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85-408: A ‘T’-antenna , ‘T’-aerial , or flat-top antenna is a monopole radio antenna consisting of one or more horizontal wires suspended between two supporting radio masts or buildings and insulated from them at the ends. A vertical wire is connected to the center of the horizontal wires and hangs down close to the ground, connected to the transmitter or receiver . The shape of the antenna resembles

170-411: A blade antenna . The quarter-wave whip and rubber ducky antennas used with handheld radios such as walkie-talkies and portable FM radios are also monopole antennas. In these portable devices the antenna does not have an effective ground plane, the ground side of the transmitter is just connected to the ground connection on its circuit board . Since the circuit board ground is often smaller than

255-442: A loading coil at the feedpoint. At medium and low frequencies, the high antenna capacitance and the high inductance of the loading coil, compared to the short antenna’s low radiation resistance, makes the loaded antenna behave like a high Q tuned circuit , with a narrow bandwidth over which it will remain well matched to the transmission line, when compared to a ⁠ 1  / 4 ⁠   λ monopole. To operate over

340-427: A loading coil , so the antenna can be efficiently fed power. Since the vertical wire is the actual radiating element, the antenna radiates vertically polarized radio waves in an omnidirectional radiation pattern , with equal power in all azimuthal directions. The axis of the horizontal wire makes little difference. The power is maximum in a horizontal direction or at a shallow elevation angle, decreasing to zero at

425-485: A central role in production theory . The concept of diminishing returns can be explained by considering other theories such as the concept of exponential growth . It is commonly understood that growth will not continue to rise exponentially, rather it is subject to different forms of constraints such as limited availability of resources and capitalisation which can cause economic stagnation . This example of production holds true to this common understanding as production

510-426: A diminishing rate of return on HDI. Just think, in a low income family, an average increase of income will likely make a huge impact on the wellbeing of the family. Parents could provide abundantly more food and healthcare essentials for their family. That is a significantly increasing rate of return. But, if you gave the same increase to a wealthy family, the impact it would have on their life would be minor. Therefore,

595-444: A large frequency range the loading coil often must be adjustable and adjusted when the frequency is changed to limit the power reflected back towards the transmitter . The high Q also causes a high voltage on the antenna, which is maximum at the current nodes at the ends of the horizontal wire, roughly Q times the driving-point voltage. The insulators at the ends must be designed to withstand these voltages. In high power transmitters

680-422: A line of transmission towers, sometimes several miles long. Several vertical radiator wires hang down from the top load, each attached to its own ground through a loading coil. The antenna is driven either at one of the radiator wires or more often at one end of the top load, by bringing the wires of the top load diagonally down to the transmitter. Although the vertical wires are separated, the distance between them

765-409: A negative value, the same idea as in the diminishing rate of return inevitable to the production process. The concept of diminishing returns can be traced back to the concerns of early economists such as Johann Heinrich von Thünen , Jacques Turgot , Adam Smith , James Steuart , Thomas Robert Malthus , and David Ricardo . The law of diminishing returns can be traced back to the 18th century, in

850-528: A radiation resistance of 73 Ohms, a quarter-wave ( ⁠ 1 / 4  ⁠ λ ) monopole will have a gain of 2.19 + 3.0 = 5.2 dBi and a radiation resistance of about 36.5 Ohms. The antenna is resonant at this length, so its input impedance is purely resistive. The input impedance has capacitive reactance below ⁠ 1 / 4  ⁠ λ and inductive reactance from ⁠ 1 / 4  ⁠ to ⁠ 1 / 2  ⁠ λ . The gains given in this section are only achieved if

935-469: A receiving T-antenna can intercept more power from the same incoming radio wave signal strength than the same height vertical antenna can. In antennas built for frequencies near or below 600 kHz, the length of an antenna's wire segments is usually shorter than a quarter wavelength [ ⁠ 1  / 4 ⁠   λ ≈ 125 m (410 feet) at 600 kHz ] , the shortest length of unloaded straight wire that achieves resonance . In this circumstance,

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1020-428: A simple 'T'antenna. The antenna was used in the powerful radio stations of the wireless telegraphy era but has fallen out of favor due to the expense of multiple loading coils. Monopole antenna A monopole antenna is a class of radio antenna consisting of a straight rod-shaped conductor, often mounted perpendicularly over some type of conductive surface, called a ground plane . The driving signal from

1105-428: A single unit of a good generally increases as a society attempts to produce more of that good. This explains the bowed-out shape of the production possibilities frontier . Part of the reason one input is altered ceteris paribus , is the idea of disposability of inputs. With this assumption, essentially that some inputs are above the efficient level. Meaning, they can decrease without perceivable impact on output, after

1190-540: A terminal near the base of the antenna. This design is used for the mast radiator transmitting antennas employed for radio broadcasting in the MF and LF bands. At lower frequencies the antenna mast is electrically short giving it a very small radiation resistance , so to increase efficiency and radiated power capacitively toploaded monopoles such as the T-antenna and umbrella antenna are used. At VHF and UHF frequencies

1275-413: A typical thickness antenna, for an infinitely thin monopole the maximum occurs at 2 π λ = 0.637 λ {\displaystyle {\tfrac {2}{\,\pi \,}}\lambda =0.637\lambda } ). The maximum occurs at this length because the opposite phase radiation from the two lobes interferes destructively and cancels at high angles, "compressing" more of

1360-429: A ‘T’-antenna is a capacitively top-loaded, electrically short , vertical monopole . Despite its improvements over a short vertical, the typical ‘T’-antenna is still not as efficient as a full-height ⁠ 1  / 4 ⁠   λ vertical monopole , and has a higher Q and thus a narrower bandwidth . 'T'-antennas are typically used at low frequencies where building a full-size quarter-wave high vertical antenna

1445-410: Is where At resonance the capacitive reactance of the antenna is cancelled by the loading coil so the input impedance at resonance Z 0 is just the sum of the resistances in the antenna circuit The efficiency of the antenna at resonance, η , is the ratio of radiated power to input power from the feedline. Since power dissipated as radiation or as heat is proportional to resistance, the efficiency

1530-684: Is a widely recognised production function in economics: Q= f(NR, L, K, t, E) : Start from the equation for the marginal product: Δ O u t Δ I n 1 = f ( I n 2 , I n 1 + Δ I n 1 ) − f ( I n 1 , I n 2 ) Δ I n 1 {\displaystyle {\Delta Out \over \Delta In_{1}}={{f(In_{2},In_{1}+\Delta In_{1})-f(In_{1},In_{2})} \over \Delta In_{1}}} To demonstrate diminishing returns, two conditions are satisfied; marginal product

1615-714: Is an omnidirectional antenna, radiating equal radio power in all azimuthal directions, while the inverted-L is a weakly directional antenna , with maximum radio power radiated in the direction of the top load wire, off the end with the feeder attached. 'T'- and inverted-L antennas are typically used in the VLF , LF , MF , and shortwave bands, and are widely used as transmitting antennas for amateur radio stations, and long wave and medium wave AM broadcasting stations. They can also be used as receiving antennas for shortwave listening . They function as monopole antennas with capacitive top-loading; other antennas in this category include

1700-427: Is an inverse relationship between returns of inputs and the cost of production, although other features such as input market conditions can also affect production costs. Suppose that a kilogram of seed costs one dollar , and this price does not change. Assume for simplicity that there are no fixed costs . One kilogram of seeds yields one ton of crop, so the first ton of the crop costs one dollar to produce. That is, for

1785-403: Is around 2–3 dBi. Because it radiates only into the space above the ground plane, or half the space of a dipole antenna, a monopole antenna over a perfectly conducting infinite ground plane will have a gain of twice (3  dB greater than) the gain of a similar dipole antenna, and a radiation resistance half that of a dipole. Since a half-wave dipole has a gain of 2.19  dBi and

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1870-403: Is around 800–2,000 Ohms; high, but manageable by feeding through a substantial step-up transformer. The horizontal gain continues to increase up to a maximum of about 6.6  dBi at a length of five-eighths wavelength ⁠ 5 / 8  ⁠ λ so this is a popular length for ground wave antennas and terrestrial communication antennas, for frequencies where a larger antenna size

1955-436: Is called constant returns. Further along the production curve at, for example 100 employees, floor space is likely getting crowded, there are too many people operating the machines and in the building, and workers are getting in each other's way. Increasing the number of employees by two percent (from 100 to 102 employees) would increase output by less than two percent and this is called "diminishing returns." After achieving

2040-418: Is conventionally placed at the base of the antenna for accessibility, connected between the antenna and its feedline. The horizontal top section of a 'T'-antenna can also reduce the capacitive reactance at the feedpoint, substituting for a vertical section whose height would be about ⁠ 2  / 3 ⁠  its length; if it is long enough, it completely eliminates reactance and obviates any need for

2125-439: Is feasible. The input impedance drops to about 40 Ohms at that length. The antenna's reactance is capacitive from ⁠ 1 / 2  ⁠ to ⁠ 3 / 4  ⁠ λ . However, above ⁠ 5 / 8  ⁠ λ the horizontal gain drops rapidly because progressively more power is radiated at high elevation angles in the second lobe. For monopole antennas operating at lower frequencies, below 20 MHz,

2210-452: Is given by It can be seen that, since the radiation resistance is usually very low, the major design problem is to keep the other resistances in the antenna-ground system low to obtain the highest efficiency. The multiple-tuned flattop antenna is a variant of the 'T'-antenna used in high-power low-frequency transmitters to reduce ground power losses. It consists of a long capacitive top-load consisting of multiple parallel wires supported by

2295-444: Is grounded. Diminishing returns The modern understanding of the law adds the dimension of holding other outputs equal, since a given process is understood to be able to produce co-products. An example would be a factory increasing its saleable product, but also increasing its CO 2 production, for the same input increase. The law of diminishing returns is a fundamental principle of both micro and macro economics and it plays

2380-471: Is not practical, and the vertical radiating wire is often very electrically short : Only a small fraction of a wavelength long, ⁠ 1 / 10 ⁠ λ or less. An electrically short antenna has a base reactance that is capacitive , and although capacitive loading at the top does reduce capacitive reactance at the base, usually some residual capacitive reactance remains. For transmitting antennas that must be tuned-out by added inductive reactance from

2465-432: Is often made of litz wire . At low frequencies the antenna requires a good low resistance ground to be efficient. The RF ground is typically constructed as a star of many radial copper cables buried about 30 cm (1 foot) in the earth, extending out from the base of the vertical wire, and connected together at the center. The radials should ideally be long enough to extend beyond the displacement current region near

2550-554: Is positive, and marginal product is decreasing. Elasticity , a function of input and output, ϵ = I n O u t ⋅ δ O u t δ I n {\displaystyle \epsilon ={In \over Out}\cdot {\delta Out \over \delta In}} , can be taken for small input changes. If the above two conditions are satisfied, then 0 < ϵ < 1 {\displaystyle 0<\epsilon <1} . This works intuitively; There

2635-458: Is small compared to the length of the LF waves , so the currents in them are in phase and they can be considered as one radiator. Since the antenna current flows into the ground through N parallel loading coils and grounds rather than one, the equivalent loading coil and ground resistance, and therefore the power dissipated in the loading coil and ground, is reduced to ⁠ 1 / N   ⁠ that of

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2720-449: Is subject to the four factors of production which are land, labour, capital and enterprise. These factors have the ability to influence economic growth and can eventually limit or inhibit continuous exponential growth. Therefore, as a result of these constraints the production process will eventually reach a point of maximum yield on the production curve and this is where marginal output will stagnate and move towards zero. Innovation in

2805-460: The transmitter is applied, or for receiving antennas the output signal to the receiver is taken, between the lower end of the monopole and the ground plane. One side of the antenna feedline is attached to the lower end of the monopole, and the other side is attached to the ground plane, which is often the Earth. This contrasts with a dipole antenna which consists of two identical rod conductors, with

2890-425: The umbrella , and triatic antennas. They were invented during the first decades of radio, in the wireless telegraphy era, before 1920. The 'T'-type antenna is most easily understood as having three functional parts: The wires of the top load are often arranged symmetrically; currents flowing in the oppositely directed symmetrical wires of the top hat cancel each others' fields and so produce no net radiation, with

2975-408: The antenna axis. Below the quarter wavelength ( 1 4 λ {\displaystyle {\tfrac {1}{4}}\lambda } ) resonance the radiation pattern is nearly constant with length. Above ( 1 2 λ {\displaystyle {\tfrac {1}{2}}\lambda } ) the lobe flattens, radiating more power in horizontal directions. Above a half-wavelength

3060-401: The antenna is made longer, the pattern divides into more lobes, with nulls (directions of zero radiated power) between them. The general effect of electrically small ground planes, as well as imperfectly conducting earth grounds, is to tilt the direction of maximum radiation up to higher elevation angles and reduce the gain. The gain of actual quarter wave antennas with typical ground systems

3145-418: The antenna is mounted over a perfectly conducting infinite ground plane . With typical artificial ground planes smaller than several wavelengths, the gain will be 1 to 3 dBi lower, because some of the horizontal radiated power will diffract around the plane edge into the lower half space, where it dissipates in the soil. Similarly over a resistive earth ground, the gain will be lower due to power absorbed in

3230-408: The antenna length is approximately one quarter of the wavelength of the radio waves. In broadcasting monopole antennas, however, lengths equal to ⁠ 5 / 8 ⁠ wavelength are also popular because in a monopole this length maximizes the power radiated perpendicular to the axis of the radiator, which with a vertical radiator optimizes efficiency for terrestrial broadcast. The monopole antenna

3315-412: The antenna, the antenna and ground combination may function more as an asymmetrical dipole antenna than a monopole. The hand and body of the person holding them may function as a rudimentary ground plane. Wireless devices and cell phones use a monopole variant called the inverted-F antenna . The monopole element is bent over parallel to the ground area on the circuit board , so it can be enclosed in

3400-440: The antenna. At VLF frequencies the resistance of the soil becomes a problem, and the radial ground system is usually raised and mounted a few feet above ground, insulated from it, to form a counterpoise . The power radiated (or received) by any electrically short vertical antenna, like the 'T'-antenna, is proportional to the square of the effective height of the antenna, so the antenna should be made as high as possible. Without

3485-424: The antenna. The radiated power varies with elevation angle, with the radiation dropping off to zero at the zenith on the antenna axis. It radiates vertically polarized radio waves. Since vertical halfwave dipoles must have their center raised at least a quarter wave above the ground, whereas monopoles must be mounted directly on the ground, the monopoles' radiation patterns are more greatly affected by resistance in

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3570-401: The apex of the vertical section, typically means that the top hat is usually not built as large as the counterpoise . Further, any electric fields that reach the ground before they are intercepted by the counterpoise will waste energy warming the soil, whereas stray electric fields high in the air will merely spread out a bit more into loss-free open air, before they eventually reach the wires of

3655-432: The capital on the floor (e.g. manufacturing machines, pre-existing technology, warehouses) is held constant, increasing from one employee to two employees is, theoretically, going to more than double production possibilities and this is called increasing returns. If 50 people are employed, at some point, increasing the number of employees by two percent (from 50 to 51 employees) would increase output by two percent and this

3740-418: The center where the vertical wire attaches. Because each wire's electric field impinges on those of adjacent wires, the additional capacitance from each added wire diminishes . The horizontal top load wire can increase radiated power by 2 to 4 times (3 to 6  dB ) for a given base current. Consequently the 'T'-antenna can radiate more power than a simple vertical monopole of the same height. Similarly,

3825-509: The cusp of the First Industrial Revolution , it was motivated with single outputs in mind. In recent years, economists since the 1970s have sought to redefine the theory to make it more appropriate and relevant in modern economic societies. Specifically, it looks at what assumptions can be made regarding number of inputs, quality, substitution and complementary products, and output co-production, quantity and quality. The origin of

3910-412: The device case; usually the antenna is fabricated of copper foil on the printed circuit board itself. This geometry would give the antenna a very low impedance if it was driven at the base. To improve the impedance match with the feed circuit (typically 50  Ohms impedance) the antenna is shunt fed , the feedline is instead connected to an intermediate point along the element, and the element end

3995-513: The dipole, one side of the transmitter and receiver was connected to a wire suspended overhead, and the other side was connected to the Earth, he could transmit for longer distances. For this reason the monopole is also called a Marconi antenna , although Alexander Popov independently invented it at about the same time. Like a vertically suspended dipole antenna , a monopole has an omnidirectional radiation pattern : It radiates with equal power in all azimuthal directions perpendicular to

4080-459: The earth, and the radiation pattern with elevation inherently differs. A monopole can be visualized ( right ) as being formed by replacing the bottom half of a vertical dipole antenna (c) with a conducting plane ( ground plane ) at right-angles to the remaining half. If the ground plane is large enough, the radio waves from the remaining upper half of the dipole (a) reflected from the ground plane will seem to come from an image antenna (b) forming

4165-418: The earth. As the length is increased to approach a half-wavelength ( ⁠ 1 / 2  ⁠   λ ) – the next resonant length – the gain increases some, to 6.0  dBi . Since at this length the antenna has a current node at its feedpoint , the input impedance is very high. A hypothetical infinitesimally thin antenna would have infinite impedance, but for finite thickness of typical monopoles it

4250-415: The effective height, and is used to determine how many metre-amps are required to achieve a given amount of radiated power. The equivalent circuit of the antenna (including loading coil) is the series combination of the capacitive reactance of the antenna, the inductive reactance of the loading coil, and the radiation resistance and the other resistances of the antenna-ground circuit. So the input impedance

4335-417: The electrical characteristics of antennas are generally not critical for modern radio receivers; reception is limited by natural noise, rather than by the signal power gathered by the receiving antenna. Transmitting antennas are different, and feedpoint impedance is critical: The combination of reactance and resistance at the antenna feedpoint must be matched to the impedance of the feedline, and beyond it,

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4420-413: The first ton of output, the marginal cost as well as the average cost of the output is per ton. If there are no other changes, then if the second kilogram of seeds applied to land produces only half the output of the first (showing diminishing returns), the marginal cost would equal per half ton of output, or per ton, and the average cost is per 3/2 tons of output, or /3 per ton of output. Similarly, if

4505-532: The form of technological advances or managerial progress can minimise or eliminate diminishing returns to restore productivity and efficiency and to generate profit. This idea can be understood outside of economics theory, for example, population. The population size on Earth is growing rapidly, but this will not continue forever (exponentially). Constraints such as resources will see the population growth stagnate at some point and begin to decline. Similarly, it will begin to decline towards zero but not actually become

4590-403: The ground plane is usually the Earth; in this case the antenna is a vertical mast mounted on the ground on an insulator to isolate it electrically from the ground. One side of the feedline is connected to the mast and the other to an Earth ground at the base of the antenna. In transmitting antennas to reduce ground resistance this is often a radial network of buried wires stretching outward from

4675-399: The ground side of the feedline; this is called a ground-plane antenna . At gigahertz frequencies the metal surface of a car roof or airplane body makes a good ground plane, so car cell phone antennas consist of short whips mounted on the roof, and aircraft communication antennas frequently consist of a short conductor in an aerodynamic fairing projecting from the fuselage; this is called

4760-415: The ground. The resistance in the coil and particularly the ground system must be kept very low to minimize the power dissipated in them. It can be seen that at low frequencies the design of the loading coil can be challenging: it must have high inductance but very low losses at the transmitting frequency (high Q ), must carry high currents, withstand high voltages at its ungrounded end, and be adjustable. It

4845-463: The horizontal wire, the RF current distribution in the vertical wire would decrease very nearly linearly to zero at the top ( see drawing "a" above ), giving an effective height of half the physical height of the antenna. With an ideal "infinite capacitance" top load wire, the current in the vertical would be constant along its length, giving an effective height equal to the physical height, therefore increasing

4930-496: The horizontal wires increase the capacitance at the top of the antenna. More current is required in the vertical wire to charge and discharge this added capacitance during the RF oscillation cycle. The increased currents in the vertical wire ( see drawing at right ) effectively increase the antenna's radiation resistance and thus the RF power radiated. The top-load capacitance increases as more wires are added, so several parallel horizontal wires are often used, connected together at

5015-423: The importance of marginal output or marginal returns . Returns eventually diminish because economists measure productivity with regard to additional units (marginal). Additional inputs significantly impact efficiency or returns more in the initial stages. The point in the process before returns begin to diminish is considered the optimal level. Being able to recognize this point is beneficial, as other variables in

5100-471: The law of diminishing returns was developed primarily within the agricultural industry. In the early 19th century, David Ricardo as well as other English economists previously mentioned, adopted this law as the result of the lived experience in England after the war. It was developed by observing the relationship between prices of wheat and corn and the quality of the land which yielded the harvests. The observation

5185-525: The letter "T", hence the name. The transmitter power is applied, or the receiver is connected, between the bottom of the vertical wire and a ground connection. A closely related antenna is the inverted-L antenna . This is similar to the T-antenna except that the vertical feeder wire, instead of being attached to the center of the horizontal topload wires, is attached at one end. The name comes from its resemblance to an inverted letter "L" (Γ). The T-antenna

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5270-451: The manner of excessive fertiliser on a field. If input disposability is assumed, then increasing the principal input, while decreasing those excess inputs, could result in the same "diminished return", as if the principal input was changed certeris paribus . While considered "hard" inputs, like labour and assets, diminishing returns would hold true. In the modern accounting era where inputs can be traced back to movements of financial capital,

5355-402: The maximum performance improvement provided by a T-antenna. So at low frequencies, even a 'T'-antenna can have very low radiation resistance, often less than 1  ohm , so the efficiency is limited by other resistances in the antenna and the ground system. The input power is divided between the radiation resistance and the 'ohmic' resistances of the antenna+ground circuit, chiefly the coil and

5440-461: The missing half of the dipole, which adds to the direct radiation to form a dipole radiation pattern. So the pattern of a monopole with a perfectly conducting, infinite ground plane is identical to the top half of a dipole pattern. Up to a length of a half-wavelength ( 1 2 λ {\displaystyle {\tfrac {1}{2}}\lambda } ) the antenna has a single lobe with maximum gain in horizontal directions, perpendicular to

5525-443: The output power is often limited by the onset of corona discharge from the wires. Radiation resistance is the equivalent resistance of an antenna due to its radiation of radio waves; for a full-length quarter-wave monopole the radiation resistance is around 25  ohms . Any antenna that is short compared to the operating wavelength has a lower radiation resistance than a longer antenna; sometimes catastrophically so, far beyond

5610-409: The pattern splits into a horizontal main lobe and a small second conical lobe at an angle of 60° elevation into the sky. However, the horizontal gain keeps increasing and reaches a maximum at a length of five-eighths wavelength: 5 8 λ = 0.625 λ {\displaystyle {\tfrac {5}{8}}\lambda =0.625\lambda } (this is an approximation valid for

5695-434: The point of maximum output, employing additional workers, this will give negative returns. Through each of these examples, the floor space and capital of the factor remained constant, i.e., these inputs were held constant. By only increasing the number of people, eventually the productivity and efficiency of the process moved from increasing returns to diminishing returns. To understand this concept thoroughly, acknowledge

5780-479: The power into the horizontal lobe. Slightly above 5 8 λ {\displaystyle {\tfrac {5}{8}}\lambda } the horizontal lobe rapidly gets smaller and the high angle lobe gets larger, reducing power radiated in horizontal directions, and hence reducing gain. Because of this, not many antennas use lengths above 5 8 λ {\displaystyle {\tfrac {5}{8}}\lambda } or 0.625  wave . As

5865-546: The prices of the products had risen due to the Napoleonic Wars , which affected international trade and caused farmers to move to lands which were undeveloped and further away. In addition, at the end of the Napoleonic Wars, grain imports were restored which caused a decline in prices because the farmers needed to attract customers and sell their products faster. Classical economists such as Malthus and Ricardo attributed

5950-465: The production function can be altered rather than continually increasing labor. Further, examine something such as the Human Development Index , which would presumably continue to rise so long as GDP per capita (in purchasing power parity terms) was increasing. This would be a rational assumption because GDP per capita is a function of HDI. Even GDP per capita will reach a point where it has

6035-404: The radiated power fourfold for the same feed voltage. So the power radiated (or received) by a 'T'-antenna lies between a vertical monopole of the same height and up to four times that. The radiation resistance of an ideal T-antenna with very large top load capacitance is so the radiated power is where This formula shows that the radiated power depends on the product of the base current and

6120-466: The radiation emitted by the T-antenna. The left and right sections of horizontal wire across the top of the 'T' carry equal but oppositely-directed currents. Therefore, far from the antenna, the radio waves radiated by each wire are 180° out of phase with the waves from the other wire, and tend to cancel. There is a similar cancellation of radio waves reflected from the ground. Thus the horizontal wires radiate (almost) no radio power. Instead of radiating,

6205-831: The rate of return provided by that average increase in income is diminishing. Signify O u t p u t = O   ,   I n p u t = I   ,   O = f ( I ) {\displaystyle Output=O\ ,\ Input=I\ ,\ O=f(I)} Increasing Returns: 2 ⋅ f ( I ) < f ( 2 ⋅ I ) {\displaystyle 2\cdot f(I)<f(2\cdot I)} Constant Returns: 2 ⋅ f ( I ) = f ( 2 ⋅ I ) {\displaystyle 2\cdot f(I)=f(2\cdot I)} Diminishing Returns: 2 ⋅ f ( I ) > f ( 2 ⋅ I ) {\displaystyle 2\cdot f(I)>f(2\cdot I)} There

6290-400: The same cancellation happening in the same way in the ground system. In principle, the capacitance hat ( top hat ) and its counterpart ground system ( counterpoise ) could be built to be mirror images of each other. However the ease of just laying wires on the ground or raised a few feet above the soil, as opposed to the practical challenge of supporting top hat's horizontal wires up high, at

6375-404: The shorter it is, the higher that reactance, and the greater the proportion of the feed current that will be reflected back towards the transmitter. To efficiently drive current into a short transmitting antenna it must be made resonant (reactance-free), if the top section has not already done so. The capacitance is usually canceled out by an added loading coil or its equivalent; the loading coil

6460-436: The signal from the transmitter applied between the two halves of the antenna. The monopole is often used as a resonant antenna. The rod functions as an open resonator for radio waves and oscillates with standing waves of voltage and current along its length. The length of the antenna, therefore, is determined based on the wavelength of the desired radio waves. The most common form is the quarter-wave monopole , in which

6545-416: The size of the ground plane needed is smaller, so artificial ground planes are used to allow the antenna to be mounted above the ground. A common type of monopole antenna at these frequencies for mounting on masts or structures consists of a quarter-wave whip antenna with a ground plane consisting of 3 or 4 wires or rods a quarter-wave long radiating horizontally or diagonally from its base connected to

6630-442: The successive diminishment of output to the decreasing quality of the inputs whereas Neoclassical economists assume that each "unit" of labor is identical. Diminishing returns are due to the disruption of the entire production process as additional units of labor are added to a fixed amount of capital. The law of diminishing returns remains an important consideration in areas of production such as farming and agriculture. Proposed on

6715-409: The third kilogram of seeds yields only a quarter ton, then the marginal cost equals per quarter ton or per ton, and the average cost is per 7/4 tons, or /7 per ton of output. Thus, diminishing marginal returns imply increasing marginal costs and increasing average costs. Cost is measured in terms of opportunity cost . In this case the law also applies to societies – the opportunity cost of producing

6800-412: The top hat. The top and ground sections effectively function as oppositely charged reservoirs for augmented storage of excess or deficit electrons , more than what could be stored along the top end of the same height bare headed vertical wire. A greater stored charge causes greater current to flow through the vertical segment between the top and base, and that current in the vertical segment produces

6885-408: The transmitter's output stage. If mismatched, current sent from the transmitter to the antenna will reflect back down the feedline from the antenna, creating a condition called standing waves on the line. This reduces the power radiated by the antenna, and at worst may damage the transmitter. Any monopole antenna that is shorter than ⁠ 1  / 4 ⁠   wave has a capacitive reactance ;

6970-424: The work of Jacques Turgot. He argued that "each increase [in an input] would be less and less productive." In 1815, David Ricardo, Thomas Malthus, Edward West , and Robert Torrens applied the concept of diminishing returns to land rent. These works were relevant to the committees of Parliament in England, who were investigating why grain prices were so high, and how to reduce them. The four economists concluded that

7055-455: The zenith. This makes it a good antenna at LF or MF frequencies, which propagate as ground waves with vertical polarization, but it also radiates enough power at higher elevation angles to be useful for sky wave ("skip") communication. The effect of poor ground conductivity is generally to tilt the pattern up, with the maximum signal strength at a higher elevation angle. In the longer wavelength ranges where 'T'-antennas are typically used,

7140-658: Was invented in 1895 by radio pioneer Guglielmo Marconi ; for this reason it is sometimes called the Marconi antenna . The load impedance of the quarter-wave monopole is half that of the dipole antenna or 37.5  ohms . Common types of monopole antenna are The monopole antenna was invented in 1895 and patented in 1896 by radio pioneer Guglielmo Marconi during his historic first experiments in radio communication. He began by using dipole antennas invented by Heinrich Hertz consisting of two identical horizontal wires ending in metal plates. He found by experiment that if instead of

7225-406: Was that at a certain point, that the quality of the land kept increasing, but so did the cost of produce etc. Therefore, each additional unit of labour on agricultural fields, actually provided a diminishing or marginally decreasing return. A common example of diminishing returns is choosing to hire more people on a factory floor to alter current manufacturing and production capabilities. Given that

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