Interesting idea.  I would like to see it though in something other then a weapon slot.  It would be tough to give up a weapon slot for something the other team might not equip.

good point... so mabye there is a mech with this ability?

Not yet...

I will think of other ideas for anti jav and mortar weapons in the future though...

i think you could design a new support mech around this kind of feature.  have a 30m range of effect where any incoming artillery drops out of the sky deactivated, any mines in range explode, and any enemy mechs in range lose target lock and have to re.acquire.  wouldn't want it as a weapon slot or else the mech sitting there at the back with rocket mortars will have 1 slot with each .. the mortars to deal damage, the anti.mortar to block return fire.  

Alright, what if it is called the Hound. This guy has decent health and movement speed, and a ability that can shut down enemy artillery, javs, mines, and scramble the lock on of javs. He is a rare mech, and looks like a zepher/guardian hybrid. Base energy capacity is 10 (like a cheeta) and max is 20. base health: 24,000 max 72,000. bthe ability sends a pulse out at 30-50 meters that shuts down enemy weapon artillary, javs, mines, and messes up the targeting syatem of javs and rocket mortars. His disavantage is that he can't run out into a firefight and destroy everyone like a guardian or a brickhouse, so if you use this mech, you won't be getting a ton of kills like other mechs. The advantage is that you are basically immune to artillary and jav strikes, and cheetas can't even touch you.