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What exactly is radio
I'm preparing an article for a local radio club magazine about the nature of
radio and electromagnetic radiation in general. While this is a non mathematical and general descriptive treatment of the subject it is a challenge to make it clear and consistent. I know this group has some expertise on this subject and would appreciate any constructive comment and suggestions regarding the attached article. http://members.optushome.com.au/vk6ysf/vk6ysf/radio.htm Thank you for your time. Regards Peter VK6YSF |
What exactly is radio
On Apr 30, 4:14*am, "Peter" wrote:
I know this group has some expertise on this subject and would appreciate any constructive comment and suggestions regarding the attached article. The two-dimensional Fig. 2-2 graph is confusing in that it could be inferred that the E and H fields are 90 degrees out of phase in time and are never zero at the same time. The E and H fields are in phase in time as demonstrated by Fig. 2-4. -- 73, Cecil, w5dxp.com |
What exactly is radio
On Fri, 30 Apr 2010 05:12:38 -0700 (PDT), Cecil Moore
wrote: On Apr 30, 4:14*am, "Peter" wrote: I know this group has some expertise on this subject and would appreciate any constructive comment and suggestions regarding the attached article. The two-dimensional Fig. 2-2 graph is confusing in that it could be inferred that the E and H fields are 90 degrees out of phase in time and are never zero at the same time. The E and H fields are in phase in time as demonstrated by Fig. 2-4. Hmmm. I'm no expert, but I thought they were 90 degrees out of phase. It's the rapidly changing H field that creates the E field and vica versa. If you look closely, Fig 2-4 also shows them 90 degrees out of phase. To the OP, heat is not electromagnetic radiation. Light and x-rays are. You can heat something by pointing em radiation at it and something that is hot gives off infra-red em radiation, but heat itself is not em radiation. Pat |
What exactly is radio
On Apr 30, 9:00*am, wrote:
On Fri, 30 Apr 2010 05:12:38 -0700 (PDT), Cecil Moore wrote: On Apr 30, 4:14*am, "Peter" wrote: I know this group has some expertise on this subject and would appreciate any constructive comment and suggestions regarding the attached article. The two-dimensional Fig. 2-2 graph is confusing in that it could be inferred that the E and H fields are 90 degrees out of phase in time and are never zero at the same time. The E and H fields are in phase in time as demonstrated by Fig. 2-4. Hmmm. *I'm no expert, but I thought they were 90 degrees out of phase. It's the rapidly changing H field that creates the E field and vica versa. *If you look closely, Fig 2-4 also shows them 90 degrees out of phase. To the OP, heat is not electromagnetic radiation. *Light and x-rays are. *You can heat something by pointing em radiation at it and something that is hot gives off infra-red em radiation, but heat itself is not em radiation. * Pat It is accepted that radiation is "an acceleration that generates or transfers a charge ". This is an empty statement if one cannot explain the mechanics of the operation.Certainly you have to determine what you have in hand to provide this action, and at the present time there is no agreement whether it is a wave flow of a constituent, what ever that may be, or a particle. Therefore one has to determine exactly what we are going to accelerate and how we are going to avoid the effects of gravity since radiation does not follow the action of a descending lob. This as yet has not been determined, so we cannot begin to understand! For me I see a wave as being an adjective and a particle as a noun. But a word of warning,physicists do not follow the same rules of the general public, so if you have a day or two to spare get a physicist to explain exactly what a 'wave' is and how does it fit with the required straight line accelerating trajectory that opposes gravity! You just cannot explain "radio" until you determine what you are accelerating and how. Sorry about that Regards Art |
What exactly is radio
On Fri, 30 Apr 2010 17:14:28 +0800, "Peter" wrote:
While this is a non mathematical and general descriptive treatment of the subject it is a challenge to make it clear and consistent. Hi Peter, Yes, your treatment does tend to veer towards the exotic topics. Stick to the basics. You have a wonderful resource that you point to in the Navy training manuals. As a former instructor for the Navy's Electronic Technician A and C schools, I can attest this material manages the balance between technical and theoretical. You may notice that the first manual introduces the concept of photons, but no where goes into "duality." And for good reason, it doesn't matter one whit. When you raise this concept, the weaker participants of your audience would then think about solar particles in competition with solar radiation (light, largely). They would probably miss the vast difference in propagation speed. Solar radiation, of course, travels at the speed of light. This is why it is called radiation. Solar particles (the erroneous dual to the photon) travels at less than 1% of the speed of light. If any of your audience were to simply consider their final's tubes, within that glass enclosure, electrons travel at 90% of the speed of light. Dribble a little air into that vacuum tube, and the speed of any electron would plummet to inches per hour. So, what value is there in opening that can of worms? 73's Richard Clark, KB7QHC |
What exactly is radio
On Apr 30, 12:59*pm, Richard Clark wrote:
On Fri, 30 Apr 2010 17:14:28 +0800, "Peter" wrote: While this is a non mathematical and general descriptive treatment of the subject it is a challenge to make it clear and consistent. Hi Peter, Yes, your treatment does tend to veer towards the exotic topics. Stick to the basics. *You have a wonderful resource that you point to in the Navy training manuals. *As a former instructor for the Navy's Electronic Technician A and C schools, I can attest this material manages the balance between technical and theoretical. You may notice that the first manual introduces the concept of photons, but no where goes into "duality." *And for good reason, it doesn't matter one whit. *When you raise this concept, the weaker participants of your audience would then think about solar particles in competition with solar radiation (light, largely). *They would probably miss the vast difference in propagation speed. Solar radiation, of course, travels at the speed of light. *This is why it is called radiation. *Solar particles (the erroneous dual to the photon) travels at less than 1% of the speed of light. *If any of your audience were to simply consider their final's tubes, within that glass enclosure, electrons travel at 90% of the speed of light. Dribble a little air into that vacuum tube, and the speed of any electron would plummet to inches per hour. So, what value is there in opening that can of worms? 73's Richard Clark, KB7QHC Obviously a problem here! Quantum mechanics states radio rotates around particles and classical physics revolves about waves. If radiation is an acceleration of charge then it is pivotable that one decides what is being accelerated in the first place! If Einstein is correct that the speed of light is not to be exceeded then one has to decide whether a wave is lighter than the smallest particle possible. Waves do have length a physicist would say where as a particle can be a point! How we get straight line trajectory while gravity is present is easily solved. Pysicists have now removed gravity from the Standard Model to get over that problem.The Navy on the other hand ignores the duallity question. |
What exactly is radio
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What exactly is radio
Roy Lewallen wrote in
: The time phase angle between E and H is determined by the medium the wave is propagating through. The (complex) ratio of E to H is called the intrinsic impedance of the medium, and for lossless media, it's always a purely real number (about 377 ohms for air or free space), meaning that E and H are in phase. Only when propagating through a lossy medium are E and H not in time phase, and then the maximum phase difference is always less than 45 degrees. If I understand this correctly, a field arrangement with E and H in time and space quadrature is not propagating energy, but rather energy exchange. In very close to an antenna, the time phase relationship of E and H may be close to quadrature due to the inductive or reactive field close to the conductors, but that changes eventually to 'in-phase' in the far radiation field in free space (as the induction field components decay more quickly with distance than the radiation field components). If that is the case, the complex value of E/H varies from very close to the far field. I have seen plots of E/H vs distance that treated E/H as a real number, but I suspect that it is more complex when all of the components of E and H are included. Thoughts? Owen |
What exactly is radio
On Apr 30, 5:05*pm, Owen Duffy wrote:
Roy Lewallen wrote om: The time phase angle between E and H is determined by the medium the wave is propagating through. The (complex) ratio of E to H is called the intrinsic impedance of the medium, and for lossless media, it's always a purely real number (about 377 ohms for air or free space), meaning that E and H are in phase. Only when propagating through a lossy medium are E and H not in time phase, and then the maximum phase difference is always less than 45 degrees. If I understand this correctly, a field arrangement with E and H in time and space quadrature is not propagating energy, but rather energy exchange. In very close to an antenna, the time phase relationship of E and H may be close to quadrature due to the inductive or reactive field close to the conductors, but that changes eventually to 'in-phase' in the far radiation field in free space (as the induction field components decay more quickly with distance than the radiation field components). If that is the case, the complex value of E/H varies from very close to the far field. I have seen plots of E/H vs distance that treated E/H as a real number, but I suspect that it is more complex when all of the components of E and H are included. Thoughts? Owen Owen By observation the E and H fields can be seen as a tank circuit where all vectors are accounted for so that one follows the notion that energy cannot be created or destroyed plus the other laws of Newton. When we stray from that scenario we get into new theories or imaginations The moment we stray from boundary laws one is coersed into thinking like somebody of a lesser nature than past masters who determine phenomina from observation that is matched by known principles. How on earth can we relate to near fields and far fields if we haven't decided what the media concists of. My approach was to stick with the laws of Maxwell which dictates static and dynamic fields where all forces are accounted for, which shows that gravity can only be negated by the use of Newton's laws. Thus my foundations were not built on a layer of sand but what is accepted via Maxwell's laws. In other words, the laws of Maxwell points to the presence of particles when dealing with fields and displacements by virtue of the units used. There are lots of things that exhibit properties of other materials and thus by observation can be compared to other things in action, but they should never be considered as one and the same unless they are matched in their entirety. Particles and waves have lurched beyond science by considering them to be one and the same purely by action and not by substance. If one is going to discuss energy exchange as with inductance and capacitance to determine relative phase angles , fields etc one cannot stray from the tank circuit observations. Regards Art |
What exactly is radio
It is accepted that radiation is "an acceleration that generates or transfers a charge ". This is an empty statement if one cannot explain the mechanics of the operation.Certainly you have to determine what you have in hand to provide this action, and at the present time there is no agreement whether it is a wave flow of a constituent, what ever that may be, or a particle. Therefore one has to determine exactly what we are going to accelerate and how we are going to avoid the effects of gravity since radiation does not follow the action of a descending lob. This as yet has not been determined, so we cannot begin to understand! For me I see a wave as being an adjective and a particle as a noun. But a word of warning,physicists do not follow the same rules of the general public, so if you have a day or two to spare get a physicist to explain exactly what a 'wave' is and how does it fit with the required straight line accelerating trajectory that opposes gravity! You just cannot explain "radio" until you determine what you are accelerating and how. Sorry about that Regards Art You are really good, Art. How do you keep it up? You make new and fresh nonsense up with very many of your posts. Not every one, but you do have to carry on your themes after all. Still, it's quite an effort you put into it. How do you continue to make almost no sense? That's really tough. I mean, even random chance would say you occasionally have to be realistic. tom K0TAR |
What exactly is radio
On Apr 30, 9:22*pm, tom wrote:
It is accepted that radiation is "an acceleration that generates or transfers a charge ". This is an empty statement if one cannot explain the mechanics of the operation.Certainly you have to determine what you have in hand to provide this action, and at the present time there is no agreement whether it is a wave flow of a constituent, what ever that may be, or a particle. Therefore one has to determine exactly what we are going to accelerate and how we are going to avoid the effects of gravity since radiation does not follow the action of a descending lob. * * *This as yet has not been determined, so we cannot begin to understand! For me I see a wave as being an adjective and a particle as a noun. But a word of warning,physicists do not follow the same rules of the general public, so if you have a day or two to spare get a physicist to explain exactly what a 'wave' is and how does it fit with the required straight line accelerating trajectory that opposes gravity! You just cannot explain "radio" until you determine what you are accelerating and how. Sorry about that Regards Art You are really good, Art. *How do you keep it up? You make new and fresh nonsense up with very many of your posts. *Not every one, but you do have to carry on your themes after all. Still, it's quite an effort you put into it. *How do you continue to make almost no sense? *That's really tough. *I mean, even random chance would say you occasionally have to be realistic. tom K0TAR As an engineer can't afford to act on theories alone only those that have already be established. In other words I can act on a full picture made of jigsaw parts but not a partial picture. Therefore one must deal with fully melded and interacting parts that are consistant to reality. Thus I adhere to classical physics and factual observances or laws without straying from the path I have chosen from interconnecting parts. Quantum theory is based on probabilities and associated math. Any body who has been to the race track knows that this form of thinking has its fallacies thus probabilities has moved towards string theory. I stick to classical physics as they have a history of success with the laws that they have established but unfortunately physicists have corrupted the language of observances. For instance we had a discussion on Leptons, colour etc. Physicists recognise that colour as the rest of the world knows it as a means of separation of its observed actions instead of labelling it lepton1 or lepton 2.Same goes for hadrons, they actually could be a single type particle but physicists label them by the action that they exhibit on observance. Why do you think that the idea of a mad scientist hangs on to this day. They did similar things with respect to waves which in their world has nothing to do with water, tides e.t.c. So for me there is merit in sticking to points raised by classical physics since they are tried and true under examination and have not exploded by categerizing particles by a particular observation. After all, both a dog and a cat have a tail they can wag but the real world can have the same observation of different entitiesand vica versa. What I desire the most is for somebody to challenge my statements based on documented observations and laws bearing in mind that the written word comes after factual examination and not before.As yet nobody has pointed out a fallacy that is in conflict with presently known laws, and I mean nobody. If there is a conflict then I will discard all. But remember, I do not make computer programs on radiators but they all confirm the presence of particles and equilibrium and I have had no way of manipulating that to conform to my thinking. They show that maximum radiation is obtained when material resistance drops to zero and radiation rises to a maximum via current flow outside the member to elevate particles at rest on the surface. I couldn't possibly string some thing like that as a joke or by not taking my medicine. |
What exactly is radio
On 4/30/2010 10:17 PM, Art Unwin wrote:
On Apr 30, 9:22 pm, wrote: It is accepted that radiation is "an acceleration that generates or transfers a charge ". This is an empty statement if one cannot explain the mechanics of the operation.Certainly you have to determine what you have in hand to provide this action, and at the present time there is no agreement whether it is a wave flow of a constituent, what ever that may be, or a particle. Therefore one has to determine exactly what we are going to accelerate and how we are going to avoid the effects of gravity since radiation does not follow the action of a descending lob. This as yet has not been determined, so we cannot begin to understand! For me I see a wave as being an adjective and a particle as a noun. But a word of warning,physicists do not follow the same rules of the general public, so if you have a day or two to spare get a physicist to explain exactly what a 'wave' is and how does it fit with the required straight line accelerating trajectory that opposes gravity! You just cannot explain "radio" until you determine what you are accelerating and how. Sorry about that Regards Art You are really good, Art. How do you keep it up? You make new and fresh nonsense up with very many of your posts. Not every one, but you do have to carry on your themes after all. Still, it's quite an effort you put into it. How do you continue to make almost no sense? That's really tough. I mean, even random chance would say you occasionally have to be realistic. tom K0TAR As an engineer can't afford to act on theories alone only those that have already be established. In other words I can act on a full picture made of jigsaw parts but not a partial picture. Therefore one must deal with fully melded and interacting parts that are consistant to reality. Thus I adhere to classical physics and factual observances or laws without straying from the path I have chosen from interconnecting parts. Quantum theory is based on probabilities and associated math. Any body who has been to the race track knows that this form of thinking has its fallacies thus probabilities has moved towards string theory. I stick to classical physics as they have a history of success with the laws that they have established but unfortunately physicists have corrupted the language of observances. For instance we had a discussion on Leptons, colour etc. Physicists recognise that colour as the rest of the world knows it as a means of separation of its observed actions instead of labelling it lepton1 or lepton 2.Same goes for hadrons, they actually could be a single type particle but physicists label them by the action that they exhibit on observance. Why do you think that the idea of a mad scientist hangs on to this day. They did similar things with respect to waves which in their world has nothing to do with water, tides e.t.c. So for me there is merit in sticking to points raised by classical physics since they are tried and true under examination and have not exploded by categerizing particles by a particular observation. After all, both a dog and a cat have a tail they can wag but the real world can have the same observation of different entitiesand vica versa. What I desire the most is for somebody to challenge my statements based on documented observations and laws bearing in mind that the written word comes after factual examination and not before. snip I couldn't possibly string some thing like that as a joke or by not taking my medicine. Ok, I'm sure that you are the expert on that subject. Who could argue how sane you always seem to be. tom K0TAR |
What exactly is radio
Owen Duffy wrote:
Roy Lewallen wrote in : The time phase angle between E and H is determined by the medium the wave is propagating through. The (complex) ratio of E to H is called the intrinsic impedance of the medium, and for lossless media, it's always a purely real number (about 377 ohms for air or free space), meaning that E and H are in phase. Only when propagating through a lossy medium are E and H not in time phase, and then the maximum phase difference is always less than 45 degrees. If I understand this correctly, a field arrangement with E and H in time and space quadrature is not propagating energy, but rather energy exchange. I believe that's correct, but there's no medium in which that would take place -- with a plane wave at least. In very close to an antenna, the time phase relationship of E and H may be close to quadrature due to the inductive or reactive field close to the conductors, but that changes eventually to 'in-phase' in the far radiation field in free space (as the induction field components decay more quickly with distance than the radiation field components). If that is the case, the complex value of E/H varies from very close to the far field. I have seen plots of E/H vs distance that treated E/H as a real number, but I suspect that it is more complex when all of the components of E and H are included. Thoughts? Yes, E/H varies a great deal in both magnitude and phase in the near field. The intrinsic Z describes only the E/H ratio of a plane wave propagating in the far field. This can be easily investigated with NEC, EZNEC, or any modeling program that provides near field results. Incidentally, the physical orientation of E and H, and I believe their time phase, can be quite different when bounded by conductors as in a waveguide. Roy Lewallen, W7EL |
What exactly is radio
Użytkownik "Peter" napisał w wiadomości ... I'm preparing an article for a local radio club magazine about the nature of radio and electromagnetic radiation in general. While this is a non mathematical and general descriptive treatment of the subject it is a challenge to make it clear and consistent. I know this group has some expertise on this subject and would appreciate any constructive comment and suggestions regarding the attached article. http://members.optushome.com.au/vk6ysf/vk6ysf/radio.htm Thank you for your time. You wrote: "I begin to appreciate a comment made by a fellow radio amateur and technician that antenna theory was 15% science and 85% black magic! " But in your paper is 85% of science. Next you wrote: "Figure 2-3 is a simple picture of an E field detaching itself from an antenna. (The H field will not be considered, although it is present.) In view A the voltage is maximum and the electric field has maximum intensity. " That is all. Radio waves are simply the alternate electric field. You should add only that in the and of the dipole the voltage is doubled (at least). At the end you wrote: "For myself, I like the humbling fact that despite building our modern technology and economy to large degree on the manipulation of electro magnetic radiation; when it comes to understanding exactly what in fact it is, there still remains some uncertainty and mystery!" Not always it was a mistery. In the radio history the radio waves were always the electric waves. Maxwell's hypothezis (EM) was a proposition for the transverse waves (to explain the light polarization). Now we can produce polarized or not polarized electric waves (by proper arranged polarity). Polarized light is emmited from dipoles. In nature no monopoles. S* |
What exactly is radio
On Apr 30, 4:14*am, "Peter" wrote:
I'm preparing an article for a local radio club magazine about the nature of radio and electromagnetic radiation in general. While this is a non mathematical and general descriptive treatment of the subject it is a challenge to make it clear and consistent. I know this group has some expertise on this subject and would appreciate any constructive comment and suggestions regarding the attached article. http://members.optushome.com.au/vk6ysf/vk6ysf/radio.htm Thank you for your time. Regards Peter VK6YSF Peter, the moment you deviate from the ARRL version of intersecting fields and refer to waves is when you are going to lose your audience. Maxwell specifically refers only to two properties inductive and capacitive both of which can be seen as fields. ARRL then states that these two fields interact at right angles to each other which is an interaction of current flow ACROSS a capacitor which is created by the displacement current. Note that waves are not even being mentioned. This is exactly the mechanism of a particle in a crt where the particle collides with a screen and the point it interacts with the screen is governed by two vectors. The only difference between radio and the crt beam is that tho both beams are particles , rotating modulation is only imprinted on the particles occillations or "spin" to form a information carrier for radio purposes. It is still a closed tank circuit which is the propelling engine at the end of all transmitters, except in the radiation cases the closed circuit crosses over itself by passing sideways thru a capacitor created in the form of a eddy current created by the reactionary displacement current flow The idea of using the "wave" term is a carry over from the old days where the aether was viewed as a viscous soup which has now been discarded and replaced by a cloud of free electrons swerling around looking for a diamagnetic place to rest and where the volume of electrons is more than the available places to rest. Why a diamagnetic place to rest? Because diamagnetic means that there is no residual magnetic content within the resting place medium. So Peter, your audience can align visually with the idea of a crt and a beam created by a combination of capacitance and inductance which provides a straight line trajectory which is a central part of radio, and gets away from a viscous water wave movement that does nothing to infer a straight line projection or the energy sinosoidal interaction created by a tank circuit or indeed a pendulum. |
What exactly is radio
On Apr 30, 5:14*am, "Peter" wrote:
I'm preparing an article for a local radio club magazine about the nature of radio and electromagnetic radiation in general. While this is a non mathematical and general descriptive treatment of the subject it is a challenge to make it clear and consistent. I know this group has some expertise on this subject and would appreciate any constructive comment and suggestions regarding the attached article. http://members.optushome.com.au/vk6ysf/vk6ysf/radio.htm Thank you for your time. Regards Peter VK6YSF Albert Einstein is frequently quoted saying: "The wireless telegraph is not difficult to understand. The ordinary telegraph is like a very long cat. You pull the tail in New York, and it meows in Los Angeles. The wireless is the same, only without the cat." |
What exactly is radio
Uzytkownik napisal w wiadomosci ... On Apr 30, 5:14 am, "Peter" wrote: I'm preparing an article for a local radio club magazine about the nature of radio and electromagnetic radiation in general. While this is a non mathematical and general descriptive treatment of the subject it is a challenge to make it clear and consistent. I know this group has some expertise on this subject and would appreciate any constructive comment and suggestions regarding the attached article. http://members.optushome.com.au/vk6ysf/vk6ysf/radio.htm Thank you for your time. Regards Peter VK6YSF Albert Einstein is frequently quoted saying: "The wireless telegraph is not difficult to understand. The ordinary telegraph is like a very long cat. You pull the tail in New York, and it meows in Los Angeles. Here is the drawing of the cat: http://library.thinkquest.org/18160/electriceasy.htm The wireless is the same, only without the cat." There is a small difference. If instant of the cat (wire) is an insulator (aether) in it flows the displacement current. The current is strong when the capacitance and the frequency is big. It is easy to achive the huge frequency but for this you must use the modulation. S* |
What exactly is radio
Peter wrote:
"----- it is a challenge to make it clear and consistent." For me. no one does a better job than Dr. Frederick Emmons Terman who wrote on page 1 of "Electronics and Radio Engineering": "Electrical energy that has escaped into free space is in the form of electromagnetic waves. These waves, which are commonly called radio waves, travel with the velocity of light and donsist of magnetic and electric hields that are at right angles to each other and also at right angles to the direction of travel." The rest is in the book which should be consulted for a complete definition. Best regards, Richard Harrison, KB5WZ5 |
What exactly is radio
Uzytkownik "Richard Harrison" napisal w wiadomosci ... Peter wrote: "----- it is a challenge to make it clear and consistent." For me. no one does a better job than Dr. Frederick Emmons Terman who wrote on page 1 of "Electronics and Radio Engineering": "Electrical energy that has escaped into free space is in the form of electromagnetic waves. These waves, which are commonly called radio waves, travel with the velocity of light and donsist of magnetic and electric hields that are at right angles to each other and also at right angles to the direction of travel." The rest is in the book which should be consulted for a complete definition. Maxwell proposed EM to explain the polarization of light. Now the radio waves are or are not polarized. Wiki wrote: " FM radio The term "circular polarization" is often used erroneously to describe mixed polarity signals used mostly in FM radio (87.5 to 108.0 MHz), where a vertical and a horizontal component are propagated simultaneously by a single or a combined array. This has the effect of producing greater penetration into buildings and difficult reception areas than a signal with just one plane of polarization. This would be an instance where the polarization would more appropriately be called random polarization (or simply unpolarized). See Stokes parameters." Why "erroneously"? Are the radio waves different than light? S* Best regards, Richard Harrison, KB5WZ5 |
What exactly is radio
Sz. Bialek wrote:
"Are the radio waves different than light?" Yes, as light waves are much higher in frequency than radio waves but, in most ways they are identical. As an example, cross-polarized receptors for both light and radio waves suffer greatly in receptivity. Best regards, Richard Harrison, KB5WZI |
What exactly is radio
Uzytkownik "Richard Harrison" napisal w wiadomosci ... Sz. Bialek wrote: "Are the radio waves different than light?" Yes, as light waves are much higher in frequency than radio waves but, in most ways they are identical. As an example, cross-polarized receptors for both light and radio waves suffer greatly in receptivity. So in most ways yes. Radio waves from the dipole are polarized. Does it mean that light is emitted by a dipoles? We can shield the one end of the dipole. Are such waves polarized? Why the dipoles exhibit the directional pattern? Are the ansfers in "Electronics and Radio Engineering"? S* |
What exactly is radio
Pat wrote:
"To the OP, heat is not electromagnetic radiation." Physics books disagree with Pat. Henry Semat, Ph.D. wrote on page 327 of "Fundamentals of Physics": "The transfer of heat by the process of radiation need not involve the use of material media. An outstanding example is radiation of energy from the sun to the earth: by far the greatest part of space between these two bodies is a very good vacuum. The fadiant energy consists of electromagnetic waves which travel with the speed of light, about 186,000 miles per second." Best regards, Richard Harrison, KB5WZI |
What exactly is radio
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What exactly is radio
Richard Clark wrote:
Hi Richard, The discussion of heat is more a metaphysical concept because it is confused by our senses. Entropy demands that everything inexorably cools by dissipating its energy (heat) into the void of cold space. Hence, everything radiates (and yet we spend very little time writing about it, except for Art). A good deal of this entropic radiation is like waiting an infinite time for a circuit with infinite-1 Q to stop ringing. The sun burns bright in the cosmos, but the greater part of the cosmos is unheated by the sun even though all of the cosmos is illuminated (radiated) by the sun. Direct observation 1: Put two plates out in the noon sun but undisturbed by the motion of air. One plate of metal, the other of glass. Which gets hotter? Same amount of radiation from a known heat source, but clearly different results in heat. . . This illustrates a classical confusion between heat and temperature, probably aggravated by our use of "hot" as a description of temperature rather than heat. Heat is energy. Absorption or transfer of heat results in a change in temperature. "Hot" (high temperature) objects radiate more heat than cold objects. The more heat an object, such as a plate, absorbs, the higher its temperature. Once this basic distinction is clear, a lot of the mystery disappears. There are, of course, other mechanisms of heat transfer other than radiation, namely convection and conduction. But heat transfer has the same effect on temperature regardless of the mechanism. When doing experiments with the sun's rays, you sometimes get non-intuitive results, because there's a lot of energy (heat) at wavelengths we can't see, particularly at the ultraviolet end. The reflective or absorptive properties of an object aren't necessarily the same at infrared or ultraviolet wavelengths as they are at visible wavelengths. For an example, you can't see the difference in my skin when coated with sun block or not. But there's sure a difference in energy (heat) absorption! Roy Lewallen, W7EL |
What exactly is radio
Roy Lewallen wrote:
ut clearly different results in heat. . . This illustrates a classical confusion between heat and temperature, probably aggravated by our use of "hot" as a description of temperature rather than heat. Heat is energy. Absorption or transfer of heat results in a change in temperature. "Hot" (high temperature) objects radiate more heat than cold objects. The more heat an object, such as a plate, absorbs, the higher its temperature. Once this basic distinction is clear, a lot of the mystery disappears. There are, of course, other mechanisms of heat transfer other than radiation, namely convection and conduction. But heat transfer has the same effect on temperature regardless of the mechanism. When doing experiments with the sun's rays, you sometimes get non-intuitive results, because there's a lot of energy (heat) at wavelengths we can't see, particularly at the ultraviolet end. The reflective or absorptive properties of an object aren't necessarily the same at infrared or ultraviolet wavelengths as they are at visible wavelengths. For an example, you can't see the difference in my skin when coated with sun block or not. But there's sure a difference in energy (heat) absorption! Roy Lewallen, W7EL There are also complications about temperature when referring to solids, liquids, and gases. The "temperature" of even a weekly ionized plasma is quite high (e.g. 11000 K per eV), but that more to do with the velocity of the ions and the mean free path. There's not much mass there, so the "heat" is small. That is, even though the ionosphere is "hot" in a temperature sense, it's not very "hot" in a sensible transfer of heat sense. BTW, I think the sunburn is not from thermal absorption, but from photons with enough energy to make the reaction go. The total energy in the UV of sunlight is MUCH lower than the total energy in the visible range. The power spectrum of sunlight is pretty close to the spectral sensitivity of your eyes (which evolved that way to match, I would think). At least one reference says that sunburn is a direct reaction to DNA damage from UV photons. Melanin protects because it absorbs the UV and turns it into heat. http://www.scientificamerican.com/ar...s-when-you-get |
What exactly is radio
Jim Lux wrote:
There are also complications about temperature when referring to solids, liquids, and gases. The "temperature" of even a weekly ionized plasma is quite high (e.g. 11000 K per eV), but that more to do with the velocity of the ions and the mean free path. There's not much mass there, so the "heat" is small. That is, even though the ionosphere is "hot" in a temperature sense, it's not very "hot" in a sensible transfer of heat sense. BTW, I think the sunburn is not from thermal absorption, but from photons with enough energy to make the reaction go. The total energy in the UV of sunlight is MUCH lower than the total energy in the visible range. The power spectrum of sunlight is pretty close to the spectral sensitivity of your eyes (which evolved that way to match, I would think). A good graph of sunlight power density vs wavelength can be found at http://en.wikipedia.org/wiki/File:Solar_Spectrum.png. Comparing areas of various graph sections shows that the UV part of the spectrum contains maybe 1/5 the amount of energy as the visible part -- plenty enough to embrittle plastics and fabrics and sunburn skin. But the infrared energy -- invisible to our eyes -- looks to be at least equal to the visible energy. At least one reference says that sunburn is a direct reaction to DNA damage from UV photons. Melanin protects because it absorbs the UV and turns it into heat. http://www.scientificamerican.com/ar...s-when-you-get Some people like to view electromagnetic waves as photons. I find waves easier to understand, but each to his own. My explanation was simplified. There's also latent heat or heat of change of state. For example, if you apply heat to ice, it'll warm up to 0C, but stay at that temperature in spite of the heat input until it melts. The heat (energy) goes into converting the ice to water instead of raising the temperature. After it all melts, continued heat application will of course raise the temperature of the water.(*) Until it reaches the boiling point, that is. Then the same thing happens again -- it stays at 100C until it all boils. If you confine the resulting steam, adding heat will raise both its temperature and pressure after the water is all converted. (*) That's why people experienced in cold weather outdoor activities never eat unmelted snow for water when there's any danger of hypothermia -- it takes about twice as much heat just to melt 0C snow into 0C water as it does to raise the temperature of 0C water to body temperature. In other words, you use up 3 times the energy eating 0C snow as you do drinking 0C water. Roy Lewallen, W7EL |
What exactly is radio
Roy Lewallen wrote:
Jim Lux wrote: There are also complications about temperature when referring to solids, liquids, and gases. The "temperature" of even a weekly ionized plasma is quite high (e.g. 11000 K per eV), but that more to do with the velocity of the ions and the mean free path. There's not much mass there, so the "heat" is small. That is, even though the ionosphere is "hot" in a temperature sense, it's not very "hot" in a sensible transfer of heat sense. BTW, I think the sunburn is not from thermal absorption, but from photons with enough energy to make the reaction go. The total energy in the UV of sunlight is MUCH lower than the total energy in the visible range. The power spectrum of sunlight is pretty close to the spectral sensitivity of your eyes (which evolved that way to match, I would think). A good graph of sunlight power density vs wavelength can be found at http://en.wikipedia.org/wiki/File:Solar_Spectrum.png. Comparing areas of various graph sections shows that the UV part of the spectrum contains maybe 1/5 the amount of energy as the visible part -- plenty enough to embrittle plastics and fabrics and sunburn skin. But the infrared energy -- invisible to our eyes -- looks to be at least equal to the visible energy. The plastics degradation is definitely an "athermal" effect (because adding carbon black to the plastic inhibits it, but doesn't change the absorbed power very much. But.. note that the scale is in wavelength and the energy is "per nm" (because that's how spectrophotometers work). the photons have less energy at lower wavelength. (or, you could plot it in frequency, and then look at the watts/Hz to integrate) If you look at power spectral density (e.g. watts/hz) it actually peaks up around 1000 nm (near IR). The Wien displacement law says that 5250K peaks up at about 550 nm, but the power spectral density at 550nm (545 THz) is about 2/3 that at the peak. By the time you get to 350nm (857 THz), the energy per hz is about 10% of what it is at the peak (at 950nm) Running a quick numerical integration... (multiplying the power spectral density every 50 nm by the frequency range).. I get 0.166 for all wavelengths shorter than 320nm, 2.09 for 320-670, and 3.6 for 670-4000 nm (there's a missing integration constant, so the numbers have some scale factor, but the relative amounts should match..) for the band around 400nm, I get .26 and for the band at 550 about 0.34 and for around 650 about .32... Yes, it peaks at 550 nm as expected. |
What exactly is radio
On Mon, 03 May 2010 18:28:25 -0700, Jim Lux
wrote: Roy Lewallen wrote: Jim Lux wrote: Hi Jim, Much of what you write looks like stream-of-consciousness writing. Did/do you have a point? The plastics degradation is definitely an "athermal" effect (because adding carbon black to the plastic inhibits it, but doesn't change the absorbed power very much. UV radiation has migrated awary from electron/atom issues to molecular/ionic bond issues. Calling it "athermal" seems to be returning the discussion to the metaphysical. But.. note that the scale is in wavelength and the energy is "per nm" (because that's how spectrophotometers work). the photons have less energy at lower wavelength. (or, you could plot it in frequency, and then look at the watts/Hz to integrate) What is the significance of changing from wavelength to frequency? (But?) If you look at power spectral density (e.g. watts/hz) it actually peaks up around 1000 nm (near IR). The Wien displacement law says that 5250K peaks up at about 550 nm, but the power spectral density at 550nm (545 THz) is about 2/3 that at the peak. By the time you get to 350nm (857 THz), the energy per hz is about 10% of what it is at the peak (at 950nm) Running a quick numerical integration... (multiplying the power spectral density every 50 nm by the frequency range).. I get 0.166 for all wavelengths shorter than 320nm, 2.09 for 320-670, and 3.6 for 670-4000 nm (there's a missing integration constant, so the numbers have some scale factor, but the relative amounts should match..) for the band around 400nm, I get .26 and for the band at 550 about 0.34 and for around 650 about .32... Yes, it peaks at 550 nm as expected. Without going into the math, it seems like you disputed a figure you then discover "as expected." What was the dispute? What wasn't expected and then came as a surprise? 73's Richard Clark, KB7QHC |
What exactly is radio
Richard Clark wrote:
On Mon, 03 May 2010 18:28:25 -0700, Jim Lux wrote: Roy Lewallen wrote: Jim Lux wrote: Hi Jim, Much of what you write looks like stream-of-consciousness writing. Did/do you have a point? The plastics degradation is definitely an "athermal" effect (because adding carbon black to the plastic inhibits it, but doesn't change the absorbed power very much. UV radiation has migrated awary from electron/atom issues to molecular/ionic bond issues. Calling it "athermal" seems to be returning the discussion to the metaphysical. All in a thread about temperature and heat.. That was actually in response to Roy's original comment "When doing experiments with the sun's rays, you sometimes get non-intuitive results, because there's a lot of energy (heat) at wavelengths we can't see, particularly at the ultraviolet end." and my response that there actually isn't much energy in the UV end. Roy commented about sunburn, and I pointed out that the mechanism in sunburn isn't thermal (and this is important to folks who worry about RF exposure limits and regulatory compliance.. thermal effects have one biological result, athermal effects are another..) My comment was that sunburn (and Roy's example of plastic degradation) are due to the energy of UV photons actually causing a chemical reaction, as opposed to making something happen because of heat. But.. note that the scale is in wavelength and the energy is "per nm" (because that's how spectrophotometers work). the photons have less energy at lower wavelength. (or, you could plot it in frequency, and then look at the watts/Hz to integrate) What is the significance of changing from wavelength to frequency? (But?) Roy's comment was about the amount of energy in the non-visible bands (presumably in response to my comment that human eye sensitivity tends to match that of the solar spectrum/ 5250K blackbody), and he cited the very commonly seen graph in W/nm, with a scale linear in nm. My point is that in the RF world, we tend look at power spectral density in terms of W/Hz, so when you are looking at the graphs (with a linear scale of wavelength or frequency, as apppropriate), a visual estimate of the "integrated area under the curve" can be misleading. If you plot the same data, but in W/Hz, and with a scale linear in frequency, you get a very different looking graph. Try it.. the equation is of the general form power density (per hertz) = constant1*frequency^3/(exp(constant2*frequency/T)-1) power density (per unit wavelength) = constant1/lambda^5 * 1/(exp(constant2/(lambda*T))-1) |
What exactly is radio
Thanks, Jim for the correction. I had failed to notice that the graph
scale was normalized to wavelength. I stand corrected. Roy Lewallen, W7EL |
What exactly is radio
Roy Lewallen wrote:
Thanks, Jim for the correction. I had failed to notice that the graph scale was normalized to wavelength. I stand corrected. Roy Lewallen, W7EL To be honest, I'm not sure which one is appropriate to integrate. In theory, if you're integrating between two limits you'd use the expression that matches how the limits are specified.. That is, if you wanted to get the energy between 350 and 600 nm, then you'd use the energy/nm OTOH, if you wanted to integrate between 470 THz and 800THz, you'd use energy/Hz. they "should" come out with the same answer (especially in the limit of actual integration with respect to d(nu) or d(lambda)). It's probably only when you do a rough and ready numerical integration (or do it by eye off the graph) that it makes a difference. Actually, it's kind of interesting that you brought it up, because, like you, I'd always seen the W/nm with a linear scale in nm graphs... |
What exactly is radio
On Tue, 04 May 2010 12:08:28 -0700, Jim Lux
wrote: That is, if you wanted to get the energy between 350 and 600 nm, then you'd use the energy/nm OTOH, if you wanted to integrate between 470 THz and 800THz, you'd use energy/Hz. The units would cancel unless that is your intent - but I am still stymied by what is being sought by these elaborations. they "should" come out with the same answer (especially in the limit of actual integration with respect to d(nu) or d(lambda)). Hence my question about the significance of changing domains when either integration must, ultimately, come to the same thing in power. None of this is currently being expressed in energy (a term being commingled with power), which for optoelectronics would be eV. This would raise a curious representation of a third domain with re-rigging the wavelength/frequency scale into the appropriate energy scale of eV vs. power. The solar radiation spectrum would thus span (left to right) 5eV to 0.5eV. Where is this leading? 73's Richard Clark, KB7QHC |
What exactly is radio
On Apr 30, 2:14*am, "Peter" wrote:
I'm preparing an article for a local radio club magazine about the nature of radio and electromagnetic radiation in general. While this is a non mathematical and general descriptive treatment of the subject it is a challenge to make it clear and consistent. I know this group has some expertise on this subject and would appreciate any constructive comment and suggestions regarding the attached article. http://members.optushome.com.au/vk6ysf/vk6ysf/radio.htm Thank you for your time. Regards Peter VK6YSF For what it's worth... I've often found it useful to consider alternate ways to think about things. In this thread, there have been some comments about electric fields, magnetic fields and electromagnetic fields. So, I ask: how do we measure fields? As far as I know, it's by their interaction with matter: we observe how an electromagnetic field accelerates electrons, for example. Do we have any way other than by observing how a (E, M, or EM) field interacts with matter to measure a field? If not, does a field _necessarily_ have any physical reality, any reality beyond a mathematical model to explain what we observe? I suppose some here won't be ready to contemplate this in any depth, though others may find it enlightening. One might say that radio is the practical use of the observed physical effect that accelerating charges in one place leads to free charges at distant points being accelerated, in a manner we're able to describe pretty accurately, so far as we know now, with our models. Cheers, Tom |
What exactly is radio
On Tue, 4 May 2010 18:16:26 -0700 (PDT), K7ITM wrote:
For what it's worth... Do we have any way other than by observing how a (E, M, or EM) field interacts with matter to measure a field? Hi Tom, You ask if we have "any way other... [than where a field] interacts with matter." In a side thread, there is the discussion of heat. Heat is a quasi-particle which means it does not exist as a physical entity, but it acts like one (shades of photon duality). Heat is wholly without matter, but in the whole absence of matter there is no such thing as heat. As to the remainder of the quote "to measure." This demands physicality and your statement is self-negating in its plea. If we rewind to the beginning of the plea, "observing" is a physical interference described by Heisenberg. The bookends of your plea are, then, doubly negating. That or (and here the thread returns to metaphysics once again) interactions go unwitnessed - which is an existential negation. Expecting any reports from the Cat in the Box? Perhaps through an entangled cat? 73's Richard Clark, KB7QHC |
What exactly is radio
K7ITM wrote:
For what it's worth... I've often found it useful to consider alternate ways to think about things. In this thread, there have been some comments about electric fields, magnetic fields and electromagnetic fields. So, I ask: how do we measure fields? As far as I know, it's by their interaction with matter: we observe how an electromagnetic field accelerates electrons, for example. Do we have any way other than by observing how a (E, M, or EM) field interacts with matter to measure a field? If not, does a field _necessarily_ have any physical reality, any reality beyond a mathematical model to explain what we observe? . . . On the first day of the first class of Electromagnetic Fields, I asked the professor (Carl T.A. Johnk, author of _Engineering Electromagnetic Fields and Waves_), "What is an electromagnetic field?" His answer: "It's a mathematical model we use to help us understand phenomena we can observe and measure." And I see that in the second paragraph of his book he writes "A field is taken to mean a mathematical function of space and time." I've been satisfied with that definition. Roy Lewallen, W7EL |
What exactly is radio
4 "Roy Lewallen" wrote ... K7ITM wrote: For what it's worth... I've often found it useful to consider alternate ways to think about things. In this thread, there have been some comments about electric fields, magnetic fields and electromagnetic fields. So, I ask: how do we measure fields? As far as I know, it's by their interaction with matter: we observe how an electromagnetic field accelerates electrons, for example. Do we have any way other than by observing how a (E, M, or EM) field interacts with matter to measure a field? If not, does a field _necessarily_ have any physical reality, any reality beyond a mathematical model to explain what we observe? . . . On the first day of the first class of Electromagnetic Fields, I asked the professor (Carl T.A. Johnk, author of _Engineering Electromagnetic Fields and Waves_), "What is an electromagnetic field?" His answer: "It's a mathematical model we use to help us understand phenomena we can observe and measure." And I see that in the second paragraph of his book he writes "A field is taken to mean a mathematical function of space and time." I've been satisfied with that definition. Wiki wrote: "The field can be viewed as the combination of an electric field and a magnetic field. The electric field is produced by stationary charges, and the magnetic field by moving charges (currents); " But what produce very slow charge? Next Wiki weote: "From a classical perspective, the electromagnetic field can be regarded as a smooth, continuous field, propagated in a wavelike manner ;" It is important to know that Maxwell's waves are rotational (oscillating magnetic whirl). Alternate electric field also propagate in a wavelike manner. But here to and fro (no rotations). The fundamental question: Are radio waves a simple electric waves or the very sophisticated Maxwell's waves? S* |
What exactly is radio
On May 3, 7:25*am, "Szczepan Bialek" wrote:
*Radio waves from the dipole are polarized. Does it mean that light is emitted by a dipoles? sure, why not? but polarized waves can be emitted from other things also. We can shield the one end of the dipole. no you can't. Why the dipoles exhibit the directional pattern? because they do, its well measured and accurately described in the equations. |
What exactly is radio
On May 5, 8:52*am, "Szczepan Bialek" wrote:
Wiki wrote: "The field can be viewed as the combination of an electric field and a magnetic field. The electric field is produced by stationary charges, and the magnetic field by moving charges (currents); " an electric field can also be created by a changing magnetic field... and a magnetic field by a changing electric field... no charges needed. But what produce very slow charge? a charge is a charge, it can neither be created nor destroyed.... well except maybe by matter-anti-matter annihilation. charged particles can move at any speed from 0 to c, nothing special about speeds. Next Wiki weote: "From a classical perspective, the electromagnetic field can be regarded as a smooth, continuous field, propagated in a wavelike manner ;" It is important to know that Maxwell's waves are rotational (oscillating magnetic whirl). no they aren't... at least not all of them. maxwells equations are just as well satisfied by linearly polarized (magnetic AND electric field) waves. Alternate electric field also propagate in a wavelike manner. But here to and fro (no rotations). if the magnetic field is rotating then the electric field also rotates. they always go together. The fundamental question: Are radio waves a simple electric waves or the very sophisticated Maxwell's waves? ALL radio waves can be described by maxwell's equations, both simple linear polarized ones and circularly polarized ones. |
What exactly is radio
The fundamental question: Are radio waves a simple electric waves or the very sophisticated Maxwell's waves? ALL radio waves can be described by maxwell's equations, both simple linear polarized ones and circularly polarized ones. The fundamental question is really how can we describe this "wave".? A wave of what "water", A wave of "water" traveling towards a beach. Is it water we are really trying to describe or what? Water has a "skin" on its surface , a skin that encasulates it like a bag , container or a boundary! Nothing is clear when describing a "wave" with respect to physics, as it is just a "F" word to substitute an unexplainable in a psuedo description There is no agreement what so ever as to what a "wave" is so there cannot exist a description of what radio "IS", "IS"!. Physicists acknowledge that radio is some thing that is unexplanable leaving just hams to fill in the unexplainable about radio and to deny the explanations made by others. What we do have is a string of mathematical equations all of which interlock which are a result of observation and seamingly reasonable deductions. Maxwell deduced b y examination of units used that a portion of his formula was also a mathematical explanation of elevation and acceleration but no description of what! A physicists named Gauss who provided a lot of Maxwells tools used Newtons laws to establish boundary laws where it can be seen that mathematically a clump of static particles in equilibrium could be made dynamic by adding a time varying field while retaining equilibrium meshes with Maxwells equations on radiation. So who on earth descided to interject "waves" into the discussion and why? And what experiment was performed that dictated its inclusion in the subject of radio or radiation that has put a screaming halt to a sustainable explanation of same for more than a hundred years where other dreams have come to fruition by utelizing the human brain. Is it the ham population that is responsible for the lack of advances in the advancement of science by denying the inclusion of particles as the basic matter involved in elevation and acceleration (displacement) as implied by Maxwell's equations, preferring instead to use 'water' and 'waves' to describe the science to the non initiated. |
What exactly is radio
"K1TTT" wrote ... On May 3, 7:25 am, "Szczepan Bialek" wrote: Radio waves from the dipole are polarized. Does it mean that light is emitted by a dipoles? sure, why not? but polarized waves can be emitted from other things also. We can shield the one end of the dipole. no you can't. A whip antennas on a car is not such? Why the dipoles exhibit the directional pattern? because they do, its well measured and accurately described in the equations. Are the measured and the calculated from the equations in agreement? S* |
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