Henning F. Harmuth was born in Vienna, Austria, on July 27, 1928. He received the Diplom-Ingenieur degree in telecommunications engineering in 1951 and the Doctor of Technical Sciences degree in 1953, both from Technische Universitaet Wien (University of Technology Vienna). He also studied at Vienna University and University of Paris, France. Some facts about his professional experiences:

• 1953-1955 Scientist at Signal Corps Engineering Laboratories, Ft. Monmouth, New Jersey;
• 1955-1959 Scientist at General Electric, Advanced Electronics Center, Ithaca, New York;
• 1959,1960 Section Head at General Dynamics/Electronics, Rochester, New York;
• 1960,1961 Independent research at Universidad Nacional de Mexico and at Tokyo University, Japan;<\LI>
• 1961-1965 Various positions at Battelle Institute, Frankfurt, Germany;
• 1965-1994 Self-employed consulting engineer (Registered Professional Engineer in Maryland 1980--1994);
• 1971-1996 Adjunct professor at The Catholic University of America in Washington D.C. He retired in 1996.

As a result of an unfortunate fall he became paralyzed below the waist in 1991 and has been living in a wheelchair ever since. Now he lives in Destin, Florida.

Additional to the above mentioned experiences Harmuth was adviser to the United Nations/UNESCO on postgraduate training of engineers in India (1972), exchange scientist of US Academy of Sciences to Soviet Union (1979) and East Germany (1979), Fulbright exchange scientist at Technische Universitaet Dresden, Germany (1988), and adviser on R&D projects at the University of Kuwait (1980-1992).

For at least one term he has lectured at Karlsruhe University, Germany (1965-1968), University of Maryland, College Park, MD, USA (1969-1971), Stanford University, Stanford, CA, USA (1971), The Australian National University, Canberra (1974), Northwest Telecommunication Engineering Institute, Xi'an, PR China (1981), University of the Witwatersrand, Johannesburg, South Africa (1983, 1984), University of Sydney, Australia (1984), Kuwait University, State of Kuwait (1985,1988), Beijing University of Aeronautics and Astronautics, PR China (1987), University of Canterbury, Christchurch, New Zealand (1988), University of Sydney, Australia (1990).

Harmuth is a member of IEEE since 1953, has the status of a Retired Chairman of the Sequency Union of the IEEE Electromagnetic Compatibility Society and is Emeritus Fellow of the American Institute for the Advancement of Science.

Harmuth is holder of some 30 patents, author of more than 150 journal publications and of 15 books:

1. Transmission of Information by Orthogonal Functions; Springer-Verlag, Berlin 1969; second printing 1970; Russian edition: Svjas, Moscow 1975.
2. Transmission of Information by Orthogonal Functions; second revised edition, Springer-Verlag, Berlin 1972.
3. Sequency Theory --- Foundations and Applications; Academic Press, New York 1977; Russian edition: MIR, Moscow 1980; reprinted in PR China; Chinese edition Publishing House of the People's Post and Telecommunications, Beijing 1980.
4. Acoustic Imaging with Electronic Circuits; Academic Press, New York 1979; second printing 1984; reprinted in PR China.

   
   Fig. 2. Covers of "Nonsinusoidal Waves for Radar and Radio Communication and "Antennas and Waveguides for Nonsinusoidal Waves".

5. Nonsinusoidal Waves for Radar and Radio Communication; Academic Press, New York 1981; Russian edition: Radio i Svjas, Moscow 1985; reprinted in PR China; Chinese translation, Beijing 1989.
6. Antennas and Waveguides for Nonsinusoidal Waves; Academic Press, New York 1984; Chinese translation, Beijing 1990.

   
   Fig. 3. Covers of "Propagation of Nonsinusoidal Electromagnetic Waves and "Information Theory Applied to Space-Time Physics".

   
   Fig. 4. Covers of "Radiation of Nonsinusoidal Electromagnetic Waves" and "Propagation of Electromagnetic Signals".

   
   Fig. 5. Covers of "Electromagnetic Signals (Reflection, Focusing, Distortion, and Their Practical Applications)" and "Interstellar Propagation of Electromagnetic Signals".

7. Propagation of Nonsinusoidal Electromagnetic Waves; Academic Press, New York 1986; Chinese translation, Beijing 1990.
8. Information Theory Applied to Space-Time Physics; Russian edition: MIR, Moscow, 1989; English edition World Scientific Publishing Co., Singapore, 1993.
9. Radiation of Nonsinusoidal Electromagnetic Waves; Academic Press, New York, 1990.

   
   Fig. 6. Covers of '"Modified Maxwell Equations in Quantum Electrodynamics" and "Calculus of Finite Differences in Quantum Electrodynamics".

10. Propagation of Electromagnetic Signals}; with co-author M.G.M.Hussain; World Scientific Publishing Co., Singapore, 1994.
11. Electromagnetic Signals (Reflection, Focusing, Distortion, and Their Practical Applications); with co-authors R.N.Boules and M.G.M.Hussain; Kluwer Academic/Plenum Publishers, New York 1999.
12. Interstellar Propagation of Electromagnetic Signals; with co-author K.A.Lukin; Kluwer Academic/Plenum Publishers, New York 2000.
13. Modified Maxwell Equations in Quantum Electrodynamics; with co-authors T.W.Barrett and B.Meffert; World Scientific, Singapore 2001.
14. Calculus of Finite Differences in Quantum Electrodynamics; with co-author B.Meffert; vol.129, Advances in Imaging and Electron Physics, Elsevier, London 2003.
15. Dogma of the Continuum and the Calculus of Finite Differences in Quantum Physics; with co-author B. Meffert; vol.137, Advances in Imaging and Electron Physics, Elsevier, London 2005.

Citations of Harmuth's publications you can find in several thousands, distributed in time and around the world. First of all there is cited the book "Transmission of Information by Orthogonal Functions", ranging in time from a "Letter to Nature" in 1969 (Gibbs, Gebbie 1969) to a "Journal of Tsinghua University" (Fang et al. 2005) in China, or IEICE Trans. on Communication in Japan in 2006 (Kitagawa et al. 2006). Reading the subjects of the journal papers written by Harmuth or connected with him you will find a lot of discussion about his findings. The papers "Correction of Maxwell's equations for signals" part I and II (Harmuth 1986a, 1986b) provoked contributions titled "Comments on the Harmuth ansatz" (Barrett 1988), "Reply to Barrett’s 'Comments on the Harmuth ansatz (Harmuth 1988)", "Third response to comments by M.J.Neatrour on Maxwell’s equations" (Harmuth, Hussain 1988), or "The challenge from Harmuth" (Wait 1993).

In several books and papers we can find a description of the basic role of Harmuth's publications (cf. Pichler 2004, Barrett 2000). Pichler writes:

From a mathematical point of view the system of sinusoidal functions is a special case of a complete system of orthogonal functions. For this reason we find in signal processing and telecommunications efforts, to make use of other specific systems of orthogonal functions. One such a system is given by the Walsh Functions, introduced in mathematics by J.L. Walsh in 1923. The successful promotion for the application of Walsh functions in communications engineering is first of all due to Harmuth's book (Harmuth 1971). Harmuth started with discovering the Walsh functions as a useful orthogonal code and their application in wireless communication (Harmuth 1960). This was followed by a patent of the concept of a multi-channel transmission system with Walsh functions as carriers (Harmuth 1964). Harmuth considered mainly – with respect to the state of the art at this time - analog transmission systems with time-continuous signals to represent information.

To develop a valid mathematical basis for such systems Harmuth contacted the Institute of Mathematics of the University of Innsbruck, Austria, where mathematical research in Walsh function was under way. The contribution of Pichler (Pichler 1967, 1968, 1970) helped to give a mathematical and systems-theoretical basis for the work of Harmuth. The symposia which were organized by Harmuth in Washington D.C. (from 1969 to 1973) roused international interest. They reported about applications in information technology and inspired further research. As a result Walsh functions and their applications are today well known in communication engineering and in signal processing. They have found important applications in modern digital information technology.

The different concepts and methods for analog signal processing and analog information transmission which exist for Walsh functions can be adapted to digital systems. That is the reason that Walsh functions today are used in modern digital systems for mobile communication as carrier signals in multiplexing. The specific CDMA system of Qualcomm Ing. uses for the forward link this approach (Qualcomm Inc. 1992). The forthcoming UMTS also makes use of multiplexing signals by Walsh functions and provides the bandwith according to user needs.

Another interesting recent application of Walsh functions which is based on fundamental historical roots is given by the idea of "sequency hopping" which is a generalization of the known method of frequency hopping. The fundamental idea of the method of frequency hopping to achieve a secure communication by a wireless system is, that the carrier frequency of the transmitter and the receiver changes in time using a pseudo random pattern. It "hops" within a certain (broad) frequency band. The Austro-American actress and movie star Hedy Lamarr (born Hedy Kiesler) known as the "most beautiful woman of the world", is considered together with George Antheil ("bad boy of music") as the inventor of frequency hopping (US patent 2,292.387 of 1942). Following Harmuth we can replace the parameter "frequency" by "sequency" if we use a communication system based on Walsh functions as carrier. In this case "sequency hopping" is a method for secure information transmission. As a further generalization "code-hopping" can be introduced, when we use arbitrary orthogonal code sequences as carriers. The development of a code-hopping system in combination with a direct sequence CDMA system is investigated (Pichler et al. 2000). Henning F. Harmuth established a milestone in the development of information technology by his work on the application of Walsh functions as an alternative to sinusoidal functions.