JED - April 2014 - 41

TECHNOLOGY SURVEY
A SAMPLING OF RADAR JAMMERS
By Ollie Holt

process and initiate a jamming response within
the received pulse. The simplest and probably oldest method of responding to this type of threat
would be a straight through repeater path that
just passes the received signal to the power amplifier to retransmit, possibly with some amplitude
and/or phase modulation to try to deceive the
radar. The problem with repeaters is they repeat
to anything in the bandwidth of the receiver,
which means that they become a beacon to other
radar systems. The challenge with these emerging
radar threats is to find new methods of denying
their ability to track own ship.

THE SURVEY
The first parameter in the survey, "internal"
or "pod" configuration is self-defining. The next
parameter is the operational frequency range. Most
of the support jammers cover frequencies as low as
100 MHz and a few even lower and go up to around
6 GHz. Most self-protection radar jammers have a
low frequency of around 2 GHz and up to around 18
GHz, though it's not uncommon to see capabilities
below 2 GHz and above 18 GHz.
The installed receiver sensitivity defines the
ability of the radar jammer to detect the radar signal and provide the necessary jamming techniques.
The lower the installed sensitivity value, the greater
the systems detection range capability. Self protect
jammers typically provide installed sensitivities
of between -45 and -60 dBm. Sensitivity has to be
balanced with the jammer ERP to prevent interference between receive and transmit paths. A support
jammer needs more sensitivity because it typically
needs to operate beyond a threat's missile range.
ERP is the maximum output power of the jammer
system; in some cases, this includes antenna gain.
For support jammers using noise techniques, the
larger the ERP, the more disruption it will cause.
For self-protection jammers, the ERP required is a
balance between radar cross section of the aircraft
and the detection range of the threat radar system.
The goal is to generate greater jamming power than
the radar return power reflected from the aircraft.
JED's next technology survey, which will be
published in the June issue, will cover spectrum analyzers. a

The Journal of Electronic Defense | April 2014

T

his month's technology survey is
focusing on radar jammers. Radar jammers are typically designated either
as self-protection jammers or support
jammers. (Some newer jammers blend
these capabilities.) A self-protection
jammer's function is to prevent a hostile radar
system from being able to track the host platform
(own ship) and launch a missile or aim a gun at it.
This is done through a combination of denial and
deception techniques. A support jammer's function is to operate at stand-off or stand-in ranges
and to prevent another friendly aircraft from
being detected and tracked by radars using denial
and deception techniques. Self-protection jammers typically are installed on aircraft and ships.
The support jamming mission usually is conducted by aircraft, such as the EA-18G Growler,
the EC-30H Compass Call and UAVs. Ground-based
support jammers are designed to jam the multimode radars of attacking aircraft.
A radar jammer is actually a complete system
that consists of receive antennas, receivers, signal
processing, technique generators (possibly including a Digital RF Memory (DRFM)), a power amplifier
and transmit antennas. The antenna, receiver and
signal processing serve as the eyes for the radar
jammer. Without these functions, the jammer could
only transmit high power broadband noise hoping
to prevent any radar receiver operating within
the transmitted frequency range of the noise from
being able to detect a target. With a receiver function, the jammer can selectively determine which
radar emissions are threats to the platform and -
through a process of determining threat mode and
ID - select the most effective technique against
that threat. Selection of the most effective technique can become a complex action if more than
one threat is to be jammed and the power amplifier
has limited duty cycle.
Today's radar systems are becoming more complex and harder to detect and jam. This also makes
them harder to ID for selecting the best technique.
They are becoming more frequency agile, some
with the ability to change frequency after each
pulse. That means the jammer needs to be able to
predict the next frequency or be able to detect,

41



JED - April 2014

Table of Contents for the Digital Edition of JED - April 2014

The Monitor
Washington Report
World Report
Interview: Rich Sorelle
The Electromagnetic Battle Management (EMBM) Challenge
Technology Survey: Radar Jammers
Show Preview: EW Europe 2014
The View From Here
Conferences Calendar
Courses Calendar
From the President
EW 101
AOC News
Index of Advertisers
JED Quick Look
JED - April 2014 - cover1
JED - April 2014 - cover2
JED - April 2014 - 3
JED - April 2014 - 4
JED - April 2014 - 5
JED - April 2014 - The View From Here
JED - April 2014 - 7
JED - April 2014 - Conferences Calendar
JED - April 2014 - 9
JED - April 2014 - Courses Calendar
JED - April 2014 - 11
JED - April 2014 - From the President
JED - April 2014 - 13
JED - April 2014 - 14
JED - April 2014 - The Monitor
JED - April 2014 - 16
JED - April 2014 - 17
JED - April 2014 - 18
JED - April 2014 - 19
JED - April 2014 - 20
JED - April 2014 - 21
JED - April 2014 - 22
JED - April 2014 - 23
JED - April 2014 - Washington Report
JED - April 2014 - 25
JED - April 2014 - World Report
JED - April 2014 - 27
JED - April 2014 - Interview: Rich Sorelle
JED - April 2014 - 29
JED - April 2014 - The Electromagnetic Battle Management (EMBM) Challenge
JED - April 2014 - 31
JED - April 2014 - 32
JED - April 2014 - 33
JED - April 2014 - 34
JED - April 2014 - 35
JED - April 2014 - 36
JED - April 2014 - 37
JED - April 2014 - 38
JED - April 2014 - 39
JED - April 2014 - 40
JED - April 2014 - Technology Survey: Radar Jammers
JED - April 2014 - 42
JED - April 2014 - 43
JED - April 2014 - 44
JED - April 2014 - 45
JED - April 2014 - 46
JED - April 2014 - Show Preview: EW Europe 2014
JED - April 2014 - 48
JED - April 2014 - 49
JED - April 2014 - 50
JED - April 2014 - EW 101
JED - April 2014 - 52
JED - April 2014 - 53
JED - April 2014 - AOC News
JED - April 2014 - 55
JED - April 2014 - 56
JED - April 2014 - Index of Advertisers
JED - April 2014 - JED Quick Look
JED - April 2014 - cover3
JED - April 2014 - cover4
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