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Loading coils: was Dish reflector now: Delay Lines
"Dr. Barry L. Ornitz" wrote in
: "Jim Kelley" wrote in message ... For a more quantitative illustration of how distributed reactance in transmission lines causes delay see http://www.rhombus-ind.com/dlcat/app1_pas.pdf 73, ac6xg In graduate school, more years ago than I care to admit, I scrapped a surplus computer for parts. The computer had been custom built for the Savannah River nuclear facility. In addition to the many hundreds of 2N404A germanium transistors, I found the core memory made of ferrite cores about 0.1 inches in diameter and about 30 mils thick. But the most unusual thing, at least to me, was a flexible coaxial cable about six feet long made of a ferrite-loaded rubber core wound with 40 gauge enameled wire, wrapped in a thin cellulose acetate film (Scotch tape?), covered with a braid shield with a vinyl covering. Of course, it was a distributed delay line. I never measured its impedance and delay properties accurately, but the cable had a significant delay that could easily be seen on a 5 MHz bandwidth scope. Even with an approximate termination, the cable's losses were quite high. Do you think this might have been a Distortionless Line? Owen |
Loading coils: was Dish reflector
"Art Unwin" wrote in message ... EZNEC and the Cecil-Corum method are in agreement. Correct if you had stopped there i would have commended you on another correct response... but you just couldn't, could you??? but the solution is in error as equilibrium demands that the radiator is in equilibrium ie equal to a period or multiples there of. you never have defined equilibrium or shown where it is a requirement on maxwell's equations. i have stated that maxwell's equations rely on NOT being in equilibrium since they describe fields and waves that can vary in time, hence they are not in equilibrium with anything. keep going art, always fun reading! |
Loading coils: was Dish reflector
On Apr 24, 6:33*am, "Dave" wrote:
"Art Unwin" wrote in message ... EZNEC and the Cecil-Corum method are in agreement. Correct if you had stopped there i would have commended you on another correct response... but you just couldn't, could you??? but the solution is in error as equilibrium demands that the radiator is in equilibrium ie equal to a period or multiples there of. you never have defined equilibrium or shown where it is a requirement on maxwell's equations. *i have stated that maxwell's equations rely on NOT being in equilibrium since they describe fields and waves that can vary in time, hence they are not in equilibrium with anything. *keep going art, always fun reading! Boundary laws are a part of nature as is mathematics.Every time you have an equation which uses the equal sign is the mathematical use of physics. It allows the movement of all metrics to one side of the equation such that all metrics used in summation must equal with zero. Maxwell used this very same fact in determining his laws when he found what he had derived was NOT equal zero which thus showed it was missing the metrics of displacement current (deduction) such that all metrics cancelled out.Again an example of Newtons laws where every action has a equal and opposite reaction To determine that tha Maxwell is not using the term Waves is to note that all metrics are nouns in equations and the term "wave" is an adjective. All elermentary. Art |
Loading coils: was Dish reflector
On Apr 24, 7:48*am, Art Unwin wrote:
On Apr 24, 6:33*am, "Dave" wrote: "Art Unwin" wrote in message ... EZNEC and the Cecil-Corum method are in agreement. Correct if you had stopped there i would have commended you on another correct response... but you just couldn't, could you??? but the solution is in error as equilibrium demands that the radiator is in equilibrium ie equal to a period or multiples there of. you never have defined equilibrium or shown where it is a requirement on maxwell's equations. *i have stated that maxwell's equations rely on NOT being in equilibrium since they describe fields and waves that can vary in time, hence they are not in equilibrium with anything. *keep going art, always fun reading! Boundary laws are a part of nature as is mathematics.Every time you have an equation which uses the equal sign is the mathematical use of physics. It allows the movement of all metrics to one side of the equation such that all metrics used in summation must equal with zero. Maxwell used this very same fact in determining his laws when he found what he had derived was NOT equal zero which thus showed it was missing the metrics of displacement current (deduction) such that all metrics cancelled out.Again an example of Newtons laws where every action has a equal and opposite reaction To determine that tha Maxwell is not using the term Waves is to note that all metrics are nouns in equations and the term "wave" is an adjective. All elermentary. Art Please allow me to correct myself on the above Equations comprising of nouns only in a static field. A dynamic field has both adjectives and nouns via the metric of time However the sum of the metrics must still equal zero. Sorry about that Regards Art |
Loading coils: was Dish reflector
"Art Unwin" wrote in message ... On Apr 24, 7:48 am, Art Unwin wrote: Please allow me to correct myself on the above you never did answer my question, but thats ok, you never have before either... now you try parsing the language and think that provides insight... just write the equation, what is equilibrium in your mind? i know this is tough, you are so far out of balance anyway, but try to amuse me a bit and write a concise definition of 'equilibrium'. |
Loading coils: was Dish reflector
On Apr 24, 10:47*am, "Dave" wrote:
"Art Unwin" wrote in message ... On Apr 24, 7:48 am, Art Unwin wrote: Please allow me to correct myself on the above you never did answer my question, but thats ok, you never have before either... now you try parsing the language and think that provides insight... just write the equation, what is equilibrium in your mind? *i know this is tough, you are so far out of balance anyway, but try to amuse me a bit and write a concise definition of 'equilibrium'. I will be happy to David It is balance as referred to by the mathematical equal (=) term where all metrics can be placed to one side and summed to the value of zero. In physics it represents the physical laws of Newton and other where "every action has an equal and opposite reaction" as used in the time worn uses when establishing a arbitrary border as per Gauss's law of Statics or Maxwell when determining the absence of metrics deduced the missing levitational force( displacement current) in his law's or calculations. All of which were established by observations thru the years of the Universe with respect to Earth in relative form . ( See Einstein's law of relativity) This can be seen as motivation of the Grand Universal Theory which Einstein gave up on because of his failure to identify what is known as the "weak force" which is part of the standard model of physics. It was Foucault that much, much later that found or discovered the displacement current which is what I determine to be the "weak force" and also the required metrics that Maxwell added to his equations to represent the measure of equilibrium. The above explanation is probably longer than what is usually found in terms of words but I tried to relate to the evolution of physics with respect to that same word to provide better understanding rather than describing it in niche terms of mechanical and electrical terms of the physical Universe I thought you were getting bored with physics! Regards Art Unwin KB9MZ..xg |
Loading coils: was Dish reflector
On Apr 24, 11:25*am, Art Unwin wrote:
On Apr 24, 10:47*am, "Dave" wrote: "Art Unwin" wrote in message .... On Apr 24, 7:48 am, Art Unwin wrote: Please allow me to correct myself on the above you never did answer my question, but thats ok, you never have before either... now you try parsing the language and think that provides insight... just write the equation, what is equilibrium in your mind? *i know this is tough, you are so far out of balance anyway, but try to amuse me a bit and write a concise definition of 'equilibrium'. I will be happy to David It is balance as referred to by the mathematical equal (=) term where all metrics can be placed to one side and summed to the *value of zero. In physics it represents the physical laws of Newton and other where "every action has an equal and opposite reaction" as used in the time worn uses when establishing a arbitrary border as per Gauss's law of Statics or Maxwell when determining the absence of metrics deduced the missing *levitational force( displacement current) in his law's or calculations. All of which were established by observations thru the years of the Universe with respect to Earth in relative form . ( See Einstein's law of relativity) This can be seen as motivation of the Grand Universal Theory which Einstein gave up on because of his failure to identify what is known as the "weak force" which is part of the standard model of physics. It was Foucault that much, much later that found or discovered the displacement current which is what I determine to be the "weak force" and also the required metrics that Maxwell added to his equations to represent the measure of equilibrium. The above explanation is probably longer than what is usually found in terms of words but I tried to relate to the evolution of physics with respect to that same word to provide better understanding rather than describing it in niche terms of mechanical and electrical terms of the physical Universe I thought you were getting bored with physics! Regards Art Unwin KB9MZ..xg While putting my definition down with respect to equilibrium it seems a good time to expand it to why particles and not waves are the subject of Maxwell's laws. Both Maxwell and Gauss generated arbitrary borders in their summation of the laws of statics and the laws of radiation. The only difference between them is one descibes a static fiels while the other descibes a dynamic field both of which the forces must be summed up to equal zero. It was Maxwell you changed the static field to a dynamic field when he saw that the metric of time was only on one side of the equation which meant that the unlikely discovery of an equation that was not in equilibrium within the boundaries of the environment under consideration. Thus he expanded the law of statics by making it dynamic which required the addition of the metric of time which would cancel out when establishing the presence of equilibrium. It should now be obvious to all on this group struggling with waves versus particles that when changing the field to dynamic one must recognise that mass or particles are present in this action and not waves. This provides authenticity of my personal position of the presence of particles in radiation and all laws of our Universe. Hopefully the above will convince all other members of this group as well as those that deny the presence of the Grand Unification Theory but I will not hold my breath. Regards Art Unwin KB9MZ xg |
Loading coils: was Dish reflector
Richard Clark wrote:
On Thu, 23 Apr 2009 15:29:04 -0700, Jim Kelley wrote: Cecil Moore wrote: Jim Kelley wrote: ... and as any good dry labber knows, it's a dead giveaway to report a precision greater than one can actually measure. :-) I have reported no precision - my 100 MHz scope has not been calibrated since I retired. Precision is the number of sig figs. You "might" have calculated three, rounded up, and reported two. Precision is NOT accuracy. No one said it was, Richard. Thanks though. ac6xg |
Loading coils: was Dish reflector
"Art Unwin" wrote in message ... On Apr 24, 11:25 am, Art Unwin wrote: On Apr 24, 10:47 am, "Dave" wrote: "Art Unwin" wrote in message ... On Apr 24, 7:48 am, Art Unwin wrote: Please allow me to correct myself on the above you never did answer my question, but thats ok, you never have before either... now you try parsing the language and think that provides insight... just write the equation, what is equilibrium in your mind? i know this is tough, you are so far out of balance anyway, but try to amuse me a bit and write a concise definition of 'equilibrium'. I will be happy to David It is balance as referred to by the mathematical equal (=) term where so any equation with an equals sign is in equilibrium?? that applies to everything then, since all equations contain an equals sign they are all in equilibrium by definition. my i'm glad you explained that art, i might have gone through life never knowing that by taking e=ir and rewriting it as e-ir=0 i have put ohms law in equilibrium and then all is well with the universe! so the conversion of mass to energy in the famous equation e=mc^2 is really in equilibrium as e-mc^2=0, so no mass is converted to energy or vice versa! wow, what a revelation! thanks again art! |
Loading coils: was Dish reflector
Art wrote:
"I thought you were getting bored with physics!" We must live with physics, bored or not. The parabola is well understood. its use as a reflector is documented by Kraus and the "ARRL Antenna Book". A good description is seen in "Principles of Radar" published by the MIT Radar School Staff in 1946. On page 9-78: "The geometrical properties of parabolas are important for demonstrating the existence of a constant-phase surface. First, a parabola is by definition the focus of points as far from a fixed point called the focus as from a fixed line called the directrix. With reference to Fig. 51A, this means that lengths AA` and AF are equal, BB`and BF are equal, and so on. Second, a line drawn tangent to a parabola at any point (as in Fig. 51B) makes equal angles with a line drawn from this point back to the focus and a line from this point parallel to the axis of the parabola. When a point source is placed at the focus, it sends out energy in a single time phase, but in various directions. This energy strikes the paraboloid at points such as A, B, and C, (in Fig.51A), and is reflected in a direction parallel with the axis because of the second property mentioned. The first property predicts that the phase change that the wave undergoes in traveling to points A``, B``, and C`` on the surface SS` is the same for each ray, the phase change being equal to the distance in electrical degrees, from the diretrix to the surface SS` plus 180 degrees, due to the phase reversal upon reflection. Thus the field reflected from the parabola has a single time phase in a plane across the mouth of the parabola. The field radiated forward by the point source tends to upset this constant-phase surface, but this effect is usually minimized through the use of sources which radiate appreciably only roward the reflector. Best regards, Richard Harrison, KB5WZI |
Loading coils: was Dish reflector now: Delay Lines
"Owen Duffy" wrote in message
... "Dr. Barry L. Ornitz" wrote in : Of course, it was a distributed delay line. I never measured its impedance and delay properties accurately, but the cable had a significant delay that could easily be seen on a 5 MHz bandwidth scope. Even with an approximate termination, the cable's losses were quite high. Do you think this might have been a Distortionless Line? With the limited bandwidth of the scope, it looked like there was little distortion. I could see no overshoot or ringing like that seen with conventional artificial delay lines, but I suspect that the junky scope was the reason. In early radars, liquid-filled tubes with acoustic sensors on each end were used to produce time delays. Typically mercury or water, being incompressible, were used to fill the tubing. I have seen commercial delay lines made from quartz rods too. The rods were generally quite small in diameter but were very long and wound into a spiral. Of course then there were audio "reverbs" that used springs stretched between transducers. Back when I was doing lots of analog computer work simulating automatic control systems, I used Padé approximations to simulate pure time delay. Since we are getting rather far away from antennas and transmission lines, I will give references rather than discuss this here. -- 73, Dr. Barry L. Ornitz WA4VZQ Padé approximant - Wikipedia, the free encyclopedia http://en.wikipedia.org/wiki/Pad%C3%A9_approximant Padé approximation of model with time delays - MATLAB (Control System Toolbox) http://www.mathworks.com/access/help.../ref/pade.html Padé Approximation of Delays http://www.ee.bilkent.edu.tr/~ee342/Laboratory/pade.pdf Padé Approximation http://math.fullerton.edu/mathews/n2...mationMod.html [Example 9 is especially appropriate] |
Loading coils: was Dish reflector now: Delay Lines
"Dr. Barry L. Ornitz" wrote in news:2BoIl.67540
: Since we are getting rather far away from antennas and transmission lines, I will give references rather than discuss this here. Well, we all like Distortionless Lines, almost all ham discussion and indeed much if not most textbook discussion is about one special case of a Distortionless Line, the Lossless Line. Nevertheless, we apply one property of Distortionless Lines to real lines, the property that Zo=Ro+j0, and that Zo is independent of frequency. But, a real Distortionless Line (real excludes Lossless) doesn't have much application for us. Though I haven't had my hands on a Distortionless Line, it occurs to me that increasing L/m is a means of diminishing the effect of changing R/m, making G/m higher is another means of making Zo real, and if the materials make R/m(f) track G/m(f) closely ... then the problem is mostly solved. Owen |
Loading coils: was Dish reflector
On Apr 24, 2:08*pm, "Dave" wrote:
"Art Unwin" wrote in message ... On Apr 24, 11:25 am, Art Unwin wrote: On Apr 24, 10:47 am, "Dave" wrote: "Art Unwin" wrote in message .... On Apr 24, 7:48 am, Art Unwin wrote: Please allow me to correct myself on the above you never did answer my question, but thats ok, you never have before either... now you try parsing the language and think that provides insight... just write the equation, what is equilibrium in your mind? i know this is tough, you are so far out of balance anyway, but try to amuse me a bit and write a concise definition of 'equilibrium'. I will be happy to David It is balance as referred to by the mathematical equal (=) term where so any equation with an equals sign is in equilibrium?? *that applies to everything then, since all equations contain an equals sign they are all in equilibrium by definition. *my i'm glad you explained that art, i might have gone through life never knowing that by taking e=ir and rewriting it as e-ir=0 i have put ohms law in equilibrium and then all is well with the universe! *so the conversion of mass to energy in the famous equation e=mc^2 is really in equilibrium as e-mc^2=0, so no mass is converted to energy or vice versa! *wow, what a revelation! *thanks again art! Well not exactly. The innards of the arbitary boundary must be in a state of equilibrium thus when making the arbitrary field a dynamic field by adding time or such things as radiators the innards must stay in equilibrium. Thus if radiators are added they also must be in equilibrium which requires all to be approximately one WL or the equivalent of one or more periods of the frequency in use. Thus the majoritory of added radiators may be the one of choice in terms of feed point |
Loading coils: was Dish reflector
"Art Unwin" wrote in message ... On Apr 24, 2:08 pm, "Dave" wrote: radiators are added they also must be in equilibrium which requires all to be approximately one WL or the equivalent of one or more periods of the frequency in use. Thus the majoritory of added radiators may be the one of choice in terms of feed point ok, if a one wl radiator is in equilibrium, give me the equation describing the current and radiation pattern from that radiator in free space. |
Loading coils: was Dish reflector
On Apr 24, 5:37*pm, "Dave" wrote:
"Art Unwin" wrote in message ... On Apr 24, 2:08 pm, "Dave" wrote: radiators are added they also must be in equilibrium which requires all to be approximately one WL or the equivalent of one or more periods of the frequency in use. Thus the majoritory of added radiators may be the one of choice in terms of feed point ok, if a one wl radiator is in equilibrium, give me the equation describing the current and radiation pattern from that radiator in free space. David you are fishing for info for your next phase of attack. Soon I will get right on it and work thru day and night and all weekends per your request of me so please do not arrest me if I do not fullfill all of your expectations of me. I have asked my wife to delay her birthday because obviously your demands of me with respect to antennas or equilibrium comes first. I would remind you that I did supply dimensions of a tipped radiator in equilibrium some time ago on this newsgroup but you showed zero interest. What has changed? Your devoted servant Art |
Loading coils: was Dish reflector
Art Unwin wrote:
I would remind you that I did supply dimensions of a tipped radiator in equilibrium some time ago on this newsgroup but you showed zero interest. What has changed? Your devoted servant Art X (sub) L = X (sub) C Is this what you mean by "equilibrium"? |
Loading coils: was Dish reflector
"Art Unwin" wrote in message ... On Apr 24, 5:37 pm, "Dave" wrote: I would remind you that I did supply dimensions of a tipped radiator in equilibrium some time ago on this newsgroup but you showed zero interest. What has changed? Your devoted servant tipping a radiator is an obvious exploit of changes in pattern by unbalancing the ground current. it gives some gain in one direction at the expense of other directions. it is not all that useful unless you want a tipsy looking antenna and are covering a fixed direction... unless you made an array of tipsy verticals for vhf and rotated them... that might be fun. besides i had enough bent elements from the winter ice, they didn't improve the yagi performance. so i've had enough of that. but 'equilibrium' as defined by art is a magic jewel to be examined. i do take exception with 'dave' though, the equation should be Xl=-Xc or Xl+Xc=0 to put it in art's form. |
Loading coils: was Dish reflector
On Apr 24, 6:48*pm, dave wrote:
Art Unwin wrote: *I would remind you that I did supply dimensions of a tipped radiator in equilibrium some time ago on this newsgroup but you showed zero interest. What has changed? Your devoted servant Art X (sub) L = X (sub) C Is this what you mean by "equilibrium"? There is something going on I am outa here. Why not just review my patent request to get the info |
Loading coils: was Dish reflector
Art Unwin wrote:
I am outa here. First accurate thing he has said in a while. Hang on, possibly I am confused. Maybe it was precise. Yup, I am resolute now. tom K0TAR |
Loading coils: was Dish reflector now: Delay Lines
"Dr. Barry L. Ornitz" wrote in news:qmxIl.84715
: .... While we have been talking about conventional electrical transmission lines, we can also analyze nerves as a transmission line. A nerve is essentially an electrical transmission line with chemical transducers on each end. When a receptor synapse detects a neurotransmitter, like serotonin or norepinephrin, it sends an electrical signal down the neuron. The neuron is the transmission line. It is essentially an ionic conductor covered with a fatty substance known as myelin. The result is a distributed resistance- capacitance line. In diabetics, the myelin sheath is partially destroyed and replaced with sorbitol, a sugar alcohol. In addition to being more conductive than myelin, sorbitol has a far higher dielectric constant. Viewing the neuron as a distributed RC line, we have both added shunt conductance and increased the capacitance. It is no wonder that nerve conduction velocity and amplitude both decrease resulting in such things as peripheral neuropathy, usually associated with diabetics. I contracted a disease when I was young, a disease that caused the body's T cells to attack the cells of the mylon sheath (in our terms, the dielectric that separates the =ve and -ve ionic material in the nerve's coaxial cable, effectively shorting the coax. During a week or two of onset of the disease, the doctors performed TDR like tests on nerves in my legs, placing a pair if needles each side of a motor nerve, at each end of the nerve, and pulsing the nerve from a signal generator. The sig gen fired a CRO with a camera and 100' roll film back. They took thousands of pics over the couple of weeks, measuring attenuation and velocity of propagation. Yes, I am aware that there are parallels. Owen |
Loading coils: was Dish reflector now: Delay Lines
Barry,
I see I got the spelling of myelin wrong. I remember things I see, and at that time I couldn't focus on things, never saw the word written, was paralysed and was distressed at drowning in my own secretions because I couldn't swallow and couldn't cough. Anyway, I have got it now, myelin! Owen |
Loading coils: was Dish reflector now: Delay Lines
"Owen Duffy" wrote in message
... Barry, I see I got the spelling of myelin wrong. Don't worry, Owen. Most of the time, I put two "l's" in the word myself! I remember things I see, and at that time I couldn't focus on things, never saw the word written, was paralyzed and was distressed at drowning in my own secretions because I couldn't swallow and couldn't cough. About two years ago I developed phlebitis. I went to the doctor who had Doppler ultrasound tests run. He told me that my circulation was good and that the swelling in the left leg would clear up by itself within a week. But one of my toes swelled up and cracked open. Being a diabetic, I immediately returned to the physician. He told me that I had just enough time to drop by my home and pick up some clean underwear to take with me to the hospital. When I got to the emergency room, admission papers were waiting. I had no idea that septicemia could set in so fast. They amputated two toes, then another, and finally my entire left foot. Meanwhile I had continuous IV injections of some of the world's strongest antibiotics. I lost weight too - from 215 to 155 pounds. Small clumps of dead blood cells were sloughing off my heart valves and one blocked a tiny capillary in my brain causing expressive aphasia. It only lasted about three days, but I will forever empathize with stroke victims. I could do complex math in my head, but I could not speak a complete sentence. Fortunately I started recovering soon after the foot was taken. I am posting this history here as a warning to other diabetics. My HgA1c had been running less than 5.5; most diabetics are considered to have good control if this number is below 7. My point is that even with good glucose control, problems can still develop. I too have had nerve conduction studies. As you said, they stick little electrodes in your muscles and nerve bundles, only now they have fancy microprocessor-controlled machines to do the tests. But the tests are just as painful! The worst thing I remember was the neurologist bragging to his nurse, telling her,"Now if I turn this knob, I can make his big toe rotate counter-clockwise." Thanks for an interesting discussion, Owen. -- 73, Dr. Barry L. Ornitz WA4VZQ |
Loading coils: was Dish reflector
"Art Unwin" wrote in message ... On Apr 24, 6:48 pm, dave wrote: There is something going on yeah, more people are understanding that you are full of hot air. I am outa here. awwww, just when it was starting to get to be fun. Why not just review my patent request to get the info patents are only meant for lawyers, they rarely have anything really interesting in them. unless of course yours is written like the faster than light antenna that also makes plants grow faster. |
Loading coils: was Dish reflector
On Apr 25, 10:22*am, "Dave" wrote:
"Art Unwin" wrote in message ... On Apr 24, 6:48 pm, dave wrote: There is something going on yeah, more people are understanding that you are full of hot air. I am outa here. awwww, just when it was starting to get to be fun. Why not just review my patent request to get the info patents are only meant for lawyers, they rarely have anything really interesting in them. *unless of course yours is written like the faster than light antenna that also makes plants grow faster. Art seems to think that getting a patent validates an idea. In fact devices/ideas that claim to violate known laws of physics are easiest to patent as they will have little to no conflict with other patents. Jimmie |
Loading coils: was Dish reflector now: Delay Lines
Dr. Barry L. Ornitz wrote:
I too have had nerve conduction studies. I also. The voltage getting to the nerves in my feet is 2% of normal. -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
Loading coils: was Dish reflector now: Delay Lines
Cecil Moore wrote:
Dr. Barry L. Ornitz wrote: I too have had nerve conduction studies. I also. The voltage getting to the nerves in my feet is 2% of normal. That's because you're longer than anyone else. 73, Tom Donaly, KA6RUH |
Loading coils: was Dish reflector now: Delay Lines
Tom Donaly wrote:
That's because you're longer than anyone else. Well, just longer than most. The doctor says that when the distance from my spinal column to the numbness in my legs gets equal to the distance from my spinal column to my fingers, they will also start to get numb. It's something that happens but nobody seems to know why. -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
Loading coils: was Dish reflector now: Delay Lines
Cecil Moore wrote:
Tom Donaly wrote: That's because you're longer than anyone else. Well, just longer than most. The doctor says that when the distance from my spinal column to the numbness in my legs gets equal to the distance from my spinal column to my fingers, they will also start to get numb. It's something that happens but nobody seems to know why. That sounds like something not to look forward to. You'd think medical researchers would be able to at least hazard a guess. I have a friend with a similar problem and the same response from his doctors. 73, Tom Donaly, KA6RUH |
Dish reflector
On Apr 11, 3:58*am, Helmut Wabnig hwabnig@ .- --- -. dotat wrote:
On Thu, 9 Apr 2009 20:05:20 -0700 (PDT), Art Unwin wrote: I made a helical end fed antenna that is inside a cone shaped reflector The reflector is made from 1/2" mesh steel with an aluminum foil liner and connected to the braid of the feed coax. No baluns are used, just direct connections. I was surprised to hear signals from the rear! I thought that a dish reflector prevented such signals getting to the receiver. So what can be wrong with the reflector or can signals get reflected back from the frontal area? Antenna is at a 40 foot height Any ideas as to what the fault could be? Regards Art I have no experience with dishes thus the question Note, the helical antenna does not protrude beyond the dish envelope. Art How do you know? The "rear" signals may come from the front side actually, having been reflected by your neighbours house, or distant mountains, or anything in between. w. Helmut I do not know if the rear signals were as you suspected., It is extremely windy here in the midwest for the last few days so I took off the new dish of it's ground stand and placed the dish in a corner outside the house with a TOA that I assume is about 10-15 degrees. Again I got rear signals but I noticed the coverage was very narrow and maybe more than one. So next two weeks or so I will repeat the test but also play around with the elevation to see if there are other observables to determine if you are correct. I am playing with circular polarisation which is a new experience for me and I believe that is capable of picking up reflections that one does not normally see with planar designs Best regards Art |
Dish reflector
On Apr 26, 5:10*pm, Art Unwin wrote:
On Apr 11, 3:58*am, Helmut Wabnig hwabnig@ .- --- -. dotat wrote: On Thu, 9 Apr 2009 20:05:20 -0700 (PDT), Art Unwin wrote: I made a helical end fed antenna that is inside a cone shaped reflector The reflector is made from 1/2" mesh steel with an aluminum foil liner and connected to the braid of the feed coax. No baluns are used, just direct connections. I was surprised to hear signals from the rear! I thought that a dish reflector prevented such signals getting to the receiver. So what can be wrong with the reflector or can signals get reflected back from the frontal area? Antenna is at a 40 foot height Any ideas as to what the fault could be? Regards Art I have no experience with dishes thus the question Note, the helical antenna does not protrude beyond the dish envelope. Art How do you know? The "rear" signals may come from the front side actually, having been reflected by your neighbours house, or distant mountains, or anything in between. w. Helmut I do not know if the rear signals were as you suspected., It is extremely windy here in the midwest for the last few days so I took off the new dish of it's ground stand and placed the dish in a corner outside the house with a TOA that I assume is about 10-15 degrees. Again I got rear signals but I noticed the coverage was very narrow and maybe more than one. So next two *weeks or so I will repeat the test but also play around with the elevation to see if there are other observables to determine if you are correct. I am playing with circular polarisation which is a new experience for me and I believe that is capable of picking up reflections that one does not normally see with planar designs Best regards Art Helmut. Re original thread on dish I found out what the problem was! The dish itself was in the antenna circuit thus the dish was part of the antenna and receiving omni.ie chassis and ground was the same connection I have discarded the dish experiment and have gone back to the original design roots. I can hold it up on one hand stretched out without problems and not only is it light but also small. Have placed a small cctv rotator and tipper on a table outside and am now setting up the controls. I suppose I will have to add a decoder to the motors at a later date so I can determine positions to follow the band conditions as they change I do not have a direction indicator so I will wait for a warm day where I can operate it and seethe position at the same time. The tipping action will give me control of the skip distance so that should prove to be very interesting. Anyway, glad that I now have direction ability back. Tks for your interest. Regards Art |
Dish reflector
"Art Unwin" wrote in message ... I found out what the problem was! The dish itself was in the antenna circuit thus the dish was part of the antenna and receiving omni. DOH! I have discarded the dish experiment AWWW, i would have loved to have a rotatable dish for 160m! |
Dish reflector
On Apr 29, 6:10*pm, "Dave" wrote:
"Art Unwin" wrote in message ... I found out what the problem was! The dish itself was in the antenna circuit thus the dish was part of the antenna and receiving omni. DOH! I have discarded the dish experiment AWWW, i would have loved to have a rotatable dish for 160m! David I still have that rotatable form for top band! I just gave up on large dish experiments! As I stated I like the idea of small and light antennas so I am keeping to those root desires. I am getting older so the idea of climbing towers has to be adressed. Thus as an engineer I solved that problem, now antennas where the height is not a necessity for low take off angles! I now have to find out what the greatest distance can be by substituting one skip for the presently used two skips ie min TOA. Since there are not the usual sun spots one has to be inovative and devise means around it. I can still add a dish ofcourse but I like the idea of a pencil beam as it will add more gain to that single skip action. You really should get off that couch and figure out how you are going to handle a poor sun spot cycle. My cctv rotator will never be able to handle such a design when tipping is required as the weight would overcome the motor and it would point into the ground, they are built for just a small camera not a tank. By the way the antenna is good for 2 meg upto 170 meg which are the range limits of my MFJ 259 meter. My guess is that it is good for broadcast band upto a giga or more. Did you fall down? Best regards Art Regards Art |
Dish reflector
On Wed, 29 Apr 2009 23:10:03 GMT, "Dave" wrote:
"Art Unwin" wrote in message ... I found out what the problem was! The dish itself was in the antenna circuit thus the dish was part of the antenna and receiving omni. On Thu, 9 Apr 2009 20:05:20 -0700 (PDT), Art Unwin wrote: No baluns are used That alone is at least one thing wrong with the design. Three weeks and 300 messages ignored to discover first principles were violated. Is this discovery in time for this year's NoBell prize? 73's Richard Clark, KB7QHC |
Dish reflector
Roy Lewallen wrote:
There's no such thing as "standing wave current". You'll find no references to this fictitious entity in any electromagnetics text. On the contrary, "Traveling Wave Engineering", R.K.Moore, page 134: Fig. 5-12. Voltage and Current Standing Waves on open-circuited line. i = Re(V+/Z0)[e^j(wt+bd)+e^j(wt-bd) This is the same equation for standing wave current that appears in "Fields and Waves ...", Ramo and Whinnery. -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
Dish reflector
Cecil Moore wrote:
Roy Lewallen wrote: There's no such thing as "standing wave current". You'll find no references to this fictitious entity in any electromagnetics text. On the contrary, "Traveling Wave Engineering", R.K.Moore, page 134: Fig. 5-12. Voltage and Current Standing Waves on open-circuited line. i = Re(V+/Z0)[e^j(wt+bd)+e^j(wt-bd) This is the same equation for standing wave current that appears in "Fields and Waves ...", Ramo and Whinnery. So I guess that ups the total now to at least two that we know of. Just exactly how many different kinds of alternating current do you reckon there are, Cecil? :-) ac6xg |
Dish reflector
Jim Kelley wrote:
So I guess that ups the total now to at least two that we know of. Just exactly how many different kinds of alternating current do you reckon there are, Cecil? :-) The point is that the current in a pure standing wave has a different equation from the current in a pure traveling wave. Any fields and waves reference book will have those equations. The current in a pure standing wave cannot be used to measure any kind of phase shift between points because the phase doesn't shift between points on a wire or on a coil. The current in a standing-wave antenna, like a loaded mobile antenna, is primarily standing wave current. Why do you think they are called standing wave antennas? -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
Dish reflector
Cecil Moore wrote:
Jim Kelley wrote: So I guess that ups the total now to at least two that we know of. Just exactly how many different kinds of alternating current do you reckon there are, Cecil? :-) The point is that the current in a pure standing wave has a different equation from the current in a pure traveling wave. No, actually the point was the name. Any fields and waves reference book will have those equations. And what they don't have is different and assorted pet names for current. The current in a pure standing wave cannot be used to measure any kind of phase shift between points because the phase doesn't shift between points on a wire or on a coil. If there is no difference in the relative phase of the forward and reflected waves, then there is no change in the amplitude of the standing wave in x. But when there is a change in the amplitude of the standing wave in x, and I max is known, then determining the shift in phase from the equation is a no brainer, Cecil. Other than Imax (and you claim that assuming it's unity is good enough), there's virtually nothing else that determines the amplitude of the standing wave envelope along x. Helloooo. The current in a standing-wave antenna, like a loaded mobile antenna, is primarily standing wave current. And you keep saying that as if it had some special significance. ac6xg |
Dish reflector
"Art Unwin" wrote in message ... On Apr 29, 6:10 pm, "Dave" wrote: David I still have that rotatable form for top band! I just gave up on large dish experiments! As I stated I like the idea of small and light antennas so I am keeping to those root desires. I can still add a dish ofcourse but I like the idea of a pencil beam as it will add more gain to that single skip action. good, when you get that rotatable pencil beam antenna for 160m let me know. |
Dish reflector
On Apr 30, 6:09*pm, "Dave" wrote:
"Art Unwin" wrote in message ... On Apr 29, 6:10 pm, "Dave" wrote: David I still have that rotatable form for top band! I just gave up on large dish experiments! As I stated I like the idea of small and light antennas so I am keeping to those root desires. I can still add a dish ofcourse but I like the idea of a pencil beam as it will add more gain to that single skip action. good, when you get that rotatable pencil beam antenna for 160m let me know. I believe I have it now but I have yet to demonstrate and thus prove. But for you tomorrow is another day and tomorrow never comes. Regards Art |
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