Why don’t fighter planes have 360 degree radar?
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Radar as we currently implement it requires a _phased array_ of small radar antennas. When you send radiation out from an antennae, depending on the design of the antennae, you get signal peaks and valleys. By using a computer to deliberately sequence or delay the signal being emitted from neighboring antennae in our array we can “steer the beam” by stacking the peaks together; this has the advantage of also minimizing the signal going off in other directions as well. Remember the downside to radar is you’re sending all this EM noise out into the ether and watching to see what it bounces off. It doesn’t take very complex electronics to triangulate where YOU are from the radar waves you send out. So phased arrays are good in that the only signal you detect from a phased array are when the radar is actively painting you (i.e. you’re about to receive a missile.)
The alternative is to use the old school rotating “send out a big wave of radar, listen for bounce backs.” method – like air traffic control radar or probably AWACS – there’s no point in hiding those systems. And they’re big and they rotate.
So if our fighter jet were to have beam steerable radar all around, you’d have to have these big flat phase arrays all over… and that would probably conflict with the design goal of making them fast and maneuverable. The _important_ role of radar is for targeting the bad guys – much easier to put that radar in the nose, but rely on dedicated AWACs radars to get you close enough and vector you to a shooting solution where you’re pointed at-ish the bad guys.
Keep in mind we can put radar _receivers_ or detectors all around our airplane – these just detect waves from radars that are painting us, and if you have a few antennae you can roughly triangulate where it is in relation to your plane.
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