I think that sadly a lot of it is "politics" all too many times. Some of the people get awarded it because of who was aware of their work and not always because of it being the absolute best work.
My only exception to your statements was that it was of "no" significance today. I do not argue, however, that they might have made better choices or that very deserving individuals have sometimes gone unsung.
I concur that it is annoying that engineers and other parties critical to some inventions are never credited for the very significant parts they play in the process of developing the idea into a practical device or procedure. Consider how many "Edison" devices were actually invented by others and purchased by Edison or developed at his laboratories but where he was not directly involved. But there it was a matter of marketing, his name was well known at the time. Sure, he invented a lot. But not everything that ended up with his name on it.
Daniel
I am familiar with the ultramicroscope because I have been (and continue to be) involved with measuring the size of small particles suspended in a liquid. Most of the money in the particle size analysis field is in medical technology. Counting and sizing of blood cells is a big business. There is also a smaller industrial component to the particle size analysis business. All kinds of particles have to be measured in industry, such as, for example, cement, copier toner, face powder for cosmetics, mix for making candy bars, and a great many other substances.
If suspended particles are more than about a micrometer in diameter, they will eventually sediment to the bottom of their container because of gravity. To keep them suspended during measurement, they are gently agitated. The particles that are so small that the thermal forces that cause Brownian movement counteract the force of gravity and keep the particles in suspension forever, are called "colloids." It looks like colloidal particles really remain in suspension forever, because some of the gold sols prepared by Michael Faraday for his research are still in suspension today.
RF plays a part in particle size analysis. One method of particle size analysis, called the "Coulter Counter," determines the size of a particle by the change in resistance that occurs when the particle, suspended in a conductive liquid, passes through a small orifice. Today, mostly DC is used to make the measurement of the change in resistance, but polarization effects make the measurement noisy, limiting the size of the smallest particle that can be measured. RF would eliminate the polarization effects, but an RF source is much noisier than a filtered DC source. RF is presently used to get white cell measurements that differentiate the white cells into different types. This is because different types of white cells respond differently to RF when they are measured in a Coulter Counter. However, differential measurements of white cells is very noisy because RF is so noisy. This is why I am interested in high-Q loading coils and have posted about them in this Forum. A really high-Q coil would allow making a low-noise RF source. The Q would have to be high in the environment it is used in, not just in the Q measurement setup. Quartz crystals have very high Q, but, unfortunately, all crystal oscillators are noisy because they cannot be operated at a sufficiently high power to make the noise of the oscillator circuit insignificant compared to the output signal. A quartz crystal will overheat or crack if too much power is applied to it.
There are particle size measurement instruments available today that, like the ultramicroscope, use light scattering. None of them work very well. The best-selling type of light-scattering instrument available today is the laser-diffraction analyzer (LDA). It is a real piece of junk. I don't consider it to be a particle-size analyzer at all because the results are pure fiction. A company I worked for pointed this fact out in their advertising when they were selling a competing tecnology. Later, they started making and selling LDAs themselves, and they changed their tune. The word about the uselessness of the LDA is slow in getting out, but some users of LDAs not involved in the manufacture of particle-size analysis equipment have done studies to show that LDAs really don't work.
There are manufacturers of light-scattering equipment for detecting the presence of small particles in ultrapure water, which, for example, is used in cleaning wafers during the manufacture of semiconductors. These intstruments only detect particlest that are larger than about 30 nm in diameter, about the same as for an ordinary dark-field microscope.
As for the ultramicroscope itself, it's simply not used today by anybody because it is too difficult to use. The last I saw mentioned about the ultramicroscope was in an article written about 40 years ago by Derjaguin, a Soviet pioneer in colloidal science, who, I admit, actually deserved his Nobel Prize, because he was among the best in his field. He is the "D" In "DLVO" theory (Derjaguin, Landau, Verwey, and Overbeek), which is the theory of the forces that keep colloidal particles in suspension. Of course, he had to embrace communism in order to survive, let alone prosper. He was, nevertheless a great scientist, although he was involved with some silliness about "polywater." Derjaguin said that there was a polymeric form of water, but he had to retract this claim after he discovered some contamination in the supposedly pure water used in his experiments. Derjaguin tried to improve the ease of use of the ultramicroscope. However, even with Derjaguin's improvements, the ultramicroscope has not survived the development of the transmission electron microscope (TEM).
Today, if one wants to measure very small particles, measurements are made with a TEM. Even though sample preparation with the TEM can take hours, the difficulty is not as great as with the ultramicroscope. Also, the ultramicroscope can only measure the average particle size in a sample, while the TEM can be used to measure the size of individual particles. Also, automated image analysis equipment can be used to get particle size statistics for many particles in the field of view of the TEM. Of course, because of the vacuum used with the TEM, it cannot measure particles while they are suspended in a liquid. Part of the sample preparation with the TEM is to first suspend the particles in a volatile liquid, such as purified chloroform, which evaporates quickly after the a small quantity of suspension is put in place for measurement.
I am familiar with the ultramicroscope because I have been (and continue to be) involved with measuring the size of small particles suspended in a liquid. Most of the money in the particle size analysis field is in medical technology. Counting and sizing of blood cells is a big business. There is also a smaller industrial component to the particle size analysis business. All kinds of particles have to be measured in industry, such as, for example, cement, copier toner, face powder for cosmetics, mix for making candy bars, and a great many other substances.
If suspended particles are more than about a micrometer in diameter, they will eventually sediment to the bottom of their container because of gravity. To keep them suspended during measurement, they are gently agitated. The particles that are so small that the thermal forces that cause Brownian movement counteract the force of gravity and keep the particles in suspension forever, are called "colloids." It looks like colloidal particles really remain in suspension forever, because some of the gold sols prepared by Michael Faraday for his research are still in suspension today.
RF plays a part in particle size analysis. One method of particle size analysis, called the "Coulter Counter," determines the size of a particle by the change in resistance that occurs when the particle, suspended in a conductive liquid, passes through a small orifice. Today, mostly DC is used to make the measurement of the change in resistance, but polarization effects make the measurement noisy, limiting the size of the smallest particle that can be measured. RF would eliminate the polarization effects, but an RF source is much noisier than a filtered DC source. RF is presently used to get white cell measurements that differentiate the white cells into different types. This is because different types of white cells respond differently to RF when they are measured in a Coulter Counter. However, differential measurements of white cells is very noisy because RF is so noisy. This is why I am interested in high-Q loading coils and have posted about them in this Forum. A really high-Q coil would allow making a low-noise RF source. The Q would have to be high in the environment it is used in, not just in the Q measurement setup. Quartz crystals have very high Q, but, unfortunately, all crystal oscillators are noisy because they cannot be operated at a sufficiently high power to make the noise of the oscillator circuit insignificant compared to the output signal. A quartz crystal will overheat or crack if too much power is applied to it.
There are particle size measurement instruments available today that, like the ultramicroscope, use light scattering. None of them work very well. The best-selling type of light-scattering instrument available today is the laser-diffraction analyzer (LDA). It is a real piece of junk. I don't consider it to be a particle-size analyzer at all because the results are pure fiction. A company I worked for pointed this fact out in their advertising when they were selling a competing tecnology. Later, they started making and selling LDAs themselves, and they changed their tune. The word about the uselessness of the LDA is slow in getting out, but some users of LDAs not involved in the manufacture of particle-size analysis equipment have done studies to show that LDAs really don't work.
There are manufacturers of light-scattering equipment for detecting the presence of small particles in ultrapure water, which, for example, is used in cleaning wafers during the manufacture of semiconductors. These intstruments only detect particlest that are larger than about 30 nm in diameter, about the same as for an ordinary dark-field microscope.
As for the ultramicroscope itself, it's simply not used today by anybody because it is too difficult to use. The last I saw mentioned about the ultramicroscope was in an article written about 40 years ago by Derjaguin, a Soviet pioneer in colloidal science, who, I admit, actually deserved his Nobel Prize, because he was among the best in his field. He is the "D" In "DLVO" theory (Derjaguin, Landau, Verwey, and Overbeek), which is the theory of the forces that keep colloidal particles in suspension. Of course, he had to embrace communism in order to survive, let alone prosper. He was, nevertheless a great scientist, although he was involved with some silliness about "polywater." Derjaguin said that there was a polymeric form of water, but he had to retract this claim after he discovered some contamination in the supposedly pure water used in his experiments. Derjaguin tried to improve the ease of use of the ultramicroscope. However, even with Derjaguin's improvements, the ultramicroscope has not survived the development of the transmission electron microscope (TEM).
Today, if one wants to measure very small particles, measurements are made with a TEM. Even though sample preparation with the TEM can take hours, the difficulty is not as great as with the ultramicroscope. Also, the ultramicroscope can only measure the average particle size in a sample, while the TEM can be used to measure the size of individual particles. Also, automated image analysis equipment can be used to get particle size statistics for many particles in the field of view of the TEM. Of course, because of the vacuum used with the TEM, it cannot measure particles while they are suspended in a liquid. Part of the sample preparation with the TEM is to first suspend the particles in a volatile liquid, such as purified chloroform, which evaporates quickly after the a small quantity of suspension is put in place for measurement.
My debate with Rich about the apparent reciprocity failure of monopole receiving antennas has ended on this thread, but another antenna expert (who has directed an antenna laboratory for many years) has taken up Rich's cause, and I still continue to discuss this subject, but not (until this post) in a public forum. The level of the discussion has progressed from an offhand dismissal of my assertions to a willingness to look into the matter. I will report to this forum if a definite conclusion is reached.
The essence of the debate is that I say that, for a given separation, the ratio of the available received power to the transmitted power is the same for a pair of monopoles over a perfect (flat) ground plane as for a pair of dipoles in free space. The contrary view is that the two monopoles have 6 dB more received power than the two dipoles.
I previously made no attempt to prove this claim, and only cited Kenneth A. Norton, who, in 1959, had proved this theorem about monopoles and dipoles. What I am doing now is giving an intuitive explanation of why two monopoles have the same system power gain as two dipoles: Let us now consider two dipoles, not in free space, but a short distance above the ground plane. Unlike the situation in free space, more than one ray goes betweem the transmitting dipole and the receiving dipole. In free space, only a single ray goes between the transmitting and the receiving antennas. Near ground, there is the direct ray, and a second ray that is reflected from the ground. If the dipoles are only slightly elevated from the ground, the two rays are only slightly out of phase, and the two rays combine nearly in phase to double the field strength incident on the receiving antenna, causing a 6 dB increase in the system gain. When I say, "slightly elevated from the ground," I don't mean that in absolute distance, but in relative terms. That is, the elevation of the dipoles is small compared to the distance between the dipoles. This 6 dB increase in system gain is the same as is expected in the contrary view of two monopoles over a ground plane. Now, let's look at two monopoles over a ground plane. These two monopoles over a perfect ground plane are similar to two dipoles in free space. The difference is that the two lower dipole arms are virtual, and not real, due to ground reflection. The ground reflection is used to produce the virtual dipole arms, but there is no additional ground reflection to produce the second ray which increases system gain. Therefore, the maximum system gain for two monopoles must be the same as for two dipoles in free space.
There is a corollary to the theorem above equating the system gain of two dipoles to two monopoles: If a dipole and a monopole are immersed in identical fields, the dipole will deliver to a matched load twice as much power as is available from a monopole. To explain this corollary, imagine a dipole in free space having a particular capture area. For a monopole above ground, the real dipole arm above ground receives the signal, but the virtual dipole arm below ground does not receive any signal, because the signal is only present above the ground plane. Therefore, the capture area for a monopole is half of that for a dipole, and the corollary is demonstrated.
If the angle of the incident radiation to the monopole receiving antenna were raised just a little bit above zero degrees, there would not be just the single surface wave ray applied to the antenna, but also an additional reflected ray, causing the field intensity at the antenna to be increased by 6 dB. With this additional reflected ray, the receiving gain of the monopole would be as high as the transmitting gain, instead of 6 dB below the transmitting gain.
Now, is there really a reciprocity failure if the representations of this post are true? I think that there actually is no reciprocity failure in the receiving monopole, but it is necessary to look at reciprocity not as a phenomenon of a single antenna in isolation, but of a transmitting and a receiving antenna forming a system. The principle of reciprocity is fulfilled if, for a system of two antennas, the receiving antenna can be interchanged with the transmitting antenna. For a system of two dipoles, or a system of two monopoles, it is obvious that the transmitting antenna can be interchanged for the receiving antenna. For the case of a system composed of a monopole and a vertical dipole, you also get the same system gain if you interchange the receiving antenna and the transmitting antenna. If the monopole is the transmitting antenna, and the dipole is the receiving antenna, the monopole has a gain 3 dB higher than for a dipole, and the system has a gain 3 dB higher than for two dipoles in free space. Now, if the dipole is the transmitting antenna, and the monopole is the receiving antenna, the monopole again has a gain that is 3 dB higher than for a dipole, because, since the dipole is elevated above the ground, there is a direct ray and a reflected ray going to the monopole, causing the receiving gain of the monopole to be 3 dB higher than for a dipole (instead of 3 dB lower than for a dipole). So, when the receiving and transmitting antennas are interchanged, the system gain is still 3 dB higher than for two dipoles in free space.
One of the causes of the confusion that surrounds the receiving gain of a monopole is that the authors of antenna books do not mention this subject. I've stated in a previous post that I thought that this omission exists for pedagogical reasons. An author of an antenna book has very limited space for explaining the entire subject of antennas. Some facts have to be omitted because it is not possible to include everything. This subject, moreover, requires a lot of nit-picking explanation, as we see in this thread, and in this post in particular. For the author who has to explain everything about antennas in one book, it is simply not worhwhile dealing with this subject.
In Chapter 2 of the first edition (1961) of Jasik's "Antenna Engineering Handbook," Table 2-1 gives the transmitting gain of an isotropic radiator, a very short dipole, a half-wave dipole, and a quarter-wave dipole [i.e. monopole] above a perfect ground plane. Two pages later, there is Table 2-2, which gives the receiving gain of all of these antennas, but omits the monopole above the perfect ground plane. This appears to me to be a deliberate omission. If Jasik had included the monopole, to be strictly correct, he would have had to give give two different receiving gains; one for surface wave reception, and another one for skywave reception. I think that Jasik thought that it was better to omit mention of the monopole receiving gain than to devote space to accounting for the dual gains. It looks like all of the other antenna authors have done the same thing. The result is that some experts who have devoted their lives to antennas do not know that the monopole has two different gains and insist that the dual gains do not exist. I am hoping that this subject will be studied thoroughly using both measurements and simulation so that the facts can be made clear.
The gentleman I referred to in my last post relented, and agreed to test the apparent reciprocity failure which is the subject of most of this thread. At first, he did not think that the subject merited any discussion at all, because, as anybody who knows anything about antennas knows, any antenna has the same gain receiving as transmitting. During his four decades as the head of an antenna laboratory, he has tested numerous full-sized antennas, and also many microwave models of larger antennas, and he had never encountered an antenna where this rule did not apply. What caused him to agree to look into my claims is that I attributed my statements to the great Kenneth A. Norton, and he was curious to know what Norton was talking about. This gentleman knew Norton (who, he told me, is only recently deceased) personally, and he respected Norton's work.
I asked this gentleman to do an NEC simulation of the kind that I did (and described in this thread) to prove the theory. He told me that he does not use NEC because he considers it to be inaccurate, so he did the simulation using wipl-d instead. Here are the results of the wipl-d simulation:
For two quarter-wave monopoles operating at 1 MHz at a separation of 10000 meters (the monopole lengths set to give a real input impedance [i.e. only resistance, and no reactance]), the transmitting monopole was found to have a gain of 3.27, or 5.15 dBi, and the receiving monopole gain was found to be 0.82, or - 0.85 dBi. The receiving monopole gain was not the same as the transmitting monopole gain, and so the postulated reciprocity failure was confirmed.
Edit; 5-24-08:
Anybody wishing to get the paper by Norton that I mentioned in this thread may be able to get it free-of-charge from their local public library through what is called "interlibrary loan." If your local library does not have this paper, they may be able to get it for you from another library. One relatively small library I know of that has this paper on file is Broward County Main Library, Ft. Lauderdale, FL. The Newark, N.J. Public Library, which is also small (and underfunded), also has an excellent reference department. Of course, the enormous N.Y.C. Public Library must be magnificent. The libraries in even moderately-sized cities have many scientific journals in their reference departments. It takes about 2-3 weeks to get a paper through interlibrary loan
I got the opportunity yesterday to discuss this subject, and other antenna-related subjects, with Prof. V. T. (whom I have previously mentioned in other threads) for a few hours. He showed me about six pages from his engineering project notebook, in which, using the Friis Transmission Formula, he demonstrated that, when transmitting and receiving surface waves, a vertical monopole above ground has 6 dB more gain when transmitting than when receiving. Although this finding is not new, it is not mentioned in any of the standard antenna books. So, the Professor thinks that this fact is worth retelling, and he intends to submit his derivation to an IEEE publication.
It should be of interest to the readers of the part15.us Forum that the subject matter of this thread has led to a major theoretical paper on antennas. Scientific discourse, even at the radio discussion board level, is important, because it can lead to new discoveries.
Strictly speaking, the subject matter of this thread is not a new discovery, but rather a new appreciation of an old discovery. Actually, the principle was first reported in 1959 by Kenneth A. Norton, but it seems to have been ignored by most antenna specialists since that time.
It is widely assumed by antenna experts that the same antenna has the same gain when transmitting or receiving. This is called the "reciprocity" principle. It turns out that this reciprocity principle only applies in free space. In the presence of a ground plane, a vertical antenna at any height has a different gain when transmitting and when receiving. In the particular case of a vertical monopole over ground, the transmitting gain is 6 dB higher than the receiving gain.
On October 15, 2009, Prof. Trainotti will be presenting his paper, "Vertically Polarized Dipoles and Monopoles, Directivity, Effective Height and Antenna Factor," to the 59th IEEE Broadcast Symposium at Alexandria, VA. Several months later, the paper will be published in the IEEE Transactions on Broadcasting.
Prof. Trainotti had sent me a pre-publication proof copy of his article. In the first paragraph, he gives me credit for making him aware of the problem that he studied for his paper. The article is 32 pages long, and is highly mathematical.
Prof. Trainotti has indirectly posted in the part15.us Forum in the past. I posted calculations he made (at my request) about antenna efficiencies of 3 meter monopoles for different ground plane sizes, loading coil Qs, and earth ground conductivities.
The paper mentioned in the previous post has been published in the IEEE Transactions on Broadcasting, Vol. 56, No.3, pp. 379 - 409, September, 2010. The paper resulted from a discussion in this thread. Trainotti and his graduate students are working on a second paper about the same subject. He discovered that the same principle applies to horizontal as well as vertical antennas. He and his students are working out the mathematics for horizontal antennas.
Here is a pre-publication pdf version of the paper. It is nearly the same as the published paper. A notable change is that Trainotti has recently been elected a Fellow of the IEEE. In the pre-publication version, he is identified as a Senior Member.
http://svn2.assembla.com/svn/tesis_gfigueroa/paper_BTS-09-143/paper/paper.pdf