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A T-pad attenuator formed from two symmetrical L sections. Because of the symmetry, R 1 = R 3 in this case. For an attenuator, Z and Y are simple resistors and γ becomes the image parameter attenuation (that is, the attenuation when terminated with the image impedances) in nepers. A T pad can be viewed as being two L sections back-to-back as ...
Pad will include pi-pad, T-pad, L-pad, attenuator, and two-port. Two-port will include pi-pad, T-pad, L-pad, attenuator, and two-port. Input port will mean the input port of the two-port. Output port will mean the output port of the two-port. Symmetric means a case where the source and load have equal impedance.
A Π-pad attenuator formed from two symmetrical L sections. Because of the symmetry, R 1 = R 3 in this case. For an attenuator, Z and Y are simple resistors and γ becomes the image parameter attenuation (that is, the attenuation when terminated with the image impedances) in nepers. A Π pad can be viewed as being two L sections back-to-back as ...
Resistive impedance matches are easiest to design and can be achieved with a simple L pad consisting of two resistors. Power loss is an unavoidable consequence of using resistive networks, and they are only (usually) used to transfer line level signals.
The L pad attenuates the signal by having two separate rheostats connected in an "L" configuration (hence the name). One rheostat is connected in series with the loudspeaker and, as the resistance of this rheostat increases, less power is coupled into the loudspeaker and the loudness of sound produced by the loudspeaker decreases.
Schematic of a flap-type waveguide attenuator: 1) resistive cord, 2) slot in waveguide, 3) adjusting knob, 4) dial, 5) reduction gear 4:1. The flap attenuator or resistive-card attenuator [1] is a flap-type waveguide attenuator that allows for precise and continuous attenuation of electromagnetic waves traveling through a rectangle waveguide.
However, if a sufficiently large attenuator is placed between the two variable impedances, this will have the effect of masking the effect. A high value attenuator will have an input impedance no matter what the terminating impedance on the other side. In the example practical chain shown above there is a 22 dB attenuator required in the chain.
Contact resistance values are typically small (in the microohm to milliohm range). Contact resistance can cause significant voltage drops and heating in circuits with high current. Because contact resistance adds to the intrinsic resistance of the conductors, it can cause significant measurement errors when exact resistance values are needed.