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30-452: Conductive guy cables for radio antenna masts can catch and deflect radiation in unintended directions, so their electrical characteristics must be included in the design. Often the guy wire is divided by strain insulators into isolated sections whose lengths are not resonant with the transmission frequencies. The guys supporting a sailboat mast are called "standing rigging" and in modern boats are stainless steel wire rope. Guys are rigged to

60-402: A dead man. This type consists of a rod with wide screw blades on the end and an eyelet on the other for the guy wire. It is screwed deep into the ground, at the same angle as the guy, by a truck-mounted drill machine. These are commonly used as guy anchors for utility poles since they are quick to install with a truck mounted hydraulic powered auger drive. A rod with a pivoted blade on the end

90-785: A longer than nominal span. Strain insulators are typically used outdoors in overhead wiring. In this environment they are exposed to rain and, in urban settings, pollution. As a practical matter, the shape of the insulator becomes critically important, since a wetted path from one cable to the other can create a low-resistance electrical path. Strain insulators intended for horizontal mounting (often referred to as "dead ends") therefore incorporate flanges to shed water, and strain insulators intended for vertical mounting (referred to as "suspension insulators") are often bell-shaped. Other than their industrial use for which they are produced, strain insulators can be collectables , especially antique ones. Capacitive coupling Capacitive coupling

120-493: A mast collapse. Egg insulators have the porcelain in compression and if it fails, the end loops of the guy wires are still intertwined. AM radio broadcast towers are often fitted with insulators at the mast base and the RF energy is fed at that point. Some are also insulated at the center for feeding the RF energy at that point. Wire rope guys are frequently used and segmented with insulators at several points. Extensive lightning protection

150-534: A steel pole/tower). The shape of the insulator maximizes the distance between the cables while also maximizing the load-bearing transfer capacity of the insulator. In practice, for radio antennas , guy-wires , overhead power lines and most other loads, the strain insulator is usually in physical tension . When the line voltage requires more insulation than a single insulator can supply, strain insulators are used in series: A set of insulators are connected to each other using special hardware. The series can support

180-483: A structural epoxy. When the grout hardens or expands, the anchor is secure. Historically, guyed structures have been some of the tallest man-made structures in the world . There are also many structures which consist of a freestanding bottom and a guyed top. These are either partially guyed towers or additionally guyed towers , the latter of which may be used temporarily to support tall buildings during their construction. Strain insulator A strain insulator

210-436: A system containing capacitively coupled units. Each coupling capacitor along with the input electrical impedance of the next stage forms a high-pass filter and the sequence of filters results in a cumulative filter with a cutoff frequency that may be higher than those of each individual filter. Coupling capacitors can also introduce nonlinear distortion at low frequencies. This is not an issue at high frequencies because

240-415: A wire attaches to a pole or tower, to transmit the pull of the wire to the support while insulating it electrically. Strain insulators were first used in telegraph systems in the mid 19th century. A typical strain insulator is a piece of glass , porcelain , or fiberglass that is shaped to accommodate two cables or a cable shoe and the supporting hardware on the support structure (hook eye, or eyelet on

270-418: Is a push-brace pole , a diagonal pole with one end set in the ground and the other butting up against the vertica pole, opposite to where a guy cable would attach. Electromagnetic fields from the antennas complicate the design of guys that support mast antennas . Conductive metal guy-wires whose lengths are near to quarter wavelength multiples of the transmitted frequency can distort the radiation pattern of

300-583: Is a simple type of capacitive coupler: two closely spaced strands of wire. It provides capacitive coupling of a few picofarads between two nodes. Usually the wires are twisted together. Capacitive coupling is often unintended, such as the capacitance between two wires or PCB traces that are next to each other. One signal may capacitively couple with another and cause what appears to be noise . To reduce coupling, wires or traces are often separated as much as possible, or ground lines or ground planes are run in between signals that might affect each other, so that

330-417: Is an electrical insulator that is designed to work in mechanical tension (strain), to withstand the pull of a suspended electrical wire or cable. They are used in overhead electrical wiring, to support radio antennas and overhead power lines . A strain insulator may be inserted between two lengths of wire to isolate them electrically from each other while maintaining a mechanical connection, or where

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360-433: Is driven into the earth. When the guy wire is attached and tensioned, its force pulls the blade open, "setting" it into the soil. These are often used by the military for rapid mast installations. These are used in both soil and rock. A hole is drilled at the angle of the guy. A steel anchor rod with an eye is inserted, and the hole around it is filled with a liquid grout consisting of concrete and an expansion agent or

390-439: Is often possible to use a grounded mast. The power to the guys is fed via wires running from a tuning unit to the feed point on the guys. When operating a crane , guy wires, known as tag lines, may be connected to unwieldy payloads, allowing ground crew to control rotation and swaying while maintaining a safe distance. Guys can be used to raise an extension ladder in a technique called a church raise. In ground-anchored guys,

420-408: Is required for insulated towers. On antennas for long-wave and VLF, the guys may serve an electrical function, either for capacitive lengthening of the mast or for feeding the mast with the radiation power. In these cases, the guys are fixed without an insulator on the mast, but there is at least one insulator in the guy if necessary. If guys are used for feeding the mast with high frequency power it

450-451: Is the spar most commonly controlled by one or more guys. Utility poles are buried in the ground and have sufficient strength to stand on their own; guys are needed on some poles only to support unbalanced lateral loads from the utility wires attached to them, or to resist ground movement. Guys are particularly needed on dead-end ( anchor ) poles, where a long straight section of wire line ends, or angles off in another direction. To protect

480-410: Is the transfer of energy within an electrical network or between distant networks by means of displacement current between circuit(s) nodes , induced by the electric field. This coupling can have an intentional or accidental effect. In its simplest implementation, capacitive coupling is achieved by placing a capacitor between two nodes. Where analysis of many points in a circuit is carried out,

510-460: The antenna. This also applies to guy wires of neighboring masts or nearby metal structures. To prevent this, each guy wire is divided by strain insulators into multiple sections, each segment non-resonant at the transmitted wavelength. Cylindrical or egg-shaped porcelain "Johnny ball" insulators (also called "egg insulators") are usually used. Non-conductive guys of Kevlar fiber (Phillystran) or extruded fiberglass rod are frequently used to not disturb

540-408: The bow and stern, usually as a single guy. Lateral guys attach to "chain plates" port and starboard attached to the hull. Multiple guys are usually installed with spreaders to help keep the mast straight ("in column"). Temporary guys are also used. A fore-guy is a line ( rope ) pulling on the free end of a spar . On a modern sloop -rigged sailboat with a symmetric spinnaker , the spinnaker pole

570-495: The capacitance at each point and between points can be described in a matrix form . In analog circuits , a coupling capacitor is used to connect two circuits such that only the AC signal from the first circuit can pass through to the next while DC is blocked. This technique helps to isolate the DC bias settings of the two coupled circuits. Capacitive coupling is also known as AC coupling and

600-456: The capacitor used for the purpose is also known as a DC-blocking capacitor . A coupling capacitor's ability to prevent a DC load from interfering with an AC source is particularly useful in Class A amplifier circuits by preventing a 0 volt input being passed to a transistor with additional resistor biasing; creating continuous amplification. Capacitive coupling decreases the low frequency gain of

630-651: The cutoff frequency far lower than the frequencies of the signal. AC coupling is also widely used in digital circuits to transmit digital signals with a zero DC component , known as DC-balanced signals. DC-balanced waveforms are useful in communications systems, since they can be used over AC-coupled electrical connections to avoid voltage imbalance problems and charge accumulation between connected systems or components. For this reason, most modern line codes are designed to produce DC-balanced waveforms. The most common classes of DC-balanced line codes are constant-weight codes and paired-disparity codes . A gimmick loop

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660-408: The plate anchor, in which the guy is attached to a rod with an eyelet extending from the center of a steel plate buried diagonally, perpendicular to the angle of the guy. In the concrete anchor, a diagonal rod with an eyelet extending in the guy direction is cemented into a hole filled with steel reinforced concrete. A sufficiently massive concrete block on the surface of the ground can also be used as

690-420: The pole, a variation called a sidewalk guy is often used: the guy line extends diagonally from the top of the pole to a spar brace extending out from the middle of the pole, then continues vertically to the ground. Thus, the bottom length of the guy is vertical and does not obstruct headroom, so a sidewalk can pass between the pole and the guy. An alternative to guy-wires sometimes used on dead-end utility poles

720-449: The public against faults that might allow utility guy cables to become electrified, they usually have a ceramic strain insulator ("Johnny ball") or a fiberglass strain insulator inserted near the top, to keep dangerous voltages away from the lower end. The length near the ground is often encased in a yellow plastic reflector to make it more visible, so that people or vehicles do not run into it. In urban areas with pedestrian traffic around

750-462: The radiation pattern of the antennas. The strength and low stretch properties of Kevlar fiber approaches that of steel. However, Kevlar is very susceptible to ultraviolet degradation, so it is enclosed in a UV resistant plastic sheath. The individual sections of conductive guys can develop large charges of static electricity , especially on very tall masts. The voltage caused by this static electricity can be several times larger than that generated by

780-443: The same strain as a single insulator, but the series provides a much higher effective insulation. If one string is insufficient for the strain, a heavy steel plate effectively bundles several insulator strings mechanically. One plate is on the "hot" end and another is located at the support structure. This setup is almost universally used on long spans, such as when a power line crosses a river, canyon, lake, or other terrain requiring

810-430: The soil to resist the forces from all of the guys attached to it. Several types of anchor are used: In this type, a hole is excavated and an object with a large surface area is placed in it with the guy wire attached, and the hole is backfilled with earth or concrete. In the historical form of dead man anchor, a log is buried horizontally in a trench with the guy attached perpendicularly to its center. Modern forms are

840-425: The structure which attaches the guy-wire to the ground is called an anchor . The anchor must be adequate to resist the maximum tensile load of the guy wires; both the dead load of the tension of the wire and the maximum possible live load due to wind. Since the guy wire exerts its force at an angle, the anchor has both vertical and lateral (horizontal) forces on it. The anchor relies on the lateral shear strength of

870-476: The transmitter. In order to avoid dangerous and unpredictable discharges, the insulators must be designed to withstand this high voltage, which on tall masts results in over-dimensioned backstage insulators. At each backstage insulator, a lightning arrestor in the form of an arc gap is required for the purpose of over-voltage protection in case of lightning strikes. The insulators and arrestors must be maintained carefully, because an insulator failure can result in

900-481: The voltage across the capacitor stays very close to zero. However, if a signal passing through the coupling capacitance has a frequency that is low relative to the RC cutoff frequency , voltages can develop across the capacitor, which for some capacitor types results in changes of capacitance, leading to distortion. This is avoided by choosing capacitor types that have low voltage coefficient , and by using large values that put

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