Extract the answer to the question from the following context. Question: What isn't ideal, but functional? Context: 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.
Ans: A SWR of 1.5:1

Extract the answer to the question from the following context. Question: What dynasty was taken down by the Tang? Context: Zhejiang, as the heartland of the Jiangnan (Yangtze River Delta), remained the wealthiest area during the Six Dynasties (220 or 222589), Sui, and Tang. After being incorporated into the Sui dynasty, its economic richness was used for the Sui dynasty's ambitions to expand north and south, particularly into Korea and Vietnam. The plan led the Sui dynasty to restore and expand the network which became the Grand Canal of China. The Canal regularly transported grains and resources from Zhejiang, through its metropolitan center Hangzhou (and its hinterland along both the Zhe River and the shores of Hangzhou Bay), and from Suzhou, and thence to the North China Plain. The debacle of the Korean war led to Sui's overthrow by the Tang, who then presided over a centuries-long golden age for the country. Zhejiang was an important economic center of the empire's Jiangnan East Circuit and was considered particularly prosperous. Throughout the Tang dynasty, The Grand Canal had remained effective, transporting grains and material resources to North China plain and metropolitan centers of the empire. As the Tang Dynasty disintegrated, Zhejiang constituted most of the territory of the regional kingdom of Wuyue.
Ans: Sui

Extract the answer to the question from the following context. Question: As part of his 5 point plan, Gaddafi instituted an administrative revolution and what other revolution Context: On 16 April 1973, Gaddafi proclaimed the start of a "Popular Revolution" in a Zuwarah speech. He initiated this with a 5-point plan, the first point of which dissolved all existing laws, to be replaced by revolutionary enactments. The second point proclaimed that all opponents of the revolution had to be removed, while the third initiated an administrative revolution that Gaddafi proclaimed would remove all traces of bureaucracy and the bourgeoisie. The fourth point announced that the population must form People's Committees and be armed to defend the revolution, while the fifth proclaimed the beginning of a cultural revolution to expunge Libya of "poisonous" foreign influences. He began to lecture on this new phase of the revolution in Libya, Egypt, and France.
Ans: a cultural revolution

Extract the answer to the question from the following context. Question: How many phases can alloys have? Context: An alloy is a mixture of metals or a mixture of a metal and another element. Alloys are defined by metallic bonding character. An alloy may be a solid solution of metal elements (a single phase) or a mixture of metallic phases (two or more solutions). Intermetallic compounds are alloys with a defined stoichiometry and crystal structure. Zintl phases are also sometimes considered alloys depending on bond types (see also: Van Arkel-Ketelaar triangle for information on classifying bonding in binary compounds).
Ans: An alloy may be a solid solution of metal elements (a single phase) or a mixture of metallic phases (two or more solutions)