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Questions tagged [vna]

VNA (Vector Network Analyzer) - Device to measure characteristics of electrical networks

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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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Filter and Antenna S11 measurement

I have this circuit below where a BLE chip is connected to the filter and then to the antenna, I've been requested to find S11 from the chip output (for the filter and antenna) when I use ENA to find ...
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Monopole antenna impedance measurement

We are using a low cost (sketchy looking datasheet) external 915 MHz monopole antenna in our product and we're seeing a large variance in RF performance across the 50 pieces that we built. Here's ...
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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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Challenges in Bandwidth in Common mode Choke Modeling

I'm currently working on characterizing a common mode choke (CMC). However, I'm encountering difficulties aligning the bandwidth of my model with the measured results. Specifically, when I attempt to ...
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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 ...
Alaska's user avatar
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NanoVNA measurements of attenuation do not match simulation results

I am measuring RF Tap in Pi configuration using NanoVNA (see attached picture for test setup). If I terminate RF Path output with 50ohm resistor and measure attenuation between RF Path input and RF ...
andrzej's user avatar
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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 ...
Isuru Bhathiya's user avatar
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Why my Common mode choke with 2 turns showing multiple Peaks in the graph?

I analyzed the CMC choke by Wurth Electronics (part no: 744830039080) using VNA and obtained the insertion loss for both common mode and differential mode. The graphs match with the datasheet: While ...
Alaska's user avatar
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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 (...
Alaska's user avatar
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Measuring impedance on VNA

Question: I would like to measure the impedance and phase of an electric piezo tranducer with a resonant frequency of approximately 1MHz - a graph of impedance in Ohms as a function of frequency. ...
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How do you de-embed a shorted 2-port fixture?

I've been working through reproducing Steve Sandler's 2-port shunt-through measurements (2019 SIJ article, Picotest slide-deck). My target is to measure capacitors with ESR down to 1 mΩ with an ...
Daniel's user avatar
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Origin (t=0) of the time axis shifted after TDR on two sets of different S11 data

I have two sets of S11 data (S1P format) which are measured on an open co-axial cable (~ 20 cm long) and open-end as reference (see the hand-draw figures below) correspondingly. I used the Python skrf ...
Keyan's user avatar
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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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NanoVNA software not showing impedance

I am trying to use a NanoVNA to see the impedance on a Smith chart. But in the software I don't see any impedance value. Does anyone know how to get it to show up? I've tried the software on both ...
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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 ...
Kelvin's user avatar
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Can you calibrate your VNA to show matching circuit behavior, without the antenna connected?

We need to make a matching circuit for an antenna, but the antenna feed point is in an inconvenient location. Is there a way to calibrate the VNA at the feed point such that the VNA will show the ...
KJ7LNW's user avatar
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2 votes
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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 ...
DRF's user avatar
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Is my VNA broken or miscalibrated, or are these weird results normal?

My company got a new vector network analyzer recently and I'm using it to try to learn more about microwave circuits, especially the resonant cavities that we use in our measurement systems. I've seen ...
Adam Haun's user avatar
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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 ...
Paul Blase's user avatar
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When calibrating a VNA, does the feedline length matter?

We need to measure an antenna feedpoint (to record an .S1P file) that is far away from the VNA. We can calibrate the VNA to the feedline that will ultimately be attached to the antenna before it goes ...
KJ7LNW's user avatar
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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 ...
Ferrofluid's user avatar
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Choosing between diplexer and resistive power divider

I want to use a passive device to apply a 1V and 1MHz signal in a transmission line, While I am sweeping the frequency from 300kHz to 6GHz by Vector Network Analyzer (VNA) in that transmission line ...
Ferrofluid's user avatar
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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 ...
T. Pluess's user avatar
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Bias tee in Vector Network Analyzer

Can I use a bias tee in the back of a VNA (E5080B) as a port 1 and 2, or do I need a mixer for it? I want to measure the network parameters of a device that requires bias.
Ferrofluid's user avatar
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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 ...
electroGeek's user avatar
1 vote
1 answer
90 views

Vector Network Analyser (VNA)

I am trying to achieve impedance matching using load-pull mechanism and I recently found out that on a Smith chart in the VNA, the S21 doesn't make any sense as I have to plot transmission parameters ...
Viswanath Nimmagadda's user avatar
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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 ...
Ferrofluid's user avatar
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87 views

The meaning between raw and calibrated S parameters

VNA: E5071C Cal kit: 85033E DUT: cable end bandpass filter This figure shows measuring S21 of filter: Upper figure shows real part of S21 and lower one shows imaginary part of S21. Blue line is raw ...
radiosan's user avatar
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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 ...
Wallflower's user avatar
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Can a BNC through-load be used as the load to SOL-calibrate a VNA?

Related to this question, I'm having a hard time finding a female 50-ohm load to calibrate a reference plane at the end of a male BNC feedline. However, feed-through loads are readily available. Is ...
KJ7LNW's user avatar
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11 votes
4 answers
2k views

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 ...
KJ7LNW's user avatar
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1 vote
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How vector network analyzer measures S-parameters of lumped element?

i've seen video lecture where S-parameters of 50 Ohm resistor placed in series between input and output port of VNA with reference resistance also of 50 Ohm are calculated by hand. S11 was calculated ...
user92888's user avatar
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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 ...
dnyberg2's user avatar
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Pi matching off-board antenna with module pigtail

I have an Iridium 9603 satellite modem integrated in a project and would like to tune its antenna feed line using a pi matching circuit on my carrier PCB. What's unique about this situation is that ...
maxmclau's user avatar
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VNA: Why does the IF bandwidth affect the measurement speed?

I believe I understand the role of the IF bandwidth (IFBW) in a VNA measurement: The signal is mixed down to the intermediate frequency (IF) and the receiver detects the signal in a frequency band ...
schtandard's user avatar
3 votes
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142 views

How to connect the VNA to RF transmission line for antenna tuning?

I am working on a 2.45 GHz(Bluetooth) project. the design has a Chip antenna with 50 Ω impedance trace to connect antenna and chip. I intend to tune the antenna impedance using the Pi network using ...
Sussy's user avatar
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1 answer
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How to measure the input impedance of a laser diode/LED using a VNA?

It would be nice to have some advice on an issue I'm having with a laser diode. I have a DFB laser diode that has no kind of series resistor connected to it in the package. I want to make a driver for ...
Ravi Pradip's user avatar
1 vote
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153 views

"Short" calibration

The following section from ST Micro's AN4974 - 'Antenna Matching' app note is a bit of a mystery. Is there a VNA / network analyzer guru out there who can tell me what the 4th line there is saying? I ...
user1621287's user avatar
1 vote
1 answer
49 views

How to choose a sweep range for a known and unknown device with a VNA?

I'm trying to determine best practices for using a VNA to measure say, an antenna. Let's say I have a known antenna with a spec sheet that says it's frequency range is between x and y. Should I set ...
jfwork's user avatar
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1 vote
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How to measure radio wave penetration and reflection through different mediums

I would like to do a few experiments to test how different EM radiation frequencies (915 MHz to 5 GHz) interact with 3D print filament materials (like PLA, PolyCarbonate, TPU, etc...). Specifically I ...
Spesemper's user avatar
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What is the frequency measurement range of a NanoVNA?

I have tried to measure a fabricated patch antenna which has theoretically multiband ranging from 1 GHz to 8 GHz, but when I tried to measure it through NanoVNA it barely shows the result from 1 GHz ...
MS-Hossen's user avatar
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How to protect measurement equipment channels from ESD?

I was wondering what is the best way to protect measurement equipment, when handling like oscilloscopes/spectrum analyzers/Vnas/sensitive circuits (especially when stored in (none esd) foam)? I was ...
ulix's user avatar
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2 votes
1 answer
220 views

How to improve measurement results with pocketVNA

I use a pocketVNA to measure the impedance of antennas and I also bought a couple of SMA connectors and a few cables to connect the antennas to the device. I run a 2-point calibration of the device (...
Kampi's user avatar
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Calibrating a VNA

I am using the Siglent SSA3032A-R spectrum analyser which has a Vector Network Analyser (VNA). Before measuring the impedance of an antenna under test so that I can match this antenna, I have to ...
MRB's user avatar
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1 vote
1 answer
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VNA Characterization of a non 75Ohm system

I'm trying to characterize a 75ohm cable using a VNA. As it differs from 50Ohm I need to do some adjustments with how I'm measuring but I'm not sure what is considered best practice for that. I was ...
user3044142's user avatar
4 votes
2 answers
3k views

Tuning an antenna using a NanoVNA, Smith chart and impedance readings

I am new to antenna design and teaching myself how to optimize antennas using a VNA. I have created a monopole antenna on a PCB (i.e. a single length of track.) The antenna can be fed via a PI network ...
Daveo's user avatar
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1-port VNA quality factor measurement

I am using an Anritsu VNA (MS2034B) to obtain the LINEAR MAGNITUDE and PHASE of S11 via a calibrated 1-port measurement. The DUT is an inductively coupled RLC resonator (schematic below). However, I ...
D. Zambrano's user avatar
3 votes
1 answer
792 views

Match SMA antenna input connector to 50ohm

I'm using an "IOT" radio module designed with a 50 ohm single ended antenna output. The working frequency is about 868 MHz, the maximum transmit power is 14dBm. The module antenna output is ...
Theo's user avatar
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2 votes
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Spurious resonance in microstrip transmission line

We were trying to study the broadband response of a microstrip line on a 1.5mm thick Rogers AD1000 substrate whose Dk=10.7 and loss tangent=0.0023 at 10 GHz. The trace width is 1.2 mm. The S21 is ...
abir's user avatar
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