Radar Scanner allows all towers within its radius to be able to detect and target camo bloons.
Official BTD5 description
Bloons TD 5, Battles, BMC, Mobile counterparts
Medium: $2000 Hard: $2160 Impoppable: $2400 BTD Battles Mobile: $1750
Radar Scanner is the second upgrade on the second path for the Monkey Village. It allows all the towers in its radius to detect and to attack camo bloons. It also increases the range of the Monkey Village in the flash versions of BTD.
Differences Between BTD5 Flash and BTD5 Mobile Edit
Radar Scanner no longer adds extra range to the Village itself.
Update History (Bloons TD Battles Mobile) Edit
Radar Scanner price decreased ($2000 → $1750).
Top from left to right: Radar Scanner with no path-1 upgrades, with Monkey Beacon, with Jungle Drums, with Monkey Town. Bottom: Radar Scanner with High Energy Beacon.
High Energy Beacons with this upgrade will be able to attack Camo Bloons. However, it will not allow other High Energy Beacons in its range to attack Camo Bloons.
This upgrade is much more expensive than the Sonar Beacon upgrade in BTD4 ($280), which also allows towers in range to pop Camo Bloons.
The only difference between the two upgrades is the price and the fact that Radar Scanner increases range, while the Sonar Beacon doesn't.
Oddly, a "village radar scanner" is mentioned in the description of stage 3-1 of Bloons Super Monkey 2, even though the actual radar scanner village isn't seen.
The icon is a enemy radar scanner used on military ships to track the enemy similar how the radar scanner works, letting other towers detect camo bloons.