1. EVOLUTION OF MICROWAVE
COMMUNICATIONS - A BRIEF HISTORY
PRESENTED BY RICHARD U. LAINE, PE
P R I N C I PA L E N G I N E E R , AV I AT N E T W O R K S , S A N TA C L A R A , C A 9 5 0 5 4
JULY 2011
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2. Agenda
• Historical Perspective, not without controversy
• “Wireless” in its Infancy—the Intertwining of Edison, Marconi, and
Tesla
• Propagation—the Intertwining of Huygens, Newton, Fresnel, and
Einstein
• Microwave Radios—The Early Days: PPM “digital,” Analog FM-FDM
• Evolution of the U.S. Microwave Communications Industry
• Evolution to Aviat Networks
• Upgrade from Analog to Digital Microwave Hops
• Digital Microwave Attributes—A Media Comparison
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3. Wireless Communications – The Early Days
Excerpt from the Scientific American July 1892
In the specification to one of his recent patents,
Thomas A. Edison says:
“I have discovered that if sufficient elevation be obtained to
overcome the curvature of the earth’s surface and to reduce to
the minimum the earth’s absorption, electric signaling between
distant points can be carried on by induction without the use of
wires.”
MICROWAVE PATH ENGINEERING 117 YEARS AGO!
Thomas A. Edison (1847-1931)Ohio
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4. The First Wireless Communications Age
The radio is one hundred years old, but it doesn’t look it!
... it is interesting to note that Samuel F. B. Morse’s telegraph was followed
only 40 years later by the increasingly remarkable invention of radio
frequency transmission.
Thomas Edison experimented with signals that could be generated and
detected at a distance in 1883, but did not appreciate the importance of
“the Edison Effect.” Edison received a patent for wireless telegraphy in
1885, but was preoccupied with other projects. Edison sold the patent “for
a song” to Marconi, who put extensive effort into the technology. By 1901,
he sent Morse Code from Massachusetts to Cornwall, England.
Roger Rusch
Applied Microwave & Wireless Fall 1995
Samuel F. B. Morse (1791 – 1872) Scotland
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5. Wireless – Marconi Inventor of the Radio?
January 1897
An invention which promises to be of the greatest practical value in the world of telegraphy has
received its first public announcement at the hands of Mr. William H. Preece, the telegraphic
expert of the London post office. During a lecture on "Telegraphy Without Wires" recently
delivered in London, Mr. Preece introduced a young Italian, a Mr. Marconi, who, he said, had
recently come to him with such a system. Telegraphing without wires was, of course, no new
idea. In 1893, telegrams were transmitted a distance of three miles across the Bristol Channel by
induction. Young Marconi solved the problem on different principles, and post office officials had
made a successful test on Salisbury Plain at a distance of three-quarters of a mile.
Scientific American - January 1897
The roots of modern radio-links can be perceived in the first experiments carried out by Marconi, Guglielmo Marconi
(1874-1937) Italy
as he used very high frequencies—practically in the field of microwaves—and had recourse to
1909 Nobel Prize for Wireless Telegraphy
parabolic-cylinder reflectors. Here is the first invention which Marconi anticipated. Many scientists
before Marconi had devoted their work to the electric and magnetic phenomena, taking
advantage of the extraordinary synthesis which James Clerk Maxwell’s equations had given
them. In 1894, when he was only twenty, the young man from Bologna set up his first laboratory
at Villa Griffone, about fourteen kilometers from his native city. Marconi’s basic contribution, for
which he deserves the name of “inventor of the radio”, was, first of all, that he modulated by a
signal the electromagnetic waves that a spark produced in a Hertz oscillator sent in space. James Clerk Maxwell
(1831-1879) Scotland
Gian Carlo Corazza 1996 European Conference for Radio-Relay, Bologna
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6. Wireless – Marconi Inventor of the Radio? Or Not!!
On 11 June 1943, the U.S Supreme Court overturned most of Marconi’s
wireless communications patents thus upholding Nikola Tesla’s earlier
September 1897 patent for radio, that in 1904 was reversed by the U.S. Patent
Office and awarded to Marconi, based upon Tesla’s wireless communication
demonstrations in 1894.
This Supreme Court decision—five months after he died impoverished, alone
in a New York hotel room—in effect recognized Tesla (who, shortly after
arriving in the U.S. in 1884, had worked for Thomas Edison for $18 per week)
as the inventor of the radio.
This added to Tesla’s remarkable credentials as the inventor and architect of
alternating current machinery and long-distance electrical distribution, this
rendering obsolete his adversary Edison’s direct current electrical
powerhouses that had been built up and down the Atlantic seaboard.
Nikola Tesla (1856-1943) Austrian Empire
“The Man who Invented the 20th Century”
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7. Propagation – Huygens’ Principle? Or Not!!
Christiaan Huygens, a contemporary of Sir Isaac Newton, is said to have gained most of his insights into wave motion by
observing waves in a canal. In 1678, this great Dutch physicist wrote the treatise Traite de la Lumiere on the wave theory of
light, and in this work he stated that the wavefront of a propagating wave of light at any instant conforms to the envelope of
spherical wavelets (Huygens’ “Combination Wavefront” of separate waves) emanating from every point on the wavefront at
the prior instant, with the understanding that the wavelets have the same speed as the overall wave.
Christiaan Huygens Sir Isaac Newton Augustin-Jean Fresnel Albert Einstein
(1629-1695) - Netherlands (1643-1727) - England (1788-1827) - France (1879-1955) - Germany
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8. Propagation – Huygens’ Principle? Or Not!!
An illustration of this idea, now
known as Huygens' Principle, is
shown. Disbelieving, Newton
continued to push his “Corpuscular
Theory” of particle propagation of
light, so because of that it was not
until some 100 years later when
Augustin-Jean Fresnel of “Fresnel
lens” and “Fresnel zone” fame Illustration of Huygens’ Principle. Einstein and others opine the duality
revisited Huygens’ Principle in 1815 The pinholes in the mask act as that light functions as both a particle
secondary point sources of radio (per Newton) and a wave (per
that his term “diffraction” was Huygens) depending on how the
energy.
reintroduced.* experiment is conducted and when
observations are made.
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9. Microwave Radio Links - The Early Days
2 GHz PPM “Digital” Radios
6 Bays!! 24xVF or 24x300 baud data channel capacity!! General Electric’s
2 GHz “radar-like” pulse position modulated (PPM, used during WW2 then
declassified) hot standby terminal. Many hundreds of similar GE and ITT
PPM radio hops were deployed in long pipeline, power and turnpike
systems in the 1940s-50s, some up to 75 hops in length with no end-to-
end noise buildup (like modern digital systems), all over the U.S. and
worldwide for the military.
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10. Microwave Radio Links - The Early Days
AT&T Long-Haul Analog Routes Deployed 35,000 TD2 Repeaters
The San Francisco-New York transcontinental route of hundreds of 4 GHz
TD2 analog FM-FDM hops completed in 1951 for all long distance VF and
TV was upgraded with high-capacity L6 GHz TH1 radios in 1955 and
improved TD3 radios in 1962.
The performance of analog hops was far more
affected than later generation digital radio hops
to equipment nonlinearities, interference,
thermal noise, multipath distortion,
waveguide echoes and moding,
and fading.
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11. U.S. Microwave Industry Evolution Through 1991
The Early Days
U.S. Microwave Communications EXTINCT
50
Manufacturers from 1931 (ITT) through 1991
Farinon/Harris MCD (1958) and
DMC/Stratex Networks (1984) merged to form
Harris Stratex Networks (2007), which changed names to
EXTANT
20
Aviat Networks (2010)
(growing rapidly)
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13. How We Evolved into Aviat Networks
Kurt Appert* Len Erickson
1944 San Francisco
1947 San Carlos, CA
Bill Farinon
Lenkurt Electric Company
Feb 1958 Bill Gibson
1959 Merger San Carlos
Jan 1984
1980 San Jose
Merger ( )
1963
1981
Jan 26, 2007 Merger
1982 GTE Network Systems
2002
1998
1983
Microwave Communications
Division (MCD)
Siemens
1984 Transmission Systems 2010
Boca Raton Siemens Information and
Communications Networks * Bancroft Library Oral history: http://www.archive.org/search.php?query=kurt%20appert
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14. The Migration from Analog to Digital Microwave Links
It’s Been a Challenge!
• Canadian Marconi delivered the first PCM digital radios to private
microwave users in North America in 1970, some hops remaining in
service into the millennium, thus triggering the rapid development and
deployment of higher capacity (first 1152 VF ch/78 Mbit/s, then 1344 VF
ch/90 Mbit/s) digital radios for LOS (line-of-sight) radio-relay hops.
• This culminated in 1980 with the realization that the alarm/network
management systems and adaptive equalization in these trailblazing
digital radios were often found totally inadequate to accommodate the
fragile, bursty characteristics of many high capacity digital microwave
radios and spectral distortion caused by dispersive fading in hops not
before seen in FM-FDM analog radio systems.
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15. The Migration from Analog to Digital Microwave Links
It’s Been a Challenge!
• The 1980s thus brought about dramatic improvements in digital
microwave modulation efficiencies and, with new adaptive equalization
and powerful error correction, robustness to the dispersive (spectrum-
distorting) fade activity that so degraded digital radio hop performance in
the 1970s.
• The mid-1990s heralded DSP equalizers that replaced discrete devices
in far more robust advanced asynchronous (PDH) and 2016/1890 ch
SONET/SDH point-to-point TDM digital radios. The FCC’s relocation of
analog microwave hops from 2 GHz in the late 1990s to accommodate
cellular deployment sped this digital migration.
• These new PDH and SDH digital technologies supported the explosive
birth of new high-performance terrestrial Fixed Wireless Systems and
Fixed Wireless Access networks in all of their forms, e.g. Point-to-Point
and Point-to-Multipoint, in synergism with fiber optics and FSO (free-
space optical) networks.
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16. Digital Microwave Attributes - a Media Comparison
• Superior availability (“uptime”) —route security (no fiber optics cable cuts) Long
Favors
Fiber
• Rapidly expandable and upgradeable, in-service if protected
• High quality—no multihop “noise” addition as in analog microwave hops
Turn-Up Time
Microwave or Fiber
• Rapid deployment over difficult terrain and into urban areas, unlike cable
• Economical and secure—no copper or fiber optic cable deployment with
right-of-way and security issues, and very high costs Favors
Microwave
• Robust to fading and interference compared to analog microwave hops
Transport Choices
Short
• Much less sensitive to antenna feeder system and long-delayed ,on-path Low Required Transport Capacity High
echoes compared to analog microwave hops
Radio Fiber
• Highly efficient data and broadband transport
Availability/security 
• Exacting in-service visibility of radio hop performance with NMS, PCR Payload (transport) 
• Seamless interconnectivity to an ever-expanding digital transport (fiber Cost effectiveness 
optics and other), PABX/MSC switch, and LAN/IP world Implementation time 
Terrain considerations 
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