$R_{max} = (\frac{P_t (A_o)^2 S}{(4\pi) (\lambda)^2 P_{min}})^{\frac{1}{4}}$

Factors influencing maximum range of radar are :

1. The number and most obvious is that the maximum range is proportional to fourth root of peak transmitted pulse power.

2. The peak power must be increased sixteen fold, all else being constant, if a given maximum range is doubled.

3. Decrease in minimum receivable power will have same effect as raising the transmitting power.

4. Pmin is governed by sensitivity of the receiver , minimum receivable power may be reduced by gain increase of the receiver, so reduction in noise at its input.

5. First equation shows that maximum radar range depends on target area. Also ground interference will limit this range. The presence of conducting ground, has effect of creating interference pattern such that the lowest lobe of antenna is some degrees above the horizontal.