14-20] RESOLUTION LIMITS IN GROUND MAPPING SYSTEMS 785 



When the targets differ in their reflective strengths, the same type of 

 analysis indicates that the minimum resolvable separation is increased. 

 Fig. 14-21 shows the envelope of the square of the received signal voltage as 



-1.0 -0.8 -0.6 -0.4 -0.2 0.2 0.4 0.6 0.8 1.0 

 POSITION OF BEAM AXIS 

 (Beamwidths) 



Fig. 14-21 Distribution of Power Between Unequal Point Targets. 



the antenna scans past point targets which differ in reflective strength by 

 only 3 db. Fig. 14-22 shows the ratio of the minimum power between the 

 targets and the power at the smaller target. The minimum resolvable 





TARGET SEPARATION 

 (Beamwidths) 



Fig. 14-22 Resolution of Unequal Point Targets. 



separation has increased about 0.12 beamwidth over that for the equal 

 point targets. This does not represent a large increase but the assumed 

 difference in target size is quite small also. 



