urface for
al polari-
ET From the For the actual computation of f G d @ the following procedures were taken;
1) First term
KopY
] ] A2 Z dX dY
Li -6(99)45 NET XY) 2 8)
Golan 50) xv; ((X-Xa)2+ (Y-Ya)2 + Za2)3/2
lowing features :
where the suffix"a"denotes the center of the antenna, while X D Y, i X, and Ys
are the edges of the pool respectively.
positive for 2) Second term
tion.
1 - G( sine de dé ------------------- (4)
énjasS( 4, 934 9 = a"
dyes of z = cos (cos 6 sin 8- sin @ sin $ cos 8)--------- (5)
where ß is incident angle.
3) Third term = 1 - ( First term + Second term ) ----------------- (6)
The result of the computation is indicated in Table 2. Based on the value
in Table 2, Eq. (2) can be easily computed, for example in case of incident
angle 10? at 31.4 GHz, the following equation holds.
tion (Fig.5)
rization
the theo-
Ta = 0.837 T oiv B.G
Same rule is applicable to other angle of incident .
In Eq. (7), the value of T was estimated from the graph in Radar Handbook
[4.], Tg g was assumed to ES 290 K in reference with meteorological observa-
tion while Tpis the observed value, thus the value of Tg y is uniquely de-
termined. The values of Tg y's thus obtained for 5 different incident
angles are shown in Fig. 6. Comparing Fig. 4 with previously shown Fig.6,
losis (1) it can be seen that the obtained values of TB.W's for different incident an-
gles have good correspondence with those theoretical values. The
result of computation for 23.8 GHz also indicates good correspondence with
s the an- the theoretical values.
Jon angles It is interesting to notice that the relationship between (TB.w)23 GHz
od Mo and (TB.W)31GHz stated in section 3 - 2) has become opposite after correction,
e.(TB.W)31GHz has become higher than (TB.W)23GHz-
It a be stated also that large offset value described in 3 - 4) is greatly
reduced.
1 Su. (2)
Bi Concluding remark
+ 0.146 Ty + 0.017 Ty, co ee (7)
11ysis.
er», ground The foregoing analysis leads to the following conclusion. The effect of side
| T lobe is fairly extensive and can not be neglected in such a condition as this ex-
? EB. q: (2) periment. Further experiments at different water surface and meteorological
conditions are indispensable to establish reliable data processing alqorithm.
d dot
read out at
) ; References
tion of [1] Hollinger,J.P.,"Microwave Properties of Calm Sea", NRL Rep.7110,1973.
: [2] S.T.Wu,et al. E Theory of Microwave Apparent Temperature Over the Ocean",
ind sky. NASA CR-2329,1973.
[3] W.M. Truman,et al.,"Three Dimensional Vector Modeling & Restoration of Flat
Finite Wave Tank Radiometric measurements", IEEE Tran. Ant.& Prop.,Vol.AP-25
Jan.1977.
[4] King,D.D.,"Passive Detection",Radar Handbook,Chapter 39.
[5] Moore,R.K.,"Microwave Remote Sensing",Manual of Remote Sensing,Chapter 9.
