Radar Electronic CounterMeasures in Stand-in Jammer Task
Radar Electronic Countermeasures in Stand-in Task are performed by airborne platforms that have to get very close to the victim Weapon Systems so they must have a limited Radar Cross Section (RCS) in order to be very difficultly intercepted by the victim Weapon Systems (quasi-stealth platforms).
Unmanned platforms (eventually expendable) will be highly preferable because the high level of risk getting closer to the enemy air defence.
The geometry of the engagement (the stand-in platform is closer to the target enemy radar than the defended platform, so the range of the SIJ is less than the range of the EJ and very much less than the range of the SOJ) gives a number of advantages:
because the attenuation (propagation law) the stand-in jammer can use less power to have the same amplitude received in the radar (same J/S ratio).
because the time advantage (the radar wave front will hit the stand-in platform well before the defended platform):
the stand-in jammer can receive the signal and re-transmit it in a coherent way, increasing the power density in the radar receiver (matched jamming) with respect to noise jamming techniques (again less power to have same J/S ratio)
the stand-in jammer is able to reply with coherent pulses positioned before with respect to the platform echo in the radar time scale .
The radar sees false targets closer with respect to the real echoes.
it is possible, also in case of agile radars (frequency and/or PRI) to perform a coherent countermeasure on a pulse-by-pulse basis (follower mode can be used also for pulse-to-pulse agile radars), performing a real range gate pull-in.
Figure 1: False targets in Stand-In operation
Countermeasures often used to perform Stan-In Task are: