Military Embedded Systems

Radar and the kill web


July 31, 2019

Ray Alderman

VITA Standards Organization

WARFARE EVOLUTION BLOG: This is a complex topic, broad in applications and deep in technical details. Radar can be studied from several different angles: by the domain covered (land, sea, undersea, air, and space), by the frequencies used (the IEEE, EU/NATO, and ITU all use different frequency band designations, making things even more confusing), by the range of the signal (long range surveillance, intermediate-range theater coverage, and short-range fire control radar), by application (offensive radar vs defensive radar), or by radar types (there are about 13 of them). Each of these approaches spill over into the next, creating a convoluted mess if you?re not careful. So, the safest way to eliminate the confusion in a short article like this is oversimplification. Therefore, we will look at what radar does in the kill web, and a little about how it works.

There are two basic types of radar: active and passive. Active radar sends out a radio signal from a transmitter, it reflects off the target, and returns to the receiver. Monostatic radar is one transmitter and one receiver located together; bistatic is one transmitter and one receiver, but the receiver is located away from the transmitter; and multistatic uses multiple transmitters and multiple receivers, all in different places. Bistatic and multistatic radar are used to detect stealth aircraft from multiple angles. Passive radar only uses receivers, and detects existing radio signals inside the kill web bouncing off the target, like TV stations, cellphones, and radio stations (AM and FM). We’ll focus on active radar in this article.

What do we want radar to tell us? There are five basic components: (1) detect enemy targets at a distance (on land, sea, under the sea, and in the air and space), (2) accurately define the target’s behavior (position, speed, altitude, and course) (3) determine what the target is (airplanes, helicopters, ships, tanks, submarines, missiles, drones), (4) identify the target precisely (the specific type of airplane, drone, helicopter, ship, tank, missile), and (5) reveal the target’s physical attributes (size, shape, and the number of weapons, missiles, bombs, and fuel tanks on board). When radar executes elements 2 through 5, it's called "interrogating the target."

How can radar disclose all this information? By using different frequencies, beam widths, waveforms, pulse widths, and receiver locations. At this point, we’ll use the IEEE radar band designations to avoid severe reader disorientation. Starting at the lower frequencies, they are HF, UHF, VHF, L-band, S-band, C-band, X-band, Ku-band, K-band, Ka-band, V-band, W-band, millimeter wave (mm), and LADAR (Laser Detection and Ranging). Radar is just above the radio and TV frequencies, and just below the visible light spectrum. I recommend that you take a moment, find a radar frequency spectrum chart on the web, and review it. I’ll wait here while you do that.

To read more Warfare Evolution Blogs by Ray Alderman, click here.

Ok, you’re back. The kill web employs an overlapping layered approach to radar coverage. Long-range surveillance radar uses HF, UHF, VHF, and L-band frequencies to detect targets out to 2,000 miles or more. How can it see that far when the curvature of the earth limits our line of sight to about 15 miles? Two ways: ground wave propagation (GWP) and over-the-horizon radar (OTH). Low frequency radar waves hug the earth, hit the target a thousand miles away, and follow the earth again on their way back to the receiver. That’s how GWP radar works.

If you move your frequency up a little, and shoot those radar waves at the sky, they will hit the ionosphere and bounce back down to earth a thousand miles away. If they hit a target, they will bounce up to the ionosphere again and back to the receiver. That’s OTH radar. Long-range radar can tell us there’s something out there, but it can’t accurately tell us much about its behavior, or what kind of target it might be.

Next, we have intermediate-range radar. These are typically airborne radar systems that fly at 20,000 to 30,000 feet, on the edge of the kill web. The Airborne Warning And Control System (AWACS) can find enemy aircraft and helicopters in the sky out to about 400 miles. It uses the S-band for primary searches, and does frequency-hopping in other bands to discover more details about the targets. Changing frequencies rapidly and randomly makes it hard for the enemy to jam the AWACS radar signals, so the sequence of frequency changes, pulse widths, and waveforms are a closely guarded secret.

JSTARS (Joint Surveillance Target Attack Radar System) looks for enemy tanks, artillery, and missile launchers on the ground. It can track hundreds of fixed or moving targets out to 150 miles away using synthetic aperture radar (SAR) techniques. As the aircraft flies near the Kill Web, it can see the target from many different angles. The radar processing computers put those snapshots together and can easily tell the difference between a tank and a school bus. K and Ka band radars fit into this segment. We also have radar systems on satellites in space, that search for ships, submarines, aircraft, helicopters, tanks, and artillery. They operate in the X and Ku-bands, and can actually detect minefields in the war zone. JSTARS is now being replaced by the Advanced Battle Management System (ABMS), with better resolution and range.

How can radar detect submarines? The Navy operates numerous satellites, along with the P-3 Orion, P-8 Poseidon, and MQ-4C Maritime surveillance planes, to monitor the sea. Submarines are very large heavy chunks of metal. When they move through shallow waters submerged, like off the coasts of Iran, North Korea, China, or Russia, they push the displaced water up to the surface (the Bernoulli Hump) and they leave a turbulence trail that rises to the surface behind them (the Kelvin Wake). Radar can detect both the hump and the trail under the right conditions. Also, we can see the periscope, or the air-intake and exhaust snorkels on diesel subs, if they raise them above the water line.

On the ground, in the kill web, we have active electronically scanned array (AESA) radar systems looking for enemy airplanes, helicopters, and missiles. These systems have large flat panels pointed at the sky. Inside each panel are a number of transmitters and receivers, all operating at the same or different frequencies in the radar spectrum, sending out beams sequentially or simultaneously. The latest AESA radar can see targets more than 200 miles away. These systems are also installed on our jet fighters (F-18, F-22, F-35), and on Navy ships. This is where the C-band is used, along with other bands for target details.

Finally, we have fire-control radar (FCR). In the vectoring phase, intermediate-range surveillance radar finds and identifies a target, and passes it to the fire-control radar system. In the acquisition phase, FCR will send out a high-frequency signal with a narrow beam width (1 to 2 degrees wide), acquire the target, and lock on it. This is called "lighting up the target." In the tracking phase, the FCR fires a weapon at the target while maintaining the tracking beam. The weapon (a missile in this case) receives the radar reflections bouncing off the target and homes in on them with an internal radar receiver. When the target explodes, the FCR turns off the beam and goes back into the vectoring phase. Some of our missiles contain the FCS radar transmitter and receiver integrated inside, in front of the explosive warhead (fire-and-forget weapons).

Stealth aircraft (F-22, F-35, B-2, etc.) are designed to defeat frequencies in the C, X, Ku, and S-bands used by enemy radar. In late July 2019, a Kuwaiti newspaper (al Jarida) reported that in March of 2018, a group of new Israeli F-35s flew over Tehran and four other Iranian cities at high altitude, looking for sites associated with Iran’s nuclear program and the anti-aircraft missile systems in the area. The Israeli fighter planes entered Iranian airspace from Syria, found, mapped, and photographed those facilities, and flew back across the border undetected. Iran and Russia, both bastions of honesty and integrity, disputed the story and offered a litany of technical reasons why such a breach of their airspace and radar systems could never happen.

So, let's look at some facts. The Russian-made S-300 anti-aircraft radar used by Iran is multistatic, with components as far as 25 miles apart, and uses the S-band for its best view. It can detect targets with an RCS (radar cross section) of 3 square meters flying over 200 miles away, according to web information. The F-35 has an RCS of 0.005 square meters from the front, but multistatic radars will see something bigger when looking at the sides and the rear.

Second, I remind you of Operation Opera (1981). Israeli F-15s (with an RCS greater than 5 square meters with bombs under their wings) flew into Iraq undetected and destroyed the nuclear reactor near Bagdad. Third, I remind you of Operation Orchard in 2007 (also referred to as Operation Outside-The-Box). Israeli F-15s flew into Syria undetected and destroyed a reactor near Deir ez-Zor. Fourth, the Kuwaiti article reported that Iran’s supreme leader, Ayatollah Khamenei, sacked his air force commander (Brigadier General Farzad Ismaili), shortly after he read the article in al Jarida. Fifth, reports reveal that in June 2019, U.S. cyber forces hacked into Iran's command and control system and disabled the computer systems they use to fire their missiles and rockets. Therefore, I suggest that this Israeli mission did take place in 2018, through a combination of stealth, electronic warfare (EW) tricks, cyber attack, and inept Iranian radar operators.

Everything that flies, floats, moves on the ground, or stands still has a radar signature. All Russian SU-35 fighters have the same signature. All Chinese J-11 fighters have the same signature. Look-up any aircraft in the threat library (or with a simple web search), and you’ll know their fuel load (combat radius), bomb and missile loads (lethality), fuel consumption (range), wing loading (turn radius), thrust-to-weight ratio (climb rate), and ceiling (max altitude). If we know the specific target from the radar signature, then we know all this other information too.

All 737 airliners have the same signature, but our radar systems can tell the difference between a 737-400 (188 passengers) and a 737-500 (145 passengers). Radar can tell us if an enemy fighter plane is “flying wet” (with fuel tanks under its wings), which means that his target is far away. Radar can also tell if the enemy fighter plane is flying in “beast mode” (no fuel tanks, but with bombs and missiles under its wings), which means his targets are close by. We can count the number of bombs and missiles attached under the wings, and we can see their size and shape. One source I read said that we can count the fan blades on his engines. That gives you a basic idea about the details radar can expose.

Where are we going with radar? Incrementally, we’ll see improvements in resolution and radar ranges within the present frequency bands. Research is underway on millimeter wave forms and lasers beam frequencies. And, we are beginning to integrate radar, infrared sensors, and electro-optical sensors (cameras) together with artificial intelligence algorithms, making our detection systems incredibly fast and accurate over longer distances. There’s also study being done on quantum radar.

If you want to speculate about radar further into the future, you need to read the Star Trek Technical Manual (available from Amazon). The Enterprise uses quark packets, neutrinos, magnetic flux detection, and gravimetric distortions to detect threats. They can even tell the difference between Humans, Klingons, and Vulcans on a planet from high orbit. Humans have red blood (iron content), Vulcan blood is green (copper content), and Klingons have pink blood (bismuth content). So, maybe radar can detect the atomic and molecular makeup of targets in the future.

If the kill web concept has a motto, I think it would be: “Never get into a fair fight with the enemy. Always have an overwhelming advantage.” Radar is just one of the elements making that motto a reality. If an innocent sparrow should fall from the air inside the kill web, from anything other than natural causes, we will detect it instantly and be capable of putting an explosive weapon on that exact spot in 10 minutes or less.

We have barely scratched the surface on this subject. There’s lots of math, geometry, and physics involved in radar, which we have successfully avoided here. Radar is just one of the electromagnetic sensors in the kill web. Signal intelligence (SIGINT) receivers, that intercept enemy radio communications, are another. There are also acoustic sensors (sound), motion detectors (movement), magnetometers (metal detectors), seismic sensors (vibrations), electro-optical sensors (cameras), chemical sensors (chemical agent detectors), heat sensors (infrared), radiation sensors (Geiger counters), biological sensors (germ detectors), thermometers, hygrometers, barometers, and laser sensors scattered all around. You can read about any of these topics for hours.

How can we put explosive weapons precisely on a target, from thousands of miles away, in 10 minutes or less? That’s the thrust of our next adventure. The answer is hypersonic missiles that fly at speeds above Mach 5 (3,836 MPH). Time (minutes) and distance (miles) are interchangeable, so we’ll be doing some math next time. And at the speeds we’ll be traveling, you could experience G-LOC.


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