Ultra High Frequency - Advantages and Disadvantages

Advantages and Disadvantages

The point to point transmission and reception of TV and radio signals is affected by many variables. Atmospheric moisture; solar wind; physical obstructions, such as mountains and buildings; and time of day all affect the signal transmission and the degradation of signal reception. All radio waves are partly absorbed by atmospheric moisture. Atmospheric absorption reduces, or attenuates, the strength of radio signals over long distances. The effects of attenuation degradation increases with frequency. UHF TV signals are generally more degraded by moisture than lower bands, such as VHF TV signals. The ionosphere, a layer of the Earth's atmosphere, is filled with charged particles that can reflect some radio waves. Amateur radio enthusiasts primarily use this quality of the ionosphere to help propagate lower frequency HF signals around the world: the waves are trapped, bouncing around in the upper layers of the ionosphere until they are refracted down at another point on the Earth. This is called skywave transmission. UHF TV signals are not carried along the ionosphere but can be reflected off of the charged particles down at another point on Earth in order to reach farther than the typical line-of-sight transmission distances; this is the skip distance. UHF transmission and reception are enhanced or degraded by tropospheric ducting as the atmosphere warms and cools throughout the day.

The main advantage of UHF transmission is the physically short wave that is produced by the high frequency. The size of transmission and reception antennas is related to the size of the radio wave. The UHF antenna is stubby and short. Smaller and less conspicuous antennas can be used with higher frequency bands.

The major disadvantage of UHF is its limited broadcast range and reception, often called line-of-sight between the TV station's transmission antenna and customer's reception antenna, as opposed to VHF's very long broadcast range and reception, which is less restricted by line of sight.

UHF is widely used in two-way radio systems and cordless telephones, whose transmission and reception antennas are closely spaced. UHF signals travel over line-of-sight distances. Transmissions generated by two-way radios and cordless telephones do not travel far enough to interfere with local transmissions. Several public-safety and business communications are handled on UHF. Civilian applications, such as GMRS, PMR446, UHF CB, 802.11b ("WiFi") and the widely adapted GSM and UMTS cellular networks, also use UHF cellular frequencies. A repeater propagates UHF signals when a distance greater than the line of sight is required.

  • See "Radio horizon".

Read more about this topic:  Ultra High Frequency

Other articles related to "advantages and disadvantages, advantages, disadvantages, advantage":

C-4 (explosive) - Characteristics and Uses - Advantages
... A major advantage of C4 is that it can easily be molded into any desired shape ... C4 can be pressed into gaps, cracks, holes and voids in buildings, bridges, equipment or machinery ...
Superheater - Advantages and Disadvantages
... The main advantages of using a superheater are reduced fuel and water consumption but there is a price to pay in increased maintenance costs ... In locomotives used for mineral traffic the advantages seem to have been marginal ...
Learning By Teaching By Martin (LdL) - The LdL Approach - Advantages and Disadvantages
... They state the following advantages and disadvantages Advantages Student work is more motivated, efficient, active and intensive due to lowered inhibitions and an increased ... planning abilities reliability presentation and moderation skills self-confidence Disadvantages The introduction of the method requires a lot of time ...
Leather Currency - Advantages and Disadvantages
... Banknotes have a natural advantage over coins in that they are lighter to carry but are also less durable ... The different disadvantages between coins and banknotes imply that there may be an ongoing role for both forms of bearer money, each being used where its advantages ...
SQLJ Part 0 - Advantages and Disadvantages
... Some advantages of SQLJ over JDBC include SQLJ commands tend to be shorter than equivalent JDBC programs ... Disadvantages include SQLJ requires a preprocessing step ...

Famous quotes containing the word advantages:

    The advantages found in history seem to be of three kinds, as it amuses the fancy, as it improves the understanding, and as it strengthens virtue.
    David Hume (1711–1776)