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Questions tagged [rf]

Short for Radio-Frequency. Frequencies at which radiation (intentional or not) plays a role. Typically associated with wireless communications, but also relevant for high-speed PCB design.

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5answers
1k views

Difference between these RF adapters

Can someone explain me the differences between these two RF adapters. I know the one on the right is better (and much more expensive as well) but is there a difference in the functioning of these ...
0
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1answer
23 views

Connected RF Trace to Multiple Pads

I'm trying to improve my RF routing skills. I want to connect a 450 MHz trace (21mil width) to a RF6886TR13 power amplifier that has 6 RF_OUT pins. What is the best way to make this connection? I've ...
0
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1answer
44 views

How to determine the frequencies in which the L&C model of an artificial transmission line works?

I want to model an artificial transmission line with L & C. So far I used the following circuit and used the values of L=400 pH and C=0.16 pF so that Z=sqrt(L/C)=50 ohms. So, expected S21 and S31 ...
0
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1answer
30 views

How exactly averaging is performed in the diode sensor based power meter?

I was just wondering how the power averaging works in the diode sensor based power meter. Can you please enlighten me? Thank you.
1
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1answer
209 views

How to convert Inductor to series transmission line?

My objective is to understand the travelling wave amplifiers, but I am stuck on how to realize inductors in transmission lines. But, I am basically stuck on how to convert a series inductor to a ...
0
votes
1answer
57 views

How to design a 180 degree phase inverter for the feedback?

I am currently working on a multi-stage wideband amplifier (80-110 GHz) design with the goal of having 5-6 dB for each stage. The transistor that I am using has the transit frequency around 300 GHz (...
3
votes
1answer
253 views

The S parameters of an attenuator--but what is actually wrong with it?

I have measured S parameters of an 10 dB attenuator on hand--please see the attachment. In my view, this attenuator is not performing as expected, e.g., |S12| / |S21| is not giving 10dB attenuation ...
0
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1answer
36 views

In what way VBW and trace averaging are different in spectrum analyzer?

We know both VBW and trace averaging intends to smooth the fluctuations of a spectrum. But how do they differ from each other?
0
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1answer
100 views

Impact of “reference level” and “RBW” on the time domain signal in spectrum analyzer?

Two questions: (1) What is the impact of "reference level" on the time-domain signal viewed on the spectrum analyzer? [My attempt] Mean power level of a time domain signal would move up and down on ...
2
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2answers
49 views

Questions related to the calibration of a VNA?

I am seeking answers to these two questions related to the calibration of the VNA. (1) What type of VNA calibration is required to measure the reflection, transmission, and phase of an attenuator? [...
2
votes
1answer
127 views

Converting dBuA to dBuV at 3m and 10m

I'm looking for some advice on converting from dBuA/m to dBuV/m at 10m. I'm trying to convert 10dBuA/m @ 10m. I'm struggling with the uA to uV conversion at distance and can't find online tools to do ...
0
votes
1answer
100 views

Matching impedance network for an LC ladder network

Let's say I have a 5 stage L-C ladder network with L= 4.7 micro Henry and C= 60 pF. The characteristic impedance of the network becomes 280 ohms (square root(L/C)). However, from circuit analysis, the ...
3
votes
1answer
80 views

RF layout bend over Component

We lay out the RF trace for below model. GSM 900MHz RF trace maintain at 50Ω impedance. As I know, the RF trace needs to be as short as possible for better signal. Do we need to bend RF trace ...
1
vote
0answers
29 views

2 tone test with RF mixer

I am designing a system that uses RF to probe the nonlinearity of a target. It works as follows. Transmitter sends out 2 RF frequencies, such as 900 and 910MHz. The target/reflector has a ...
0
votes
1answer
122 views

Effects of impedance mismatch on RF signals from antenna

I'm building an antenna array that operates at high frequencies (around 2 GHz). I want to use a SDR dongle that has a 75 ohm input impedance as receiver, I've also bought the coax cable, a 4 way ...
0
votes
2answers
117 views

Conversion from dBm to dB\$\mu\$V?

I am trying to derive the conversion from dBm to dB\$\mu\$V. So, please correct me If I am wrong. \begin{align} \textrm{dBm} &= 10 \log_{10} \left( \frac{P}{1\textrm{mW}} \right) = 10 \log(P) + ...
0
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1answer
63 views

Design emission (harmonics)

I attached a image of ESP32's datasheet where it say to add a series 470 ohm resistor to Tx transmission line. I wonder is it talking about which line, what are the pins? And why that specific value? ...
24
votes
5answers
9k views

How could have Banksy kept an RF receiver running for 12 years? [closed]

I'm talking about Banksy's "Girl with balloon" painting that shredded itself at auction. I think the general consensus is that he didn't, and that it was set up before the auction (or a couple years ...
1
vote
1answer
87 views

Reference Plane In Impedance Calculation

I'm designing an 8-layer PCB with 10 distinct region of power. To attain 50Ohm trace I used Stripline calculators (like this fancy EEWeb) and they work great If you know that you have a complete solid ...
0
votes
1answer
49 views

Radio activated on/off switch

TL;DR: I want to know if there is anything, That on which when a radio frequency falls, and it turns on an LED. Basically an on off switch but controlled when radio waves hit it. What I hope to ...
-1
votes
2answers
70 views

Half-duplex wireless: Is a tuned antenna more important for the transmitter or the receiver?

I intend for this to be a general/conceptual question that could apply to any wireless communication hardware, however I will use a specific example to talk about. Let's consider the nRF24L01. (...
1
vote
2answers
58 views

Measure ~300kHz Induction Heater RF Power

I have been tasked to gather data from an old running 335kHz 5kW induction heater system. It has no outputs available to give amperage, power etc. Basically there is an assumption that the unit is not ...
1
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0answers
40 views

Generate ultrashort rise times with photoconductive switch or photodiode

I am trying to produce voltage pulses with very short rise time (<15 ps), medium width (20 ns) and amplitudes up to 15 V. As a promising candidate I selected photoconductive switches and ultrafast ...
0
votes
1answer
52 views

Un-masked Copper Boundary across RF section

I have seen so many PCB which has an un-masked (without solder mask), copper boundary across RF sections. The boundary has via-stitching and there are also few ...
0
votes
1answer
57 views

When deforming a resonant circuit into an antenna, why can we cut the inductor in half?

The working principle and fields of an antenna can often be shown by considering a parallel LC circuit. The plates can be moved to opposite ends and the inductor can be stretched out, both of which ...
0
votes
1answer
72 views

What is the relation between carrier signal and local oscillator in RF system?

I have a confusion between the carrier signal and the local oscillator and based on my understanding, IQ signal (data) is mixed with carrier signal to become a modulated RF signal and before ...
1
vote
0answers
22 views

CST Studio Space State Matrices

I am new to using CST Studio and I am trying to figure out how to see the state space matrices (A,B,C,D) of a designed antenna to describe its radiation pattern in other software. Any help on the ...
1
vote
0answers
24 views

Load Impedance Derivation

I'm having some trouble deriving this equation for transmission line theory: From: http://www.antenna-theory.com/tutorial/txline/transmission3.php When I sub the Telegrapher's equations into eqn ...
0
votes
1answer
52 views

How to determine operating frequency range of an unknown 2-port device (with VNA)? [closed]

I have a question on hand: "You have an unknown 2-port device, the black box. Find the operating frequency range. Show how to do this with a VNA. Think of the settings, why?" VNAs can have a very ...
4
votes
1answer
187 views

Effect of VIA fence on grounded coplanar waveguie (GCPW)

I'm working on a RF Frequency board with up to 6GHz signals. To connect components on the board (Mixer, Attenuator, ...) I decided on using GCPW. I designed my GCPW Using AppCad calculator (free ...
1
vote
1answer
75 views

How to use the UART functionality in this Bluetooth module?

I'm using a Bluetooth module called SPBTLE-1S whose datasheet is here - https://www.st.com/resource/en/datasheet/spbtle-1s.pdf In the datasheet, it says that I can use the UART functionality by ...
0
votes
1answer
33 views

SAW Filter input power restriction

I have front end module (915MHz freq band) in circuit Which is having 30dBm output power. Between This FEM and antenna I have to insert filtering circuit. I came across few SAW filters from Murata, ...
3
votes
0answers
385 views

How to analyze/decode a Manchester encoding?

I have a barcode scanner working on 433Mhz (FSK). Since this is relatively old product and the PC software is not working with Windows 10's and I can't use the SDK anymore. I therefore have decided to ...
1
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1answer
60 views

Difference between hybrid and resistive RF power splitters, and Frequency Response?

I am new into RF measurements, and have got a couple of questions regarding power splitters (hopefully common for all the models that exist in the market). What's the difference between resistive and ...
1
vote
1answer
111 views

Impedance matching a capacitor load

I am currently trying to impedance match a capacitor as a load. In detail, it is an insulating thin film grown on top of a conductive layer (grounded). We now sputtered small Pt electrodes on top and ...
0
votes
2answers
168 views

Can I use more than one antenna with a radio module (say rfm69) and switch between those antennas electronically, say by a transistor

I need to know the approximate direction of the radio signal coming to my module, and I have to use very simple hardware and software for this. (Just a microcontroller and one module) What came up ...
1
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0answers
75 views

Amplitude Modulating a simple Laser using an RF transformer

I know I can modulate a laser using an audio transformer see pic and website below. Pen Laser website I was wondering if it’s possible to modulate a simple pen laser using RF signals in the RF range ...
5
votes
1answer
247 views

Routing large RF trace to small SMD pad

I am designing an RF board in Altium where due to the dielectric selected and its thickness, the trace width for a 50 ohm characteristic impedance is thicker than some of the SMD component pads. What ...
1
vote
1answer
36 views

How to calculated weighted gain of antenna?

I have this test specification for testing antennas and it defines weighted gain as follows: The weighted gain is calculated from the transfer function (S21) using only the gain values within the ...
2
votes
1answer
40 views

PIN diode in RF switching vs. PIN diode used as photodiode

From what I understand, there are traditional photodiode components that are designed with PIN diodes, in which the gate is activated by light saturation. For a PIN diode component made for RF ...
0
votes
2answers
26 views

RF connector/ interconnect for Gate signals

I need connector as shown in pictures. I spent good couple of hours trying to find them on Farnell but the lingo for such connectors is little difficult for me. I read a lot too but couldn't find ...
3
votes
1answer
131 views

Microstrip and CPWG transitions on PCB

I've been doing some simple RF boards as part of an internship in a lab, mainly to test particular ICs and prototyping, and mainly using coplanar waveguides. I've now been tasked with designing a ...
0
votes
2answers
59 views

rf amplifier saturation when input chirp

I am trying to generate an 11 MHz pulsed chirp signal with center frequency of 4 GHz at a power level of +10 dBm. I have an arbitrary waveform generator that can generate the correct chirp signal, but ...
0
votes
1answer
94 views

Through Hole (Vertically Mounted) SMA Connector on PCB - Feasible for GNSS Application?

Due to space constraints on a board I am designing, it is ideal to have the GNSS cable connecting vertically onto the top of the board. I haven't been able to find any edge-mounted connectors that go ...
1
vote
2answers
95 views

To see an encoded AM radio wave, what kind of Oscilloscope do I need?

I want to see an AM carrier wave and the resulting encoded frequency and the DC (I think) out of the wave, the information getting to my earpiece. What kind of Oscilloscope do I use for seeing the ...
1
vote
0answers
110 views

LoRa RX-Single Mode Inconsistent RX-Timeout Interrupts

I'm trying to implement LoRa communications using an SX1276 module (DRF1276G) and an ATmega328P on a custom PCB. I've got it mostly working but I'm having a strange issue with the timeout interrupt. I'...
0
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1answer
43 views

Type of RF Coil [closed]

I am trying to source parts for a project (Listed Below) and unsure what kind of RF Coil the blogger is mentioning. I am a novice and have managed to source most the other parts but this one component ...
0
votes
3answers
195 views

Can a USB Oscilloscope be used reliably and accurately for RF projects?

Are USB based oscilloscopes "sensitive" or able to be used with RF circuits? In particular, are they able to see the waveforms, carrier wave, etc. of something like a crystal set? I saw something ...
2
votes
1answer
161 views

Oscilloscope waveform shows overlapping levels, second harmonic?

What could be causing this 40 GHz signal to look like two overlapping waveforms on a 63 Ghz real time oscilloscope? On the scope I see the signal out of a 40 GHz signal generator outputting a CW sine ...
0
votes
1answer
71 views

Drone's Remote control not powering on! [closed]

I am using bayangtoys X16 GPS drone. I managed to solder the "alfa APA-M04 7 dBi gain RP-SMA directional panel antenna Wi-Fi" on the board, and it was working absolutely fine. Until, I put hot glue on ...