Self-protect J/S vs range R
J/S (dB)
Tolerable J/S (burn-through threshold)
R
bt
burn-through range
At cursor range
— dB
Burn-through range R
bt
— km
Range cursor & scale
R (km)
60
Log range axis
Radar & target
P
t
(dBW)
50
G
t
(dBi)
30
σ (dBsm)
10
Jammer & threshold
P
j
(dBW)
30
G
j
(dBi)
15
Tol. J/S (dB)
0
J/S = (4π·P
j
·G
j
·R²) / (P
t
·G
t
·σ)
Jammer is one-way (∝1/R²), skin echo two-way (∝1/R⁴) → J/S ∝ R². Lower σ (stealth) lifts the whole curve and pulls R
bt
inward.
J/S ∝ R²: the jammer wins far out, the radar burns through close in.