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English: This pictorial periodic table is colorful, boring, and packed with information. In addition to the element's name, symbol, and atomic number, each element box has a drawing of one of the element's main human uses or natural occurrences. The table is color-coded to show the chemical groupings.
The idea to give each band a number, in which the number is the logarithm of the approximate geometric mean of the upper and lower band limits in Hz, originated with B. C. Fleming-Williams, who suggested it in a letter to the editor of Wireless Engineer in 1942. For example, the approximate geometric mean of band 7 is 10 MHz, or 10 7 Hz.
At last count 96/97 of the 97 elements (hydrogen through einsteinium, except astatine and francium) isolated in pure form and in macroscopic quantities have images. There are few images of very low encyclopedic quality for which it should be relatively easy to obtain higher quality: Ca. One element is still missing an image: Rn.
[18] Tags may either be read-only, having a factory-assigned serial number that is used as a key into a database, or may be read/write, where object-specific data can be written into the tag by the system user. Field programmable tags may be write-once, read-multiple; "blank" tags may be written with an electronic product code by the user. [19]
Graphs illustrating the problem of image response in a superheterodyne. The horizontal axes are frequency and the vertical axes are voltage. Without an adequate RF filter, any radio signal S2 (green) from the antenna at the image frequency is also heterodyned to the IF frequency along with the desired radio signal S1 (blue) at , so they both pass through the IF filter (red).
The length of the line would then be scaled to P 1 assuming the Smith chart radius to be unity. For example, if the actual radius measured from the paper was 100 mm, the length OP 1 would be 63 mm. The following table gives some similar examples of points which are plotted on the Z Smith chart. For each, the reflection coefficient is given in ...
The 6 metre amateur band falls into this category, often called "the magic band", will often "open up" from one small area into another small geographic area 1 000–1 700 km (600–1 000 miles) away during the spring and early summer months. This phenomenon occurs during the fall months, although not as often.
In the box at the focus of the dish, called a low-noise block downconverter (LNB), each block of frequencies is converted to the IF range of 950–2150 MHz by two fixed frequency local oscillators at 9.75 and 10.6 GHz. One of the two blocks is selected by a control signal from the set top box inside, which switches on one of the local oscillators.