Questions tagged [s-parameters]

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Which matrix index should be used when Y (admittance) is shown to compose a circuit segment mapped to an ABCD matrix? Y21? Other?

I would like to cascade a serial capacitor with a shunt inductor to form an L-match network by multipling two ABCD parameters and convert the result to S-parameters that represent the composite ...
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How do the 5 elementary two-port networks map to unbalanced networks with a common ground?

Background (questions below) I've been trying to understand how to use S/Y/Z/A-parameter matrixes to create circuits mathematically with 2-port components in series, parallel, and ground-shunt. For ...
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What does \$\beta\$ represent with respect to the length of a transmission line?

The picture below shows the ABCD parameters for a transmission line of length \$l\$ from this video. Question: What does \$\beta\$ represent?
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Are T-parameters the same thing as ABCD parameters?

S-parameters can be converted to either T-parameters or ABCD-parameters, and both are considered a "transfer matrix". The conversion from S-parameters to T- or ABCD-parameters are defined ...
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How are S-Parameters and Reactance related, can one be calculated from the other?

I know that, for example, \$X_L=2\pi f L\$ will calculate reactance of an ideal inductor, but can this be calculated for a real component model? Given the S-Parameter values at some frequency from an ...
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Antenna port S11(dB) > 0

I'm simulating a microstrip patch antenna in microwave office at 35 GHz. When plotting the S11 in dB of the antenna port I get values greater than zero at frequencies below 28 GHz. How is this ...
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Converting measured S-parameter to Z-parameter does not match the Z-parameters measured on the same circuit

I have measured the S-parameters for a 4 port circuit. For a certain frequency those values are: ...
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How to calculate the differential impedance from an s-parameter file

I have an s4p Touchstone file with a reference impedance Zr, then I think the differential impedance should be as below but I am not sure because I am not sure what the meaning of the reference ...
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Which capacitor equivalent circuit should I use in an AC PSPICE sim?

I am trying to simulate the frequency response of a buck converter with the specific ceramic caps that I will be using on my board. The goal is to evaluate stability (phase margin). The OEM does not ...
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Converting S-Parameters to a Shunt C

I'm relatively new to RF design and I am looking at running some simulations based around a specific power amplifier chip that I have the datasheet and S-Parameter file for. I am looking at running an ...
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1 vote
1 answer
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Voltage along transmission line with scattering parameters and VSWR given

A transmitter is connected to an antenna with a coaxial cable with length \$l=1.5 \:\text{m}\$. The characteristic impedance of the cable is \$Z_0 = 75 \: \Omega\$ and the scattering parameters are \$\...
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Common mode choke - Why only impedance?

Why are most common mode chokes only given with a impedance curve, inductance at a specific frequency and current rating (this is clear😅). Wouldn't be S-parameter better? I know it's more work, but ...
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How to interpret S parameters on a Smith chart

I am trying to understand S parameters on RF transistors. I chose the BFP840ESDH6327XTSA1 as my RF transistor, to operate it at 10 mA, 12GHz. The design should be optimal for simultaneously matching ...
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-1 votes
2 answers
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Two-port network parameter measurement using an LCR meter

I was wondering if it's possible to find the admittance parameters of a pi two-port network experimentally using an LCR meter. For the network shown below, we have $$ \begin{bmatrix} I1\\ I2 \end{...
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Recommended Fixture for a 10 MHz to 40 GHz S-Parameter Collection

I would like to characterize a range of SMD and TH components in order to show how different components have different parasitic elements that must be accounted for as frequency increases. I would ...
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Deriving S-Parameters for Hybrid 90° Coupler with Isolated and Delayed P Shorted from 90° Hybrid Coupler S-Param Matrix

I'm trying to derive the s-parameters for a 90 degree hybrid coupler using the s-parameter matrix that is known for a coupler of this type when the ports are configured correctly. In this situation, I'...
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2 votes
2 answers
217 views

How to compute S21 when port 1 and port 2 reference impedance (Zo) are different

The attenuator given in the figure is a 6 dB attenuator when both port 1 and 2 have a reference impedance of 50 Ω. Then, their S-parameter matrix (when port 1 and 2 have 50 Ω reference impedance) ...
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Passivity and Causality of PCB channel

We use S parameters to analyze a PCB channel. Once the S parameters are extracted, what I have seen is SI engineers will check the S parameters obtained are passive and casual. I have some questions ...
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Combining S-parametric Blocks

I would like to ask you, please, how I can combine general S-parametric blocks together. Consider the situation in the following picture. Considering this example, I would like to connect these three ...
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1 answer
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Calculating the real power consumed in a two-port network using its S-parameters

I would like to express the real power consumed in a two-port network using its S-parameters. Assume for simplicity \$\underline{Z}=R\in\Re\$ (1) My idea was using energy conservation: $$ P_{in} = P_{...
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RLGC extraction from the Asymmetric S-paramter

In the signal integrity of high speed interconnect, in case of extraction of RLGC from S-parameter of it, they assume the S-parameter is symmetric and reciprocal. but in practical case S-parameter of ...
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2 answers
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Why do we use S parameters for channel modelling, rather then using Z, Y, h or any other parameter?

For channel modelling in high speed PCBs we always use S parameters. What is the specialty of S parameters for this purpose? Why we are not using Z, Y, h or any other parameter? How do we determine ...
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Can port parameters in one representation (mag-angle, decibel-angle, or real-imaginary) be converted to the other?

I'm trying to figure out what network parameter data would be "best" to use when generating a Touchstone file, or if the different data representations are equivalent in terms of the ...
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1 answer
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S Parameters Channel Modelling Time domain representation of insertion loss

Below is the insertion loss waveform obtained after S parameter of a channel.The waveform is in frequency domain. May I know what is the equivalent time domain waveform and how to obtain it from this ...
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How to interpret VNA data?

I'm looking at the raw data from a VNA (HP 8720A) and I want to understand how to interpret it, and how to do after-the-fact calibration (ie: read raw data, then apply to it whatever corrections a ...
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What is the significance of a negative imaginary component in a S21 measurement?

What is the significance of a negative imaginary component in a S21 measurement ? For example, in the following plot of a passive network, the linear magnitude of the S21 parameter decreases with ...
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2 votes
0 answers
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De-embedding ceramic filters

I want to design a diplexer using two ceramic filters. S2P files of the filters are not provided. Therefore, I designed a PCB which can be shown below to obtain their S2P parameters. In the first ...
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S21 derivation on this schematic

I saw this equivalent model for a switch device on a book. The resulting S21 equation is shown below. It seems not too complicated, but I cannot derive this equation. Could somebody enlighten me and ...
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1 answer
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Differential Pair Mode Conversion [closed]

What is the purpose of using these mode conversions? SCD Input: Differential Output: Common SDC Input: Common Output: Differential
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1 answer
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Are multiple reflections accounted for in S-parameters?

When the S-parameters of a 2-port device whose input and output impedance are different from 50 Ohm are calculated/measured in a 50-Ohm system, multiple reflections occur at port 1 and port 2. Let's ...
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How to find Z impedance if I have only S11 (db) and phase

I need to measure Z line impedance. Using VNA I measured S11 it is -53.8785 dB and phase at this point is 175.6706. Could you explain using these numbers how to find R and jR S11 = (Zx-Z0)/(Zx+z0) = -...
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Confusion regarding connecting nport in cadence while trying to find input impedance

I am a little bit confused on how to to connect the nport in the case where I try to find looking in impedance of a transmission line which is loaded by a 1pF capacitor on the one side. As shown in ...
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2 votes
3 answers
321 views

Bad Reflection from SMA Board Connector at 4-8 GHz

recently I have tried to design a simple SMA-to-microstrip connector PCB intended for 4-8 GHz. The connectors used are vertical with surface-mounted centerpin (link). The design idea was to simulate ...
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Causes for negative port resistance of passive device (or obtaining |S11|>0 from measurements)

Suppose you have two reciprocal (passive) devices, A and B, both described with S-parameters \$S_a\$ and \$S_b\$. With a VNA, you measure \$S_a\$ and \$S_{\rm tot}\$ (S-parameters of AB, both devices ...
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3 answers
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Deriving the S-parameters, different Matched Loads possible?

I guess this is more of a conceptual question but for the problem below Im having trouble getting started on how to derive the S parameters for the network. I noticed that the network at 28.025 GHz ...
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1 vote
2 answers
328 views

How is Wilkinson power divider lossy?

In an ideal Wilkinson power divider(because in practical there will always be resistive loss), the scattering parameters, or S matrix is given as: From the condition that checks if network is loss-...
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-2 votes
2 answers
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Why 20 is multiplied for the SdB=20 Log (Smag)?

Why factor of 20 is multiplied while converting the ratio of two powers/voltages to dB value? SdB=20 Log (Smag) where: SdB = value of the magnitude, in dB Smag = value of the magnitude, as a number
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1 vote
0 answers
163 views

S21 phase vs phase shift measure

Hi am simulating in ADS microstrip T-lines for a 3 bit phase shifter, the lines are calculated to insert 55,110 and 220 phase shift for 2.16Ghz. With the S-Parameter simulation i can see the phase of ...
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What is a "loading capacitor for pin parameter measurement?"

I am designing my first PCB with an MCU and I see this section in the datasheet that brings up a loading capacitor used for pin parameter measurement. I don't believe this is load capacitance for a ...
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1 answer
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S-parameters vs device model

Many vendors provide both S-parameters and simulation models for their devices. Having encountered device models that when simulated, don't result in exactly the same S-parameters as the touchstone ...
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1 vote
1 answer
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Measure antenna S11 next to another source

I have a dipole antenna designed to work on ~800MHz and 2.44GHz frequency, and a miniVNA Tiny USB device that I can use to measure return loss of the antenna. I connect the antenna directly to the DUT ...
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2 answers
1k views

What's the S parameter in an Antenna

So, I'm struggling to understand what the S-parameter is in real-life terms; I mean, what does the S-parameter tell us about an antenna? I have designed a microstrip Wi-Fi antenna that should work at ...
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1 answer
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3-phase inductance calculation homework

This is a homework question where i am stuck. Please help me out in this: Three similar impedances are connected in star across 2000 V, 50 Hz three phase supply. Power absorbed is 300 kW. ...
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2 answers
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What is the theory behind these current equations? (for Z paramaters)

In the photo below is shown the method for deriving z-parameters of the circuit. Apologies for my badly drawn values for resistors as they weren't shown in the original image. Basically I'm struggling ...
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1 answer
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Can these S-parameters be derived?

I have been trying to derive the S-parameters of a lossless T-junction of transmission lines. Here's a diagram from Google: This is an exercise in microwave network analysis, not in design, so the ...
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1 vote
1 answer
403 views

Soldered wire or test connector for VNA measurement?

I am designing a PCB for a IoT device, which will have an antenna inside a space-constrained plastic enclosure with metal screws. I know that I will have to tune the frequency response of the antenna ...
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1 answer
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Can I get the S21 parameter from a one-port open, short and load reading?

I am currently working with a custom rectangular waveguide, which has one port abled to connect to a VNA,(call it port a) but the other side cannot, (its part of a bigger system but for now its only ...
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1 answer
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Can a Unilateral Amplifier be Unstable?

When designing microwave amplifiers, stability is an important factor to consider. Stability is usually measured with the K factor. In a unilateral network, S_12 = 0, and this makes the K factor ...
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Can I determine 2-port s-parameters from 1-port measurements?

I have a 1-port impedance bridge. Can I get the four s-parameters of a 2-port device by measuring each "sending" port with the "receiving" port terminated in Z0 and reversing the measurement to get ...
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1 answer
134 views

Coupling coefficient of microstrip resonators

I am working in HFSS and I'm trying to determine the coupling coefficient between two microstrip resonators (k) so that I can design a filter using a certain resonator shape. I have the formula I need....
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