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Our Radar-Laden Weapons Attract Their Own Doom

May 14, 1987|THOMAS S. AMLIE | Thomas S. Amlie, former technical director of the China Lake Naval Weapons Center, is an analyst for the Department of Defense. His commentary, which does not necessarily reflect the opinions of the Department of Defense, was written for the Washington Post.

The invention of radio detection and ranging--or radar--transformed the nature of modern warfare.

American high-technology weaponry ranging from the B-1 bomber to the Aegis cruiser is now so dependent on radar that without it, these weapons cannot perform their missions.

But radar is a double-edged sword, and increasingly the use of it endangers the very weapons that are dependent upon it. This issue--the extreme vulnerability of systems that radiate strong and distinctive signals--has been thoroughly understood by specialists since World War II, but largely overlooked by just about everyone else.

Radars emit powerful and very distinctive pulses of electromagnetic energy. There is a tremendous asymmetry between the distance at which a radar can detect a target and the distance at which a relatively simple "listening" apparatus can detect the radar.

For instance, a typical fighter aircraft radar might be designed to detect another fighter at a range of 50 miles. But a simple, receive-only system can detect and classify the radar at, li1952805473line-of-sight conditions prevail.

Radars also have distinctive "signatures." Relatively simple receiving equipment can classify the type of radar and hence, in general, the type of platform it is mounted on.

Further, if similar radars are to be operated in a formation of ships or aircraft, they must be tuned to different frequencies so as not to interfere with each other.

Thus, the receiving equipment can tell with some precision how many ships or aircraft there are, what type they are and where they are. One could make an argument that we have gone to considerable trouble and expense to give a potential adversary very useful information.

The most serious problem with operating radars full-time is that they are excellent targets for anti-radiation missiles, or ARMs. These missiles pick up radar signals and track them to the source in much the same way that heat-seeking missiles go to the heart of the flame.

The Soviets have been building ARMs (and apparently good ones) since the late 1950s. Indeed, their first air-to-surface (anti-ship) missile, the AS-1, was an ARM. Since that time, they have built several more models of anti-ship ARMs. Defense media in the West have reported that the new Soviet air-to-air missile, the AA-10, is an ARM.

But the United States has not been particularly successful in developing and manufacturing its own anti-radiation missiles. The Navy-developed Shrike was purchased in large quantities in the 1960s. Because of some unfortunate design decisions it was, practically speaking, a failure. The Air Force and Navy are now buying the high-speed anti-radiation missile, or HARM. I believe that the HARM will also be a failure for the same reason--reliance on faulty technology.

The United States spends billions each year to acquire electronic counter-measure equipment, or "jammers," while the Soviets over the last 20 years have been busily converting their air-defense systems to electro-optical guidance. These systems are essentially very sensitive televisions. Thus, there is no electronic signal for us to jam, or to warn our pilots that their aircraft are under attack.

In bad weather, when electro-optical equipment cannot be used for detecting attacking aircraft, the Soviets can use surface-to-air ARMs instead. That's because the attacking aircraft would be using radar in order to carry out a bombing mission.

Therefore, to the extent that the United States is spending money to install jamming equipment--which emits powerful signals--in its aircraft, it is making them more, rather than less, vulnerable.

A major reason that our fighter aircraft are large, require a great deal of maintenance and cost upwards of $40 million each is that they are designed around expensive and troublesome radar fire-control systems.

In the presence of air-to-air and surface-to-air ARMs, these radars could not be operated without suffering unacceptable losses. This conclusion applies to both fighter radars and radars used for bombing.

A reasonable question to ask might be, "If we have known for 30 years that a simple ARM could make these complex and expensive systems unusable, might it not have been better to buy larger numbers of smaller, simpler and much cheaper aircraft?"

The media are now reporting that the defense avionics (read "jammers" again) on the B-1B will not be ready for two years or so. This is actually good news, because the jammers make the aircraft more vulnerable. Les Aspin, the chairman of the House Armed Services Committee, has said the B-1B's defensive electronics system serves as a beacon illuminating the B-1B as a target.

The B-1B also carries a terrain-following radar, the transmissions of which can be detected at long range. It would also be an excellent target for an air-to-air or surface-to-air ARM.

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