Radar technology stems basically from the 30's (although first inventions and observations were made before WWI).
Back in WW2 radars were already capable of supplying recognizable images of a landscape below the aircraft (H2S radar) and radars were able to see outstanding buildings (the very first radar-guided glide bomb"Bat" was even able to 'lock on' a bridge).
Back in the 60's radars were used as poor weather and night bomb aiming devices in aircraft like the A-6 Intruder. OV-1 Mohawk aircraft meanwhile carried a side-looking airborne radar (SLAR) that was capable of both synthetic aperture radar mode (SAR; creating almost photo-like images of the ground in a useful resolution) and ground moving target indicator mode (GMTI; detection and display of moving objects like trucks).
At about that time the original Star Trek series were aired for the first time. Some episode featured the Enterprise's capability to detect individuals on a planet's surface from its orbit. Crew members on the surface were able of voice comm with the Enterprise in orbit. Both seemed to be quite unrealistic Sci-Fi, yet both is actually feasible with today's technology, less than two generations (instead of three centuries) later.
The progress of radar technology is quite visible in both radar satellites (even civilian ones are great) and long range aerial SAR/GMTI radars. SAR and GMTI modes have become standard for strike fighter radars (all-weather attack capability).
Long-range air/ground surveillance aircraft like the Desert Storm veteran E-8 and several other designs since it can create images with resolutions in the low decimetre range from 300 km away and at the same time detect moving vehicles, their speed and direction of movement at the same range.
(I intended to add a SAR screenshot graphic of an electronics company here, but the company did not respond to my request and thus didn't allow the use of said graphic. It looks like someone still has to learn basic marketing.)
Early applications of such capabilities were about getting a general picture of where and how much is moving to where. It helped on the operational level of war. Today we can search for individual buildings and vehicles, search and pinpoint field fortifications and much more.
Today's more networked systems could be much more useful. One example:
An artillery radar could spot an enemy artillery system's projectiles and calculate the point of origin. An airborne SLAR uses SAR mode to spot the launcher and GMTI to determine whether it uses the 'shoot & scoot' tactic; trying to change position asap after compromising its old firing position. If not, it could compare the SAR image with a map to pinpoint the exact location most accurately and supply the target information to the artillery for counterfire. A scooting artillery team could instead be tracked with SAR and GMTI till it stops in a new position and could be engaged over there.
Such a complex operation would require some luck (many complex elements involved, thus many things can go wrong) and the artillery team could shake off its observers by breaking contact in a city or behind hills. Nevertheless, this kind of combination shows that such eerie air power technology should be taken seriously almost down to the level of individual soldiers. Actually, the detection of some grunt's foxhole behind a battlefield should be feasible by comparing old and new SAR imagery as well!
Similar radar technology can be built into much smaller platforms than an E-8; high-end business jets (British ASTOR) down to drones like Reaper (follow link for interesting graphics), for example. It's a technology to reckon with - and that needs to be done by the young leaders; lieutenants up to majors.
NATO is in a particularly comfortable, but also somewhat risky situation. It has an obvious dominance in this area of sensory. That's on the one hand a huge advantage (if it works nearly as advertised) and on the other hand it poses a risk that we might be late with the development and deployment of specific countermeasures because we need none to date.
The Russians certainly have not slept over this kind of tech. The early GMTI radar incarnations were to be defeated with simple maskirovka (deceptions) such as pulling a string with tin cans behind cars to fake a convoy march or mounting metal radar reflectors along roads to permanently create false signal returns. Modern processor power and memory sizes likely rule such simple countermeasures out in the future.
Their more promising countermeasure is a very expensive one and likely capable against all usually highly valuable standoff support aircraft, including AEW&C (a.k.a. 'AWACS'), passive electronic reconnaissance aircraft, jammer aircraft and tankers.
That countermeasure is the super-long-range 40N6 missile (said to have a range of 400 km) of the S-400 "Triumf" air defence system (NATO designation: SA-21 "Growler"). This missile is likely capable to keep support aircraft at a very long distance by its sheer repulsion value.
I've heard and read again and again about how such long-range air defence systems could create huge no-go areas against Western offensive air power. My interpretation of military (air defence) history, military theory and disclosed information is that the enforcement of a safety distance for support aircraft is likely their primary if not their only raison d'être.
This assumption was partially contributing to my interest in supersonic business jets as potential air force support aircraft. This interest has since cooled down because the economic crisis has hit those projects and the British experience with ASTOR suggests that for the time being a small airliners' volume and payload is probably an advisable for really long-range radar aircraft. Regrettably, small airliners tend to be short-range airliners and they also tend to be both relatively slow (in comparison to the Boeing 707-based E-8) and not designed for flying very high (which is useful for radar aircraft).
A part of the Russian air-to-air missile development is about ultra long range air/air missiles; the Novator K-100 and the Vympel R-37. Both are regularly seen in context of AWACS aircraft, but J-STARS should be considered to be their target as well.
The Russians also developed active radar jammers against air/ground radars, the SPN series. That hardware appears to be meant for the protection of high-value targets such as river crossings and such. I am sceptical about their ability to jam in protection of more than point targets.
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Radar technology is tricky and understanding it requires years of university studies. Nevertheless, an understanding of the potential of radars is necessary even at junior leader levels. Contemporary radar aircraft may fall short of expectations or not; the potential is eerie and was in the realm of Sci-fi until few years ago.
Such technologies can have game-changing consequences for all military forces up to 300 km away from the battlefield. Ships can be identified at long distance by radar imagery, aircraft can be identified by fighter radars, even missiles like a late AMRAAM version can create an image of their target and thus discern the target from decoys. Vehicles, Foxholes and mere tents could be detected from a safe distances.
This has to have an impact on military doctrine and the need for countermeasures is blindingly obvious because you must not grant your enemy such a powerful surveillance tool (even if he hasn't got the staff and procedures to make full use of it) if you can avoid it.
A reliance on air superiority alone may be a too risky approach because battlefield reconnaissance missiles such as CL-289 can be and have been equipped with radars as well.
P.S.: This blog text became quite long and contrary to my original intent I didn't even mention half of the most eerie radar stuff!