Missile designed to detect and home on an enemy radio emission source
An
anti-radiation missile
(
ARM
) is a
missile
designed to detect and home in on an enemy
radio emission
source.
[1]
Typically, these are designed for use against an enemy
radar
, although jammers
[2]
and even radios used for communications can also be targeted in this manner.
The earliest known anti-radiation weapon is a variant of the
Blohm & Voss BV 246
radar guided bomb.
[3]
Air-to-surface
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]
Most ARM designs to date have been intended for use against ground-based radars. Commonly carried by specialist aircraft in the
Suppression of Enemy Air Defenses
(SEAD) role (known to
United States Air Force
as "
Wild Weasels
"), the primary purpose of this type of missile is to degrade enemy air defenses in the first period of a conflict in order to increase the chance of survival for the following waves of strike aircraft. They can also be used to quickly shut down unexpected
surface-to-air missile
(SAM) sites during an air raid. Often, SEAD escort aircraft also carry
cluster bombs
, which can be used to ensure that, after the ARM disables the SAM system's radar, the command post, missile launchers, and other components or equipment are also destroyed to guarantee that the SAM site stays down.
Early ARMs, such as the
AGM-45 Shrike
, were not particularly intelligent; they would simply home in on the source of radiation and explode when they got near it.
[4]
SAM operators learned to turn their
radar
off when an ARM was fired at them, then turn it back on later, greatly reducing the missile's effectiveness. This led to the development of more advanced ARMs such as the
AGM-78 Standard ARM
,
AGM-122 Sidearm
, and
AGM-88 HARM
missiles, which have
inertial guidance systems
(INS) built-in. This allows them to remember the radar's direction if it is turned off and continue to fly towards it. ARMs are less likely to hit the radar if the radar is turned off shortly after the missile is launched, as the longer the radar is off (and assuming it never turns back on), the more error is introduced into the missile's course. The
ALARM
even has an added loiter mode, with a built-in parachute, enabling it to descend slowly until the radar activates, whereupon the rocket motor will re-ignite. Even a temporary shut down of the enemy's missile guidance radar can be of a great advantage to friendly aircraft during battle.
Defence Research and Development Organisation
is working on the
Rudram
series of anti-radiation missiles for
Indian Air Force
.
SIATT
with
Department of Aerospace Science and Technology
of
Brazilian Air Force
are jointly developing
MAR-1
.
Surface-to-surface
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]
Several
surface-to-surface missiles
, like the
P-700 Granit
,
P-500 Bazalt
,
MM40 Exocet
,
B-611MR
, and
Otomat
, include a home-on-jam capability wherein the receiver component of their
active radar homing
is used to home in on enemy radar, ECM or communications. This makes these missiles significantly harder to defeat with ECM and distraction countermeasures, and makes the use of
semi-active
missiles against them dangerous. Surface launched anti-radiation missiles also found application in the Israeli defense forces, such as an
AGM-45
shrike variant which could be fitted on an M4 Sherman tank chassis.
[5]
Surface-to-air
[
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]
Due to experiences with jamming by US-built aircraft in
Vietnam
and during Middle Eastern wars in the late 1960s, the Soviet Union designed an alternative tracking mode for their
S-75
(SA-2) missiles, which allowed them to track a jamming target without needing to actively send out any radar signals. This was achieved by the SAM site's radar receiver locking on to radio noise emissions generated by an aircraft's jamming pod. In cases of heavy jamming, missiles were often launched exclusively in this mode; this passive tracking meant that SAM sites could track targets without needing to emit any radar signals, and so American anti-radiation missiles could not be fired back in retaliation. Recently, the
People's Republic of China
developed the FT-2000 system to counter
AEW
and
AWACS
targets. This system is based on the
HQ-9
, which is in turn based on the
S-300PMU
. These anti-radiation missile systems have been marketed to Pakistan and various other countries.
Air-to-air
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]
More recently, air-to-air ARM designs have begun to appear, notably the Russian
Vympel R-27EP
. Such missiles have several advantages over other
missile guidance
techniques: they do not trigger radar warning receivers (conferring a measure of surprise) and they can have a longer range.
[
citation needed
]
In the 1970s,
Hughes Aerospace
had a project called
BRAZO
(Spanish for ARM). Based on a
Raytheon
AIM-7 Sparrow
, it was meant to offer an air-to-air capability against proposed Soviet AWACS types and also some other types with extremely powerful radar sets, such as the
MiG-25
. The project did not proceed.
See also
[
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]
- AGM-88 HARM
? U.S. high-speed air-to-surface anti-radiation missile
- AKBABA
[6]
- ALARM
? British air-launched anti-radiation missile
- DRDO Rudram
? Indian anti-radiation, air to surface missile system
Pages displaying short descriptions of redirect targets
- Hormoz-2
? type of ASBM, ARM
Pages displaying wikidata descriptions as a fallback
- Kh-31
? Soviet/Russian anti-ship cruise missile
- Kh-58
? air-launched anti-radiation missile
Pages displaying wikidata descriptions as a fallback
- MAR-1
? type of Anti-radiation missile (ARM)Air-to-surface missile
Pages displaying wikidata descriptions as a fallback
- Stand-in Attack Weapon
[7]
- TC-2A
? Taiwanese beyond-visual-range air-to-air missile with active radar homing
- YJ-91
? Chinese anti-ship cruise missile
References
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General references
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External links
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