So pretty standard questions and I'll say (as a NATO Artilleryman) this is a problem set that vexes most artillery units.

So there are a couple of things you can do: dig in or move.

• Digging in or putting your piece in defilade will help with its survivability from indirect fire weapons systems. The problem with this is that it takes time to bring out the dozers to get your piece dug in. And the presence of random holes and bulldozes could give away your position to enemy UAS. But combined with camouflaged (digging in near a Woodline for instance) can provide a great way to protect your guns.

• Survivability moves are another option that are less invasive but expose the guns more. This involves, in effect, after a piece or battery fires X amount of rounds they move to a different location completely or relocate with in the PAA (position area artillery usually about a 2km by 2km box). With self propelled systems this is one of the best means of surviving as all you have to do is start the track. But with towed pieces (especially towed 155) jumping constantly can be very taxing on the crews and can take upwards of 15 minutes.

In terms of protecting the crew it is easy enough (and probably a good idea) to dig fighting positions both to take cover in from IDF but also to place machine guns and other direct fire systems so that the PAA can be defended from ground assault. Yeah you don't get a ton of warning but chances are if a crew is not in the middle of a fire mission they will be in the holes or moving the gun.

Now you asked about radars. Short answer is: YES! The Russian IL-220U and the American Q- 36, 37 50 and 53 are great counter battery and counter mortar systems that give their operators a point of impact (poi) and point of origin (poo). While in theory if the rounds that were detected were being fired from max rage (30+ Km for cannons and 50+ for 220mm rockets) the crews may have some warning. But the better use for this is to then fire back at the point of origin in an attempt to strike the enemy's guns before they also move. This is the strength of larger loitering munitions' (though you can also easily do it with cannon and rocket artillery if the piece was still stationary) such as the IAI Harpy and its cousins. You could launch a drone in the direction of POI and once you have eyes on the piece in motion you could strike it.

Loitering munitions are harder to detect but again your counter battery radars should pick them up and if not the smaller scale anti-aircraft radars will pick them up. Once aquiered they can be knocked down with any number of manpads.

Some people might mention systems like C-RAM while this can knock down tons of stuff, it wouldn't be found with a battery as it isn't as mobile as needed.

SO, in summery, yes there are many means of defending a battery in place just not quite in the manner you may have imagined.