AESA will ensure harder to jam, Harder for enemy aircraft`s RWR to make out source of guidance also the band as AESA has ability to change multiple band waves ( Their are other radars does the same but not same as AESA ) ..
An Missile seeker is design to operate at some range until then its guided by more powerful AESA from other aircraft ..
Hard to say this is for Astra but may be for Akash or PAD as the AESA seeker or radar are heavy compare to other traditional radars as they are liquid cooled not air cooled for cooling means extra equipment ..
Minor nitpick and may even be wrong but still you may need to take care a little.
AESAs can do phase changes and interference patterns to be able to generate a digital signal where you could be lighting up x position and in the next moment lighting up the y position without having to go through the whole lot of space between x and y positions unlike an analogue equipment.
But I believe that even an AESA cannot simply move around from one Bandwidth to another Bandwidth. Not even to the near-about bands like from S to L and vice versa.
Band is a bunch of frequencies (theoretically infinite) that are very near to each other and wherein the highest and the lowest frequencies (out of these bunch of frequencies) form the two boundaries of the Frequency Band. The bunch gets defined essentially by the ability of these frequencies to cause interference (constructive/destructive), unless some multiplexing techniques are used. The multiplexing will allow use of the same space/time domain to effectively cause 2 or more final signals.
If the transmitter has a capability to use these multiplexing techniques using several different carrier signals, then it can do frequency hop. But even these frequency hops will remain within the overall Band the AESA is designed for. This limitation whereby you remain within the overall Band getting decided not by the theory of interference patterns but by the amount of signal loss suffered if there is a mismatch between the design limit of the hardware (TR modules and swashplate) and the design limit of the signal.
You see the design of the TR modules (spikey ones for X bands and big clunky ones for L bands) have a bearing on the kind of wave these TR modules can produce. Moreover the space required between these TR modules also has to be specific to what you want to achieve as to frequency use. If the design of the TR module and the design of the space between these TR modules was not relevant then we would easily have multiple types of Multi-Band antenna. But we have only a limited type of Multi-Band antennas. Moreover since nobody, normally has access to hardware of others so they do signal-sniffing (like the Rafales sniffing the Su30MKI signals in the Cope Whatever Ex.).
Thus even AESAs have to honour the Band limitation/discipline. No escaping there.
Just my 2 phooti kaudi.