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. S

    Measuring RF Voltage at Antenna Ground Contact

    Hello all, I encounter some RF burn issue on the metal contact between an antenna with the grounding. The metal is actually connecting to the ground. I suspect that it could be due to the grounding effect which may be too long or too short for that frequency that is radiating. Because of...
  2. M

    Plasma Physics - RF Discharges, Sheaths

    Hi all, exams in a few weeks and having a bit of trouble understanding the characteristics of plasmas/sheaths. E.g. the following question from a sample paper "Describe the characteristics of the sheath that forms at the boundaries of confined plasma. In your answer state what is meant by the...
  3. _maxim_

    Cylindrical glass boll (sealed, containing solvent) for RF detector

    Dear all, here's my first request for a little help (maybe also in finding the proper subforum...) I'm working as developer and scientific consultant in a lab for Nuclear Magnetic Resonance at high field (> 21 Tesla), and I have to create a suitable probe for checking the stability of a...
  4. R

    RF Amplification: Is it a Bad Idea?

    My home is about 1.2KM LOS from work. I want to use my work's internet connection at home. I have a pole available as well. Right now from rooftop to rooftop, I do get a signal but it's weak and goes off sometimes. I'm using a 200MW wifi bridge. So at a recommendation of a friend, I got a 1watt...
  5. J

    How Do You Design an RF PIN Diode Switch for High Isolation?

    Hi, This is my first encouter with anything to do with RF design. I'm trying to design an RF PIN diode switch to meet certain specifications. I'm having considerable difficulty putting together a circuit schematic that will accomplish this. My specs are: Center frequency: 15GHz Bandwidth...
  6. M

    RF reflection from ground through dense snow

    Hello all I work at a BC Ski-hill... what I need is a method to quickly but accurately measure the depth of dense snow (man-made snow, some might call it ice). Traditional method of mechainically boring through to ground is slow, inaccurate & messy. New GPS based methods require detailed gps...
  7. R

    Start Learning Wireless Communications and RF Electronics

    Hey guys, I'm a student in electrical engineering and I'm interested in learning about wireless communications and RF electronics but I don't really know where to start. I've taken three semesters of engineering electromagnetics but I still wouldn't say that I know much of anything about...
  8. M

    Chemistry: Comparing the Rf values of carotene and lycopene?

    Comparing the Rf values of carotene and lycopene? Why does carotene have a higher Rf value than lycopene in TLC chromatography with a silica plate and a solvent of (3:10) dicholormethane:hexane? I know it's because carotene is less polar making it more soluble in the TLC solvent and...
  9. A

    Making keyboard controlled RF Car

    I have embarked on my first real project of making a wireless controlled car. But here the remote is going to be my keyboard. I am also thinking of mounting a camera on its top for live feed. Please suggest resources on everything, especially USB interfacing as I want it to be UPnP.
  10. R

    Adding a Power Amplifier to an RF IC Circuit

    Hello all, I'm trying to design a circuit that utilizes the http://www.analog.com/en/rfif-components/short-range-transceivers/adf7020/products/product.html" . What I'm worried about is getting everything to match properly; the PA requires a 50 ohm input, and after dropping it into the...
  11. Y

    Calculating Transmission of Electromagnetic Wave in COMSOL

    Hello All, I have a fundamental Comsol question that maybe you can help me with. If I am in say a 2-D In-Plane TE Mode. I am inputting a wave that will propagate left to right. What is the best way solve for the resulting field that is transmitted to the right boundary, regardless of what...
  12. V

    How do I design a 5 GHz circuit with RF components?

    Hi all, I don't know if it's the right section in the forum, but here is my problem. I have to design a small pcb working at about 5 GHz, and I don't know how to start exactly... It's very simple, 2 sma connectors and 1 resistor. Here is the schematic...
  13. B

    Determining Frequency of RF Signals: Seeking Guidance

    The idea has been bounced around, and i thought to see if anyone here had any guidance before i tear into the literature. What kind of circuit is necessary to determine the frequency of an rf signal? The situation: An rf transmitter is pumping out waves (no modulation or data to be decoded)...
  14. N

    Higher Rf Value? (TLC Chromatograpghy)

    Homework Statement Suppose you carry out a TLC separation of acetaminophen and phenacetin on silica gel using a nonpolar developing solvent. Which should have the higher Rf value, and why? Homework Equations Im not sure. Is polarity a factor here? I don't think the polarity difference is...
  15. B

    Find 500 MHz UHF Transistor for Project

    I am trying to find an 500 MHz uhf transistor for a project and I need one which is big enough that i can solder (i.e., not a mm wide) and it has to have the s parameters on the data sheet. If anyone can help me with what i am looking for that would help out a lot! Thanks
  16. S

    New Superconducting RF Cavity: Potential for EMdrive Propulsion?

    Here's an interesting article about a new breakthrough in the manufacture of a superconducting radio-frequency cavity: http://nextbigfuture.com/2009/09/superconducting-radiofrequency-cavity.html If this new cavity were tested for EMdrive purposes, could it reveal a new mechanism for...
  17. C

    RF transmit circuit/RF receive circuit? (Hard to explain; I made a diagram.)

    Okay, basically what I'd like to be able to do is have some sort of "universal" RF (FM) audio circuit. Actually, two: One for transmitting, and a separate one for receiving. (I'd prefer to keep it simple, and therefore not a transceiver circuit. This is for one-way communication.) My ideal...
  18. M

    Using SPI mode to interface msp430 with RF transciever and SD card

    Hi, I am planning to use SPI mode to interface a eZ430-RF2500 with a Sandisk Secure Digital Card. The eZ430-RF2500 includes a MSP430 microcontroller and a CC2500 RF transceiver. According to the schematic, the RF transceiver interfaces the MSP430 utilizing the SPI mode, using the SOMI, SIMO...
  19. F

    RF testing: Balistics Gel for human analog?

    I am designing an antenna for a consumer product. The consumer will be very close to the device. I have designed antennas for products like this many times before and have the proper equipment to do so. It's low power, meets all FCC regs for our band etc... I am tired of doing the...
  20. X

    RF blocking stickers for cell-phones

    RF blocking "stickers" for cell-phones I still see these things around! It drives me nuts that I even have to explain it to people, but it's so hard to cover my judgemental feelings toward the lunacy (and outright fraud) with a kind semi-technical explanation that I think they just shut me...
  21. R

    COMSOL RF Module: Seeking Help on IR Heating

    COMSOL RF module: urgent Hi i am a new user to comsol RF module. Actually I a want to model the heating of a material using IR waves... can i use the RF module (which illustrates microwave heating as an example) to model the IR heating...do we have options to change the frequency of wave from...
  22. T

    Designing RF Antennas: From Intuition to Simulation Tools

    I have a lot of general questions on the design of RF antennas. Where do the geometries come from? I've been looking at embedded PCB antennas and also modules that attach to PCBs and they always have exotic looking notches and curves. Some are 3D while others are flat 2D styles. How does...
  23. S

    COMSOL-nanoparticles-PML-scattering formalism in RF module

    Hi, all, I am starting with calculating scattering cross sections of metallic nanoparticles. I have some doubt about what type of scattering boundaries conditions and PML to use, since near field shows some surface waves on PML´s inner side and some reflections which affect my far-field...
  24. S

    What materials block RF interference?

    My interest is in reducing RF interference in electric guitars in RF-noisy environments by shielding the body cavities with sheet metal. Would copper sheeting block RF? Or would it need to be some ferric material? I imagine aluminum alloy would be RF-transparent - is that true? Ideally, I...
  25. F

    Ground in RF System: Separating Analog and Digital

    Hi all. I'm working on an RF system including a 2.4G transceiver and a GPS receiver. I'll use a ground plane. What I intend to is to separate analog ground and digital ground and connect them together at the entry via a 0ohm resistor. My friend argues that a whole ground layer that connect to...
  26. P

    Can Radio Waves Penetrate Through a Solid Steel Box Enclosing an RF Transmitter?

    Can radio waves propagate through the walls of a solid steel (1/2" wall thickness) box that completely encloses the RF transmitter? Do lower frequencies work better? Any insight would be great. I'm a newbie her, so please be gentle.
  27. F

    Experience in RF module Comsol?

    Hello, anyone with some experience in Comsol? I have a few basic questions on the RF module thanks!
  28. S

    Question about rf signals(yes i think this does relate to physics)

    i briefly read that magnetic ferrites can block rf signals. if so, how. what range limit if any is there on the ferrrite.. or did i post this question in the wrong area if not the wrong forum? I'm really REALLY curious about this. if I've gotten this wrong. well, I'm sorry. thanks...
  29. B

    Water Electrolysis and Water Dissociation with RF waves

    THIS IS NOT A HOMEWORK QUESTION. As Physicist of course I'm sure you've heard about the water dissociation with Radio waves that john kanzius discovered and I have a few questions on my mind listed below 1) What is the difference between this phenomenon and water electrolysis? Is it true...
  30. K

    What is the concept of rf heating in a Paul trap?

    Hello, I have a question on rf heating in Paul trap. There are papers which say that in a Paul trap, the ion cloud eventually comes to a state of thermal equilibrium with the background gas. And at the same time there is a concept of "rf heating" in these traps. I am slightly confused about...
  31. C

    NMR Q: Why an RF pulse can rotate Mz so fast

    Learning about Nuclear Magnetic Resonance for a while. I have read than when the main field B0 is applied along the Z axis, it takes a time (T1) in the order of seconds for the M0 field to be created in the body we are studying. Yet we can apply a short (maybe in the order of one wave...
  32. D

    Why is the bandwidth of the RF filter is wider compared to that of an IF Filter?

    Help!
  33. F

    RF Chip Selection for SDR Transceiver Design

    Hi all. I'm designing an SDR transceiver. I need a RF chip/module that at least contains PA, LNA and Tx/Rx switch. It should perform conversion between analog or digital baseband/IF signal and 2.4GHz radio signal. Modulation/demodulation will not be done in this chip. The radio signal is...
  34. E

    Visualization of RF electromagnetic radiation

    CCDs can capture visible/infrared/etc... EM radiation. Is there any way to visualize or capture lower frequency radiation such as microwaves or radio frequency radiation?
  35. A

    How to measure parasitic capacitance between rf cable and metal surface

    dear all can anyone tell me.. if i have a transmission line passed above a metalic surface, there will be a parasitic capacitance between the line and the surface. and it induces interference how can i measure it. and if there is any refrenece about the allowable induce voltage...
  36. M

    Help Identifying Pigment by Rf Values

    I'm trying to find the corresponding pigment to the Rf values I obtained in a lab. However, I'm not having any luck, and I was wondering if someone here could help me out. The Rf's that I have are: 0.15, 0.19, 0.23, 0.28, 0.35, and 0.47. I already have 0.23 = Neoxanthin, and 0.35 =...
  37. S

    Programs EE CS expert help - CE major but want RF background

    Hi everyone, It is so nice to have such as website to provide people(me) with some very good advice from expert in the field. First of all, thank you for reading/replying my post. I'm going to be 3rd CE student in sept 07, however, I was in EE during 2nd year, I changed to CE because I want...
  38. T

    Does anyone know of a good RF electronics book?

    I need to design a radio wave transmitter that transmit a specific code and a receiver that will only receive this code. what would be the best book to look into as a crash course for designing this?
  39. A

    RF MEMS for Silicon: Find Permittivity, Permeability & Conductivity

    Hello, can any tell website where i can find Permittivity,Permeability and conductivity(or resistivity) of silicon, silicon nitride and aluminum.thanks and also if anyone has worked in ELECTROMAGNETIC module of Intellisite (version 8.1)for RF MEMS Switches please do tell me i need some guide line.
  40. E

    Exploring RF Tag Collision Emulation for Open Space Storage Systems

    Hi. We are developing a system of RF tags for open space storage place. This are mostly containers. I need to make simulation of collisions in simultaneous Tag's transmission. Let's say I need 10 Tags to send update to base stations at exactly the same time. The idea to connect tags with wires...
  41. S

    Electromagnets, high voltage/amps, and RF

    I was wondering what the reaction would be if you aimed RF signal/s into a high powered circular electro-magnet (i think the proper term is a toroid ?). I ask because its too dangerous for me at the moment to conduct experiment. (220v @ 20amps). would the signal be shot out the side that has...
  42. J

    RF emitted from Lightning strikes

    Hello All, I’m still perusing the whole idea of tapping into the energy in the Schumann Resonance cavity. But, even if I can manage to do that, I figured it would be a good idea to at least find out how much energy is actually there to couple with. Recently, I corresponded with a...
  43. A

    Calculating RF Range & Amplitude from Spark Gaps

    How does one calculuate/analyz RF range and amplitudes given off buy discharging spark gap.
  44. C

    Standard Rf Values - Biology (Photosynthesis)

    Would anyone happen to know where I could find the standard Rf values (for Chlorophyll a, Chlorophyll b, Xanthophyll, and Carotene) if varsol is the solvent? I'm trying to identify those plant pigments via Paper Chromatography, and I'd like to compare my results to the standards. The problem is...
  45. M

    RF Detection for Radio-Controlled Vehicles: Need Advice

    I'm looking to make/buy an RF(radio frequency) to detect and display the level of an incoming RF signal. This is going to be used on a radio controlled vehicle. Any suggestions and info would be greatly appreciated.
  46. F

    RF gurus-A question from a wireless dullard

    RF gurus---A question from a wireless dullard Ok, I need to collect and send data to/from a remote device about 500ft away. I'm looking for a single IC transceiver in a small smt package if possible. I'd like a transceiver that handles the communications with little to no control from either my...
  47. R

    RF Engineering: Exploring the Science of Radio Frequency Technology

    What is RF engineering?
  48. M

    RF Measurement: Do I Need a Unit?

    just a simple question, do Rf have a unit? i'm measuring in cm, so do i use cm as unit for Rf or do just leave it blank?
  49. X

    Understanding Rf Values for BIO Lab

    rf value!?#@$%^& Hey guys, Before doing a lab tomorrow, we need to find out what Rf values are, i can't seem to find a defintion about it online so some help would be great. Basically we are doing this BIO but the teacher won't tell us exactly about the lab but it is about chlorophylls and...
  50. M

    What Are the Standard Rf Values for Plant Pigments in Spinach Chromatography?

    Hi for biology we had to do a lab which we separated the plant pigments by chromatography of spinach. We used a solvent of 90% petroleum ether:10% acetone. After we did the experiment we ran out of time in class so the teacher went and recorded everyones results on there paper. The problem with...
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