Locating the target isn't the problem, you don't need a Doppler shift to calculate range by time of flight. The problem is detecting the target at all. Radar in these sorts of defense environments will pick up an enormous number of returns off of the carrying vessel and sea surf, which is actually a rather difficult problem for radar because it reflects in myriad directions, it moves, etc. By far the easiest way to select an "interesting" radar return is to use Doppler shift to find something that is moving very quickly. That can't be just a wave, it has to be a missile.
The problem is that rotary wing drones are very slow (compared to missiles) and so they don't present an obviously different shift from the background. A lot of R&D is going on right now into better ways to select slow-moving, low-cross-section objects like drones from the background.
This sort of thing is much more difficult for missile defense than the more conventional radar application of airspace surveillance, because for several reasons (including the fact that this makes radar detection hard) missiles tend to come at you from close to or below the horizon. This means you're getting a huge amount of clutter (radar returns from the environment) around them.
Not to minimize the challenges, but I think it's worth pointing out that a lot of the drones of topical interest are -not- quadcopters.
The Houthis (for example) have been using UAVs (Samad and Qasef) are prop driven fixed wing drones with total mass in the 50kg+ class (and warheads in the ~20kg class). They have max speeds of 200+ kph, wingspans in the 2-5m range. The Samad has ranges in the 1000km+ range. Obviously, they could slow down in terminal stages of attack, and I have no idea what their stall speed would be like.
These are more akin to the Shahed class drones that Russia has been deploying in Ukraine (though still much smaller), than the FPV drones we see attacking tanks/trenches.
The US Navy used radar guided artillery to knock down wave after wave of Japanese kamikazes, which flew at similar speeds. They were still sometimes overwhelmed by saturation attacks.
Modern US surface warships still have the same capability but most mount only a single large cannon (separate from the shorter ranged CIWS). There's no space for more. Research is underway to supplement those with lasers but those aren't operational yet and can only work with a clear line of sight.
Really? I had heard that sometimes pilots would nudge them off course or shoot them down but nothing about artillery, I thought radar came along a bit too late to use it for targeting with regard to the V1
> Automatic gunlaying (using, among others, the SCR-584 radar) and the proximity fuze played an important part in Operation Diver, (the British operation to counter the V1 flying bombs). Both of these had been requested by AA Command and arrived in numbers, starting in June 1944, just as the guns reached their free-firing positions on the south eastern coast of England. Seventeen per cent of all flying bombs entering the coastal 'gun belt' were destroyed by guns in the first week on the coast. This rose to 60 per cent by 23 August and 74 per cent in the last week of the month, when on one extraordinary day 82 per cent were shot down. The rate increased from one V-1 for every 2,500 shells fired to one for every hundred.
> 90mm anti-aircraft guns were normally operated in groups of four, utilizing the SCR-584 microwave computer and being controlled by the M9 Director. The SCR-584 was accurate to about 0.06 degrees (1 mil) and also provided automatic tracking. Direction and range information was sent directly to the M3 Gun Data Computer, and M9 Director, which directed and laid the guns automatically. All the crews had to do was load the guns.
Wow. I honestly find it amazing what they accomplished back then.
I spent like 6 hours reading the history of AEGIS when someone posted it here last year
"The answer to Pile's problems of directing the guns was the American S.C.R. 584 radar, the one used on the American 90mm anti aircraft gun, which had power elevation and traverse and an automatic fuse setter. The S.C.R. 584 was a gun-laying radar and "the most successful single application of the micro-wave ten-centimeter technique to ground fighting in World War IL It could automatically track an unseen target at night or in cloud or fog, supplying range,
azimuth and elevation data to a gun director." The S.C.R. 684 had a range of 90,000 yards for early warning, and as a target got within 32,000 yards the set acted as a gun layer. It had no blind spots and could detect low-flying targets like the Fi 103. Unlike the British radar sets, it was also immune to Window. However, it was a complex piece of electronic equipment and required a number of scarce materials like tantalum, molybdenum and tungsten, as well as 140 vacuum tubes
which were then in short supply in the United States. The fielded version weighed several tons and cost $100,000."
Impact, pg 174-175
"Aside from the redeployment, one of the reasons for the gunners' success was that new equipment had arrived. Anti-Aircraft Command received 135 of the long-awaited S.C.R. 584 radar sets and Pile was able to "borrow" an additional 165. Adapting these to the static British 3.7-inch gun required 200 modifications to the gun. Along with the radar sets came proximity fuses and 20 American batteries armed with the radar-controlled 90mm gun."
Impact, pg 207
"When controlled by the S.C.R. 584 radar set, the U.S. 90mm Ml Antiaircraft Gun was the finest antiaircraft gun of World War II. During the campaign they were operated 22 hours a day with two hours a day for maintenance."
Near the end of the blitz, the Brits claimed they were getting one kill per 100 rounds fired. That's an insane number, possible only with VT (proximity) fuses and radar directed gunnery.
The numbers from before those two advancements were closer to 100k rounds per kill
I've read opinions that radar was the single most effective innovation in WW2. It essentially doubled the effectiveness of anti-aircraft gunnery.
For example, the Bismarck battleship was loaded up with anti-aircraft guns. But it was unable to stop a handful of slow moving stringbags that attacked it, and one torpedo from one of them crippled the ship, leading to its destruction.
In contrast, radar directed anti-aircraft guns proved extremely effective against Kamikaze attacks.
The proximity fuse also used radar. Me, I would never have developed such a shell because I couldn't believe such a mechanism could survive being fired out of a cannon.
Pilots chasing down V-1s who shot at them from directly behind would risk immediately flying at high speed into the wall of shrapnel created by blowing up essentially a large powered bomb, often destroying or damaging their own aircraft in the process, which was very dangerous.
To avoid this, some pilots developed the tactic of flying along side the V1 then using their wingtip against the V-1 wingtip they would then flip it over and off course disrupting the primitive autopilot system so it would then spiral out of the control and hit the ground and explode hopefully in relatively harmless field.
I thought so too, but lately I have heard and read accounts akin to a lot of what happened in late WW2 with regards to radar technology was highly classified and much didn't enter the history books.
Pilots shooting and nudging definitely happened but likely other, more advanced stuff happened too. The germans had fully automatic radar controlled flak guns.
They used both (and barrage balloons as well). The space between the ~middle of the English channel and London was divided into "belts", with one type of defense operating in each belt to prevent interference (like flak shooting down your own fighters).
At first the flak guns were located near London (as that was the same flak guns that were protecting London against aircraft). It didn't work so well because it was very hard to hit a fast moving target like the V1, as crews not used to it tended to use too little lead. And even if the V1 was hit, chances were that the wreck would fall down on London anyway. So eventually the flak batteries were moved to the coast, and they got gun-laying radars and proximity fuses which dramatically improved the effectiveness of them.
The Shaheds fly much lower. You aren't likely to be able to shoot at them until they're close, unlike V1s where you could just send wave after wave of flak and destroy most of them.
Also, the drones are getting faster and faster, with the latest ones having turbojet engines.
Totally. I just guess the US didn't procure/deploy/use/turn-on the appropriate systems. Plenty of other posts in the comments identifying potential modern (and modern-ish) solutions that match your parameters.
The problem is that rotary wing drones are very slow (compared to missiles) and so they don't present an obviously different shift from the background. A lot of R&D is going on right now into better ways to select slow-moving, low-cross-section objects like drones from the background.
This sort of thing is much more difficult for missile defense than the more conventional radar application of airspace surveillance, because for several reasons (including the fact that this makes radar detection hard) missiles tend to come at you from close to or below the horizon. This means you're getting a huge amount of clutter (radar returns from the environment) around them.