Historical Highlights of Microwaves
A quick review of important points in history related to microwave science
The history of our industry is a productive mix of theory and pragmatism. James Clerk Maxwell, a brilliant theoretician, predicted the existence of electromagnetic (EM) waves in a paper presented in 1864, although their form was not the four-equation set used today. James Rautio has penned a more complete history of James Clerk Maxwell1 in this issue of Microwave Journal. While Maxwell’s work predicted EM waves, credit to proving their existence fell to Heinrich Hertz, a student of Kirchhoff and Helmholtz. In 1886, 22 years after Maxwell’s paper, Hertz used an induction coil and spark gap to produce a spark in a gapped receiving loop resonant at about 450 MHz. Hertz, asked what his discovery was useful for, replied, “Nothing, I guess.”2 Hertz also discovered the photoelectric effect, later described by Einstein.
The IEEE Heinrich Hertz Medal was established in 1987 “for outstanding achievements in Hertzian waves…” It is presented annually for theoretical or experimental achievements. In the summer of 1894, Oliver Lodge demonstrated Hertzian waves before the Royal Society in London. Like Hertz, Lodge did not view EM waves as useful, declaring a half-mile as the maximum range, and certainly not beyond line of sight.3 Lodge used a coherer for detection rather than a ring with a gap. The coherer is a simple device that I constructed as a boy. Two wire terminals embedded in a small tube filled with metal fillings has a relatively high resistance until cohered by a nearby spark. Tapping the tube returns the resistance to its original state. In 1896, Bose of India gave a lecture at the Royal Society describing his experiments with special spark gaps to produce frequencies as high as 60 GHz.4 He also carefully investigated the coherer. Reference 4 is an interesting technical book on the history of wireless.
These researchers, however, did not capture the world’s imagination. Rather, it was a young Italian by the name of Guglielmo Marconi, born in 1874. He was not a theoretician, certainly not of Maxwell’s caliber. In fact, his education was rather haphazard, consisting largely of miscellaneous tutors. But of the men of his time, he was the first with the vision and determination to use Hertzian waves for the purpose of long-distance communication. By shear trial and error, constantly seeking greater range, he improved the coherer, discovered the effectiveness of taller antennas and ground systems, and developed antenna loading. By 1895, he triggered a coherer at 1500 yards. He traveled to England and garnered the support of William Preece, the Chief Electrical Engineer of the British Post Office. In 1897, with the financial aid of a cousin, Marconi formed what was later named Marconi’s Wireless Telegraph Company Limited. By the spring of 1899 he spanned the English Channel from Wimereux, France to South Foreland Lighthouse, England. He claimed to span the Atlantic on December 12, 1901, from Poldhu, Cornwall to St. John’s Newfoundland (see Figure 1).
Because of a lack of independent confirmation and the weakness and brevity of the signal, this claim was met with skepticism. Nevertheless, by 1902, repeated successes silenced his critics. Due to conflicting records, the wideband frequency is not certain but was probably near 500 kHz. Marconi did not develop new technologies. He was a pragmatist and secretive about his equipment. Above all, he was a promoter. The aid brought to the Titanic by wireless SOS and the apprehension of London’s infamous Hawley Crippen escaping to the United States by ship were just a few of the events that brought Marconi wireless to the attention of the world. Thunderstruck3 is a fascinating, non-technical read about the development of wireless. Once Marconi demonstrated the importance of wireless, Lodge and others developed renewed interest, and numerous tiffs over patents and credit erupted. Marconi was awarded the Nobel Prize along with Braun in 1909. Marconi tarnished his reputation by embracing Fascism between the World Wars.
In the timeline that accompanies this article, I categorized five periods in the history of our industry. These periods are oversimplified, but they illustrate trends. The first period is the Fundamental period. Of course, fundamental discoveries continue to be made, but the Fundamental period was dominated by discovery as the scientific method dawned. Wired communication existed, but wireless and microwave applications were non-existent during this period.
The advent of wireless telegraphy began the Communication and Broadcast period, a period whose heyday reigned until the 1930s. While world navies quickly embraced wireless telegraphy, this is a period of primarily commercial activity, and technological developments paving the way for the electronic explosion that soon occurred. During this period the term radio supplanted the term wireless. Like the previous period, Communication and Broadcast is dominated by individual effort, inventive minds working alone, often driven by the thirst for profit bearing and sellable patents. Large companies grew by acquiring patents.
Fessendon was one of the first to transmit voice rather than Morse code. He also used alternators to produce low-frequency radio waves and wireless transatlantic communication became routine. Working with GE, they built alternators generating coherent signals as high as 100 kHz, an improvement over the tuned broadband spark, but it was brute force and the upper frequency was limited. The electronic era began with the development of the vacuum tube diode by Fleming in 1904 and the triode by De Forest in 1906. Thereafter progress was rapid. Broadcast joined the Communication period in 1920 when 8MK, later WWJ, began regular broadcasting from Detroit. In 1920, in one of the first broadcasted sports events, Jack Dempsey knocked out Billy Miske. By 1925, radio broadcasts included music, news, sports, educational programs, commercials and President Coolidge’s inaugural address on 25 stations.
Important technological developments during the Communication and Broadcast period included the CRT by Braun in 1897, the discovery of superconductivity in 1911 by Onnes, the growth of single crystals by Czochralski in 1916, the flip-flop in 1919, the magnetron by Hull in 1920, the quartz crystal oscillator by Cady in 1922 and the Yagi-Uda antenna in 1926. These examples illustrate the latency involved in many technological advancements. It was 75 years from the discovery of superconductivity until its widespread use in microwave systems. It was 27 years from the development of the flip-flop to the ENIAC computer and 62 years to the personal computer. The application of the flip-flop and superconductivity required the additional technical developments of the integrated circuit and higher temperature superconductors. Potocnik5 suggested geo-synchronous orbital positions in 1928, but neither electronics nor booster rockets were ready. Other technologies were unencumbered by latency, such as the Yagi-Uda parasitic array and the magnetron, as it and waveguide ushered in the Military period.
While commercial electronic applications continued to advance, in the 1930s, tensions in Europe and movement by Japan onto the Asian continent gave impetuous to radar development. Enabled by the magnetron and waveguide, radar development became rampant. Page tested a pulse radar in 1934, Watson-Watt coined the term radar in 1935, Russell and Sigurd Varian developed the klystron in 1937, and by 1940 the MIT Radiation Laboratory began and England was protected by the Chain Home radar. The Military period had clearly begun. World War II was also the driving force of the quartz piezoelectric industry. Huge quantities of bulk-quartz resonators employing pressure-plate electrodes stabilized communication radios. World War II and the Cold War dominated our industry for 50 years. Governments worldwide pumped vast sums of money into the industry. The original issue of Microwave Journal was published in July/August 1958 with a Bomarc missile on the cover and with Phillip Smith’s 1939 chart in the background. A biography of Smith was included in that original Microwave Journal. Military dominance of the industry was evidenced in the original issue by all three technical features concerning radar components. Also, 13 of 21 ads included images or material for waveguide. Semiconductors were featured in only one ad!
While microwave applications were driven by the military, technology that sprang from the spending was the foundation for the periods that followed. Certainly not all developments of the period were military driven, but many were. The most important development of the period was at Bell Labs: the point-contact transistor in 1947 by Bardeen and Brattain. Shockley followed soon thereafter with the planar transistor. All three were awarded the Nobel Prize in 1956. Bardeen was a formidible engineer. He shared a second Nobel Prize in 1972 for the Bardeen, Cooper and Schrieffer (BCS) theory of superconductivity and his first PhD student, Holonyak, invented the light emitting diode (LED). A postage stamp was released in Bardeen’s honor in March 2008 (see Figure 2). In 1958, Kilby at TI and Noyce at Fairchild invented the integrated circuit (IC), and the rest is history. Other important, non-military events of the period were the approval of the National Television System Committee standard in 1941, a description of an Instrument Landing System by Pickles in 1946, experiments with NMR by Bloch and Purcell in 1946, the AT&T C-band long haul network beginning in 1950, Deschamps proposal of the patch antenna in 1953, and the first meeting in New York in 1952 of the PGMTT, now the MTT-S.6
On October 4, 1957, the Soviet Union launched Sputnik I. As a boy of 10, I kept a scrapbook with news clips about Sputnik and the failed December 1957 Vangard launch and I listened to the periodic and persistent beep from Sputnik on a shortwave radio. On January 1, 1958, the United States launched Explorer I. These events precipitated my interest in astronomy, radio and rocketry, and I later chose radio engineering as a career. I was not alone. The Soviet Union launched not only an 84 kg, 58 cm sphere, but also the careers of many engineers. It also launched the United States government into funding of local secondary schools for science, the establishment of NASA in 1958, and the Space Exploration period depicted in the timeline. Luna 1 flew by the moon in 1959 and a number of space probes followed. Yuri Gagarin, the first human to orbit Earth in 1961, died at age 34 during a routine MIG 15 flight. The first geosynchronous satellite was Syncom 2 in 1963. After successful Mercury, Gemini and Apollo test flights by NASA, on July 20, 1969, Neil Armstrong and Buzz Aldrin set foot on the moon. As a testament to the pace of technology, my grandfather never believed man set foot on the moon. I knew they at least orbited the moon. My thesis at Arizona State University was the construction of an earth station which received Unified S-band voice communications from Apollo 16 and 17. Each night I watched the moon move 13° further East, approaching the point in the sky where my antenna was pointed and Apollo was headed.
Pioneer 10 (see Figure 3), powered by a radioisotope thermoelectric 154 W generator, and built by TRW, was launched in 1972. It used a 2.74 m dish for the high-gain antenna. The downlink was an 8 W TWT at 2292 MHz. In 1973 it passed by Jupiter, and in 2003 NASA communicated with Pioneer 10 for the last time at a range of 7.5 billion miles7 on its way toward Aldebaran. What would Marconi think of that distance record? It was 172 years from Volta’s battery to the launch of Pioneer 10. For the manned near-Earth exploration that followed Apollo, NASA augmented the S-band systems with the Ku-band Tracking and Data Relay Satellite Communication Systems (TDRSS). In roughly two million years, as Pioneer 10 approaches the area of Aldebaran, what might the Aldebarians think of the parabolic dish, the transistors, the TWT and the nearly dead radioactive battery? What will be the story of mankind?
Other important events of the Space Exploration and Military periods were numerous, including the first laser by Maiman in 1960, Kurokawa’s paper popularizing S-parameters in 1965, RCA developing CMOS in 1968, AT&T proposing AMPS cellular in 1971, the first commercial microwave software in 1973, and GPS approval and RFID patents in 1973. Just as one of the first radio broadcasts was a boxing match, ironically, one of the first satellite delivered events from HBO to a cable TV operator was the 1975 “Thriller in Manila” between Muhammad Ali and Joe Frazier. GTE deployed a fiber optic link in 1977, GaAs FETs reached 10 W at 10 GHz in 1980 and AT&T divestiture occurred in 1982. In 1983 Motorola released a cell phone and by 1987 the operating temperature of superconductor materials abruptly rose.
During Ronald Regan’s eight-year tenure as President, the United States spent $2.2 trillion for the military. In December 1989, George H. W. Bush and Gorbachev, meeting in Malta, declared and end to the Cold War.8 The dissolution of the Soviet Union in 1991 left little doubt and the Commercial and Data period was born. Not that military spending would decrease, but more of the budget would go to operations. Many engineers of my era transitioned from defense related work. For me, it was somewhat earlier, from radar to cable television and earth station work. The term wireless became fashionable again.
The metonym Silicon Valley was coined by Ralph Vaerst and published by a friend in 1971, but Stanford University and the earlier founding of Hewlett-Packard in 1939 were the seeds. Many companies in Silicon Valley had either been commercially driven or made the transition from military to commercial. If his employer didn’t make the transition, an engineer often did. The Commercial and Data period made heavy use of technologies developed, or at least conceived earlier. New semiconductor processes were released, MEMS devices matured from pressure sensors to RF applications, LTCC work began in earnest and FBAR devices were used as RF filters.
On Thanksgiving Day in 1966, Howard Hughes moved into the top two floors of the Desert Inn in Las Vegas with a ten-day reservation.9 After an extended stay, the Desert Inn requested that he vacate to accommodate high-rollers. Instead, he purchased the Inn, and later several other properties on the Strip. Aside from the role Hughes and his companies played in our industry, and his Spruce Goose being the centerpiece of an MTT-S reception in Long Beach, CA in 1989, what does the Desert Inn have to do with our industry? The beautiful and classy Desert Inn was razed in 2001 to make way for the modern Wynn Las Vegas. The Wynn opened in 2005 with its casino poker chips among the first to use RFID tags.
My last entry on the timeline is the termination of NTSC television broadcasts in the United States in 2009. In the United States, television broadcast is going digital ATSC (Advanced Television Systems Committee). An obvious trend in the timeline is a bubble of increased events in the period from 1930 through the 1970s. Were there actually more watershed events during this period than later? Have important developments slowed? Or is the bubble an artifact of my selection process? It could very well be the latter. For example, few would have foreseen the significance of the printed wiring board when it was patented in 1936. It was some 30 years later before the PWB dominated electronics. From 1980 and on, I have probably missed many truly important events that are buried in the myriad of reported technologies and technical papers of our time. Certainly nanotechnology, MEMS and new material technologies are truly watershed. But what have I missed?
I intentionally avoided the association of names with important developments after 1965. The passage of time disengages us from the moment and often clears our vision. Even so, the assignment of credit can be difficult, as evidenced by the debate over whether Hertz, Marconi, Tesla or others are due the credit for wireless. The number of contributors in our industry has exploded, as evidenced by 12 papers presented to 210 attendees at the first PGMTT meeting in 1952. Compare that with MTT meetings of today. More importantly, the assignment of credit is particularly difficult for one individual specialized in a narrow field of our industry. Therefore, I put the question to you. Visit www.microwavejournal.blogspot.com and nominate your candidates for important developments and contributors, from the past to the present.
Thanks for your excellent article, “Historical Highlights of Microwaves” in your July 2008 issue of the Microwave Journal I do have one correction for pp 29, 1st column.
It reads, “Page [Naval Research Laboratory] tested a monopulse radar in 1934,---------.” but it should read, “Page tested a pulse radar in 1934,-------.” Pulsing rf was still a challenge at that time, but Page recognized the value of pulsing the radiation to obtain accurate range information and developed pulsing techniques. However, Robert M. Page did invent monopulse [tracking] radar in 1947 that he called simultaneous lobing radar. See Patent “Simultaneous Lobe Comparison, Pulse Echo Locator System,” Patent # 2,929,056 March 15, 1960. The invention was filed on Nov 5, 1947 but , because of security classification, the patent could not be published until unclassified in 1960. The term monopulse was coined later, but is a bit of a misnomer because the angle tracking can also work with CW.
I had the honor of working on the performance of the original monopulse model. It performed very well, but the four horn feed, requiring several waveguide sums and differences, was very cumbersome for lack of the modern microwave hybrids. We had to use the old ring hybrids that we could have machined in the NRL machine shop. Typically, as Randy Rea pointed out, it takes a few years of microwave component development, as in the case of monopulse radar, for needed configuration improvement to become the modern workhorse precision tracking technique.
Dean D. Howard
1. J.C. Rautio, “Maxwell’s Legacy,” IEEE Microwave Magazine, June 2005, pp. 46–53.
2. www.wikipedia.com: Heinrich Hertz.
3. E. Larson, Thunderstruck, Three Rivers Press, New York, NY 2006.
4. T. Sarkar, R. Mailloux, A. Oliner, M. Salazar-Palma and D. Sengupta, History of Wireless, Wiley-Interscience, Hoboken, NJ.
5. H. Potocnik, The Problem of Space Travel, Government Printing Office, Washington, DC (English reprint from 1928 book in German).
6. T. Saad, “The MTT Symposia,” IEEE MTT Trans., September 1983.
7. www.wikipedia.com: Pioneer 10.
8. www.wikipedia.com: Cold War.
9. www.wikipedia.com: Desert Inn.
Randall Rhea graduated from the University of Illinois in 1969 and Arizona State University in 1973 and worked at the Boeing Co., Goodyear Aerospace and Scientific-Atlanta. He founded Eagleware Corp., which was acquired by Agilent Technologies in 2005, and Noble Publishing, which was acquired by SciTech Publishing in 2006. He has authored numerous papers, the books Oscillator Design and Computer Simulation and HF Filter Design and Computer Simulation and has taught seminars on oscillator and filter design to over 1000 engineers. His hobbies include antiques, astronomy and amateur radio (N4HI). In 2004 he toured 48 states by motorcycle. He and his wife Marilynn have two adult children and reside near Thomasville, GA.