Questions tagged [rf]
Short for Radio Frequency, i.e. 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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How to understand how much current an active antenna draw?
I look for the antenna linked below, but I had one question beforehand. I wanna measure and see in real that how much current will this antenna draw. I will use a coaxial cable to power supply for the ...
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How can I fix this broken RF connector?
I have a broken RF connector. If I soldered it in place, would that work? I am not an engineer and don't know if it needs ground or soldering the connecting interface together would work.
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What is the maximum relative speed at which wireless protocols can operate? (Doppler shift)
Let's take Wi-Fi and UWB. What determines in these standards their robustness to Doppler shift? The most obvious is the range of carrier frequency tolerance. But in both standards this range is ...
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More voltage for radio carrier frequency, is that all? [closed]
I soldered one radio circuit for a wave transmission with ~107 MHz frequency and I got good results. I simulated this circuit in LTSpice, too. What I have seen was that the wave got AM modulated and ...
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SX126x IC: which is the correct frequency deviation formula?
SX126X IC datasheet page 88, I see two different formulas for the frequency deviation:
Closest clue I can find is here:
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Question about RF waves and it's effect on electronic devices
Could a let's say 50 W RF wave (2.40 GHz and 5 GHz) cause disturbance in nearby devices like Laptops? (Data corruption, random opening of applications and programs, random commands, etc.)
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Can I route PWR signals under RFIC?
I am designing an RF amplifier (< 13 GHz) and want to use a board with two layers. However, the RFIC footprint (16-VFQFN Exposed Pad) has RFIN on the left, VDD on top, RFOUT on the right, and VGG ...
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Can I use a 50 Ω attenuator with a high-Z scope?
In my project involving the measurement of current using a Pearson current transformer, the instructions specify the use of high-Z (1 MΩ) oscilloscopes. Given the need to attenuate the signal, I have ...
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Need advice on achieving 1 km non-line-of-sight wireless communication without internet
I'm currently working on a project that involves establishing a reliable non-line-of-sight wireless communication link with a range of 1 kilometer or more. The project does not have internet access, ...
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433MHz Antenna PCB Trace Design
I have designed a custom PCB which among other things has an RFM69HCW (ignore the text on the PCB, it is wrong) capable of outputting +20dBm. The antenna connection is done using a PCB trace (42[mils] ...
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Name for this kind of mixer?
I am trying to learn how a gilbert cell could be used as an amplitude modulator and tried to simplify its operation by assuming single ended inputs. While trying to visualize some concepts I ...
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How to calculate an rf amplifier stage
I changed the LC tank of the circuit below for operation in the 2m ham radio band (144-146MHz, I'm a licenced Class A Ham). Now I'd like to add an amplifier stage to increase the output by about 30dB.
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Can parasitic capacitances be decoupled?
I was working with some IC that has a bus that is really sensitive to trace capacitance and cannot be loaded with more than 8.5 pF.
I have to bifurcate the trace to an ADC because I need to see what ...
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RF connector selection
An antenna with its LNA has 3-7 V range for power supply for the LNA, and it’s written that connection is SMA for 3V, TNC for other levels. I wonder the main reason behind this. Can’t I use TNC for 3 ...
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SX126x IC: how to calculate hex value for Bandwidth setting
I am programming a SX126x IC in GFSK modulation.
I am trying to figure out if there is a formula to calculate the bandwidth.
I understand that the BW can be programmable from ~(4 to 500)kHz
In the ...
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Phenomena of antenna out-of-band mismatch effect on LNA
I m very confused about something and I wanna ask it by giving example. Let’s assume that an antenna has a frequency band of 1000 MHz to 1010 MHz with VSWR level 1.5 and impedance of 50 Ω, and uses a ...
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What is the key circuitry in a form of high frequency signal generator that means power would be sent and reflected when there's an open load
Ive asked enough questions to explain why when there is an impedance mismatch there is power reflected which from my understanding is because there is a reflection of the waves, and also the cause of ...
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On-chip Co-planar Waveguide Design on Si – SiO2 Substrate
I want to design, simulate, and fabricate on-chip Coplanar waveguides (no bottom ground) on a Silicon Dioxide layer 5um thick on a Silicon 500um thick wafer. The metal electrodes will be 1um thick ...
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Understanding FM Broadcast Receiver with RDA5807FP
I've been trying to build an FM broadcast receiver for the last few weeks know, with simple designs like with LC circuits, but I've realized that an IC based radio outperforms simple transistor radios....
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How to convert RS-422 paired-signals to one CMOS signal
I am able to find several commercial ICs for converting CMOS or TTL input levels translate to RS-422 output levels. (I.e One 5V single input to two differential output). However, I couldn’t find how ...
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Toroidal/cylinder single turn transformer to circular waveguide coupling
The questions is mostly in the title. Is it possible to effectively couple a toroidal/cylinder shaped ferrite core with thick spread out single turn of wire to a circular waveguide?
The idea is that ...
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Connect a U.FL connector to a printed PCB antenna
I want to connect a U.FL connector to a PCB antenna on the ATWINC15x0-MR210PB, which is a meandered inverted F Antenna (IFA). I am not sure where to begin termination. C21 is where the antenna signal ...
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Coaxial quality and frequency rating
Context
I aim to start playing with RF and the first thing I wish to do is some EMI tests.
I've been watching YouTube videos on the matter as you do, and I've seen plenty of people using SMA ...
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GPS signal combiner
I want to use WP4N+ as a GPS signal combiner with NEO 6M receiver. Here is my schematic.
On power on, resistor 22 Ω is getting VERY VERY HOT and I do not receive any signal from the satellites. ...
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PCB impedance calc and clearance
I am using Altium Designer and it has a nice impedance calculator which tells you the required track width for a desired impedance given the layer stack you have configured.
So if layer 1 and layer 3 ...
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Stubs on shielding vias
Shielding vias are used around high speed digital and RF traces. The return current for these kinds of traces primarily flows through the adjacent reference/ground planes.
If blind/back-drilled vias ...
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"2.4GHz RF" used in some LED lighting products: what protocol is it?
There are a number of LED light control devices about, which boast a "2.4G RF" wireless protocl, which is neither WiFi, Zigbee, nor anything else.
I was wondering if someone could shed some ...
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Scattering matrix of quarter-wave transformer
I am trying to solve for the scattering parameters of a quarter wave transformer. The example that I am given is a transformer with characteristic impedance 100 Ohms, and the reference impedance (...
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Check of PDN for RF Amplifier - Revised
This is an update to my previous post. I was recommended to post it again.
For optimal working conditions, HMC863ALC4TR needs Vdd = 5.5 V and Vgg = -0.75 V. I have tried to design such a network to ...
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Is the RF/DC power on/off sequence for my simple radio beacon design good enough?
I'm using a RFPA5542 PA module. Does the power on/off sequence have to be followed exactly? Do I risk damage to the IC? I am delaying PA_EN by 2ms by an RC circuit of R13 and C5 and that is all. The ...
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Interdigital filter ground connection on PCB
I have used an online designer utility for my 5 GHz to 6 GHz RF output filter, on the schematic it generated it had shown ground attach points, but I am not sure if I designed ground connections and ...
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What is the L-Matching Bandwidth?
Image source: OpenLab at City Tech (New York City College of Technology) - Lesson 04: Matching networks – impedance matching
What would be their resonance frequency ω_0? In an L-sections, Β=ω_0/(Q ). ...
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Proper way to combine same-frequency PCB antennas
I want to combine 2 identical PCB antennas to increase gain. The antennas are designed to work on 2.4GHz and have 50ohm impedance, linear polarization with Omni-Directional radiation pattern, they are ...
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Where and how I can calculate and simulate PCB antenna?
For example, if have inverted "F" PCB antenna and I need use it in my PCB project to 2.4 GHz (for ESP32). Of course, I can use calculated cases, but I want learn how it’s calculated and ...
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Are transistors on MMICs considered lumped elements?
Are transistors, in practice, always small enough to be considered lumped elements in Monolithic Microwave Integrated Circuits (MMICs)? Similarly for discrete transistors used in hybrid microwave ...
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How does a PI or L network match impedance even though it does not have a real component?
Let's say I have an IC (ESP8266) with an output impedance of 39+j6 ohms, and I want to connect it to a 50-ohm antenna. The IC has a real (resistive) part of 39 ohms and an imaginary (reactive) part of ...
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What is the name of those ports circled in red please?
I know those ports are u.fl but I am not what they are they and where can I find cables that plugs into them and have SMA connector on the other end.
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RF amplifier class A
I have simulated a class A RF amplifier. When I simulated the output impedance, it is around 50 Ω for the frequency range that is of interest (50 kHz to 100 MHz), now at the input impedance is around ...
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Books/Material for RF transmitter/receiver design [closed]
I am doing my thesis for my BSc in EE. Due to a lack of equipped laboratories in my universities, I cannot do a project in microwave-integrated circuits, as I would have preferred. I am therefore ...
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Identify RF 433 MHz chip in remote to reproduce it
I've recently bought a ceiling fan (Suilon Cambil) and I wanted to automate it substituting the remote it comes with, with a DIY one connected to Alexa.
Main problem is that I haven't been able to ...
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The effect of the wavelegth on the receiving power in Friis equation
In the Friis transmission equation,
$$\frac{P_r}{P_t} = G_t G_r \left( \frac{\lambda}{4 \pi d} \right)^2,$$
it seems that if the frequency is halved while the other parameter values are fixed, the ...
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Can two or more RF noise signals (or noise sources) still be added together if they have been attenuated below the thermal noise floor?
Can two or more RF noise signals (or noise sources) be attenuated below the thermal noise floor, and still add together to be higher than TNF?
If a noise signal experiences path loss or attenuation ...
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Pie shaped stubs in RF supply PCB layout
In a recent question there is a photo of a RF PCB
And it shows several pie shaped pads on the supply end of the biasing network.
How are these pads designed. Is there a rule of thumb for the two ...
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Keysight vs Tektronix: AWG+RT SigAn or VSG+RT Oscilloscope?
I'm evaluating some new RF hardware for one of my university's research labs, for antenna testing. We are between a Keysight vector signal generator and a real-time oscope versus a Tektronix AWG and a ...
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Calculate RF shielding property of aluminum sheet
I want to quantify the radio-frequency shielding properties of a sheet of aluminum. I have an RFID antenna shooting at 865 MHz and I want to shield the antenna so that I don't pick up tags behind the ...
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How do I calculate insertion loss for a dual input receiver?
Typically my test setup consists of:
Antenna->Antenna Feed Cable->switches->Filter->LNA->Spec An feed Cable->Spec An
I calibrate the cable loss by simply getting the S21 (S1 ...
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My LC tank circuit doesn't seem to work as a RF generator
I'm trying create a super simple frequency generator to create RF in a specific frequency (for sending Morse code). I have a HF SDR receiver which I use to see waterfall of frequencies.
Based on this ...
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Smith Chart is giving me an answer I didn't expect - Am I using it right?
I'm trying to track down a VSWR issue with a RF power amplifier (25 W, 150 MHz). The radio we're using to drive it has a VSWR alarm, which triggers during transmit. Older manufacture runs of the PA ...
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Where does power entering at the LNA's output go when output return loss and reverse isolation are so low?
I am looking at the QPA2609 amplifier's datasheet. I noticed that the Output Return Loss is about -20 dB at 13 GHz and the reverse isolation is around -60 dB at 13 GHz.
My understanding is that output ...
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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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