Satellite or parabolic dishes are tools that translate into the power to boost social, technological, or economic development throughout the universe. It is a very useful resource in terms of information transmission, among other contributions that we will disaggregate.
What are satellite dishes or parabolic dishes?
We walk on any street or avenue and see frequently on the roofs of houses or on the top of buildings and also on small hills in urban areas, giant plates such as aluminum of all sizes, and even with other equipment incorporated into they making them even more extravagant.
In addition to this, towers with links and pieces of many meters high installed on the roof part of the buildings, connected with cables are also achievedaa. But many times, like any episode of everyday life, we completely ignore the existence or reason for such devices.
We have asked ourselves; What are Parabolic or Satellite dishes for? What is their name really beyond antenna? What is its scope? We begin with the term antenna in the first place to break down the subject and know in-depth everything related to the differences and their importance.
parabolic or satellite dishes; In the simplest term, they are devices of very different forms that, in the emitters and receivers of electromagnetic waves, are used to emit or receive them.
In other terms used by telecommunications experts, or wave reception or simply in a radio transmitter system, an antenna is an element that has the mission of throwing into space the electromagnetic energy supplied by a generator and driven by an appropriate transmission line.
In a receiving system, it is intended to collect the energy of the waves that come from the surrounding space and send it, always through a convenient line, to the appropriate apparatus.
In both cases, the antenna functions as a link between two media, space and the transmission line, in which electromagnetic waves propagate following different laws. That is, the antenna constitutes an adapter between two systems; line and space.
Meaning of Transmission
We will pause to explain what the term transmission consists of. We have that it is the action of sending a message, that is, communicating news or broadcasting a radio and television station, music programs, shows, etc.
Experts in this area explain that transmission allows driving or being the means through which vibrations or radiations pass.
Continuing with the theme of the antennas, in its most characteristic form it is presented as a metal structure equipped with two input terminals, through which it feeds. For any given antenna, the magnitudes that characterize its way of functioning can be defined.
Radiation diagrams, directivity, gain, impedance, bandwidth or bandwidth are vitally important, that is, the frequency range for which the best performance and polarization is obtained.
Impedance
In physics, this term is used to identify the total apparent resistance of a circuit to the passage of an alternating current. It is measured in ohms.
The bandwidth of Parabolic or Satellite dishes
As for the bandwidth, this refers to the absolute energy of an amplifier or any quadrupole, is given by the separation between the two frequencies for which the amplification is less than the maximum in three decibels; The frequency field between these values is called the passband and the two frequencies that limit it are the cutoff frequencies.
In addition, the absolute bandwidth can be defined as a relative bandwidth, given by the relationship between the absolute bandwidth and the center band frequency, defined as the square root of the product of the two cutoff frequencies. Learn how to choose the satellite dish size for the best reception.
Authors who started satellite dishes or parabolic dishes
We will begin with a beginning beyond the idea, with the German physicist Heinrich Rudolf Hertz who discovered the low-frequency electromagnetic waves, called in his honor Hertzian waves. He showed that they are subject to the same laws of reflection and refraction as the luminous ones and measured their speed, the same as those of light and infrared radiation.
In this way he confirmed the electromagnetic nature of light and the electromagnetic theory of Maxwell, giving way to the development of radio wireless telegraphy. He also discovered the phenomenon known as the photoelectric effect, whereby light and other forms of high frequency electromagnetic energy cause the emission of electrons in some metals.
In his honor, he gave the name of hertz to the frequency unit. Between his works, they emphasize Principles of the mechanics and On the relations between the light and the electricity.
Among those who ventured into this issue of waves, broadcasting, and everything related to satellite dishes or components and components was also Isaac Newton, however, his studies took another approach for certain results with his experiments that apparently were not what they expected with respect to the initial idea.
However, it is important to describe this author in mathematics discovered at the same time as Leibniz, the calculation of fluxions, and generalized the formula of the binomial demonstrating that it was applicable to any speaker.
Mathematically demonstrated that the course of the planets around the Sun is explained by admitting mutual attraction between the stars, which generalized all kinds of masses, which are attracted, according to the famous Law of universal gravitation.
He also determined with great accuracy the masses of the sun and the planets and several of the particularities of the movement of Planet Earth. Similarly, among his discoveries based on prolonged research, he showed that the tides are due to the attraction of the sun and the moon, calculated various cometary orbits, etc.
On the other hand, in the history of the principles of parabolic or satellite dishes, there is also James Clerk Maxwell, a British physicist, and mathematician who investigated almost all fields of physics: he said that Saturn’s rings are made up of small isolated masses.
He determined that electromagnetic waves propagate with the speed of light, which led him to affirm that this was also a form of electromagnetic energy.
After these intellectual authors who dabbled in the interesting world that began to emerge in relation to electromagnetic waves were for example Grote Reber, who advanced an important step in technology with the development of radio astronomy with the construction of a radio telescope.
Such a structure included the shape of a parabolic mirror that allowed it to demonstrate the existence of an exorbitant amount of very low energy signals, while Marconi Guglielmo, who used the parabolic reflectors to transmit UHF by sea.
Marconi, From an early age he became interested in Hertz’s discoveries about wave transmission and in 1895 he managed to make wireless telegraphy transmissions; the following year he founded the Marconi Wireless Telegraphy Company, and in 1899 the signals were transmitted through the English Channel.
In December 1901, wireless communication was established between Europe and America. Thanks to his discoveries, very rapid progress was made in all media with ships on the high seas and in many other directions. In 1909 he received the Nobel Prize in Physics.
Parabolic or Satellite dishes: What is directivity?
The directivity of an antenna is the relationship between the intensity of the radiated bonnet in the direction of maximum radiation and that of the field irradiated by a hypothetical antenna with a spherical diagram, with equal irradiated power. The more pronounced the main lobe of an antenna, the greater its directivity.
The radiation pattern of an antenna that radiates equally in all directions (isotropic antenna) would be a sphere with its center in the center of the antenna, but such an antenna is of impossible physical realization.
What is a parable?
A parabola is the conic that is obtained as a geometric place of the equidistant points of a fixed-line MN (director) and a fixed point F (focus); It is also the intersection line determined by a conical surface and a plane parallel to a generatrix.
Every parabola can be represented by an equation of the form y² = 2px (equation of the parabola in canonical form) where p is a constant (parameter of the parabola). A material point thrown with a certain initial velocity in a uniform force field describes a parabola arc.
Since the gravitational field is uniform, as long as it is considered a region not too large, it can be said that the trajectory of a projectile in a vacuum is an arc of the parabola. The name of parabola also designates other curves represented by equations of the type y = axª (parabola of order n) with a = constant.
Satellite or parabolic dish antennas
The word radar is an acronym for the English name Radio Detecting and Ranging, which covers all electronic systems capable of detecting the presence of obstacles, locating them, and determining their distance to the observation post.
These systems are based on the properties of electromagnetic waves that, when they reach a target endowed with sufficient electrical conductivity, are partially reflected in it. Guglielmo Marconi sensed the possibility of detecting the presence of moving objects through the modifications caused by them in the characteristics of the radio waves that reach them.
In 1922, Taylor and Young, in the USA, picking up Marconi’s ideas, managed to detect the presence of a ship. Breit and I had, in 1925, by means of an impulse procedure, managed to determine the height of the ionosphere. These studies were resumed in 1930, based on the method of continuous-wave interference that allows only to notice the presence of an obstacle.
From then on it began to be presumed that this would be possible by resorting to methods in which higher frequencies than usual were necessary if only to reduce the importance of the necessary antennas.
In 1936, a pulse radar operating at 200 MHz began operating in the US. Between 1939 and 1941, several ships in the US squad were equipped with radar. At the same time, the main European nations began to take an interest in radar: France, Germany, and especially England, which found a great filmmaker in Sir Robert Watson.
Decisive importance for progress
The effectiveness of the radar was increasing until it became a factor of decisive warlike importance when the technique managed to dominate the microwave field, thanks to the research and two fundamental inventions: the magnetron and the Klystron, two microwave power generating tubes.
From a technological point of view, every radar consists of a transmitter and a receiver. Depending on the type of modulation chosen there are: unmodulated continuous-wave radar (Doppler effect), frequency modulated continuous wave radar and pulse radar.
Just as in the radio communications at the receiver’s output the signals act on the speaker or other device that replaces it, on the radar they act on a device, called an indicator, variable according to the types of radar, whose structure depends on the kind of representation of information about the position, speed or other similar data related to the obstacle.
In Doppler radars, a frequency wave F affects the object with a velocity v (in the direction of wave propagation) and is reflected with a frequency f ‘= f + 2v / c, different from the previous one (c is wave propagation speed).
The frequency f ‘is higher as if the reflective surface approaches the transmitter. This effect can be used by a continuous wave radar for the detection of objects equipped with radial movement with respect to the radar, and for the measurement of that speed, comparing with the radar receiver the frequencies f and f’and deduce, by the batting, its difference 2v / c.
This frequency is sent to an acoustic detector or to a suitable frequency meter. Knowing c, v can be calculated. The frequency meter itself is usually graduated so that it directly supplies the reading v.
The frequency modulated radar is based on the emission of a continuous signal that, modulated in frequency and reflected in the obstacle, returns to the starting point with a delay Λt. If the frequency modulation is obtained by a sinusoidal modulation of frequency f, as is generally the case, the corresponding phase difference between the output and arrival modulations is Λφ = 2π · Λt.
As for the pulse radar, it is the most common and is based on the irradiation, by means of directional antennas and more or less wide area scanners of the horizon, of radiofrequency waves modulated to impulses, that is, with a modulation of the all or nothing.
This radar allows the detection of many obstacles, even in different directions, always within the radiation beam of the antennas.
In most cases, the antenna is unique and is used for both transmission and reception; in the antenna power line, it is necessary to exchange a switching device, called TR-anti TR that prevents strong radiofrequency output pulses from damaging the receiver’s input circuit.
The delay in the arrival of the reflected impulse, with respect to the output, analogically to what was said above, and starting the same notations, Λt = 2D-c. To avoid ambiguities in the determination of distances, it must be less than the repetition period with which the radiofrequency impulses occur.
The duration of each pulse influences the minimum range of the radar and its resolving power or the minimum distance at which two different obstacles must be found in order to be distinguished by the radar.
IMPORTANT UTILITY OF SATELLITE DISHES OR RADAR SATELLITES
Both features improve by decreasing the pulse duration. In a parabolic dish or satellite sighting antennas, the repetition period is usually given a value of 1000 μsec and each pulse has a duration of 1 μsec. Thus, 100 kW pulses of power correspond to an average radiofrequency power of 100 watts.
Similar to what happens with the frequency modulation radar, the distance rating is calculated by multiplying Λt by half the speed of light.
In order to locate the obstacles located in the area of considerable amplitude, it is necessary that the antenna can carry out certain movements, the whole of which constitutes the exploration. The various obstacles appear at successive times, depending on the antenna positions.
The most common modalities of exploration, which must be carried out automatically, are circular, helical, conical, and spiral.
In circular exploration, the antenna rotates continuously around its axis, generally vertical, with constant angular velocity over the entire horizon, or with alternative movements within angles below 360 °.
The speed of rotation of the antenna must be regulated so that the pulses that reach a certain target during rotation are not too scarce to obtain a correct representation of the said target.
For the exploration of these parabolic or satellite antennas, an antenna with a narrow irradiation diagram and rotation symmetry is needed. During movement, the main lobe of this diagram describes a spherical propeller around the vertical axis.
If the opening of the irradiation beam is b, it is varied at the height of the b / 2 antenna during the time it takes to effect a complete revolution in a horizontal direction. The exploded helical belt has an equal overlap ab / 2, which constitutes an adequate safety margin for the discovery of the target.
Also, the conical scan requires an antenna with a narrow irradiation diagram. The axis of the main irradiation lobe and therefore the antenna describes a circular conical opening surface equal to the semi-coverage of the said lobe.
If the target is located on the axis of the cone, all the impulses it receives have the same intensity, whatever the position of the irradiation lobe with respect to the said cone. For this reason, the cone axis is called the direction of the equiseñal.
Minimum reliable power. A signal present at the exit of the radar receiver contains, not only the echo power received but also disturbances due, first of all to causes of industrial origin and to discharges from the atmosphere that affect the low frequencies little; secondly, the existing radiations in the atmosphere and finally fluctuations in the intensity and voltage of the electric component current.
In order to increase the sensitivity of the receivers and therefore the radar range, very sensitive amplifiers, such as the maser, have been built, with which extremely low noise factors are achieved. In the following graph we see what a maser is, what they call the cousin of lightning, which will potentially revolutionize technology. Later we will describe it.
The radar range also accuses all phenomena related to the propagation of electromagnetic waves. The reflections produced on the ground reach the obstacle, not only the direct wave but also those coming from these reflections.
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The result of both invests in reaching the obstacle more time than the direct wave would need, thus producing a gap between the two. The greater path traveled by the reflected wave also implies its greater absorption by the terrain.
The effects of atmospheric refraction and terrestrial curvature on the propagation of radio waves can be deduced from the geometric relationship between the shape of the curve actually traveled and what it would have if the radius of curvature of the earth’s surface became infinite and the Earth It could be considered flat.
With respect to traditional transmitting and receiving devices, the impulse-type radar devices, considered below, have a greater degree of differentiation.
- Receivers So that the impulses can be reconstructed with the minimum possible deformation, after passing through the detector, it is necessary that the operating band in the radar receiver is much larger than in normal receivers. For the usual radars, bands a = 2/3 MHz are required for values of about 30 MHz of the average frequency.
- Transmitters In pulse modulation, which is of the all or nothing type, the radiofrequency power takes its maximum value or null value, following the rate of the modulating pulses. The frequency of radio frequency can be generated by a power tube driven by an oscillating tube or by a chain of steps.
The small tactical land use radars, fundamentally fulfill the mission of saving the necessary deployment of units to monitor the large spaces imposed by the atomic war and the insidious insights that characterize those of guerrillas.
An example of this type of radar is the French Rasura, which is installed in a light vehicle or portable version, consisting of three elements of 20 kg each, and detects moving bodies at 10 km if it is a vehicle and 7 km In the case of a man.
Another variety of radars in full development are those mounted on aircraft for observation of the terrain that fly over for purposes of surveillance and location of objects or navigation, to make possible the low-level flight, that is, flush with the cups of the trees, in order to avoid the detection of enemy radars.
This special type of radar is called Terrain following in English. The signals it provides about terrain accidents and obstacles automatically pass to the airplane controls that, without pilot intervention, avoid them.
Parabolic or Satellite dishes
As for Satellite or parabolic dishes, they are instruments that serve in many phases of scientific research applicable to various sectors to promote evolution and progress, which cover a large amount of data.
For example, we can distinguish those of civil order, with projections for future commercial or military uses, which in turn promote the collection of photographic material from the environment, warnings of possible offensive actions, direct war threats, etc.
SATELLITE DISHES OR FLAT-TYPE SATELLITES
This type of satellite dish or flat-type satellites are also called the planar matrix, and they have to be constructed with light, simple, and very practical pieces with the mission of making them as little as possible, both sight and space.
They have been the most compact satellite reception antennas that are designed for the convenience of users and their optimization will depend on their situation with respect to the area of the footprint area of the satellite coverage that has been selected.
However, the negative part of the use of this type of satellite dishes or flat-type satellites, is that their elements do not allow the choice of several satellites for the fulfillment of their objectives, that is, the flat antennas are limited to using only one satellite.
However, they turn out to be quite discreet but with a lot of power, which can be installations on the balconies of apartments, on the terraces of houses or buildings, which also allows adjusting to the aesthetic and protocol structure of living in residences, avoiding attracting attention and complying with the rules also.
In case you don’t know how to install a TV Antenna for better coverage, read our guide.
Those who designed this type of discrete antennas, also made it possible to have outputs for the distribution of the signal to be captured by more than one receiver, and in addition to this, these models can be incorporated into panels or decorated to conceal them even more than strange or ill-intentioned looks. Or simply shelter them.
Parabolic or Satellite dishes FOR CELL PHONES
As for this type of satellite dish or cell phone antennas, it can be added that it is linked to telecommunications and a specific sector that affects a link that benefits a large part of a nation.
For example, speaking of sectors, we specify certain services provided by the security forces, the fire department, clinics and hospitals and other networks that merit the use of both mobile and fixed telephony such as companies, schools or residential areas.
We know that mobile telephony is one of the fundamental pillars in the era of telecommunications, and once they began to emerge thanks to the discoveries of scientists and researchers along with these needs, technologies evolved and are now much more advanced and avant-garde by the current requirement that globalization has established and society has been marking and demanding.
The antennas come to form the root or matrix of all these aspects of importance and according to the mathematical and geometric particularities for their elaboration, there are three types or categories of antennas that are linear, flat, and volumetric.
Cellular telephony is given by the functioning of the cells, which allows the user to keep moving and communicating, and the theory is that the greater the number of cells, the better the signal a person receives on his phone to communicate.
Previously, according to the history of satellite dishes or telephony antennas, towers with a lot of height were used or built frequently for that purpose, pedestal, self-supporting, braced, monopole, among others, but currently and with the studies at par of the evolutions in technology have been reduced to antennas, much more comfortable and practical.