Question: As an electro-magnetic wave travels through the different parts of the antenna system (radio, feed line, antenna, free space) it may encounter differences in impedance (E/H, V/I, etc.). At each interface, depending on the impedance match, some fraction of the wave's energy will reflect back to the source, forming a standing wave in the feed line. The ratio of maximum power to minimum power in the wave can be measured and is called the standing wave ratio (SWR). A SWR of 1:1 is ideal. A SWR of 1.5:1 is considered to be marginally acceptable in low power applications where power loss is more critical, although an SWR as high as 6:1 may still be usable with the right equipment. Minimizing impedance differences at each interface (impedance matching) will reduce SWR and maximize power transfer through each part of the antenna system.
Try to answer this question if possible: What is created by a portion of a radio waves energy reversing?
Answer: standing wave
Question: St. Barthelemy has a small airport known as Gustaf III Airport on the north coast of the island that is served by small regional commercial aircraft and charters. The nearest airport with a runway length sufficient to land a typical commercial jet airliner is on the neighboring island of Sint Maarten: Princess Juliana International Airport, which acts as a hub, providing connecting flights with regional carriers to St. Barthelemy. Several international airlines and domestic Caribbean airlines operate in this sector.
Try to answer this question if possible: Which side of the island does the Princess Juliana International Airport lie on Saint Maarten?
Answer: unanswerable
Question: The Royal School of Mines was established by Sir Henry de la Beche in 1851, developing from the Museum of Economic Geology, a collection of minerals, maps and mining equipment. He created a school which laid the foundations for the teaching of science in the country, and which has its legacy today at Imperial. Prince Albert was a patron and supporter of the later developments in science teaching, which led to the Royal College of Chemistry becoming part of the Royal School of Mines, to the creation of the Royal College of Science and eventually to these institutions becoming part of his plan for South Kensington being an educational region.
Try to answer this question if possible: What school was established in the 18th century?
Answer: unanswerable
Question: In the next two years, the company established its first factory in south India in the town of Machilipatnam on the Coromandel Coast of the Bay of Bengal. The high profits reported by the company after landing in India initially prompted King James I to grant subsidiary licences to other trading companies in England. But in 1609 he renewed the charter given to the company for an indefinite period, including a clause that specified that the charter would cease to be in force if the trade turned unprofitable for three consecutive years.
Try to answer this question if possible: why did King James I licence other trading companies from england?
Answer:
high profits