JED - March 2018 - 24

The Domain of the Tube -
By John Haystead

A
The Journal of Electronic Defense | March 2018

24

At 7:55 a.m. EDT on September 15 of last
year, NASA's Cassini spacecraft plunged
into the planet Saturn's atmosphere,
transmitting a final set of science observations to Earth from its 20-year
voyage of discovery through the solar
system including a 13-year tour of the
ringed planet itself.
The joint Cassini-Huygens mission
represented a tremendous scientific
achievement for NASA, the European
Space Agency (ESA) and the Italian
Space Agency. The wealth of data and
new knowledge of the solar system it
provided will be invaluable, as will the
lessons learned in benefit of future
manned and unmanned space exploration. There is, however, one other important lesson clearly demonstrated by
the Cassini spacecraft that may not be
as immediately appreciated.
Nearly all of the RF systems on
Cassini were powered with traveling
wave tubes (TWTs), including science
research instrumentation, telemetry

TWTs still power most of the jammers used
today, such as the jamming pod on the outerleft weapons station of this A-10. (USAF)

and control, and its data link back to
earth. Launched in 1997, there was
major debate at the time of its development whether its systems should be
built not with vacuum tube technology
but with solid-state amplifiers, an argument based largely on the perception
that tube technology was unreliable. As
it turned out, however, arriving at Saturn in 2004, NASA extended Cassini's
mission twice - first for two years, and
then for seven more, unquestionably
proving the viability and reliability of
Cassini and its tube-technology-based
systems over a 20-year, deep-space environment lifetime.

TWTS CRITICAL TO NEXT-GENERATION
REQUIREMENTS
Today, the tube vs. solid-state competition continues apace with reliability
questions often still cited by advocates
of the latter. But, as Dr. William Devereux (Dev) Palmer, (at the time of
this interview, program manager at the

Defense Advanced Research
Projects Agency's Microsystems Technology Office), points out, "In
truth, if you look at the debates that
have gone on over tubes and solid-state
electronics over the decades (and in fact
one of the reasons that it has gone on
for so long), you'll see that it usually
centers around the outer edges of the
power/frequency design space." The history of this, as described by Palmer, can
be seen in the evolution of technology
aimed at meeting the requirements of
the time for operation in the microwave
region of the spectrum. "Before GaAs
[gallium arsenide] transistors began to
become useful in the microwave space,
the only solution was tubes. Then, GaAs
began to displace tubes at lower frequencies, but there were still always
applications that wanted to stay ahead
of the commercial electronics market,



JED - March 2018

Table of Contents for the Digital Edition of JED - March 2018

The View From Here
Conferences Calendar
Courses Calendar
From the President
The Monitor - DOD Rolls Out $686 Billion FY2019 Budget
World Report - Russia Developing More Sophisticated Approach to EW
The Domain of the Tube – Millimeter Wave and Beyond
A Wild Weasel EWO Kills a SAM – from an AC-130E Gunship
Resilient and Ready: NATO JEWCS in Transition
EW 101
2018 AOC Industry & Institute/ University Member Guide
AOC News
Index of Advertisers
JED Quick Look
JED - March 2018 - intro
JED - March 2018 - cover1
JED - March 2018 - cover2
JED - March 2018 - 3
JED - March 2018 - 4
JED - March 2018 - 5
JED - March 2018 - The View From Here
JED - March 2018 - 7
JED - March 2018 - Conferences Calendar
JED - March 2018 - 9
JED - March 2018 - Courses Calendar
JED - March 2018 - 11
JED - March 2018 - From the President
JED - March 2018 - 13
JED - March 2018 - 14
JED - March 2018 - The Monitor - DOD Rolls Out $686 Billion FY2019 Budget
JED - March 2018 - 16
JED - March 2018 - 17
JED - March 2018 - 18
JED - March 2018 - 19
JED - March 2018 - 20
JED - March 2018 - 21
JED - March 2018 - World Report - Russia Developing More Sophisticated Approach to EW
JED - March 2018 - insert1
JED - March 2018 - insert2
JED - March 2018 - 23
JED - March 2018 - The Domain of the Tube – Millimeter Wave and Beyond
JED - March 2018 - 25
JED - March 2018 - 26
JED - March 2018 - A Wild Weasel EWO Kills a SAM – from an AC-130E Gunship
JED - March 2018 - 28
JED - March 2018 - 29
JED - March 2018 - 30
JED - March 2018 - 31
JED - March 2018 - Resilient and Ready: NATO JEWCS in Transition
JED - March 2018 - 33
JED - March 2018 - 34
JED - March 2018 - 35
JED - March 2018 - 36
JED - March 2018 - 37
JED - March 2018 - 38
JED - March 2018 - 39
JED - March 2018 - 40
JED - March 2018 - 41
JED - March 2018 - EW 101
JED - March 2018 - 43
JED - March 2018 - 44
JED - March 2018 - 45
JED - March 2018 - 2018 AOC Industry & Institute/ University Member Guide
JED - March 2018 - 47
JED - March 2018 - 48
JED - March 2018 - 49
JED - March 2018 - 50
JED - March 2018 - 51
JED - March 2018 - 52
JED - March 2018 - 53
JED - March 2018 - 54
JED - March 2018 - 55
JED - March 2018 - 56
JED - March 2018 - 57
JED - March 2018 - 58
JED - March 2018 - 59
JED - March 2018 - 60
JED - March 2018 - 61
JED - March 2018 - 62
JED - March 2018 - 63
JED - March 2018 - 64
JED - March 2018 - 65
JED - March 2018 - 66
JED - March 2018 - 67
JED - March 2018 - 68
JED - March 2018 - 69
JED - March 2018 - 70
JED - March 2018 - AOC News
JED - March 2018 - 72
JED - March 2018 - Index of Advertisers
JED - March 2018 - JED Quick Look
JED - March 2018 - cover3
JED - March 2018 - cover4
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