What is Rf: Definition and 255 Discussions

Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around 20 kHz to around 300 GHz. This is roughly between the upper limit of audio frequencies and the lower limit of infrared frequencies; these are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves. Different sources specify different upper and lower bounds for the frequency range.

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  1. N

    Setting Up a RF Lab for Low Frequency DSP Projects | Nate Duong

    Dear everyone... I am trying to set up a RF lab at home to help me do DSP projects with very low frequency, as low as possible. Anyone who has experiences about RF lab, please give me some ideals and what machines from basic to advance will be needed for the lab? Thank you, Nate Duong.
  2. L

    RF radiation out of closed steel container

    Suppose you have an RF generator feeding a vacuum system with argon ionized by that RF. With the tuner you see the VSWR is very good. That is version A, no ground or poor ground. Version B is the same thing, the container is stainless steel half inch thick to hold the vacuum. But in this case...
  3. TheDemx27

    Low Power Signal Processing -- Bouncing an RF signal off the Moon

    I'm doing a project that has been done many times before, bouncing a signal off the moon, but I'm trying to do it with low power. I'm told the expected S/N ratio is -30dB. The problem I'm trying to figure out is whether or not it is theoretically possible to pull out the signal out from the...
  4. F

    RF Workings of a Wifi Receiver

    I am curious to know how the RF front end of a Wifi receiver works. From my understanding, most RF receivers have to use networks of various oscillators, mixers, and filters to select a given frequency and remain insensitive to undesired signals at different frequencies, and I suspect that WiFi...
  5. S

    Rf basics, digital vs analog info tx

    Sir, i need some basic information about analog vs digital signal/information transmission. i have few Questions and and idea to discuss weather its feasible or not. [Q1] can digital data requires same bandwidth as analog data contains as if i convert analog information to digital using DAC and...
  6. G

    Exploring "Audible" RF Allocation in USDOC Chart

    USDOC Radio Frequency allocation table (http://www.ntia.doc.gov/files/ntia/publications/2003-allochrt.pdf) lists part of the radio spectrum as "Audible." Radio waves are electromagnetic (e.g. light), while audible waves are pressure waves in a medium (e.g. air.) They travel at very different...
  7. H

    RF energy between charged plates?

    I have two parallel conductive plates. The plates are charged to a high voltage by a HVDC power supply. When the plates are charged rf energy is present between them. What could be causing this? I am thinking field emission at the cathode is causing it ,but not really understanding physics is...
  8. W

    RF Susceptor Heating (KHz range) Graphite Foil vs Iron Foil (or thin film)

    Which do you believe is the best choice for a low temperature RF heating susceptor, i.e. - greatest rise in temperature vs. field strength. I am aware that Graphite (expanded graphite foil) has excellent thermal conductance in plane and therefore makes for very even heating patterns over large...
  9. B

    How does the size of an object affect RF propagation?

    Hi there, can anyone please advise how the size of an obstructing object affects the propagation of an RF transmission? Eg, for instance does refraction only occur in objects that are larger than the wavelength or does it occur in objects smaller than the wavelength? I can find heaps of info...
  10. chakr

    What is the Best Software for RF PCB Design and Simulation?

    Hi all, can anyone recommend a good software to help in design and simulation of PCB traces, matching circuits, and microstrip lines. Thank you.
  11. J

    Walking sinusoidal as you follow a RF Standing Wave?

    A friend who was in Civil Air Patrol once told me he was using some RF Locator equipment and was "homing in" on a target. His walking path to the target was sinusoidal because of the wavelength of the frequency used. He said he was literally walking the wave.... Standing wave, I assume? Or...
  12. F

    Engineering What is RF engineering and what job opportunities does it offer?

    I am currently in college for a 2 year EET degree. Now, before you all jump onto me saying that it is not an engineering degree I already know this. I am using this time to make sure I am prepared for EE in a 4 year university. I am going to take cal 1-3, diff eq, linear algebra, calculus based...
  13. D

    RF Small Signal Amplifiers and Cooling

    I know that in the pursuit of low noise amplifiers, the cooler the better, generally speaking. But when does it make sense to try and go through the work required to cool an amp? One of my passions is radio astronomy. I have a good collection of LNA's around of various types and an eight foot...
  14. G

    Question about RF absorbers and radar

    Hi everyone , new to forum, but not new to forums. I am a radar detector hobbyist and have some knowledge of how radar works. Specifically and to be on point and productive, here's my question(s): First, are there any materials readily available to general consumers that will readily absorb...
  15. chakr

    Have you used nRF24LU1P for wireless communication?

    Hi, has anyone had any experience developing a wireless link using nRF24LU1P? I have hard time understanding what are different communication pipelines. Are we switching between different frequencies when we switch from one to another? Thank you.
  16. F

    General-Purpose and RF JFET and MOSFET

    Hey guys, I'm looking for some general-purpose N-channel JFET and/or MOSFET transistors (depletion-zone) to be used as audio frequency and radio frequency amplifiers (although probably not higher than 50 MHz). They likely won't be subject to voltages over 12 volts or current higher than 200...
  17. S

    RF amplification to power IR LED

    Hello, I am new here so my apologies if I have posted in the wrong place. I am trying to amplify the radio waved I get from a receiver to power led that will ultimately be used as a remote for the AC. I have contemplated "charging" a capacitor until it has enough power to power the led...
  18. parazit

    Thomas Wangler's RF Linear Accelerators

    Hi fellows. Once I asked a question in here and some advised me to check the Wangler's RF Linear Accelerators book and solve the questions. Now, I am trying to do this and want to check my answers. Does anybody know anything about the existence of a solution book or answers sheet or something...
  19. perplexabot

    What is the Design Process for Building an RF Mixer Circuit?

    Hello all. So I have been trying to build a mixer lately, I have done my research on google but I am still kind of lost. I know now many mixers exist; single diode, multiple diodes, single balanced, double balanced, unbalanced and so on. I don't want to build a circuit blindly, so I am trying to...
  20. D

    Can Crystals Absorb X-rays and Gamma Rays to Emit RF for Movement Tracking?

    Hi guys, Could someone refer me to sources which explain and give examples for crystals which absorb xray / gamma ray and emit RF ? Meaning that if I radiate a crystal with xray I get RF so I can theoretically track its movement in the enclosed are. Thanks a lot!
  21. C

    Building a device for RF transmission/detection

    Hi Physics Forums, I'm a biochemist whose electronics experience is limited to resonant RLC circuits. I have been tasked with building a device that essentially acts as an RF antenna. In transmit mode, this device must create a sine wave of specific frequency (current plan is 40.05 MHz)...
  22. R

    RF Radiation Beam tilt question

    Hi, I am reading about how a radio station may "null fill" to direct RF radiation downward from the broadcast antenna; without this the area where the antenna is located would not receive a good signal, if any. Does anyone know what limits apply to this? If someone...
  23. J

    RF Medical Imaging Systems - Get Answers & Solutions Now

    hi, i have to prepare a presentation about rf imaging. But i didn't found any medical imaging system using rf. Is there anyone know commercial rf medical imaging system, please help me.
  24. D

    Understanding RF Transmission Lines: From Circuit Theory to EM Field Theory

    I really hope i can get some answers to the questions that have been plaguing me for some time. I'm more conceptual, and math does not satisfy my curiosity so I was hoping the experts here could fill in some blanks: In making a jump from learning DC/low frequency AC to RF, i studied...
  25. Z

    Engineering Question about going in to RF engineering

    Hi there, I am currently a second year electrical engineering student in Canada. I am thinking about get into the field of RF engineering for my next year of study. However, from i have heard online, I am having doubts about getting into this field. Here are the doubts i have. 1: Does this...
  26. parazit

    High Repetitive Photocathode RF Gun

    Hi fellows, I've been looking for "High Repetitive Photocathode RF Guns" for more than a couple of days. It seems, first I need to understand the RF Guns. I deciced to search such a document that gives the history of RF Guns and explains their historical background with working principle...
  27. N

    (Confused) RF circuit concepts- Voltage division?

    how could you calculate the input voltage at an input impedance from a voltage source? I saw they use voltage division law to find the voltage at the input impedance(Zin) from a voltage source(Vs). They do it like Vs * Zin/(Zin+Zs). The problem came... We all know that we can determine the...
  28. B

    Fastest way to become RF engineer

    Please humor this question. I know it is ridiculous but please give me your best answer. Suppose a young EE student has seen the light and wants to become a master RF engineer. He wonders what the fastest and best possible way to go about this process as opposed to the non-linear path many...
  29. S

    Using RF Transmitter/Receiver to power LEDs from a Sensor?

    I have a pressure sensor that gives off 4 volts when actuated and I would like to transmit it a distance to an LED light. So I found these RF Link Transmitter/Receiver at 434MHz: https://www.sparkfun.com/products/10534 https://www.sparkfun.com/products/10532 The data sheets and...
  30. C

    Creating an RF Signal using analog methods

    How is this done. Been reading about sputtering and DC sputtering is extremely simple. However, I'm not very experienced with RF circuitry so understanding exactly how to design that circuit confuses me a bit. Been reading about RF circuits but to generate an RF signal every method I find uses...
  31. M

    Looking to sniff out smart meter RF

    Hey everyone I hope I am posting this in the right place.. After all this is my first post here. I am looking to track down what RF (radio frequency) my local smart meters are broadcasting in. I have been doing some research but would like to know if anyone has any experience with...
  32. M

    Can RF Sputtering cause the the ejected target to ionise?

    Hello, I am currently working on sputtering method for thin film deposition of III-Nitrides. The target used was a gallium nitride (GaN) plate and plasma generation was achieved by radio frequency (RF). After running the sample through phase analysis, interestingly a gallium oxide (Ga2O3)...
  33. U

    Fourier transform of RF signal with a prism ?

    Fourier transform of RF signal with a "prism"? We can use a prism to decompose visible light into components of different frequencies. This is a Fourier transform by nature. For an ideal prism, the energy is conserved in the process. How about RF signals? There is no fundamental difference...
  34. J

    Evaluating Metal's Effect on RF: Wi-Fi in the 2.4 GHz Range

    I am preparing a document for my co-workers re. metal & the effect that it has on rf (spec. Wi-Fi in the 2.4 GHz range of the spectrum). Could you please check for accuracy & edit as necessary? It is as follows: "Metal – metal can attenuate & reflect Wi-Fi. Placing an antenna in a metal box...
  35. B

    Determining the value of B1 (or RF) in NMR

    Hello If the time that takes for magnetization to rotate from its initial position (parallel with external magnetization) to x,y plane is given, how do we determine the value of B1? The formula I know: ω = γB1 = 2∏f1 lB1l < lBol angle between the magnetization and the external...
  36. A

    Can you boost RF signal power with a generic op amp?

    Sorry if this seems like a simple question, but I am new to RF systems. Is there a difference between an RF amplifer and a single rail operational amplifer? Or can you boost the power of an RF signal with a generic op amp? Also, when dealing with an RF signal, are coax cables and SMA...
  37. D

    Limits on exposure to high power RF

    Are there limits to exposure to microwave frequency power within a certain range, for example with workers on a transmission tower? What would be the applicable standards? I understand that RF is non ionizing radiation, but I have read that high power RF radiation can cause burns if too...
  38. P

    Engineering RF Test Engineering - Curious about the field

    RF Test Engineering -- Curious about the field Hi guys, I just graduated college and I have an offer for an RF Test Engineering position that sounds pretty amazing to me. The company is a telecommunications company that works mostly with gateway routers. I would be responsible for designing...
  39. H

    Understanding the Legalities and Limitations of Building a PM RF Transmitter

    How can I build a transmitter using radio waves with pulse modulation (Which I think [PM] means sine waves that either transmit or don't)? I can't find anything on how to build a PM transmitter, I can only find FM/AM ones, and I'm not smart enough to convert that information to the way I want...
  40. S

    What Career Opportunities Exist in RF Circuits and Microwaves Field?

    My school offers a concentration in RF Circuits and Microwaves in their EE program. I have an idea about what some potential jobs/careers that use these topics are but am not sure. Can anyone tell me more about the concentration are/field and what jobs would be available in it or what some...
  41. I

    Design a Tuned RF Amplifier with Gain 100 for 720KHz

    Hey...I was trying to design a practical of mine...There is this question where I am supposed to design a tuned RF Amplifier with gain 100 for a frequency 720KHz with BJT. I know that I will get frequency with LC tank circuit but the gain is a different story. I have searched 5-6 books and am...
  42. J

    Metal's Effect on RF: Attenuation, Reflection, Absorption?

    What is the exact effect that metal has on rf (any electromagnetic waveform)? Is it attenuation, reflection, absorption or all of the these?
  43. M

    NMR - does rf cause transitions or simply rotate the magn vector?

    Am I wrong in thinking that the rf radiation used in nmr is not "absorbed" by protons to cause transitions between spin states but rather it is only there to provide a magnetic field which can rotate the magnetisation vector away from the primary field?
  44. F

    Measuring RF Frequency in Hertz for Science Projects

    Hi, i have been doing a science project about radiation of smartphone functions. I have tried to use a EM wave receiver to measure the frequency of RF but it didn't work.How can i measure it (in hertz)?
  45. D

    Wired USB devices shown to lose power due to RF interference

    I previously posted about an RF interference issue that was affecting a pair of Klipsch ProMedia 2.1 speakers here. I have since found that a neighbor living across the parking lot broadcasts transmissions of up to 2,000 Watts from his apartment, which has been the cause of this issue. I have...
  46. O

    Relation between the two Radii Rf and Ro

    Homework Statement A planet orbits a massive star in a highly elliptical orbit, i.e, the total orbital energy is close to Zero. The initial distance of closest approach is 'Ro'. Energy is dissipated through tidal motions until the orbit is circularized with a final radius of 'Rf'. Assume the...
  47. K

    Is there a suitable amplifier for my RF signal?

    Hi, I'm an A Level student at college (take it easy, I'm still very much learning) and I'm currently looking into a small demonstration of resonant inductive coupling, or "Wireless Electricity".. I'm fairly confident with the theory behind it and the majority of the build for it. However, one...
  48. I

    Designing a rf based tracking robot

    i am trying to design a robot which can track a transmitter which produces rf signals in a given range of frequencies(example:- 400-900 MHz). i want to know the following details. 1. i have a design of wireless robot with A433MHz RF modules. i need to change the frequency of transmission...
  49. K

    Removing RF Frequencies from Smart Meter w/Capacitor

    I got a dirty electricity problem from a smart meter There is supposedly filters on the market that remove the incoming RF frequencies and puts them onto the neutral. Does anyone know how a capacitor plugged in would remove RF frequencies from the hot wire and send them back on the...
  50. D

    Power control of Class D Rf AMP

    I need to design a class D low power RF amp that I can control the RF output of without tampering with the input signal. I need about 200mW out @ 50 MHz but the input drive is a digital coded pulse train I can't tamper with in any way. I need class D for best efficiency and battery life. How...
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