Radio Definition and 671 Threads

http://en.wikipedia.org/wiki/Coaxial_cable http://en.wikipedia.org/wiki/Poynting_vector Could a coaxial cable be used for electric current instead of radio signals? 'For example, the Poynting vector within the dielectric insulator of a coaxial cable is nearly parallel to the wire axis...

I am trying to understand why radio waves are not greatly attenuated by the atmosphere due to scattering or absorption? I have tried searching the internet and can't find any satisfactory answers. Please help. Oh and does this property somehow relate to why they are used to transmit information...

How does one know how many coils one needs to pick up a given frequency? AM frequency requires how many coils? I have a VC w/ inductor setup running into an AM IC but I'm not getting anything out of it. Pretty sure I have it set up correctly, alas no music!

My friend and I had an idea to put camera on the weather balloon and we wanted to have like a live picture from camera. But because we don't know so much about electronics we don't know how to do it. Fe figured out that we can do it via radio waves, maybe there is some more efficient way. That...

I am interested in the medical field of electrophysiology and I have a few questions regarding the procedures done on patients with atrial fibrillation. What is the purpose of radio frequency ablation on the tissue of the heart? How does damaging the tissue relieve atrial fibrillation...

How can you make radio waves? Explain it scientifically

Hello assume I sample signal between Transmiter to Reciver T->R Is the chanell respone would be the same to R->T also? especially I wonder about knife difraction effect ( Fresnel zone )

Hello, I have 2 problems that are currently bothering me, and I would enjoy help with either. The more immediate of these problems is with my family's gas stove. Whenever we need water to boil, we put the pot on and turn the burner all the way up. My father then comes in and turns it...

I remember a long time ago I read or watched something that talked about a guy that had a three story antenna and he was using a tesla based circuit to draw enough electrical power to power his household- for free. I recently ran across this [crackpot link deleted] nowwww, I also ran across...

Ive been going through some landers of Venus and Mars and I found they were equipped with radio doppler experiment(http://en.wikipedia.org/wiki/Venera_9 ) I was wondering what this does. I mean there is radio signal transmitted through space everywhere and i suppose the device would measure...

Hi: I'm new in this site I need help here please I need a circuit that works as : 1- transmitter uses radio waves or any type of waves 2- sends waves for long way more than 3 km 3- consist of simple component than can be found in old electronic instruments such as old TV or radio...

I am confused by the design of this AM receiver/tuner circuit. http://imgur.com/f9n05 I don't understand how the inductor and capacitors on the left design a circuit that resonates at a certain frequency, and I also don't understand why the resistor and capacitor in parallel after the diode...

I realize this might be a complicated question, but I can't seem to find any textbooks or papers that address this head on. Perhaps I am naive in this field. What happens to the electric and magnetic parts of a radio wave as it passes through the human body? As far as I understand: The...

After googleing the formula to calculate impedance of a radio antenna, I came up with this formula Z = R + jX where X is reactance and R is resistance. I figured resistance could be measured with an ohmmeter. Then, it seems like there are two kinds of reactances, capacitive and inductive. The...

at what radius can you send peer-to-peer text messages / SMS over "ham radio"? suppose we have lots of people concentrated in a small area, like a college campus. Maybe a mile or so in diameter. We would like to set up a packet switched peer-to-peer SMS transmission using low cost long wave...

RF question -- Plane radio aliasing? I hope this is the right place to post it. My buddy and I were working on a jet earlier and turned on the HF communication system to perform an operational check out of the system. We tuned the radio to 2.5 MHz and picked up a local AM radio station. The...

Hi, I have a Worldspace radio receiver lying around and I listen to internet radio throughout the day using a PC... I was wondering if there was anyway I could modify the radio receiver and connect it to my modem so that it can access the internet and I can listen to internet radio without...

Two Questions: 1. I am new to electrical engineering but I want to know how I would Invert a signal. By this I mean, how do I turn a weak signal from, let's say a walkie-talkie, and turn that "weakening" signal into a "strengthening" signal. I would like for the signals to be inverted, in...

I'm trying to understand the entry labeled 1.2.3 on this page - http://setifaq.org/faq.html#1.2.3 The main point of confusion, for me, is what they mean by Tsys. At first, I assumed it referred to the temperature of the telescope, but in the table of results, its value changes depending on...

Homework Statement I'm in grade 11 working on a science fair project I found on this site: http://www.sciencebuddies.org/science-fair-projects/project_ideas/Elec_p014.shtml Grade 11 physics doesn't cover much so I'm confused about why the radio is set up the way it is... I know that...

I was reading somewhere that radio waves can actually light up gasses in these tubes. How does this work?

Hi All, Always wondered a few things about radio transmission, hoping to get some questions answered. 1. Is there a reason why certain frequencies are free to use by everyone and certain ones are reserved? Is it something to do with the fact that the cost (or means) to send signals on...

Okay. So i am planning to make this project in which i want to use two transmitters and two receivers. I want to make one of them to transmit waves that go only for say 3+ feet and another than can only transmit around 1 feet. 4 Is it possible? I know frequency plays an role and so...

I need a help with a question. we want to implement a commercial radio station with proper licensing in Bangladesh. the regulatory board allow maximum 10kW transmitter and highest 16db by combining 6db antenna each or 40 ERP. how many KM/mile we can cover with this spec or what will be the...

Would radio waves emitted by an antenna be considered Bremsstrahlung radiation caused by pushing the electrons back and forth?

Homework Statement Explain why if your car is tuned to FM, it cuts out when you enter a tunnel but doesn’t if you are tuned to long wave reception. (λ of FM: 3m, λ of long wave: 1500m) Homework Equations The Attempt at a Solution Well, what I think is that.. As the λ of the long...

Hello, I had heard from a friend that during World War II, Japan had openly broadcasted over the radios about atrocities committed, detailing rape and murder of Chinese women and men, by Japanese forces. My friend told me he heard this over a television program. He did not cite sources. If...

Hi, I am designing an RF link. Before my spectrum analyzer, I have an RF low noise amp with a NF of 2.5 dB. Without this amplifier, my error vector magnitude or error rate is 2.1%, after an amplifier it goes down to 0.7%. My question is, the receiving signal will have its own SNR and with...

Homework Statement Estimate the Doppler shift for a radio wave reflected from an airplane moving directly toward you at a speed of 292 m/s. Assume the radio wave has a frequency of 9.7x10^6 Hz. Homework Equations fo = fv/(v − vt) The Attempt at a Solution Using the above...

How do radio waves carry the information? I mean the information is digital: 1 or 0, but what is 1 and what is 0 from perspective of radio waves?

I am an electronics technician, and I work on various types of electronic equipment including radio communications devices which is the reason for asking this question. I was recently troubleshooting a radio communications malfunction, basically when squelch was broken, there was a “noise”...

I've read that ionosphere mirrors the short radio waves (25-30 MHz). So 2 questions: Why this happens? There is material on the internet, but it's rather complicated for me so far, I've just started to study physics. So I'd appreciate if someone explains this in more or less simple way. Why...

Typical radio active decay question Half time = 1 year λ = ln 2 here Q 1: if we have 1024 atoms at t=0, what is the time at which the expected number remaining is one. Easy, I get 10 years Q 2: The chance that in fact none of the 1024 atoms remains after the time calculated in c...

Sooo I wasn't sure if I should put this here or in the astrophysics section, but I figured electrical engineering was more relevant for my question. I'm involved in a project at my university to build a (very) simple radio telescope, but I'm having a bit of trouble with the radiometer...

I am looking for a strictly hardware radio signal system. Something along the lines of what you would find in a RC car or plane. Any suggestions? Hopefully something relativily cheap, and fairly durable. Thanks for any response.

What method is usually used to locate exact place of radio signal source? Do exist some type of radio signals, exact place of origin which is completely impossible to locate?Well,at least up to few hundreds of feets?

I need some clarifications on the following concepts: 1.When an α-particle is released by a radio active sample, it loses a charge of +2. Similarly, when it loses a β particle it gains one positive charge. But there is no change in the number of electrons in the outer orbits of the radio...

In my experience pictures from radio antennae are far less accurate than pictures from other areas of the EMR spectrum, why is this?

Can radio waves penetrate steel? What about titanium? Maybe a characterization of what they can't penetrate would be more informative? ...Or a way to figure out what materials they can penetrate. Thanks, Jake

I don't think I have to write out the problem but let me know. There are two radio antennas emitting radio waves and a point was given to me to determine if constructive or destructive at that point. I found the wavelength is 100m and the path difference is 200m. How can I determine if it is...

could anyone help me by giving information about radio frequency antennas if possible provide me powerpoint pesentation

What I am interested in here specifically is - how are bits represented? Is it as "1" is represented with a sent photon [at those specific frequencies] and "0" with a .. silence (no photon sent) ? ... but this, in that case, would get really complicated, because other photons from other...

What does it mean physically when radio stations mix? As in if you are listening to one station, but you begin to here another and eventually only here the wrong station.

I want to know the forum's opinion on the best Science Talk Radio Show that they know of. For instance I like to listen to Michio Kaku's Science Fantastic. So please tell me what you all think is the best science radio show.

I have to wonder and thought maybe someone has done a study. Given the popularity of political radio [right, and what little there is of left - NPR?] and given that people are mostly listening to this on the job, I have to wonder how much this might be affecting productivity and employee...

I have just had a very strange experience, and would like to know if there is an explanation for it. There was a small tin of black olives on my kitchen work surface. I put a teaspoon into the tin, to get an olive. The moment I did this, I heard what sounded like a radio broadcast of a...

Homework Statement Describe how the concept of wave superimposition is used to create AM radio waves. Homework Equations The Attempt at a Solution O.K, I am not sure that I understand how this works. In the picture attached it shows the carrier frequency inside of the audio...

Hi All, I wonder if the modulation of RF waves (Amplitude Modulation, Frequency Modulation, and Phase Modulation) can be explained in terms of photons. Thanks, Srini

Just some background - I am trying to measure spurious radio signals around a carrier in dBc units. It seems easy until you consider the resoultion bandwidth you are going to set your specan up with. If you start with a large bandwidth the spurious signals can get mixed up with the carrier and...

I am merely getting curious in thinking about building a radio-wave laser. I'm not seriously pursuing this, but I think it would be cool to build a laser that is ~10km in length. Is anyone aware of any research into this type of monstrosity? Any thoughts about the feasibility or the potential...