Impedance matching

matching networkimpedance matchmatchingimpedance mismatchmatchedimpedancematched loadmatchimpedance mismatchesimpedance-matching
In electronics, impedance matching is the practice of designing the input impedance of an electrical load or the output impedance of its corresponding signal source to maximize the power transfer or minimize signal reflection from the load.wikipedia
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Signal reflection

reflectionreflectionsreflected
In electronics, impedance matching is the practice of designing the input impedance of an electrical load or the output impedance of its corresponding signal source to maximize the power transfer or minimize signal reflection from the load.
The ratio of energy bounced back depends on the impedance mismatch.

Impedance bridging

bridging
An alternative to impedance matching is impedance bridging, in which the load impedance is chosen to be much larger than the source impedance and maximizing voltage transfer, rather than power, is the goal.
A different configuration is an impedance matching connection in which the source and load impedances are either equal or complex conjugates.

Antenna tuner

tunerpi networkantenna coupling
These passive (and active) impedance-matching devices are optimized for different applications and include baluns, antenna tuners (sometimes called ATUs or roller-coasters, because of their appearance), acoustic horns, matching networks, and terminators.
Antenna tuner, matchbox, transmatch, antenna tuning unit (ATU), antenna coupler, and feedline coupler are all equivalent names for a device connected between a radio and its antenna to improve power transfer between them by matching the impedance of the radio to the combined impedance of the antenna and feedline.

Telephone

phonetelephonesLocal Telephone Service
In older audio systems (reliant on transformers and passive filter networks, and based on the telephone system), the source and load resistances were matched at 600 ohms.
The junction box (B) arrests lightning (B2) and adjusts the line's resistance (B1) to maximize the signal power for the line length.

Input impedance

load impedanceinput resistanceload resistance
In electronics, impedance matching is the practice of designing the input impedance of an electrical load or the output impedance of its corresponding signal source to maximize the power transfer or minimize signal reflection from the load. Whenever a source of power with a fixed output impedance such as an electric signal source, a radio transmitter or a mechanical sound (e.g., a loudspeaker) operates into a load, the maximum possible power is delivered to the load when the impedance of the load (load impedance or input impedance) is equal to the complex conjugate of the impedance of the source (that is, its internal impedance or output impedance).
If the impedance matches, the connection is known as a matched connection, and the process of correcting an impedance mismatch is called impedance matching.

Transmission line

transmission linestransmissionbalanced transmission line
Where Z S represents the characteristic impedance of a transmission line, minimum reflection is obtained when
Transmission lines use specialized construction, and impedance matching, to carry electromagnetic signals with minimal reflections and power losses.

Transmitter

radio transmittertransmittersradio transmitters
Whenever a source of power with a fixed output impedance such as an electric signal source, a radio transmitter or a mechanical sound (e.g., a loudspeaker) operates into a load, the maximum possible power is delivered to the load when the impedance of the load (load impedance or input impedance) is equal to the complex conjugate of the impedance of the source (that is, its internal impedance or output impedance).
An impedance matching (antenna tuner) circuit to match the impedance of the transmitter to the impedance of the antenna (or the transmission line to the antenna), to transfer power efficiently to the antenna. If these impedances are not equal, it causes a condition called standing waves, in which the power is reflected back from the antenna toward the transmitter, wasting power and sometimes overheating the transmitter.

Smith chart

SmithSmith-Chart
Optimal matching circuits can be designed for a particular system using Smith charts.
The Smith chart, invented by Phillip H. Smith (1905–1987), is a graphical aid or nomogram designed for electrical and electronics engineers specializing in radio frequency (RF) engineering to assist in solving problems with transmission lines and matching circuits.

Electrical termination

terminatedterminationterminator
These passive (and active) impedance-matching devices are optimized for different applications and include baluns, antenna tuners (sometimes called ATUs or roller-coasters, because of their appearance), acoustic horns, matching networks, and terminators.
The terminator is usually placed at the end of a transmission line or daisy chain bus (such as in SCSI), and is designed to match the AC impedance of the cable and hence minimize signal reflections, and power losses.

Balun

matching transformerchoke balunmatched
These passive (and active) impedance-matching devices are optimized for different applications and include baluns, antenna tuners (sometimes called ATUs or roller-coasters, because of their appearance), acoustic horns, matching networks, and terminators.
The Guanella transmission line transformer (Guanella 1944) is often combined with a balun to act as an impedance matching transformer.

Loudspeaker

speakerloudspeakersspeakers
Whenever a source of power with a fixed output impedance such as an electric signal source, a radio transmitter or a mechanical sound (e.g., a loudspeaker) operates into a load, the maximum possible power is delivered to the load when the impedance of the load (load impedance or input impedance) is equal to the complex conjugate of the impedance of the source (that is, its internal impedance or output impedance).
The main reason for this is the difficulty of achieving proper impedance matching between the acoustic impedance of the drive unit and the air it radiates into.

Maximum power transfer theorem

maximum power theoremMaximum powermaximize the power transfer
In electronics, impedance matching is the practice of designing the input impedance of an electrical load or the output impedance of its corresponding signal source to maximize the power transfer or minimize signal reflection from the load.
A related concept is reflectionless impedance matching.

Electrical impedance

impedanceimpedancescomplex impedance
The energy involved can be electrical, mechanical, acoustic, magnetic, or thermal.
Impedance matching

Output impedance

source impedanceoutput resistancesource resistance
In electronics, impedance matching is the practice of designing the input impedance of an electrical load or the output impedance of its corresponding signal source to maximize the power transfer or minimize signal reflection from the load. Whenever a source of power with a fixed output impedance such as an electric signal source, a radio transmitter or a mechanical sound (e.g., a loudspeaker) operates into a load, the maximum possible power is delivered to the load when the impedance of the load (load impedance or input impedance) is equal to the complex conjugate of the impedance of the source (that is, its internal impedance or output impedance).
This is called impedance matching or a matched connection.

Antenna (radio)

antennaantennasradio antenna
A typical RF load is a quarter-wave ground plane antenna (37 ohms with an ideal ground plane); it can be matched to 50 ohms by using a modified ground plane or a coaxial matching section, i.e., part or all the feeder of higher impedance.
For non directional portable use, a short vertical antenna or small loop antenna works well, with the main design challenge being that of impedance matching.

Line level

line-levelline inline out
Power loss is an unavoidable consequence of using resistive networks, and they are only (usually) used to transfer line level signals.
transmission line effects can be disregarded and impedance matching need not be used.

Stub (electronics)

stubstubsresonant stub
Applications requiring only a narrow bandwidth, such as radio tuners and transmitters, might use a simple tuned filter such as a stub.
Stubs are commonly used in antenna impedance matching circuits, frequency selective filters, and resonant circuits for UHF electronic oscillators and RF amplifiers.

Hybrid coil

hybrid transformerhybridhybrid transformers
Another reason was to ensure correct operation of the hybrid transformers used at central exchange equipment to separate outgoing from incoming speech, so these could be amplified or fed to a four-wire circuit.
It does not produce a high voltage, but like the high-voltage variety, it is a step-up transformer in order to impedance match the low-impedance carbon button transmitter to the higher impedance parts of the system.

Standing wave

standing wavesstationary wavestationary waves
The reflection creates a standing wave if there is reflection at both ends of the transmission line, which leads to further power waste and may cause frequency-dependent loss.
Such a standing wave may be formed when a wave is transmitted into one end of a transmission line and is reflected from the other end by an impedance mismatch, i.e., discontinuity, such as an open circuit or a short.

Horn loudspeaker

hornhornshorn-loaded
This principle is used in both horn loudspeakers and musical instruments.
The horn can be thought of as an "acoustic transformer" that provides impedance matching between the relatively dense diaphragm material and the less-dense air.

Megaphone

bullhornloudhailerspeaking trumpet
Acoustic impedance matching (or the lack of it) affects the operation of a megaphone, an echo and soundproofing.
A megaphone increases the volume of sound by increasing the acoustic impedance seen by the vocal cords, matching the impedance of the vocal cords to the air, so that more sound power is radiated.

Standing wave ratio

SWRvoltage standing wave ratioVSWR
Standing wave ratio
In radio engineering and telecommunications, standing wave ratio (SWR) is a measure of impedance matching of loads to the characteristic impedance of a transmission line or waveguide.

Maximum power point tracking

maximum power point trackermaximum power point trackersdifferent MPPT
For example, a maximum power point tracker is used to extract the maximum power from a solar panel and efficiently transfer it to batteries, the power grid or other loads.
If the resistance is lower or higher than this value, the power drawn will be less than the maximum available, and thus the cell will not be used as efficiently as it could be. Maximum power point trackers utilize different types of control circuit or logic to search for this point and thus to allow the converter circuit to extract the maximum power available from a cell.

Line isolation transformer

Wet Transformer
A line isolation transformer for telephone use is a special type of impedance matching transformer that is used to couple telephone land lines to subscriber equipment to prevent dangerous common mode voltages from appearing on the line.

Medical ultrasound

ultrasoundultrasonographysonogram
The gel used in medical ultrasonography helps transfer acoustic energy from the transducer to the body and back again.
Materials on the face of the transducer enable the sound to be transmitted efficiently into the body (often a rubbery coating, a form of impedance matching).