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In case the two measurement ports use the same reference impedance, the insertion loss is defined as: [1] [2]= | |. Here is one of the scattering parameters.Insertion loss is the extra loss produced by the introduction of the DUT between the 2 reference planes of the measurement.
The extra loss may be due to intrinsic loss in the DUT and/or mismatch. In case of extra loss the insertion loss is defined to be positive. The negative of insertion loss expressed in decibels is defined as insertion gain and is equal to the scalar logarithmic gain (see: definition above).
The insertion loss is not such a problem for an unequal split of power: for instance -40 dB at port 3 has an insertion loss less than 0.2 dB at port 2. Isolation can be improved at the expense of insertion loss at both output ports by replacing the output resistors with T pads. The isolation improvement is greater than the insertion loss added ...
Impedance matching is an important part of RF system design; however, in practice there will likely be some degree of mismatch loss. [1] In real systems, relatively little loss is due to mismatch loss and is often on the order of 1dB [dubious – discuss]. According to Walter Maxwell [2] mismatch does not result in any loss ("wasted" signal ...
The combination of the effects of signal attenuation and impedance discontinuities on a communications link is called insertion loss. Proper network operation depends on constant characteristic impedance in all cables and connectors, with no impedance discontinuities in the entire cable system.
For example, a certain antenna used well away from its resonant frequency may have an SWR of 6:1. For a frequency of 3.5 MHz, with that antenna fed through 75 meters of RG-8A coax, the loss due to standing waves would be 2.2 dB. However the same 6:1 mismatch through 75 meters of RG-8A coax would incur 10.8 dB of loss at 146 MHz.
The input impedance of an infinite line is equal to the characteristic impedance since the transmitted wave is never reflected back from the end. Equivalently: The characteristic impedance of a line is that impedance which, when terminating an arbitrary length of line at its output, produces an input impedance of equal value. This is so because ...
Various tables and calculators are available that provide a means of determining the appropriate resistor values for achieving particular loss values, such as that published by the NAB in 1960 for losses ranging from 1/2 to 40 dB, for use in 600 ohm circuits. [1]