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Questions tagged [vna]

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

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0answers
22 views

Permittivity measurement using open-ended coaxial probe

I am trying to understand how the complex permittivity of liquids can be measured using an open-ended coaxial probe. For this kind of measurement, we put a open-ended coaxial line into the liquid ...
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2answers
93 views

Why do long cables measured with a VNA show a “drop” in their attenuation curve?

I'm measuring the attenuation of several cables with a VNA (Keysight N5234A). When I measure the attenuation of long cables (10 m, 30 m, 40 m or 50 m) I realize that a "drop" appears at 500MHz (see ...
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2answers
68 views

Z=50 and Xs=0 but SWR is not 1.0:1

I measured an antenna with a VNA and differently to all other cases the SWR isn't low as expected. Here are some screenshot showing this: Similar situation, on the same antenna in the same ...
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1answer
55 views

Where to connect the VNA during matching network tuning

I'm trying to design the matching network between an antenna and its transmitter, running at 868MHz, as shown below. There's probably about 20mm between the transmitter output and the Pi network. ...
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1answer
100 views

S parameters measurement inside VNA

How does Vector Network Analyzer (VNA) measures S parameters in reality? Namely we have equations: \$b_1=S_{11}a_1+S_{12}a_2\$ \$b_2=S_{12}a_1+S_{22}a_2 \$ In theory, if i wanted to calculate ...
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0answers
30 views

S11 parameter measurements of NFC PCB antenna by VNA

I'm trying to measure the S11 parameter of the NFC PCB antenna (actually PCB coil) by VNA. Desired Smith chart pattern is like the below picture (probably with different values, because of different ...
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1answer
26 views

S Parameters 75 ohm Coax in 50 Ohm System

What are the 50 ohm scattering parameters for a piece of 75 ohm coax? (I just need two of them of course). For simplicity assume that the length of 75 ohm coax is 2 electrical wavelengths at the ...
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1answer
38 views

S21 VNA Connector & Cable Loss?

I've tuned plenty of RF devices using my VNA for impedance matching. But I've never done an S21 measurement. I have a shielded tent with some connectors and SMA cables that are going to introduce ...
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1answer
72 views

Interpreting scattering parameters on a Smith chart.

I'm trying to become reacquainted with microwave circuits and how to analyze them, especially with a VNA. Just to get some practice I'm using Keysite ADS simulator. To get the feel of it I used the ...
1
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1answer
34 views

The meaning and role of the phase in antenna measurements with VNA

VNA measurements of an antenna return Z, RL, Xs, Rs... and also phase. I usually check Z=50 and Xs=0 to reach the max Return Loss and the lowest SWR 1.0:1, without having care of phase values. ...
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1answer
37 views

Are Cal Kit (SOLT) definitions unique by serial number?

I have an E5071B Network Analyzer and 85033E cal kit. One of the standards is broken now and needs to be replaced. This is the Male OPEN standard (Part number 85033-60018). Question: Will the ...
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1answer
31 views

How do the Ripple Limit lines get determined on antenna measurements?

I'm doing an S21 ripple measurement through a VNA and I understand how the measurement is done, but I don't understand how the limit is determined. I know you can specify the limit in dB and then you ...
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2answers
123 views

Connection to PCB from VNA

I currently intend to measure the Plane Capacitance of a PCB I'm going to build. I do have the measuring equipment (an VNA from R&S) but am unsure how to design the testpoints I am going to use (...
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1answer
282 views

Measure 4-port device with 2-port VNA

I need to measure a 4-port device (a directional coupler) using a 2-port VNA. This answer covers the basics, and this document goes into more detail. My problem is that I'm not sure how to perform ...
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1answer
84 views

How can I design a double pole eight throw microwave (2-6 GHz) switch?

I need to design a DP8T microwave switch for a microwave imaging senior design project. The frequency range is 2 to 6 GHz. I need to switch between 8 antennas and a 2 port VNA. So each antenna ...
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1answer
312 views

Measure RF impedance of PCB or IC using a VNA Network Analyzer

I have a VNA and want to measure the impedance looking into my PCB. My VNA is pretty old, it's a 8753ES. My PCB includes a commercial Nordic or Dialog MCU with Bluetooth Low Energy (BLE). The path ...
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1answer
49 views

Measuring PSR of a current reference chip

Some Background: I'm designing a test board to characterize noise and PSR of a multiple voltages(1V) and currents(1uA) reference IC. The chip has a single voltage source. I use ultra low noise MUX ...
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2answers
4k views

What is wrong with my 50 Ω grounded coplanar waveguide?

I've been working on a 4-layer design built around the EFR32BG13 Bluetooth Low Energy SoC. While trying to measure the impedance of the antenna to build a matching circuit, I discovered that my short ...
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1answer
85 views

Current to Voltage Gain using Network Analyzer

Suppose I have an Voltage to Current Amplifier. And I'm characterizing it over a frequency range, can a Network Analyzer directly measure current to voltage gain (Iout/Vin)? (Or) do I have to use a ...
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2answers
447 views

VNA calibration using cal kit vs PCB

So, its my understanding that the VNA (vector network analyzer) is designed to inject a known signal into an unknown device and analyze the reflected signal's amplitude and phase (both voltage and ...
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0answers
42 views

VNA reflection and transmission of stripline stub

Testing this stub board. I understand S12 is attenuated at 1.79GHz due L=λ/4. So I calculate relative permitivity: εr = (c / 4Lf)2 = 3.3 But what does (εr) represent in a ...
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2answers
1k views

How to measure antenna S21?

Please explain in detail how to take an S21 measurement for an antenna? I know what it is... but how do I physically connect the antenna to the VNA to take the measurement? Thank you in advance!
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1answer
409 views

Methods for measuring cable path loss in RF Testing

I have been reading about various methods to perform a Cable Path Loss for RF Testing but not being a core RF person, I needed some insights on how it is done in Field or Lab. Here is my understanding ...
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3answers
325 views

VNAs and different characteristic impedances

What is the right technique to measure a matching network, cable, etc that is at a different characteristic impedance than 50Ω? In my case, I need to measure the SWR of a matching network that needs ...
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1answer
73 views

Measuring small capacitor parallel to big inductance (Network Analyser)

So what I have at hand is a cheap network analyser that can present the measured impedance in form of the values of different equivalent circuit topologies, e.g. R-L series or RL parallel. What I ...
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1answer
112 views

Designing a matching network with biasing inductor

I'm designing a 345MHz transmitter using the MAX 7044 ISM transmitter with an electrically small antenna and need to test the matching network. I will connect the VNA in place of the transmitter using ...
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1answer
264 views

What options do I have to measure directly impedance change (ohm) or deduce it indirectly from S-Parameters?

Basically I want to measure how impedance (Ohm) relative to Z0 (50 Ohm) waveguide is changing by varying a parameter. I currently measure the reflection coefficient S11 in a 1-port setup. Our VNA can ...
2
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1answer
543 views

Where to Measure S11 with a VNA

I have someone else's design that I have been asked to choose matching components for. The antenna is a chip antenna and the filter is a band pass SAW filter in a single package. The SAW filter is a ...
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2answers
164 views

Procedure for experimentally determining decoupling capability?

I'm looking for a bullet-point list of a technique to experimentally determine a design's decoupling capability. I have a design that I'm working on that seems to be susceptible to ESD events in the ...