220 



REFLECTION AND TRANSMISSION OF RADIO WAVES 



SAMPLE NO. 262 

 Sept. 24,1954 

 Altitude -lOOOff 

 Ronge- 13,050yds. 

 Depression- 1.46° 

 Wave height-2.0ft. 

 3db bandwidth-82cps 



WIND 

 9 knots 

 80° 



SAMPLE NO. 140 

 Sept. 22,1954 

 Altitude-2500ft. 

 Range- 15,080 yds. 

 Depression-3.l7° 

 tieight-S.Oft. 



3db bandwidth -I72cps A 



Wind 16 knots ^^J^ 



<iep. 



2400 2500 



FREQUENCY cps 



(b) MEDIUM SEA STATE 



2200 2400 2600 2800 

 FREQUENCY cps 



Fig. 4-41 Doppler Spectrum of Sea Clutter, Showing both the Spectrum Averaging 



over the Sample (a) and the Spectrum vs. Time or Range. A/C velocity refers to 



Ground Track. 



a form of clutter known as nndtipk-time-aroioid echo (MTAE). This 

 clutter is therefore important for ground targets whose range is given by 



R„ = R.^nR^rs (4-71) 



