
69-6 Medical, Biomedical, and Health
When the target moves toward or away from the transmitting antenna, the frequency of the reected
ra
diation
wi
ll
ch
ange
. u
s,
if th
e
ta
rget
is mo
ving
aw
ay
wi
th
ve
locity
v, th
e
re
ected
fr
equency
wi
ll
de
crease
an
d
it wi
ll
in
crease
fo
r
th
e
ap
proaching
ta
rgets
. i
s
is ca
lled
th
e
Do
ppler
e
ect,
a
er
th
e
Au
strian
sc
ientist
Ch
ristian
Jo
hann
Do
ppler
(1
803–1853)
.* Al
though
th
e
e
ect
r
st
wa
s
di
scovered
fo
r
so
und,
it is ap
plicable
to el
ectromagnetic
ra
diation
as we
ll
. In co
ntrast
to so
und
wa
ves
th
at
ma
y
pr
opagate
wi
th
th
e
ve
locities
de
pendent
on mo
vement
of th
e
so
urce
of so
und,
el
ectromagnetic
wa
ves
pr
opagate
wi
t