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Millimeter Wave RADAR Power-Range Spectra Interpretation 87

MMW RADAR 1 2 i
P INC1 P INC2 P TRANi
P TRAN1 P TRAN2
P
P REF1 REF2
P INC21
P TRAN21
P REF21 P INC32
P TRAN32
P REF32

P INCi1
P TRANi1
P REFi1

FIGURE 2.27 Power definitions for reflections, absorptions, and transmissions for i
multiple line-of-sight features.

be the normalized absorption cross section of the first feature.
RCS and ϒ a 1
The power received by the RADAR receiver from the first feature is given by
2
P = P REF1 A e /(4πR )
ˆ
REF1 1
A
P t G ˆ ϒ R 1 I
P ˆ = (2.28)
REF1 2 ˆ 4 A e
(4π) R
1
where A e is the antenna aperture. It is shown in the RADAR literature that
2
A e = Gλ /4π [21]. Substituting for A e in Equation (2.28), the power return
from the first feature is
2 2
A
P t G λ ˆ ϒ R 1 I
P ˆ = (2.29)
REF1 3 ˆ 4
(4π) R
1
The power P TRAN1 that passes through the first feature is given by
])
P t GA I (1 −[ ˆ ϒ R 1 + ˆ ϒ a 1
P TRAN1 = (2.30)
ˆ 2
(4π)R
1

© 2006 by Taylor & Francis Group, LLC

FRANKL: “dk6033_c002” — 2006/3/31 — 17:29 — page 87 — #47