana fizikisto Carl Friedrich Gauss postulis ke regiono dil atmosfero kapabla por konduktar elektro povus explikar la varii observebla en magnetala feldo di la Tero. Sis yardeki pose, ye la 12ma di decembro 1901, en St. John's, Newfoundland e Labrador, Guglielmo Marconi unesmafoye recevis trans-Atlantika radiotransmisado uzanta 152-metra anteno ligita a kaito. La radiosignalo transmisesis de Poldhu, Kornwal uzanta cintilo-radiotransmisilo qua produktis frequesi di 500 KHz, kun povo 100-foye plu granda kam irga radiosignalo ante produktita. La signali transmisita reprezentis la litero S. Un yaro pose, Marconi iteris l'experimento en Glace Bay, Nova-Skotia^[1].

En 1902, Angla fizikisto Oliver Heaviside propozis l'existo di atmosferala strato che ionosfero qua nun recevas lua nomo, "strato Kennelly–Heaviside". En 1912, Usana kongreso aprobis lego qua restriktis l'operaco di radio-amatori a frequesi super 1,5 MHz. La guvernerio pensis ke ca frequesi esis neutila. To enduktis la deskovro di radio-propagado di alta frequesi (HF), anke konocata kom kurta ondi (infre 200 metri) a longa disti, en 1923^[2].

En 1925, Usan injenioro Alfred Norton Goldsmith deskovris dum eklipso ke kurta ondi (HF) afektesis da sunala radiaco, kontre ke longa ondi ne afektesis, do kontributis por komprenar la rolo di ionosfero en radio-propagado.

En 1926, Robert Watson-Watt kreis la vorto "ionosfero", che letro a la revuo Nature publikigita erste en 1969. Dum la komenco dil yari 1930a, neatencema probo-transmisioni de Radio Luxembourg furnisis evidenteso di modifikuri en l'ionosfero. En 1947, Edward Victor Appleton recevis la Nobel-premio pri Fiziko por la deskovro di ionosfero. En 1962, Kanadana artificala satelito Alouette 1 lansesis por studiar l'ionosfero. Altra sateliti kun la sama skopo lansesis pose.

Referi[redaktar | redaktar fonto]

↑ Marconi and the History of Radio. Nomo di la publikigo: IEEE Antennas and Propagation Magazine. Volumo: 46. Idiomo: Angla.
↑ Broadcast listening in the pioneer days of radio on the short waves, 1923 1945 - Autoro: Jerome S. Berg. Publikigita da worldradiohistory.com:. Idiomo: Angla.
Segun on povas lektar en la texto: "...In addition to having to obtain licenses - a constraint to which they adapted only slowly - the amateurs were, with some exceptions, restricted to the range below 200 meters (that is, above 1500 kc.), bands that were largely unexplored and thought to be of little value. The navy attributed most interference to the amateurs, and was happy to see them on the road to a hoped - for extinction. From the amateurs' point of view, their development of the shortwave spectrum began less as a love affair than a shotgun marriage. However, all that would change...It took several years before experimenters ventured above 2-3 mc. and started to understand such things as shortwave propagation and directionality. The short waves, as they were called, were surrounded with mystery...Also in 1928 Radio News publisher Hugo Gernsback began shortwave broadcasting on 9700 kc. from his station, WRNY, New York, using the call W2XAL. "A reader in New South Wales, Aus- tralia," reported Gernsback, "writes us that while he was writing his letter he was listening to WRNY's short-wave transmitter, 2XAL, on a three-tube set; and had to turn down the volume, otherwise he would wake up his family. All this at a distance of some 10,000 miles! Yet 2XAL ...uses less than 500 watts; a quite negligible amount of power. "6...The 1930s were the golden age of shortwave broadcasting...Shortwave also facilitated communication with people in remote areas. Amateur radio became a basic ingredient of all expeditions...The term shortwave was generally taken to refer to anything above 1.5 mc., without upper limit..."

[1] Marconi and the History of Radio. Nomo di la publikigo: IEEE Antennas and Propagation Magazine. Volumo: 46. Idiomo: Angla.

[2] Broadcast listening in the pioneer days of radio on the short waves, 1923 1945 - Autoro: Jerome S. Berg. Publikigita da worldradiohistory.com:. Idiomo: Angla.
Segun on povas lektar en la texto: "...In addition to having to obtain licenses - a constraint to which they adapted only slowly - the amateurs were, with some exceptions, restricted to the range below 200 meters (that is, above 1500 kc.), bands that were largely unexplored and thought to be of little value. The navy attributed most interference to the amateurs, and was happy to see them on the road to a hoped - for extinction. From the amateurs' point of view, their development of the shortwave spectrum began less as a love affair than a shotgun marriage. However, all that would change...It took several years before experimenters ventured above 2-3 mc. and started to understand such things as shortwave propagation and directionality. The short waves, as they were called, were surrounded with mystery...Also in 1928 Radio News publisher Hugo Gernsback began shortwave broadcasting on 9700 kc. from his station, WRNY, New York, using the call W2XAL. "A reader in New South Wales, Aus- tralia," reported Gernsback, "writes us that while he was writing his letter he was listening to WRNY's short-wave transmitter, 2XAL, on a three-tube set; and had to turn down the volume, otherwise he would wake up his family. All this at a distance of some 10,000 miles! Yet 2XAL ...uses less than 500 watts; a quite negligible amount of power. "6...The 1930s were the golden age of shortwave broadcasting...Shortwave also facilitated communication with people in remote areas. Amateur radio became a basic ingredient of all expeditions...The term shortwave was generally taken to refer to anything above 1.5 mc., without upper limit..."

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