# 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 ...
16 views

### 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 ...
38 views

### 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?
1 vote
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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 ...
58 views

### 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 ...
28 views

### 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 ...
64 views

### 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: ...
45 views

### 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 ...
1 vote
57 views

### 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 ...
43 views

### 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 ...
1 vote
47 views

631 views

### 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 ...
1 vote
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-...
173 views

### 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
1 vote
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 ...
108 views

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 ...
70 views

### 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 ...
1 vote
65 views

### 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 ...
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 ...
89 views

### 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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### 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 ...
1 vote
126 views

### 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 ...
1 vote
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 ...
1 vote
135 views

### 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 ...
58 views

### 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 ...