This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
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Question: However a log-periodic dipole array consists of a number of dipole elements of different lengths in order to obtain a somewhat directional antenna having an extremely wide bandwidth: these are frequently used for television reception in fringe areas. The dipole antennas composing it are all considered "active elements" since they are all electrically connected together (and to the transmission line). On the other hand, a superficially similar dipole array, the Yagi-Uda Antenna (or simply "Yagi"), has only one dipole element with an electrical connection; the other so-called parasitic elements interact with the electromagnetic field in order to realize a fairly directional antenna but one which is limited to a rather narrow bandwidth. The Yagi antenna has similar looking parasitic dipole elements but which act differently due to their somewhat different lengths. There may be a number of so-called "directors" in front of the active element in the direction of propagation, and usually a single (but possibly more) "reflector" on the opposite side of the active element.

Answer: What type of antenna formation is made up of multiple dipole elements of varying lengths?


Question: In total, 156 prisoners have been either acquitted, or received pardons or commutations on the basis of possible innocence, between 1973 to 2015. Death penalty opponents often argue that this statistic shows how perilously close states have come to undertaking wrongful executions; proponents point out that the statistic refers only to those exonerated in law, and that the truly innocent may be a smaller number. Statistics likely understate the actual problem of wrongful convictions because once an execution has occurred there is often insufficient motivation and finance to keep a case open, and it becomes unlikely at that point that the miscarriage of justice will ever be exposed.

Answer: Between 1973 and 2015, how amny prisoners were acquitted or received pardons or commutations of their death sentences due to possible innocence?


Question: As one of the earliest centers of book-printing in Europe (see above: History), Strasbourg for a long time held a large number of incunabula—documents printed before 1500—in her library as one of her most precious heritages. After the total destruction of this institution in 1870, however, a new collection had to be reassembled from scratch. Today, Strasbourg's different public and institutional libraries again display a sizable total number of incunabula, distributed as follows: Bibliothèque nationale et universitaire, ca. 2 098 Médiathèque de la ville et de la communauté urbaine de Strasbourg, 394 Bibliothèque du Grand Séminaire, 238 Médiathèque protestante, 94 and Bibliothèque alsatique du Crédit Mutuel, 5.

Answer:
What are incunabula's?