History of UWB signals
It is always interesting to find out, how pioneers in each field of knowledge acted and how this new knowledge fought way in life. UWB technology passed quite thorny road in its history, including the periods of dark oblivion and flare of enthusiasm. But this history continue to be written and in our days as well, and we hope to make in it our feasible contribution.
The very notion of UWB signal was first introduced, probably in 1950-1960 's in works of Austrian scientist, D.Sc. Henning F. Harmuth. However, the usage of UWB signals has begun much earlier. Namely these kind signals, but not narrow-band ones, were used in the nineteenth century, starting with the first experiments of H. Hertz, in 1893. In the first radio transmitter, built by inventor of radio from Russia A. S. Popov in 1895, were used high-frequency evanescent modes, received by means of electrical spark. The signals generated by him also were ultra-wideband. The same signals created by electrical spark, were applied by G. Marconi in 1901 while a communication session through the Atlantic Ocean has occurred. Coding of information thereby was carried out using Morse code. In 1885-1905 exclusively evanescent modes were used. Transition from evanescent modes to continuous waves took the whole decade (1905-1915). Since 1915 electronic lamp generating of continuous electromagnetic waves became applicable. One of the reasons of it was creation of continuous-wave oscillator by German engineer Alexander Meissner in 1913, followed the invention of the vacuum triode. UWB signals appeared completely forced out by narrow-band signals. They were forgotten for more than on four decades. Such was the death knell for the first operational stage of UWB signals.
The second surge of interest in UWB signals has occurred in the late fifties due to development of radar technology, both in the USA, and in the USSR. In the USA at that time, several research centers were engaged in research of response of microwave systems (e.g., antenna elements) to narrow-pulse (nanoseconds and less) impact. Such kind research activity took place also in
Sperry Research Center (later Sperry Rand Corporation) within the framework of creation of a radar based on implemented phased array. In 1965, the officer Gerald Ross headed a team of researchers “time domain electromagnetics". As a result a number of pioneer works have been published. In 1972-1973, D. Ross and another team member of Sperry Rand Corporation, Kenneth Robbins, have received basic patents in the field of ultra-wideband systems: “Transferring and detecting system for generation and reception of pulse signals without distortions of narrow-pulse communication system” and “Narrow-pulse receiver”. The works of Ross and Robbins laid the basis for narrow-pulse communication and location in the USA. Suffice it to say that Ross is the author (or co-author) of more than 40 United States patents in this field. In total, by 1989 staff members of Sperry Rand have got around 50 US patents in UWB systems and various aspects of their application.
In parallel to Ross and Robbins, Professor Henning Harmuth at American Catholic University conducted similar researches and published in 1969 -1984 a number of articles and books devoted to UWB. Another researcher - Paul van Ètten at Roman Research Center of the U.S. Air Force (now AFRL Rome NY) – studied use of UWB radars and discovered a number of important effects. In 1974, Morey designed an UWB radar system for ground penetration, which gave an impulse to a new direction – UWB radars for geolocation and location "through the wall". Development of stroboscopic oscillographs with frequency of scanning over 10 GHz both abroad (Hewlett-Packard), and in the USSR became an important stage in development of UWB technologies. There were also active academic programs (e.g. at Lawrence Livermore National Laboratory, Los Alamos National Laboratory and University of Michigan), which focused on physics of short pulse transmissions that differed from physics of continuous or long pulse signals. It is worth also to remember works of company Multispectral Solutions, Inc.(now acquired by Zebra Technologies), which has created on order of the USA Government with the assistance of D. Ross communication system with high electronic-emission security and a noise immunity (with low probability of detection and counteraction), accepted in 1987.
The list of researchers and works can be continued. During this period (1970-1980) essentially new methods of generation, reception and processing of UWB signals were actively developed and the corresponding new technical base was created. The main efforts on UWB signals application were concentrated in the field of location. At this time UWB radar for air and space targets acquisition, UWB radar of subsurface sounding were constructed. Distinguishing features of such radars were not only high resolution, but also possibility of obtaining non-coordinate information of a target. At this time skeptical appraisals of UWB technologies often sounded. So, it was noted that there is a number of the physical restrictions interfering their development. The following was declared. First, properties of antenna systems limited band don't allow radiating low-frequency spectral components of signals and dramatically reducing the required signal directional characteristics of systems using them. Secondly, pacing factor is dispersion existence in transmission medium. Thirdly, spectrum broadening of radiating systems as well as ensuring their reliability and operating conditions require a significant investment of financial resources. Fourthly, the difficulties of a practical and economic nature, which will inevitably arise when will be combined use of UWB systems and conventional radio systems, questioned the advisability of developing UWB technology as such. However, thanks to the efforts of many researchers, especially Henning F. Harmuth, the idea of using UWB signals proved their right to exist, both in terms of the theoretical soundness, and in the form of operational systems.
Similar researches were conducted in the USSR as well. As far as one can judge by the publications, almost all of them (as in the United States) were associated with the radar. Russian and foreign experts have noted the works of the laboratory of Mr. Zernov, Kartsevich, Astanin, Kobzarev, Kostylev, Kardo-Sysoyev, Glebovich, Meleshko and others. The first works on UWB communication systems in connection with Code Division of channels were implemented in Russia in the mid-80 's, Vladimir Krylov at Gorky Polytechnic Institute. However, since the early 90 's, many of the works were stopped.
In 1987, the United States Larry Fullerton received his first patent in the field of ultra-wideband communications and founded “Time Domain” company. In ten years of the company work with its PulsOn technology has become one of the leaders in the field of portable UWB communication systems and radars, in its asset – over 60 patents in UWB.
The fourth surge of interest in UWB signals started in the second half of the 90-ies of the XX century and continues to our days. It can be described as infiltration of UWB signals in all new fields of science and technology. At the beginning of 1998, three American companies - U.S. Radar, Time Domain and Zircon applied to the United States Federal Communications Commission (FCC), asking their approval to use their UWB systems (radar, capable to "see" through walls and communications systems) as experiment on unlicensed basis. The application of these companies as well as the total pressure of producers and developers resulted in the event: on February 14, 2002, the FCC has given limited permission to use UWB systems. This laid the foundations of the beginning of a process of commercialization of UWB technology on the unlicensed basis for three different categories of devices: data transmission systems, portable radars and measuring systems.