Radio Definition and 671 Threads

If you produced a focused beam from, say, a cassegrain transmitter which consisted of two waves merged but one inverted what would be the result. I presume there would be destructive interference. My question is, where does the energy go?

I have a friend of mine which is an extraterrestrial. She travels in a ship around the Milky Way. She was likely in the Solar System, and she wants to attend tomorrow New Year's Eve at Plaza del Sol in Madrid, Spain. Her last communication was that she had faced a violent cosmic ray storm, and...

Hello, I am just wondering whether it is theoretically possible to create radio waves through bioluminescence. I realize that most organisms produce only UV to infrared light. Are there such compounds out there that would allow an organism to make radio waves instead?

The FCC's propagation models for the FM broadcast band seem grotesquely inaccurate in some places, where stations can be received that the models say are absolutely out of range. I'm not even talking about DX conditions like ducting or skip, I'm talking about baseline. When I lived in...

https://www.amazon.com/dp/0716703297/?tag=pfamazon01-20 guys! is anybody of you by any chance in possesion of the book from A. Pacholczyk called Radio Astrophysics: Nonthermal Processes in Galactic and Extragalactic Sources? I just need value of one constant from there :) it is the constant c14...

Homework Statement How much energy is transferred to a radio if a current of 0.40A run through it for 1.5 minutes with 115V? V=115V I=0.40A t=1.5 min Homework Equations Not sure which equation to use. The Attempt at a Solution Not sure which equation to use.

what are cosmic waves and radio waves made of? What's the difference between the two? Can waves like them transfer energy ?

Homework Statement Suppose you are stranded on an island and need to make a radio so that you can get weather updates. You know that weather updates for your general area can be found on short-wave radio within the frequency range f-low to f-high . Also, you manage to scavenge some thin...

I have poorly made computer speakers - Logitech X-530. They sometimes pick up AM radio stations and pops up when lightning is turned off. What AM radio frequency is picked up by computer speakers? I am curious becaous some kinds of popping is picked up by computer speakers but it is not picked...

I have a few questions about AM, FM and PM. 1. If FM (or PM) radio modifies the frequency of the signal, how is the signal picked up without having to change the frequency constantly? 2. If PM modulates phase, which modulates frequency, what is the difference between PM and FM? 3. Why is AM...

Homework Statement Determine the rotation period of a disc with 2m radio , that makes 20 rotations per minute. Homework EquationsThe Attempt at a Solution I did T= 60/20 to find the period , but is that it ? what about the 2m?

So I was thinking that radio waves travel at the speed of light, approximately 300,000,000 m/s.I was wondering how much time it would take if the average distance from Earth to the Moon is 384,000 km.

I need help explaining that this assumption is not correct or correct: A product uses Radio waves to turn on a LED. Radio waves can be a form of electromagnetic fields therefore, a Hall Effect sensor could be used in this device to turn on that LED.

<< Mentor Note -- ZIP files are a security risk, and the file has been deleted. Please post the individual files instead. Thanks >>[/color] I saw a post from 2009 of someone who needed a mixer component to play with. So for learning purposes I zipped a symbol, schematic, and .sub file...

I need to trace a simple radio transmission for school. It's a signal that is broadcasting some talk radio. If I could locate the signal within a couple hundred feet I get an A. Extra credit is for jamming, re-directing or scrambling the signal. Any ideas for any of the said process. It's...

Before I start, I apologise for the information dump that is to follow. I don't expect all questions to be answered or all models to be addressed; I simply feel it is appropriate to provide the community with my current knowledge and stage of research so you may not have to search for it...

Radio is usually used as RADAR blips but has anyone tried to make a visual DSLR type camera and producing images? I'm not talking about a waveform showing the frequency placement but a real image of objects the radio bounced off of? We have tons of radio stations as the 'light' source here in...

Sources A and B are on the horizontal x-axis and both emit a long-range radio wave of wavelength 400m, with the phase of emission from A ahead of that from source B by 90 degrees. The distance r(A) from Source A to the detector (D) in the y-axis is greater than the distance of r(B) by 100m. What...

I am using GNU companion ,in that i am not able to plot random source which i am giving as bytes . how to plot in a sink?

What causes radio blackouts to occur when, for example, a manned space capsule is descending through the Earth's atmosphere? If the atmosphere itself is in some way responsible for these blackouts (as surely it must be)* then how exactly? NB. Surely it can't be due to the ionosphere. I suggest...

I've recorded the output hiss from a small battery powered radio operating inside a metal tin. From related posts, I can say that the radio is effectively shielded from receiving any FM transmission, and the resultant hiss is thermal noise in the early stages of the receiver. I believe that...

I've put a small battery powered commercial radio inside a Quality Street tin. The tin is all metal with rolled joints and the lid is a tight fit. I'd be willing to bet that there are no holes greater than 0.1mm around the lid's closure. Why does the radio work when receiving an AM station (1...

Hi there I recently lost the adapter for my radio. On the back of my radio, it says "INPUT: DC 5.9V --- 0.8A". So I am guessing I need an adapter that has an OUTPUT of DC 5.9V and 0.8A to match... . The only problem is having done a quick search online, the closest adapter I can find has an...

http://www.stuff.co.nz/world/europe/68883327/danish-radio-station-defends-killing-baby-rabbit-live-on-air I'm totally disgusted. I will be investigating the Danish laws around animal abuse, and seeing whether this constitutes a breach of law.

I am a video and sound engineer. There is clearly AM radio coming from my wall heater. An earlier thread on this topic discussed the possibilities but ultimately left the subject with an assumed crazy old lady's false perception. I assure you this is happening. There is a 50,000W AM station...

Is there a way to change a photon of visible light to a radio wave? I know scattering and doppler effect can reduce frequency but is it possible to reduce the frequency enough to get in the radio wave range?

We've discussing with students the certain radio astronomical receiving system is designed for equipping the antenna systems, operating within band 2-40 GHz: Ka - band 28-34 GHz S - band 2.2-2.6 GHz X - band 7.0-9.5 GHz and provides the radio reception, amplification, selection of the operating...

Homework Statement Describe what optical astronomers would consider the properties of an active galaxy and also describe what radio astronomers would describe as the properties of an active galaxy and explain how two sets of astronomers came up with these differing conclusions. Homework...

Hi. I'd like to learn how to calculate the probability of a photon being emitted from a radio antenna where the energy per wavelength is below the threshold to emit photons. Let's assume the electrical thermal noise is insignificant. The antenna temperature could be sufficient low or the...

If both a transmitter and receiver antennae were submerged, and within a defined range and depth, what range might be available to a civilian operator? Are two divers able to communicate by radio? B

a simple idea. Maxwell’s theory of magnetic fields says there is two components ,an electrical field and a magnetic field. (put simply). I have an idea to pick up radio waves using a magnetic beam. rather than the normal dipole set-up, just wondering if you think this idea is possible to make...

So let's say a radio station sends out AM waves with a wavelenght of like >50m. You are standing with a receiver at a distance of <25m, what happens to the signal? Is it different or the same as if you were standing a longer distance away then 1 wavelenght? Thanks

DISCRETE STEPS IN DISPERSION MEASURES OF FAST RADIO BURSTS (emphasis mine) And no, this wasn't published in April 1st! Link to New Scientist article: Is this ET? Mystery of strange radio bursts from space. Garth

Hey all, firstly, sorry for my terrible phrasing and grammar in the title but I was severely limited by character count. I was wondering if there are any known methods existign that would allow nanites to communicate since they seem too small to absorb radio waves or microwaves, Any input...

I have an Antenna that receives signal coming from a wide band of distances, 10-2000 meters from a 10mW transmitter. I am working with 868 MHz band. What is the cheapest method ( or cheapest circuit ) to amplify this signal with an Automatic Gain Control LNA so that the received signal stays...

<< Mentor Note -- post separated out of a different thread to deal with a separate question >> Hi, I am looking transmit as well as receive power within close proximity. Currently I am looking at 27.255 MHz AM in the citizens band. It is listed on Wikipedia and in statues I found to be for...

Alright, so for a school project that I am doing right now involves harnessing the power in the air from radio waves and the picking it up with a 75 ft of coated copper wire antenna then having the AC current go through a diode bridge to convert it to DC current and get measured. I did this...

Homework Statement antennas can both receive and emit electromagnetic radiation depending on wetter their connecting cicuit is monitored for, or driven by a current. the pattern of emitted radiation is identical to the pattern for absorbed incident radiation. As shown in the notes, far-field...

Hello, I was wondering if there exists a decent radio channel which main focus would be science/technology and academia ? I'm listening radio pretty much all the time while working, all I could find were "sensational" tech talk show about UFOs, zombies and time travel, nothing serious. The...

Having not been set up with a station for quite a few years I am thinking of setting up an end fed antenna for HF. It seems the only way I will enjoy a little 'hamming' again is to start out simple and quick. Trying to avoid clutter in the middle of the yard. I have enough tower sections get...

when astronomers receive bursts of high energy radio waves from distant parts of the universe, how are they able to tell how far they have traveled? does it have to do with the wavelength?

http://www.wsj.com/articles/radioshack-store-closings-to-jolt-some-developers-1423095564

I've been told that magnetic field does not mask or influence any GHz transmissions; TV, Radio, Wi-Fi, etc. and should not pose a problem. Can someone explain why they do not interact? Credible documentation such a law or theory? Educational documentation? Thanks in advance.

I'm operating with the understanding that everything emits radio waves (electromagnetic/light waves). Is this correct? Whatever the answer is, what particle or element or molecule emits the most/greatest radio waves?

Hello Physics Forum! I'm in desperate need of proof that magnets or magnetic field will not effect the operation or range or wireless access (Wi-Fi). I have 1/2" rare Earth magnets within a metal housing every 5' within the same area as wireless routers and the customer is concerned that it will...

I'm trying to explain an FM or AM radio receiver using photons. When the photons are absorbed by the antenna, they arrive in discrete pulses, where in the case of FM, each wave front contains photons of the same energy (frequency) and the following wave fronts contain photons of different...

hi all. I have been scouring the Internet looking for a forum to help me. This seems like my best bet. I live next to a house with an enormous Christmas light display. It causes traffic littering loitering and a blocked driveway. I have talked to the neighbors the police and the town for help to...

A thought occurred to me In precalculus class. At the moment we are learning about sin/cos/tan/cot/sec/csc and their amplitude, periods and phases shifts. I've studied electronics on and off for about a year. I would like to know if we actually know what radio waves look like? do they actually...

I want to find a simple example of using the Feynman propagator: 1/(|x-x'|2-(t-t')2) and also to show that no signals an travel faster than light. So I was thinking about waves emitted from an antenna. Tell me if I got this right? Assume a static source in space at x=0 and varying in time...

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...