Outdoor
See also: Yagi antenna See also: Log-periodic antenna See also: Phased arrayAn outdoor TV antenna generally consists of multiple conductive elements that are arranged such that it is a directional antenna. The length of the elements is about one half of the signal wavelength. Therefore, the length of each element corresponds to a certain frequency.
In a combination (combo) VHF/UHF antenna the longer elements (for picking up VHF frequencies) are at the "back" of the antenna, relative to the device's directionality, and the much shorter UHF elements are in the "front", and the antenna works best when "pointing" to the source of the signal to be received. The smallest elements in this design, located in the "front", are UHF and use Yagi antenna principals. The longest elements, located in the "back" of the antenna use VHF Log-periodic principals. Combining these two types of antenna creates the combination VHF/UHF antenna commonly used.
An antenna can have a smaller or larger number of directors; the more directors it has (requiring a longer boom), and the more accurate their beamwidth the higher its gain will be. For the commonly used Yagi antenna this is not a linear relationship. Antenna gain is the ratio of the signal received from the preferred direction to the signal from an ideal omnidirectional antenna. Gain is inversely proportional to the antenna's acceptance angle.
Two or more directional rooftop antennas can be set up and connected to one receiver. Antennas designed for rooftop use are sometimes located in attics.
Sometimes television transmitters are organised such that all receivers in a given location need receive transmissions in only a relatively narrow band of the full UHF television spectrum and from the same direction, so that a single antenna provides reception from all stations.
Read more about this topic: Television Antenna
Famous quotes containing the word outdoor:
“From my experience with wild apples, I can understand that there may be reason for a savage’s preferring many kinds of food which the civilized man rejects. The former has the palate of an outdoor man. It takes a savage or wild taste to appreciate a wild fruit.”
—Henry David Thoreau (1817–1862)
“Close to the academy in this town they have erected a sort of gallows for the pupils to practice on. I thought that they might as well hang at once all who need to go through such exercises in so new a country, where there is nothing to hinder their living an outdoor life. Better omit Blair, and take the air.”
—Henry David Thoreau (1817–1862)
“We put [young children] into kindergarten where their reasoning powers are ruined; or, if we can afford it, we buy Montessori outfits that were invented for semi-imbeciles in Italian slums; or we send them to outdoor schools and give them prizes for sleeping.”
—Katharine Fullerton Gerould (1879–1944)