Atmospheric effects on Radar and Communications
Operating in Millimeter and Sub-millimeter wavelengths
Prof. Yosef Pinhasi, Ariel University Center
1. Introduction
The growing demand for broadband wireless communication
links and the deficiency of wide frequency bands within the
conventional spectrum, require utilization of higher microwave
and millimeter-wave spectrum at the Extremely High Frequencies
(EHF) above 30GHz (see table 1).
Table 1: The electromagnetic spectrum.
BAND
Extremely Low Frequency
Super Low Frequency
Ultra Low Frequency
Very Low Frequency
Low Frequency
Medium Frequency
High Frequency
Very High Frequency
Ultra High Frequency
Super High Frequency
ELF
SLF
ULF
VLF
LF
MF
HF
VHF
UHF
SHF
Extremely High Frequency EHF
Sub-millimeter (TeraHertz) FIR
Mid infra-red
MIR
Near infra-red
NIR
IEEE FREQUENCY
3 - 30Hz
30 - 300Hz
300 - 3,000 Hz
3 - 30 KHz
30 - 300 KHz
300 - 3,000 KHz
3 - 30 MHz
30 - 300 MHz
300 - 3,000 MHz
L
1 - 2 GHz
S
2 - 4 GHz
3 - 30 GHz
C
4 - 8 GHz
X
8 - 12 GHz
Ku
12 - 18 GHz
K
18 - 26.5 GHz
Ka
26.5 - 40 GHz
30 - 300 GHz
V
40 - 75 GHz
W
75 - 110 GHz
300 - 3,000 GHz
3 – 30 THz
30 – 300 THz
WAVELENGTH
1,000 - 100 Km
100 – 10 Km
10 - 1 Km
1 - 0.1 Km
100 - 10 m
10 – 1 m
1 - 0.1 m
10 - 1 cm
1 - 0.1 cm
1 – 0.1 mm
100 – 10 µm
10 – 1 µm
Some of the principal challenges in realizing modern wireless
communication links at the EHF band are the effects emerging
when the electromagnetic radiation propagates through the
atmosphere. When millimeter-wave radiation passes through the
atmosphere, it suffers from selective absorption in molecules of
the gases composing the air.
2. The Atmosphere
The atmosphere of Earth is a composition of gases surrounding the
planet Earth that is retained by Earth’s gravity. The atmosphere is
divided into several principal layers as shown in Table 2. Pressure
and density decrease in the atmosphere as height increases, while
temperature may remain relatively constant or even increase with
altitude in some regions.
Table 2: The layers of the atmosphere
70,000Km
10,000Km
800Km
500Km
80Km
50Km
8-18Km
Outer space
Exosphere
Ionosphere
Thermosphere
Mesosphere
Stratosphere
Atmosphere Troposphere
Plasmasphere
Magnetosphere
The lower layer of the atmosphere is the Troposphere beginning at
the surface and extends to between 8Km at the poles and 18 km at
the equator, with some variation due to weather. The troposphere
is mostly heated by transfer of energy from the surface, resulting
in descending temperature with altitude. The tropospheric air is
a mixture of gasses containing roughly 80% of the mass of the
atmosphere. Dry air contains 78.084% Nitrogen (N2), 20.948%
Oxygen (O2), 0.934% Argon (Ar), 0.0314% Carbon dioxide
(CO2), and small amounts of other gases. Humid atmosphere also
contains a variable amount of water vapor, around 1-4%. The air
also contains of dust, haze and other pollutant particles.
In addition to the fact that the EHF band (30-300GHz) covers a
wide range, which is relatively free of spectrum users, it offers
many advantages for wireless communication and RADAR
systems as follows:
3. Millimeter wave propagation in the Troposphere
* Broad bandwidths for high data rate information transfer
At lower frequencies, up to the UHF regime, the atmosphere
* High directivity and spatial resolution
transparent to the electromagnetic radiation propagating in the
* Low transmission power (due to high antenna gain)
medium. However, as the frequency is increased, absorption is
* Low probability of interference/interception (due to narrow
revealed. When millimeter-wave radiation passes through the
antenna beam-widths)
t  represents
The time dependent
fieldit Esuffers
an electromagnetic
wave propagating
atmosphere,
from selective
molecular absorption
due to in a
* Small antenna and equipment size
rotationalofresonances
* No multipath fadings (although fading can be caused
by Themolecular
medium.
Fourier transform
the field is:mainly in water and oxygen.
time
dependentfield
field E t  represents
represents ananelectromagnetic
wavewave propaga
TheThe
time
dependent
electromagnetic
atmospheric conditions)
propagating
in
a
medium.
The
Fourier
transform
of
the
field
is:
Among the practical advantages of using the EHF region for
of the field is:
satellite communications systems is the ability to employ smaller medium. The Fourier transform
E f    E t   e  j 2ft dt
transmitting and receiving antennas. This allows the use of a

In the far field, transmission of a wave, radiated from a
smaller satellite and a lighter launch vehicle.

22
2012 ‫ נובמבר‬,43 ‫גליון‬
E f   E t   e  j 2ft dt
In the far field, transmission of a wave, radiated froma localized (point) isotropic
source and propagating in a medium is characterized in the frequency domain by the
approximate transfer function:
In the far field, transmission of a wave, radiated from a localized (point)
d
 j k  f dz

medium. The Fourier transform of the field is:

medium. The
transforman
of electromagnetic
the field is:
The time dependent
fieldFourier
E t  represents
wave propagating in a
E f    E t   e  j 2ft dt


Inmedium.
the far field,
transmission
of
a
wave,
radiated
from
a
localized
(point)
isotropic

E f    Et   e  j 2ftj 2dt
 j 2ft
ft
The Fourier transform of the field is: 
E f  
 E t   e
dt
E f    E in
t the
e frequency
dt
domain

source and propagating in a medium is characterized
by the
 j 2ft
Ef  
 j 2ft
 E t   e
E f    E t   e
dt
dt

  a localized (point) isotropic
approximate
transfer
function: of a wave, radiated
In the far field,
transmission
from

2ft
band),of130GHz
and 220GHz,
which (point)
are known
a wave, radiated
from a localized
isotropicas atmospheric transmission
E f    E t  In
e  jthe
dt far field, transmission
the far field,
transmission
of
wave,transmission
radiated
aa localized
(point)from
isotropic
In the
farafrequency
field,
wave, radiated
a localized (point) isotropic
source and propagating in In
a medium
is characterized
in the
domainfrom
byofthe

In the far field, transmission Eof ajf wave,
radiated
 j  k  f dz from a localized (point) isotropic
, d  1source and propagating 'windows'.
in a medium
is isotropic
characterized in the frequency domain by the
Intransfer
the far function:
field,source
transmission
of awave,
from
a localized
(point)
 out
 esource
H  jf and
propagating
in aradiated
medium
is characterized
in the frequency
domaininbythethefrequency domain by the
and propagating
in a medium
is characterized
approximate
Εin  jf  is characterized
d
source and propagating in a medium
in
the
frequency
domain
by
the
approximate
transfer
function:
source and propagating
in
a
medium
is
characterized
in
the
frequency
domain
by
the
approximate
transfer
function:
approximate
transfer
function:
In the approximate
far field, transmission
of a wave,
radiated
from a localized
(point)
isotropic
transfer function:
E  jf , d  1  j  k  f dz
approximate transfer
 e
H function:
jf   out
E  jf , d  1  j  k  f dz
source andlocalized
propagating
in a medium
in the frequency
domain by
Εcharacterized
d propagating
(point)
isotropicissource
in a medium
j  kjf
the
f dz
in  jf  and
 outEout  jf , d 1e  j  k  f dz
Eout  jf , d  1 H
 j  k  f dz
factor,
  approximate
 jf  Εin  jf  d  e
jf the
 jf , d   1Hby
E propagation
k  f   is
2fcharacterized
 isfunction:
a frequency
where εand eµ Hare
Here,
in thedependent
frequency
approximate
transfer
H  jf   out domain
d
Εin  jf 
d
E  jf , dd  e 1  j Εk inf dzjf 
transfer
function:
 e
H  jf Ε in jfout
the local permittvity and the permeability of the medium,
The transfer
Εin  jf  respectively.
d
d
0
d
d
0
d
0
d
0
d
0
d
0
0
d

Eout  jf , d  propagation
1
 is a frequency
factor, where
and µ are
Here, k Hf  jf ,2df describes
function
theHfrequency
response
In a εdielectric
 jf  dependent
  eof the medium.
Εin  jf 
d
Here, k  f   2f  is a frequency dependent propagation factor, where ε and µ are
  2of
  dependent
k  fthat
f the
 vacuum
is amedium,
frequency
where
ε and µ are
Here,
2f permittivity
is propagation
a frequency
dependent
propagation
factor, where ε and µ are
Here,
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of
the
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is factor,
medium
thepermittvity
permeability
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equal
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where
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permeability
ofare
the medium, respectively. The transfer
Here,
aa frequency
dependent
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factor,
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is
frequency
dependent
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ε
and
µ
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thethe
local
permittvity
and
permeability
the
medium,
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transfer
thethe
local
the
permeability
of theThe
medium,
respectively. The transfer
function
frequency
response
of
thepermittvity
medium.ofInand
a dielectric
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fwhere
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medium
introduces
losses
and
dispersion,
the
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given
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are
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the
permeability
of
and
thelocal
permeability
of
the
respectively.
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function
H  jf , d  describes the frequency response of the medium. In a dielectric
the
local
permittvity
and
the
permeability
of
the
medium,
respectively.
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transfer
 jf , doftransfer
 the
function
 jfand
H
describes
the
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the
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function
H
, d where
describes
frequency
response
of the medium. In a dielectric
The
function
describes
 the
k  fthe
 2permeability
medium,
f  is arespectively.
frequency
dependent
propagation
factor,
ε andthe
µ
Here,
 frequency
function.
the
permittivity
is medium.
medium
is
tothe
that
vacuum
0 the
dielectric
constant
a equal
complex,
frequency
dependent
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resulting
function
H  jf
describes
frequency
response
of
medium.
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r  ,fd is
medium
permeability
is equalIn
to athat
of the vacuum   0 and the permittivity is
the
frequency
of the
medium.
Inresponse
athedielectric
medium

function
H  jf , dresponse
describes
the
frequency
of
the
medium.
dielectric
 that
medium
the permeability
is equal
to dispersion,
that of the vacuum
medium
the
permeability
istransfer
equal to
of the
the permittivity
vacuum  is0 and the permittivity is
the
local
permeability
of
the
medium,
respectively.
0 and
 f refraction
 permeability
of
 r  permeability
f  and
 0can
. Ifthe
the
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and
the
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given
by permittvity
local
index
be
   andThe
the
is
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the
is equal
to
thatof
ofthe
the
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thepermittivity
the
ispresented
equal
toby:
that
vacuum
 f    r  f0 and
vacuum
the
medium
introduces
losses and dispersion, the relative
given
by
0. If
and
the
permittivity
is
medium
the
permeability
is
equal
to
that
of
the
0 a
the
 describes
function
Hconstant
jf , d refractivity
the
frequency
the
dielectric
The
term in
thatby
is constant
by
real
 fin  frequencies
isffunction.
given
 f In
 f  frequency
  rresponse
If of
the
medium
losses
and dispersion,
relative
permittivity
is given
theby
medium
introduces
medium.
 introduces
 The
thequantity
medium
introducesthe
losses
and dispersion, the relative
0 .given
0 .a If
dielectric
dependent
resulting
If the medium
introduces
losses
andr dispersion,
the relative
given
by  f r fr  fis  a0 .complex,

dielectric
 rand
f  dispersion,
is
a
complex,
frequency
dependent
function. The resulting
is
a
losses
anddispersion,
the
relative
dielectric
constant



f


f


.
If
the
medium
introduces
losses
the
relative
given
by
requal
0to of
a6is
acomplex
constant
thefunction
is function.
theof
permeability
isdielectric
that
vacuum
Nmedium
frequency
dependent
term
refractivity
index
constant
complex,
Thedependent
resulting function.
 rpermittivity
f  isdependent
aconsisting
complex,
frequency
0 andfrequency
0 . The
local
index
refraction
can
presented
by:
r f fdielectric
 is10
fis 
 r the
f of
function.
1the
frequency
N
(a) The resulting
complex,
frequency
The resulting
dielectric
constant
 r  be
f n dependent
a complex,
dependentlocal
function.
The resulting
local
index
of
refraction
can
be
presented
by:
termgiven
in the
refractivity
that
is
constant
in
frequencies
is
given
by
a
real
quantity
 f Nis' 'of
complex,
frequency
dependent
The be
resulting
rindex
of
bemedium
presented
by:
dielectric
f' (refraction
 imaginary
Iflocal
the
losses
andpropagation
dispersion,
the
by N
can
be
presented
by: function.
local
index
of
refraction
canrelative
be presented
by:
f)  f  constant
( af introduces
)refraction
of a real
quantities.
The
factor
can
0 .can
local indexr and
of refraction
can be presented
by:
The dielectric
frequency
dependent
term
of
the
refractivity
is
a
complex
function
consisting
local index
be
 f  can
 f presented
 is:
nrefraction:
in ppm
 1  N dependent
f by:
 106
 refraction
constant
 r  fof
is a of
complex,
function. The resulting
Where
given
rfrequency
writtenthe
in complex
terms
of refractivity
the
index
6
 j k  f dz
0
n f    r  f   1  N  f   10 6
 f     f  factor
   r  f   1  N  f   10
nis:
1  N  f can
 10n6 fbe
N 'index
( f ) and
N 'presented
' ( f ) quantities.
reallocal
imaginary
The
Where
the complex
refractivity
given in
ppmpropagation
of refraction
can be
n f by:
  r  f   1  N  f   106 r
by
6
The term in the refractivity that is constantnin
frequencies
is
given
a
real
quantity





f


f

1

N
f

10
N ppm
 N'6(is:
f )2frjN ' ' ( f ) The
2f refractivity
2Ngiven
f( f )  in
2f in the refractivity
en inWhere
termstheofkcomplex
index
of refraction:
that is constant in frequencies is given by a real quantity
6
the
 f0 refractivity
 constant
f   dependent
 n f    jterm N
'The
'the
10
 Where
 is
1 athe
Ncomplex
10 6  term
 N ' is
fconsisting
10 given
0 complex
refractivity
ininppm
is:
N 0 . The frequency
of
function
term
inc
the
refractivity
frequencies
is given by a real quantity
6 given by cathat
c
c
rm in the refractivity
that
is
constant
in
frequencies
is
real
quantity
Where
the
complex
refractivity
given
in
ppm
is:

























Where
the
complex
refractivity
given
in
ppm
is:






n
f


f

1

N
f

10
Thetheterm
in the
refractivity
that
is constant
in
is dependent term
r
N 0 .frequencies
frequency
of the refractivity is a complex function consisting
Where
complex
refractivity
in ppm
is:
 given
f
 The
f
N ' ( f ) by
f )0N. quantities.
of a real dependent
and
imaginary
The
factor
The
term
theberefractivity is a complex function consisting
given
real quantity
frequency
dependent
term
ofofcan
Where
theacomplex
refractivity
givenfrequency
in
NN
( refractivity
f' ')(N

) appm
jN
' ' (is:
f propagation
)dependent
he frequency
term
complex
consisting
0  N ' ( fis
2the
2fisofa the
2f
2function
f refractivity
fareal
6
6
6
N ( f imaginary
)  N 0  N ' ( f )N ' 'jN
)
complex
function
consisting
of
real
N
'
(
f
)
( f' ')( f quantities.
of
a
and
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









k
f


n
f


j

N
'
'
f

10


1

N

10


N
'
f

10
0
writtenthe
in terms
of the
index
of refraction:
N ( f imaginary
)  N 0  N ' ( f )N' 'jN
(Nfquantities.
)( f )  N 0  N ' The
( f )  jN
''( f )
'
(' (fpropagation
( f' )'be
propagation
factor can be
c
c imaginary
Where
complex
refractivity
given
in
is:
c



quantities.
of




jN
'
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
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and
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The
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factor
can
be
Nppm
(af 
)real
N
N
N
f) ) 
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) 
N identify
' ( f ) and
N
'
'
(
f
)
ealWe
quantities.
The
factor
can
0
the expression of the
coefficient:
  f  field attenuation
)f 
 jN ' ' ( in
N ( f )  N 0  N ' ( fwritten
f ) terms of the index of refraction:
written in terms of the index of refraction:
n in terms of the index of refraction: written in terms of the index of refraction:
2f
2f
2f
2f
6
0  N
k f  
 n f    j N (Nf' ') f N10
 ' ( f ) 1 jN
 N' '0(f10) 6  
 N '  f  10 6
f
f 

2
c
c
c2
c









 2f
dentify the expression
 the
k ( f )attenuation
  fof
 Imfield
 f 
 Imncoefficient:
( f ) 
 N ' '  f   10 6 
2f
2f
2f
6
6
 nf6  2fj
 N ' '  f 610 62
c
c2f   f 
2kf f  
f c  1  N 0 610   c  N '  f  10
2fWe identify2
f
2
f
2
f


c1
 6 of the fieldk attenuation
6
6 N ' ' cf  10







f


n
f


j



N

10


N
'
f

10
(b)
the
expression
coefficient:

























0
k f  
 n f    j
 N ' '  f  10 
 1  N 10  
 N '  f  10
0
c
c
 
f

 c
c
 f 
c

 c
c

 
 f  1: Millimeter wave a)
 fattenuation

1 e)    f  in [dB/Km] and
Figure
coefficient
20 log(
  f  2f
f 
propagation model (MPM),
developed
by Liebe
. Curves are
f
2coefficient:
6
We
identify
the
expression
of
the
field
attenuation
and the wavenumber:
  f    Imk ( f )  
 Imn( f ) 
 N ' '  f   10
drawn
for
several
values
of
relative-humidity
(RH),
assuming
c
c
2f
6
c
[deg/Km]
for of
various
of relative
humidity (RH) at
b)   f  clear sky
  10field
N '  f and
noinrain.
Inspection
Figurevalues
1.a reveals
absorption
We identify the expression
attenuation
coefficient:
c of the
We
identify
the
expression
of
the
field
attenuation
coefficient:
peaks at 22GHz and 183GHz, where resonance absorption of
2f
2f
entify the expressionof
the field
coefficient:
2f attenuation
6
 n( f )Im2nf( f )1 N  10
 N 6' 'f 2
10f 6 N '  f  10sea
level.water (H O) occurs, as well as absorption peaks at 60GHz and
  f   Refk(f )Im
 k ( f )Re
0
c
c
the wavenumber:
2
c
c
c
and the wavenumber:
119GHz, due to absorption
resonances
of oxygen (O2). Between
2f
2f
  f 
 Imn(6 f ) 
 N ' '  f   10 6
2ff    Imk ( f )2f 
f
f


2
2
c
k ( fEHF
  10
f  6 at
atmosphere
Imthe
)  
 Im1 n(H.f )J.Liebe:

 N c' ' –fAn
“MPM
atmospheric millimeter-wave
propagation model”, Int.
f   transmission
 The
 Imk ( f )  characteristics
 Imn( f ) of the N
' '  f  10
c
c
and the wavenumber:
c
c  6 with
2f in Figure
21,fwas calculated
2f the millimeter
band,
as
shown
6
J.
of
Infrared
and
Millimeter
waves
10,
(6),
(1989),
631-650
  f   Rek ( f ) 
 Ren( f ) 
 1  N 0 10  
 N '  f  10
The transmission characteristics
of the
the
EHF
band, as shown in
c
c atmosphere at 
c

and
the wavenumber:
Figure 1, was calculated with
(MPM), developed
f
2f the millimeter
2f propagation
2model

f )  the wavenumber:
  f   Rek ( f ) 
 Ren( and
1  N 0 10 6  
 N '  f  10 6
e wavenumber:
1
c
c
c





(RH), assuming
by Liebe . Curves are drawn for several values of relative-humidity
  f 
  f

transmission
of the
atmosphere
at theabsorption
EHF band,
asatshown
clear sky andcharacteristics
no rain. Inspection
of Figure
1.a reveals
peaks
22GHzinand 2f
2f
2f
  f   Rek ( f ) 
 Ren( f ) 
 1  N 10 6  
 N '  f  10 6
f k ( f )  2 6f  Ren( f )  2f  1 c N 0 10 6   2f c N '  f  100  6
2f
2f
2Re
c
 6 f  


 f  calculated
k ( f )resonance
absorption
as
n(millimeter
f ) 
N 0 10(H2O) model
Re
 with Re
 1propagation
water
 N '  f(MPM),
10well
re 183GHz,
1, was
the
developed
occurs,
as absorption
where
c
c
  f 
c
c
c of
c
The transmission
characteristics
of the
atmosphere
at 
the
EHF

band,
 as shown in
1
f 
. Curves
are drawn
for several
of relative-humidity
(RH),(Oassuming
Liebe
peaks
at 60GHz
and 119GHz,
due tovalues
absorption
resonancesof
oxygen
2). Between
  f

Figure 1, was calculated with the millimeter propagation model (MPM), developed
r sky
no 1rain.
Inspection
ofattenuation
Figure
1.avalues
absorption
at 22GHz
and(Wthese
frequencies,
minimum
isreveals
obtained
at 35GHz
(Ka-band),
94GHz
. Curves
are drawn
for
several
of relative-humidity
(RH),
assuming
byand
Liebe
The peaks
transmission
characteristics
of the atmosphere at the EHF band, as shown in
The
transmission
characteristics
of the inatmosphere at the EHF band, as shown in
ansmission
of theofatmosphere
EHF
band,
as
shown
O)the
occurs,
as
well
as22GHz
absorption
GHz,
where
resonance
of
water
2at
clear
sky characteristics
and
no rain. absorption
Inspection
Figure
1.a(H
reveals
absorption
peaks
at
and with the millimeter propagation model (MPM), developed
Figure
1, was
calculated
Figure
1,
was
calculated
with
the
millimeter
propagation model (MPM), developed
calculated
with the
millimeter
(MPM),
developed
s1,at was
60GHz
and
119GHz,
dueabsorption
to absorption
resonances
ofbyoxygen
Between
occurs,
as well1.(O
as
absorption
183GHz,
where
resonance
ofpropagation
water
(H2O) model
2).
Curves
are drawn for several values of relative-humidity (RH), assuming
Liebe
1
1
.resonances
are
drawn
for
several(Wvalues of relative-humidity (RH), assuming
Liebe
Curves
are
drawn
for
several
values
of relative-humidity
(RH),
assuming
1 .peaks
at “MPM
60GHz
and
119GHz,
due to
absorption
of
(O294GHz
). Between
ebe
frequencies,
minimum
attenuation
isby
obtained
atCurves
35GHz
(Ka-band),
H. J. Liebe:
– An
atmospheric
millimeter-wave
propagation
model”,
Int.clear
J.
ofoxygen
Infrared
and
Millimeter
sky and
no rain.waves
Inspection of Figure 1.a reveals absorption peaks at 22GHz and
10, (6), (1989), 631-650
clear
sky and
rain. peaks
Inspection
of Figure
ky and
rain. Inspection
of Figure
1.a
reveals
absorption
at 22GHz
and
thesenofrequencies,
minimum
attenuation
is
obtained
atno
35GHz
(Ka-band),
94GHz
(W- 1.a reveals absorption peaks at 22GHz and
183GHz, where resonance absorption of water (H2O) occurs, as well as absorption
183GHz,
where
resonance
of water (H2O) occurs, as well as absorption
occurs,
as well absorption
as absorption
Hz, where resonance absorption of water
(H2O)
peaks at 60GHz and 119GHz, due to absorption resonances of oxygen (O2). Between
peaksresonances
at 60GHz and
119GHz,
to absorption resonances of oxygen (O2). Between
at 60GHz and 119GHz, due to absorption
of oxygen
(O2due
). Between
Liebe: “MPM – An atmospheric millimeter-wave propagation model”, Int. J. of these
Infraredfrequencies,
and Millimeter waves
minimum attenuation is obtained at 35GHz (Ka-band), 94GHz (Wthese
frequencies,
minimum
attenuation
is obtained at 35GHz (Ka-band), 94GHz (W, (1989),
631-650“MPM – An atmospheric
1
requencies,
attenuation
is obtained
atmodel”,
35GHz
94GHzwaves
(WH. J. Liebe:minimum
millimeter-wave
propagation
Int. J.(Ka-band),
of Infrared and Millimeter
10, (6), (1989), 631-650
1
1
H. J. Liebe: “MPM – An atmospheric millimeter-wave propagation model”, Int. J. of Infrared and Millimeter waves
H. J. Liebe:
“MPM
AnInfrared
atmospheric
millimeter-wave
10, (6),and
(1989),
631-650
ebe: “MPM – An atmospheric millimeter-wave propagation
model”,
Int. J.– of
Millimeter
waves propagation model”, Int. J. of Infrared and Millimeter waves
2012 ‫ נובמבר‬,43 ‫גליון‬10, (6), (1989),
631-650
1989), 631-650
24
(a)
these frequencies, minimum attenuation is obtained at 35GHz
Prof. Yosef Pinhasi
(Ka-band), 94GHz (W-band), 130GHz and 220GHz, which are
Yosef Pinhasi is the Dean of the Faculty
known as atmospheric transmission ‘windows’.
of Engineering at the Ariel University of
(b)
Samaria. He was born in Israel on May 3,
(b)Figure 1: Millimeter wave a) attenuation coefficient
Figure 1: Millimeter wave a) attenuation
coefficient
20 log(e)   f  in [dB/Km] and1961, received the B.Sc., M.Sc. and Ph.D.
and
er wave a) attenuation coefficient 20 log(e)   f  in [dB/Km] and
degrees in electrical engineering from Tel
2
f
6
Aviv University, Israel in 1983, 1989 and
in
[deg/Km]
for
various
values
of
relative
humidity
(RH)
at
b)






f


N
'
f

10
in
[deg/Km]
for
various
values
of
b)
6
of relative humidity (RH) at
10 in [deg/Km] for various values
c
1995
respectively.
He served as the head of the Department
relative humidity (RH) at sea level.
of Electrical and Electronic Engineering between the years
sea level.
2004-2007.
The transmission characteristics are determined by weather
Since 1990 he is working in the field of electromagnetic
conditions such as temperature, pressure and humidity. The
radiation, investigating mechanisms of its excitation and
absorption is proportional to air density, and thus reduces with
generation in high power radiation sources like microwave and
height. Attenuation due to fog, haze, clouds, rain and snow is
millimeter wave electron devices, free-electron lasers (FELs)
and masers. He developed a unified coupled-mode theory
one of the dominant causes of fading in wireless communication
of electromagnetic field excitation and propagation in the
links operating in the EHF band. Raindrops and dust scatter
frequency domain, enabling study of wideband interactions of
millimeter wave radiation, resulting in amplitude fluctuations and
electromagnetic waves in media in the linear and non-linear
phase randomness in the received signal. This further degrades
(saturation) operation regimes.
the availability and performance of the communication links.
Prof. Pinhasi investigates utilization of electromagnetic waves
Sufficient fade margins are essential for a reliable system.
in a wide range of frequencies for various applications such
as communications, remote sensing and imaging. The space4. Summary
frequency approach, which developed by him, is employed
The inhomogeneous transmission in a band of frequencies causes
to study propagation of wide-band signals in absorptive and
absorptive and dispersive effects in the amplitude and in phase of
dispersive media in broadband communication links, and
wireless indoor and outdoor networks as well as in remote
wide-band signals transmitted in the EHF band. The frequency
sensing Radars operating in the millimeter and Tera-Hertz
response of the atmosphere plays a significant role as the data
regimes.
rate of a wireless digital radio channel is increased. The resulting
Prof. Yosef Pinhasi is the Chairman of the Communication
amplitude and phase distortion leads to inter-symbol interference,
and Information Technology Chapter, of the Society of
and thus to an increase in the bit error rate (BER). These
Electrical and Electronic Engineers, Member of the executive
effects should be taken into account in the design of broadband
board of the Israeli Association of the Plasma Science and
communication systems, including careful consideration
Applications serving as its secretary, Chairman of Technical
of appropriate modulation, equalization and multiplexing
Standardization Expert Committee of Communication in
techniques.
smart Grid, The Standards Institution of Israel (SII).
26
2012 ‫ נובמבר‬,43 ‫גליון‬