So the title may sound a bit stupid but here's essentially my idea in a nutshell: The AA mine would be an engineer item (replacing tank mines/prox mines) that has the placement rules of spawn beacons (outside only) and can be thrown up, have rocket assists that boost the mine upwards about 75m and travels in a circle with a visible trail for about 45 seconds before despawning. If an aircraft gets within 30m of any point on the ring the mine will have a coyote effect and start seeking it. The mine does 1335 damage to aircraft (Descimator rocket) so it will only be able to kill an ESF in one hit. Up to 3 mines can be carried at once since they will despawn after a short time and 6 with utility pouch.
I'm going to skip passing opinions on the item you outlined to say this: seriously, no more Engineer toys for a while. My favorite class is overly saturated with stuff to deal with without needing something else. I'm honored that it's favored so much but it's not a dumping ground. Give something to the Light Assaults for a change.
How about attaching this to a Valkyrie in one of the subsystem slots? No class bias, and it would give the Valk a more unique role as the sole mine-laying vehicle.
There's a few anti-aircraft mine designs that would work. In this design (so far unnamed, but goes by PVM-100 or AHM-100), any aircraft 200m up is detected. A mix of acoustic and IR sensors detect low-flying aircraft within range and then it launches 12 explosive charges straight up. While the main disadvantage is that it can only target aircraft flying directly above it, it is also inexpensive and extremely difficult to counter. This type (Temp-20) is a bit more advanced because it is capable of targeting aircraft not directly above the mine. It detects aircraft by acoustic and IR sensors and can hit them with a single explosively-formed penetrator at 150m. So anything within a 150m bubble of this device is likely to die. The last category isn't usually what we think when we are talking about "mines", but technically they are. That's because many SAM vehicles (like the Tor M2 pictured above) can either be operated remotely or completely autonomously. So you take a SAM vehicle, park it out somewhere, and it automatically detects, tracks, and engages aircraft. These types are the largest threats to aircraft as they can engage aircraft hundreds of kilometers away, but of course are more expensive than a simple mine. I think all of these could be implemented in PS2. AA mines should OHK ESFs and Valkyries and 2HK Liberators and Galaxies. This would encourage aircraft to maintain an altitude of at least 150m at all times to avoid being the victims of mines, which in turn would force them out of cover for other AA to hit (which is the primary role of most AA mines anyhow).
