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#27
September 27th 06, 06:34 PM
posted to rec.radio.amateur.antenna
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Yagi efficiency
"art" wrote in message oups.com... Dan, you know quite well what the post that started this thread asked for. I only added the TOA comments to fill in some body where I was coming from not for advice on what antenna to build. People are quibling over the word "efficiency" which I find rather wierd especially since I am supposed to be in the company of fellow engineers. The subject was antenna radiation patterns and ascertaining the relative volume of the main lobe which is the reason for an antenna and comparing it to the total volume of the array which one accepts to obtain the desirable primary lobe. Oh yes, when we talk of efficiency one must multiply the ratio by 100 Some may have forgotten that! Obviously this group comprises of a swarm of tadpoles with a few little goldfish in a small pond none of which are qualified to be termed faculty. Now you have something to get your teeth into since you deign to respond to the initial post This term "I don't understand" is usually used by student who enter class after late night partying and it didn't work then either. A dull brain is a dull brain unless one activates it. Carry on with a thread of your own choice and quibble amongst yourselves about what "is" is really meant by use of the word "is" For what was a very short question this thread has gone amok and is way to long Art wrote: The moral of inventing meanings for words is that those meanings have a short shelf life. This kind of thing doesn't even last out a week in the white house press room. True, true. If only all this word-twisting energy could be harnessed as valid antenna design... the chipster seems to have relegated himself these days to fairly innocuous posts elsewhere regarding staying on the good side of your neighbors' graces by putting up visually low profile antennas... Certainly a change from the f-word antenna wars of old. I was a regular reader of r.r.a.a. in those days... not much of a poster back then, though. I wonder if a thousand-mile long, five mile high stack of rhombics might meet Art's requirements... of course, at that point you could just run open wire line to any distant receiver. That would be quite efficient, from Art's standpoint. 73, Dan Your definition of efficencency was accepted and then a very good answer within the boundaries of your definition was given which you rejected. The fact is if you could recover all the energy that goes into the sidelobes or radiates from the rear of the antenna and place it in the main beam you would increase power in that direction precious little. Apparently what you are seeking is a LASER beam performing in the HF spectrum. Even this would not be very "efficent" for communicating from one point on the surface of the earth to another point below the horizon that is to say you cant send a signal through the Earth. Communication through the air via radio is inherently inefficent if you look at it from the standpoint of thousands to millions of watts at the transmitter with only microwatts being received. In the futre we may learn to transmit nearly all of the power to a distant point. If this happenes the most efficent method of getting an HF signal across the ocean will be a moot point. By then will will be doing matter/energy/matter conversion so that we will be able to transmit ourselves over long distances if this is at all possible. In the mean time hams will continue to make do with a very inefficent medium even by todays standards It is true that in the past we have accepted many thing that were true which was not, many of these errors have been corrected at what seems to be an expotential rate over the past couple of hundred years. Much of this was accomplished by people viewing the world with a degree of open-mindedness that had never existed in the past and this is a very good thing. Being totally opened minded has it fallicies in making us not being able to recognize when we have the correct answer. My mother as I am sure a lot of other mothers have said this best. "I am open minded, just not so much as to let my brains fall out." It is our closed mindedness that keeps of from running off accepting every BS explantion that comes along It has been your choice to deem anything someone says to you that you do not agree with as RUDENESS. Perhaps we should all be POLITE to you and let you go ahead with your fools errand. I doubt if most of us could be that cruel. Actually most people are very polite to you in the truest snese of the word carefully trying to explain things to you that you clearly do not understand, trying to explain to you a reality you refuse to accept. |
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