Radio Definition and 691 Threads

I'm trying to get my head around radio wave propagation in conductive media such as water, saturated rock, etc. What I know is that propagation is poor but better at lower frequencies and this has something to do with "skin depth". I have read what I can on skin depth but I struggle to relate it...

Radio or any other wave in electromagnetic spectrum? Sound perhaps? And at what frequency(ies)

Hi pf, please could someone help explain some concepts relating to bandwidth and radio transmission. As I understand it, radio transmission involves modulating a carrier wave with the signal you wish to send. The bandwidth is the range of frequencies that are contained within the signal. I have...

There are a lot of florescent proteins in the visible range, but why haven't we fount any above or below that range? I think a protein that emits radio waves could be very helpful both biologically and scientifically. Are we not looking for such proteins, or do they not exist?

Homework Statement A coaxial transmission line consists of an inner cylindrical conductor of radius 1mm and a cylindrical outer conductor chosen to make the characteristic impedance 75 ohms. The space between the conductors is filled with a gas that can stand a maximum field of 10^5 Vm^-1...

I am working on a project, however I am having trouble finding the right material for it to work. I am looking for a nano-material or any molecule that will emit a radio frequency when subjected to a voltage or a current at around 37 degrees Celsius. I would really appreciate it if someone could...

That is probably a badly worded question but I understand electrostatics and I want to send simple but efficient radio signals. If I switch on a strong charge in one place it'll effect a charge away from it depending on "Coulomb's law". How is this equation expanded to explain more efficient...

Homework Statement A radio telescope, whose two antennas are separated by 55 m, is designed to receive 3.0-MHz radio waves produced by astronomical objects. The received radio waves create 3.0-MHz electronic signals in the telescope's left and right antennas. These signals then travel by...

Hello everybody :) This is my first post! I have a mystery about radio communication that I was wondering about for a long time: If I have understood correctly, most computers have a single WiFi antenna in the shape of a rod, which is placed in a particular orientation. My question is this...

Hello members of this awesome looking science forum! I'm Misha. ...an educated general physics novice! I came here after running into a very strange phenomenon. ...all off a sudden my good old trustt speajers stopped responding to the information sent to them from the conputer and instead...

Heat up and remove capacitors (see blue) C307, C301, C201, and C207. Simply land your RCA wires to the pins highlighted in red. Purple pin is GND. This should give you a solid 2V line level out. Enjoy your un-eq'd radio:)The above is a tutorial on how to bypass the built-in loudness circuit and...

Hi guys I am struggling on this question and was wondering if anyone could steer me into the right direction with it Q: Radio X transmits on wavelength 2000m at a frequency of 100kHz. Radio Y transmits at a frequency of 1.5MHz. Calculate the velocity of the radio waves. So for radio X I used...

I was wondering If anyone knows if this is possible, or why it might be a silly idea.

I am trying to model an FPGA FM radio demodulator in Python. I will have a mixer that converts an FM channel to 36MHz IF, and I plan on undersampling this IF signal. If in the digital world (my Python model), I have a high sample rate FM signal at 1.2MHz, should I be able to resample to a...

Hi I wonder if anyone could advise how a radio wave would propagate around a metal object? Basically, I have a GPS antenna and due to mechanical issues the antenna is obscured by a mounting screw that sits in front of the antenna by about 2~3cm. I understand that the radio wave would become...

The AM/FM radio on my boat has a simple wire about 70 cm long as an antenna. It is much less effective than a car antenna. I say that because it has difficulty picking up stations that the car gets easily. At sunrise/sunset the effects of radio propagation become evident as the stations...

Suppose there is a set of twenty tiny radio sources that are distributed randomly in an area of 1 mm2. What is the best way to locate each of these sources - as in identify them and their locations? We can suppose that all of them are of the same frequency of 1 Mhz. Thus if the radio telescope...

Hi Just wondering if 16.4 GHz (or so) is a commonly encountered frequency in radio astronomy ? Because I'm theorising a possible secondary photon emission following photon emission and electron recoil in the Hydrogen 1s - 2s transition.

Suppose I have a transmitter and receiver and my friend in the next room also has it. Can we both talk with each other with radio waves as we do in cell phone. I know we can't talk if he is several miles apart. But if he is just in the next room, can we communicate?

Can someone please tell me the basics to how a cystal radio works? And also what are all the components that makes up a crystal radio? Thank you!

Homework Statement 1+\dfrac{2^2}{2!}+\dfrac{3^2}{3!}... \infty The Attempt at a Solution t_n = \dfrac{n^2}{n!} \\ \dfrac{n}{(n-1)(n-2)...1} I tried applying the Ratio Test but couldn't find another function which would give me a finite limit when divided by that function.

I'm trying to find out what material might best block or limit radio frequency interference (or at least I think that's the problem, as I understand it). I have a phone, the antenna inside the phone is next to a chip that controls a touch button. Whenever the phone boosts the signal to...

Hi, I'm hoping I'm in the right section, I wasn't quite sure. For a couple of days I've been trying with no success to make a crystal radio. To save me the trouble of having to build my own components, I decided to build a tuned circuit that should resonate at a radio frequency (and insert...

Hi, I'm interested in AM radio transmissions causing interference (not just noise, but the transmission actually being demodulated by the speaker and leaking into the amplifier circuit) in devices such as unshielded speakers (that are not designed to work with radio). I'm currently having...

dear sir i want to know what happens in certain stars that helps it give out radio wave we detect by radio telescope. can we compare with inductor in electronic circuit?

Hello all, I'm trying to compile a list of schools (mainly in the US) that offer Ph.D. programs with research in radio astronomy. Here's what I've come up with so far: Caltech Cornell Harvard New Mexico Tech Ohio State University UC Berkley UC Los Angeles UC Santa Cruz University of Arizona...

i'm building fm radio jammer for project for my ee class in physics department. a circuit is here. http://www.circuitstoday.com/fm-radio-jammer i bought the components, soldered on PCB. it hasn't worked. an oscilloscope shows sine oscillation even if there is no L and C for tank circuit...

How do transmitters convert electrical signals into photon energy?

I have experienced first hand, and have heard many cases of CB radio causing interference in speakers. I had a couple of questions related to it: 1. What type of modulation (AM or FM or both) causes this interference? 2. How big does the antennae need to be for this to happen? 3. My...

Physics: An 84-kW AM radio station broadcasts at 1000-kHz. How many photons are emitted each second by the transmitting antenna? (h=6.626E-32 Js)

We’ve all experienced strong versus weak radio signals while driving a car and listening to the fm radio. The fading signal could be caused from traveling too far from the radio station transmitter, or from being blocked by hilly terrain or buildings. Lately I have been noticing something...

Please help me with this... Why a radio station can be broadcast to a whole city from a single antenna, whereas a mobile phone system needs a network of basestations? Thanks,,,

So, let's say a spacecraft at a large distance from any star needs to dump a tremendous amount of stored electrical energy overboard in a limited timeframe. Normally, spacecraft dump excess/waste energy using heat radiators. In this unusual case, however, the energy is electrical, and heat...

Homework Statement Two radio antennas separated by d = 294 m as shown in the figure below simultaneously broadcast identical signals at the same wavelength. A car travels due north along a straight line at position x = 1 290 m from the center point between the antennas, and its radio...

I would like to know if a a inductively coupled power transfer system also emits electromagnetiv waves. The system contains of two inductance coils one generating the magnetic field with AC, the other picking up the magnetic energy and transforms it into an AC, also. The current frequency is...

Dear colleagues. please help in solving the actual problem: Our company operates in the field of space communications . For reception and transmission of signals via satellite is used parabolic antenna with a diameter of 12 m Frequency of received signal is 4000 MHz. The receiver is a Low...

Homework Statement Two antennas located at points A and B are broadcasting radio waves of frequency 99.0 MHz, perfectly in phase with each other. The two antennas are separated by a distance d= 12.40 m. An observer, P, is located on the x axis, a distance x= 58.0 m from antenna A, so that APB...

Hey people ! I want to start to make a radio with one of my friends. The radio that I will make,will not use 'ready' things like "leds". I want to learn from this project. So first of all,is it possible? Secondly,from where I can start,to learn??

hello everyone! this is a new single-dish radio telescope, FAST, under construction: http://nextbigfuture.com/2011/06/chinas-five-hundred-meter-aperture.html The aperture is 500 m. But the illuminated aperture is only 300m. So what is the advantage of bigger aperture? is the angular...

Hi, Reading through an Introductory Mechanics Textbook, I don't understand a part of an example on Nonuniform Acceleration - The effect of a Radio Wave on an Ionosphere Electron. I've attached the link. Can someone please explain how: a0 = (-eE0/m)sinωt By my reasoning, since...

Hello, I’m a beginner to interferometer technology. While reading the attached article about this technology I find two formulas are missing. Please help me with them. 1. On page 5-8.8: rms angular accuracy. 2. In Table 3 on page 5-8.9: DF Accuracy. As far as I understand the space...

First off, this is my first post here. If this is in the wrong section I apologize and ask that it be moved. I am a amateur radio operator. We have experienced issues with a rogue radio operator recently, who is maliciously transmitting noise. I think it is possible to determine his position...

Homework Statement Homework Equations w = 1 / sqrt(LC) The Attempt at a Solution hi there, I 1. I decided to choose, 93.3 MHz so 93.3 x 10^6 Hz is my freq. 2. I googled how a band pass filter diagram should look like and I found this, is the only way to create a low...

I am a beginner at electronics, and wanted to make a simple (non-audio) radio transmitter and reciever, with no inductor-capacitor resonator, since I don't understand it and I am not making an audio radio. Here is my transmitter, with the input wire to the BJT being the signal: Here is my...

Hi All, This seems to be the place to ask for help on a fun project I am playing with. I am wanting to make something like laser tag but with radio. I am no expert on radio so excuse my ignorance. Everyone would where a vest with a simple radio transmitter and when you pull the trigger it will...

There is an example for the radio signal for Twin Paradox from the book "Classical Dynamics of Particle and Systems, Thornton, Marion". Refer "1.jpeg", example 14.5, it said that "However, Frank continues to receive a signal every 3 years for the 8 years it takes the last signal Mary sends when...

Composition > Illustrative Essay On "Radio" Goal: 2-3 page essay on a topic of your choice. Must provide relevant photo's. My topic of choice is electromagnetism. I chose this topic because we live in a wireless age. I thought it'd be neat to provide some back round info on how it all...

Hi. I am having trouble visualising radio waves. Assuming a perfect isotropic antenna (I know they don't exist) an electromagnetic is just a spherical pulse that radiates outward, this is quiet easy to visualise. However all texts refer to the magnetic and electric fields being 90 degrees...

I have a 75w 2meter mobile transceiver (Yaesu FT-2900R – 13.8 volts DC, 15 Amp max draw, min draw is .3 A-.7 A ) that I would like to use in a camp type setup. The power source will be Two 12volt batteries (not dedicated) on a small enclosed utility trailer, which will be 20’-50’ away from the...

I hesitate to post this as it sure sounds like woo but it comes from an Irish University Prof. and appears to be endorsed by the Royal botanic gardens at Kew! Does anyone know of a peer reviewed paper...