Focus On Early Secret

 THE TESLA KOTATING MAGNETIC FIELD. MOTORS WITH CLOSED CONDUCTORS. SYNCHRONIZING MOTORS. KOTATING FIELD TRANSFORMERS. THE best description that can be given of what he attempted, and succeeded in doing, with the rotating magnetic field, is to be found in Mr. Tesla's brief paper explanatory of his rotary cur- rent, polyphase system, read before the American Institute of Electrical Engineers, in New York, in May, 1888, under the title " A New System of Alternate Current Motors and Trans- formers." As a matter of fact, which a perusal of the paper will establish, Mr. Tesla made no attempt in that paper to de- scribe all his work. It dealt in reality with the few topics enu- merated in the caption of this chapter. Mr. Tesla's reticence was no doubt due largely to the fact that his action was gov- erned by the wishes of others with whom lie was associated, but it may be worth mention that the compiler of this volume who had seen the motors running, and who was then ...

A New System of Alternating Current Motors Introduction : In the late 19th and early 20th centuries, the development of electrical engineering revolutionized industries, transportation, and daily life. Central to this transformation was the discovery and utilization of alternating current (AC) motors. These motors, as opposed to direct current (DC) motors, offered several advantages, including increased efficiency, longer transmission distances, and more straightforward regulation. In this article, we will delve into the historical context of AC motors, the key contributions of various inventors, and the development of a new system of alternating current motors that paved the way for the modern electrical era. Historical Context: The idea of utilizing electrical power for practical applications was first demonstrated by Michael Faraday in the early 1830s when he discovered electromagnetic induction. Faraday's work laid the foundation for the understanding of the relationship betw...

 PHYSICAL METALLURGY OF LEAD-FREE SOLDER ALLOYS Use of lead-bearing solders, such as the Sn-Pb eutectic solder, can be dated back to early human history. In the last 50 years, the Sn-Pb solders have found extensive usage in electronic and semiconductor industries for large volume production for printed circuit board (PCB)/component assemblies with highly automated processes and process controls. In principle, solders are used for joining purposes because they possess the following use- ful characteristics: a liquidus temperature lower than melting points of the materials to be joined; molten solders wet or spread on the substrate metallic or metalization surfaces and form sound metallic bonds without significant erosion of the surfaces to be joined [1]. Strengths of the final solder interconnections are determined by the solder chemical compo- sition, processing conditions, and particularly by the metallurgical reactions of the molten solder with the metallic surfaces to be join...

 Types of Orbits The orbits of satellites that might be used for personal communications systems can be grouped into four categories: low Earth orbit (LEO), medium Earth orbit (MEO), geostationary orbit (GEO), and elliptical Earth orbit (EEO). Each has advantages and disadvantages in PCS designs. Table 5.1 shows sample orbital elements for each of the satellite orbit types in units suitable for use with most of the general-purpose orbital-prediction computer programs. The Iridium (Iridium is a trademark of Iridium, LLC) system [11, 12] is a LEO constellation of 66 satellites (plus 6 in-orbit spares) approximately 778 km above the Earth in six equally spaced orbital planes at nearly 86.4° inclination to the equator. Every point on Earth is in view of this “infrastructure in the sky,” and the system is planned as a complement, or adjunct, to the existing “islands” of terrestrial communications infrastructures. The MEO characteristics are typified by the Global Positioning Satellite (...

 Basic Radiowave and Antenna Parameters Terms and definitions commonly encountered in the study of antennas and radio wave communication can be found in Institute of Electrical and Electron- ics Engineers (IEEE) [19, 20] and European Telecommunications Standards Institute (ETSI) [21] standards, as well as in FCC rules [3] and ITU-R reports and recommendations [22]. Here, we will present some of the parameters and definitions that are especially relevant and specific to the problems in this textbook. Antenna factor (AF) in a receiving antenna is the ratio of electric field strength to the voltage across the terminating impedance connected to the antenna. By common usage in the telecommunications industry [23], the antenna factor is sometimes stated under conditions where the field incident on the antenna is not uniform along the antenna. Antenna factor is therefore, by common usage, a parameter that is measurement site dependent. Antenna illumination efficiency, sometimes called the...

 The Immediate and Short Distance Sky-Wave books can be had just for the asking. Write to: Commanding General USAESEIA ATTN: ASC-E-TP Fort Huachuca, Arizona 85613-5300 or call AUTOVON 879-7685. Every division or higher level unit should have a book for their area. There are 35 volumes covering all areas of the world. For our use, we will use column 5 from the ISD book and column 7 from the GW book. 11. Let's do a couple of sky-wave frequency selection problems. a. Situation 1. Let us say that we have a radio net with only two stations which are 50 miles apart. The radio set used is the AN/GRC-142. We are using radioteletype during a period of low sunspot activity. We need to select two frequencies for 24-hour communications. We will use a doublet antenna erected less than a quarter wavelength above the ground for our highest frequency so that our radiation pattern is straight up. Keep in mind that we might have to vary the antenna height from 40 feet down to 10 feet (any lower than...

 FREQUENCY SELECTION. 1. Prior to selecting frequencies for a radio circuit, thought must be given as to what type of antenna will be used. Often, during displacement or during an alert, at least two types of antennas will be used -- a whip while moving; a doublet or suitable compromise antenna while mobile at a halt. Antenna selection will determine the choice of frequency, not the other way around. Looking at the various Immediate Sky-Wave Distance (ISD) charts, page 125 to page 141 (we will use column 5 on the charts) for various antennas, we see that the most reliable antenna is a doublet with reliability dropping until we reach the poorest antenna -- the whip. We also see on the ISD charts that for the same distance, the frequency increases with each type of antenna, with the whip having the highest frequency. What conclusions can we draw from these comparisons? First, we must have two frequencies for sky wave use -- a day and a night frequency. Also, when forced to use a whip...