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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.
Figure 2. A general L-section circuit with shunt admittance Y and series impedance Z. The values of resistance of the attenuator's elements can be calculated using image parameter theory. The starting point here is the image impedances of the L section in figure 2. The image admittance of the input is,
For example, if the DUT has 5 ports and a two port VNA is connected with VNA port 1 to DUT port 3 and VNA port 2 to DUT port 5, the measured VNA results (, , and ) would be equivalent to , , and respectively, assuming that DUT ports 1, 2 and 4 were terminated in adequate 50 Ohm loads . This would provide 4 of the necessary 25 S-parameters.
An L pad used to match a source to a load of a different impedance. If a source and load are both resistive (i.e. Z1 and Z2 have zero or very small imaginary part) then a resistive L pad can be used to match them to each other. As shown, either side of the L pad can be the source or load, but the Z1 side must be the side with the higher ...
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 ...
Z-parameters are also known as open-circuit impedance parameters as they are calculated under open circuit conditions. i.e., I x =0, where x=1,2 refer to input and output currents flowing through the ports (of a two-port network in this case) respectively.
Mismatch loss in transmission line theory is the amount of power expressed in decibels that will not be available on the output due to impedance mismatches and signal reflections. A transmission line that is properly terminated, that is, terminated with the same impedance as that of the characteristic impedance of the transmission line, will ...
Iterative impedance of an infinite ladder of L-circuit sections Image impedance of an infinite ladder of L-circuit half-sections. Iterative impedance is a similar concept to image impedance. Whereas an iterative impedance is formed by connecting port 2 of the first two-port network to port 1 of the next, an image impedance is formed by ...