Remember the little folding 40mm drones? Imagine a slightly larger one with a FLIR Boson based 640 res IIR sensor. When a drone is detected passively by a staring IIR sensor or MMW radar on the host vehicle, a Chaff/Flare like dispenser kicks one out, the arms and motors unfold, and it zips off to the target queued by the APS, destroying it with a little golf ball sized warhead.   A dispenser might be the size of a piece of luggage and easily hold 25+ drones.

Because it's intercepting a known target at relatively short range and isn't returning, it can trade endurance for acceleration.

https://www.youtube.com/watch?v=YHvC3KRTxO0
 

I don't thing the use of counter drones is a viable and especially cost effective option.
To be really reliable they sensor and guidance would need to be rather complex. In addition the propulsion system is unnecessarily complex.
Why not go all the way and use a rocket engine and call it small anti drone missile. Because even without rocket engine this is basically what it is.

If we talk 40 mm why not use a 40 mm HV Frag-Grenade with programmable fuse. These could either be launched by a 40 mm AGL or by boxed lauchers using the Metal Storm principle.

To get the smaller, cheaper end of drones under controll IMHO its paramount to use a cheap solution. Otherwise it will not be available everywhere and not in the numbers required. Therefor again in MHO guided munitions are out. To complex and to expensive. Programmable airburst or proximity fused can allready be borderline costwise but the advantage is it can be used from existing systems which just get an addition function.

That's why I was thinking MG with high ROF

graylion said:

I have been thinking further about how I'd configure an anti drone system

All of the above as per a modern SPAAG, but also an ECM system and probably a high ROF MG for the wee drones

I don't think its a viable approach to think in a single one system fits all problems way.
As with air defense drone defense needs to be layered. In fact drone defense is just air defense with additional inner layers.
So you have the theatre layer, local layer, area layer, and point defense layer.
In addition and as a difference to air defense is the possibility of striking the drone user of tactical drones.

graylion said:

but also an ECM system and probably a high ROF MG for the wee drones

I would think that an MG would only be useable in a sparsely populated area.  Otherwise you would need something that would self-destruct to avoid "friendly fire" problems.

graylion said:

That's why I was thinking MG with high ROF

Its certainly an option.
Which approach is the most effective needs to be researched. MG with high ROF can work but hitting could be such a problem that ammo consumption might be an issue. Endangering the sorounding area certainly is. Because the MG rounds will keep going. Not so much a problem for high angle fire but drones also come in low and very low. An auto tracking high ROF MG might give people headaches.
Airburst has the advantage of a more defined area of effect and danger.

I think a dispenser with anti drone drones have a place as part of a layered approach. I work with both drones and software development, it is not that complex in principle.

Once the vehicle active protection system detects a drone actively or passively its pretty straightforward to feed that relative location information to the interceptor drone which will orient and lock on after launch.

Each interceptor would run a few thousand mostly the IIR core, and while that is more expensive than ammunition, it has some advantages. First, you're not just slinging 40mm or machine guns ammo in the sky (or against a background of friendlies if the threat is flying nap of the earth) when you can 1:1 kill the drone with a drone.  Second, the engagement cycle doesn't need to commandeer the remote weapons station which the commander might be using in that moment against ground targets or as a CITV.  Third, this is also more durable a solution as far as hard kill options for small drones goes because as soon as RWS starts popping them out of the sky operators will change tactics and constantly be moving or incorporating  random perturbations to exploit time of flight to frustrate the RWS predicted lead.  The camera is stabilized and this doesn't affect operator view at all.  Finally, this can handle multiple engagements simultaneously so when we start seeing cluster bombs dropping swarms of drone submunitions someday it can address them automatically.

If we assume a 5x5 dispenser thats 25 interceptors per vic or 100 per platoon, and it scales easily enough. That's $350,000 to potentially save a platoon of armor worth $50 million plus crew.

The system also has the potential to be manportable for dismounted light infantry application, albeit with more limited capabilities, and would at least provide some protection since it's not practical for dismounted infantry to carry a RWS with them on patrol or at an OP.

To be clear I'm talking about countering things like small consumer or small military suicide drones, not larger drones like Harpy, for which a RWS or SPAA is probably more appropriate.

I hope this is compelling enough for your consideration as one small part of a comprehensive approach.

It could be interesting to try out frangible small-arms ammo in a fast-firing MG. Make the bullets lightweight, fired at very high MV. That should increase the hit probability against drones at short range, but also drastically reduce unwanted collateral damage at longer ranges.

This be interesting  - CV90 seems to have some AA capability, needing more sensors. So could maybe just use an added radra per platoon

YouTube

Why is NATO not taking Combat Drones seriously? | CV90 COUNTER UAS CAPABILITY

Drones are deadly today against Infantry and infantry fighting vehicles that join them in battle. But why is that? And why is are militaries not taking them ...