Questions tagged [vna]
VNA (Vector Network Analyzer) - Device to measure characteristics of electrical networks
137 questions
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How to layout a transmission line for impedance matching when using a chip antenna
I will be designing a PCB layout for a LoRa module very similar to this one, but with a chip antenna instead of a U.FL connector.
It seems that this one has a pi matching network for matching the ...
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Where should I connect my VNA for impedance matching on a wireless module?
I’m new to RF design and need some guidance. My board has a wireless module where the ANT output goes through a matching network and then to a U.FL connector, which connects to the antenna. This chip ...
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How do I measure a coax cable’s group delay with a VNA without standing-wave ripples?
Goal
I’m trying to get a clean, flat plot of group delay vs. frequency for a coaxial cable so I can derive the propagation speed as a function of frequency.
Setup
DUT: 10 m RG-58 coax.
Instrument: ...
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How can I convert S-parameters between series and parallel?
We evaluate RF amplifiers using actual equipment and a simulator (ADS).
Since there are few types of inductance values for air-core coils that can be used in matching circuits over 100W, we make our ...
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Weird loop on Smith chart
I'm testing my own made interdigital capacitor. It is for 1.5 T MRI (63.8 MHz). Right now I have soldered a SMA connector to a custom capacitor board and connected the SMA connector with a cable to ...
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Measuring inductance of a cable with a VNA
I would like to measure the inductance of a cable for a frequency range 100kHz to 85MHz.
I have a nano-vna. When measuring I use a 50 ohm termination on one of the SMA connectors soldered to the cable....
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Second port of the VNA is reading a very low level signal
I have a 4-port VNA and I want to measure the S21 value of a two-port antenna.
When I use the first, third and fourth ports (ex. S13,S14,S41,S31), I get the same value, but when I use the second port (...
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VNA frequency step
Assume you have a 10m wire between the 2 ports of a VNA and you want to measure the S parameters from 100MHz to 100GHz. What are the properties of the VNA? How many samples should we get in the ...
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Obtain phase spectrum from frequency/phase modulated signal
I have a homodyne rf setup in which I measure spectra by stepping frequency by frequency. The phase reference resets every time I change the signal frequency, so I can only measure the amplitude, but ...
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S21 calculation
In this post
It mentioned that there's a factor 2 in S21 value.
But I'm still don't understand why there's a 2 in it.
My schematic is shown below.
Shouldn't S21 = Vout/Vgen?
My question is: where is ...
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How to create schematic of common mode choke that reflect on Common mode, differential mode and mixed mode? [closed]
I aim to create a schematic that can replicate the results exactly as seen in the measured S4P file. I have conducted the measurement using a VNA and am attempting the schematic simulation in CST. ...
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Why is a bandwidth discrepancy occurring despite consistent Q factors in the given Graph?
I was trying to do curve fitting the common-mode choke in CST Studio according to the selected S4P file from TDK (ACT1210G-800-2P-TL05).
However, the common-mode impedance measured from the file does ...
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Does the minimum value of the S11 (return loss curve) at the resonance frequency depend on the resistance of the antenna?
I was trying to fabricate a flexible NFC antenna. Initially, I fabricated my design on a copper PCB. It worked perfectly fine with my NFC chip and facilitated NFC communication. I observed its S11 ...
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Why is the core resistance modeled as 2*Rp and capacitance as Cp/2 in a common-mode choke?
I directed my attention to a paper regarding the modeling of common-mode chokes. Within this paper, the authors structured the circuit in such a manner that they designated the core resistance (...
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Testing antenna without anechoic chamber or RF foam absorber
I have to test an inset-fed microstrip antenna operating at 2.4 GHz. My objective is to measure S11 and the radiation pattern. The problem is I cannot count on an anechoic chamber or microwave ...
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Impedance matching on VNA does not match calculation (with detail steps included)
I have a PCB with a pi-matching network, and I want to calculate the component values for the matching network.
I use LiteVNA and a WE-MCA Multilayer Chip Antenna for this project.
Here is the basic ...
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S parameters calculation from VNA file
I am trying to validate that our broadband LNA(Low noise amplifier) is working correctly. I wanted to measure the S21 of the LNA, I calibrated the VNA for the specified frequency range and measured ...
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What's the difference between a vector network analyzer (VNA) and a frequency response analyzer (FRA?)?
I know what a VNA does, but what does an FRA do that's different? From what I can find, an FRA seems to be primarily used in electrochemistry and other physical sciences, where what is being tested ...
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Signal modulation with VNA
I want to apply a 1 V, 1 MHz signal to my DUT (coaxial waveguide) while sweeping the frequency from 300 kHz to 6 GHz by the VNA.
Right now, I applied the signal by the signal generator to the bias tee ...
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Understanding TRM calibration in network analyzers
I am trying to figure out how TRM calibration in network analyzers works. I have read a couple papers about it, but didn't understand it properly, therefore I tried to develop it myself. I do this by ...
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Source impedance influence on DC/DC converter input impedance measurement
simulate this circuit – Schematic created using CircuitLab
I have been tasked to verify the input impedance of a medium powered DC/DC converter (<1kW), and no experienced colleagues to ...
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Need help with signal modulation
To capture a mammalian cell, I need to have a constant 4MHz AC signal (coming from a function generator) while sweeping the frequency from the vector network analyzer (VNA) 9kHz to 9GHz to read the ...
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Convert dB to ohms
I did some impedance measurements in high frequencies using a VNA.
I did not pay attention to the format of the measured values that were in dB so it is now to late for me to reperform measurements.
I ...
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Is there anything particularly special about a "short" and an "open" in a VNA calibration kit?
I would like to calibrate a VNA with the reference plane at the end of a male BNC feedline. Surprisingly, female SOL kits are hard to find. There are many BNC 50-ohm loads available but I'm having ...
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VNA discovery question
I was playing with my VNA yesterday and noticed in the Smith chart view of a surface mount device that the trace went from an open at 30 KHz, through inductive to some capacitance at 6 GHz. Nothing ...
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