Central processing unitA central processing unit (CPU)—also called a central processor or main processor—is the most important processor in a given computer. Its electronic circuitry executes instructions of a computer program, such as arithmetic, logic, controlling, and input/output (I/O) operations. This role contrasts with that of external components, such as main memory and I/O circuitry, and specialized coprocessors such as graphics processing units (GPUs). The form, design, and implementation of CPUs have changed over time, but their fundamental operation remains almost unchanged.
Microwave transmissionMicrowave transmission is the transmission of information by electromagnetic waves with wavelengths in the microwave frequency range of 300MHz to 300GHz(1 m - 1 mm wavelength) of the electromagnetic spectrum. Microwave signals are normally limited to the line of sight, so long-distance transmission using these signals requires a series of repeaters forming a microwave relay network. It is possible to use microwave signals in over-the-horizon communications using tropospheric scatter, but such systems are expensive and generally used only in specialist roles.
Radio-frequency engineeringRadio-frequency (RF) engineering is a subset of electronic engineering involving the application of transmission line, waveguide, antenna and electromagnetic field principles to the design and application of devices that produce or use signals within the radio band, the frequency range of about 20 kHz up to 300 GHz. It is incorporated into almost everything that transmits or receives a radio wave, which includes, but is not limited to, mobile phones, radios, WiFi, and two-way radios.
Studio transmitter linkA studio transmitter link (or STL) sends a radio station's or television station's audio and video from the broadcast studio or origination facility to a radio transmitter, television transmitter or uplink facility in another location. This is accomplished through the use of terrestrial microwave links or by using fiber optic or other telecommunication connections to the transmitter site. This is often necessary because the best locations for an antenna are on top of a mountain, where a much shorter radio tower is required, but where locating a studio may be impractical.
Collinear antenna arrayIn telecommunications, a collinear antenna array (sometimes colinear antenna array) is an array of dipole or quarter-wave antennas mounted in such a manner that the corresponding elements of each antenna are parallel and collinear; that is, they are located along a common axis. Collinear arrays are high gain omnidirectional antennas. Both dipoles and quarter-wavelength monopoles have an omnidirectional radiation pattern in free space when oriented vertically; they radiate equal radio power in all azimuthal directions perpendicular to the antenna, with the signal strength dropping to zero on the antenna axis.
Dipole antennaIn radio and telecommunications a dipole antenna or doublet is the simplest and most widely used class of antenna. The dipole is any one of a class of antennas producing a radiation pattern approximating that of an elementary electric dipole with a radiating structure supporting a line current so energized that the current has only one node at each end. A dipole antenna commonly consists of two identical conductive elements such as metal wires or rods.
Reflective array antennaIn telecommunications and radar, a reflective array antenna is a class of directive antennas in which multiple driven elements are mounted in front of a flat surface designed to reflect the radio waves in a desired direction. They are a type of array antenna. They are often used in the VHF and UHF frequency bands. VHF examples are generally large and resemble a highway billboard, so they are sometimes called billboard antennas. Other names are bedspring array and bowtie array depending on the type of elements making up the antenna.
Invention of radioThe invention of radio communication was preceded by many decades of establishing theoretical underpinnings, discovery and experimental investigation of radio waves, and engineering and technical developments related to their transmission and detection. These developments allowed Guglielmo Marconi to turn radio waves into a wireless communication system. The idea that the wires needed for electrical telegraph could be eliminated, creating a wireless telegraph, had been around for a while before the establishment of radio-based communication.
Transmission lineIn electrical engineering, a transmission line is a specialized cable or other structure designed to conduct electromagnetic waves in a contained manner. The term applies when the conductors are long enough that the wave nature of the transmission must be taken into account. This applies especially to radio-frequency engineering because the short wavelengths mean that wave phenomena arise over very short distances (this can be as short as millimetres depending on frequency).
LongwaveIn radio, longwave, long wave or long-wave, and commonly abbreviated LW, refers to parts of the radio spectrum with wavelengths longer than what was originally called the medium-wave broadcasting band. The term is historic, dating from the early 20th century, when the radio spectrum was considered to consist of longwave (LW), medium-wave (MW), and short-wave (SW) radio bands. Most modern radio systems and devices use wavelengths which would then have been considered 'ultra-short'.
Radio jammingRadio jamming is the deliberate jamming, blocking or interference with wireless communications. In some cases, jammers work by the transmission of radio signals that disrupt communications by decreasing the signal-to-noise ratio. The concept can be used in wireless data networks to disrupt information flow. It is a common form of censorship in totalitarian countries, in order to prevent foreign radio stations in border areas from reaching the country.
Smart deviceA smart device is an electronic device, generally connected to other devices or networks via different wireless protocols (such as Bluetooth, Zigbee, near-field communication, Wi-Fi, LiFi, or 5G) that can operate to some extent interactively and autonomously. Several notable types of smart devices are smartphones, smart speakers, smart cars, smart thermostats, smart doorbells, smart locks, smart refrigerators, phablets and tablets, smartwatches, smart bands, smart keychains, smart glasses, and many others.
