JED - March 2018 - 25

The Journal of Electronic Defense | March 2018

25

which meant pushing further out in frequency
and power-generation capabilities."
And, this (leading-edge) domain, says
Palmer, "is always going to be the domain of the vacuum power tube."
Outlining the discussion in general
terms, Palmer says this is because TWTs
have two principle advantages over
solid-state systems. The first is that the
tube's vacuum operating environment
itself means that the electron-transport
process doesn't involve electrons bouncing against a semiconductor lattice and
generating heat, and thus limiting their
efficiency in terms of the power vs.
heat-generation equation. Also, TWTs
incorporate a device known as a "multistage depressed collector" that captures
the energy from the spent electron beam
and recycles it back it into the system
to further increase the efficiency of the
amplifier as a whole. Palmer points out

that this (power-generation efficiency) is one of the primary reasons that
vacuum tubes are particularly popular
for space-based applications. "Any time
you decrease the power efficiency of an
amplifier, you increase the size of the
power supply required, which means you
can therefore generally make the size
of an overall system smaller by using a
vacuum tube."

A HIGH-POWER PATH TO
THE MM-WAVE BAND
The truth of the view that leadingedge applications are the "domain-ofthe-tube" can be seen today with the
growing interest in reaching further and
further into the millimeter-wave band
(30-300 GHz) of the spectrum. Located
between the microwave and IR frequency spectrums, mm-wave is in increasingly high demand, particularly for defense
applications with the greater throughput demands being placed on data links

overall, and more specifically with the
growing use of UAVs. Says Palmer, "Generally speaking, you want to operate in
clear air, where other people aren't already operating, and millimeter-wave
offers you the opportunity to do that.
And, it's also efficient at transmitting
large amounts of data at high speed.
To do this, you need an especially high
power, very linear amplifier, like you
get from vacuum electronics."
Another reason that TWTs are of particular interest for millimeter-wave applications is that as applications move
up in these frequencies, atmospheric
absorption gets much higher than that
found at lower frequencies. As a result,
says Palmer, "If you want to put a certain amount of power on target or close
a link, you need a bigger amplifier. So,
as you push out higher into the millimeter-wave arena, you're also upping your
power axis to get sufficient transmit
power to do what you want to do."



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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