292 Ad ances in Elec ical and Elec onic Enginee ing
ANALYSIS OF PULSED ELECTROMAGNETIC
FIELDS RADIATED BY
POWERFUL SOURCES
K. Maceika
Vilnius Gediminas Technical Uni e si y, An anas Gus ai is a ia ion ins i u e,
Rodunios kelias 30, LT-02187 Vilnius, Li huania
Tel.: +3705 2744816, E-mail: kazimie as.maceika@ai. g u.l
Summa y Calcula ion me hod p oposed o powe ul sou ces adia ion e alua ion. Taken a en ion ha in calcula ions i is
necessa y o use a e age adia ed powe . Fo example in case o ada s i depends on wo ac s: ada adia es sho adio
impulses wi h long pauses be ween hem and o a ed an enna wi h na ow pa e n o di ec i i y in ho izon al plane adia es
in o chosen poin a sho pa o an enna’s o a ion pe iod. Calcula ion is made o Thomson ada acco ding p oposed
equa ions. I is shown ha an enna in 5 m heigh adia es powe lux densi y in o le el o man head mo e imes smalle han
pe mi ed le el acco ding Li huanian no ma i e - 20,0 W/cm2.
1. INTRODUCTION
Public heal h se ice equi es calcula ions o
elec omagne ic ield in ensi y a ound powe ul
adia ion sou ces be o e hei moun ing. Such
e alua ion akes place in spi e o he manu ac u e s
heo e ical analyse and expe imen al measu emen s o
e e y conc e e equipmen adia ion. The me hod o
e alua ion is e y simple and has been used many
imes. I is necessa y o use an a e age alue o
adia ed powe in calcula ions o an enna
elec omagne ic ield exposu e. The pulse du a ion is
hund ed imes sho e han pulse epe i ion, hus an
a e age alue o powe densi y is hund eds imes
lowe han a peak alue o he adia ion. Addi ionally
he o a ing ada an enna adia es he EM ield a he
measu emen poin pe iodically wi hin a e y sho
ime, which s ongly depends on he wid h o he main
lobe o pa e n and scan sec o o he an enna.
Li huania has acc edi ed no ma i e o pe mi ed
le els o elec omagne ic adia ion, so esul s o
calcula ions can be compa ed wi h hese le els and
p ac ical conclusions can be made o ada
es ablishing. Example o e alua ion o Thomson
ada an enna adia ion in ensi y is shown in his
pape . The calcula ed adia ion is many imes smalle
han he pe mi ed le el and is no dange ous o
popula ion. The eal si ua ion will become clea a e
moun ing o he ada a place and expe imen al es s
o EM ield in ensi y.
2. CALCULATION OF RADIATED POWER
DENSITY
The densi y o adia ed powe o he powe ul
sou ce is e i ied a equencies g ea e han 300
MHz. This densi y calcula ion me hod is known [1, 2,
5] and o en has been used. Figu e 1 explains he
si ua ion.
Fig. 1. Finding o an enna adia ed powe lux densi y a
poin B
Wa es sp ead om he ada an enna and each poin
B a le el o a man’s head in wo ways: di ec and
e lec ed om Ea h su ace. The ene gy may each
e y high alues o powe densi y in peak, a
ela i ely low le els o powe densi y a e aged in
ime. This is because he pulse du a ion
τ
o he
ada adia ion is many imes sho e han pulse
epe i ion T
p
, hus an a e age alue o powe densi y
is many imes lowe han he peak alue also. Due o
he o a ion o he ada an enna, he poin B is
exposed o pulse modula ed mic owa e adia ion
pe iodically wi hin a e y sho ime ag eeably o he
wid h o a main lobe o he an enna in ho izon al
plane. I is easy o guess ha an a e age alue o
powe P
a
, a e aged o e pulse epe i ion and o e a
pe iod o an enna o a ion, is low:
,
360
0
0
ατ
p
peaka
T
PP = ( 1 )
in such a si ua ion he p oposed pa ame e o
cha ac e ize he ada adia ion will be a e age
powe lux densi y Sa a poin B:
).1()(
4
202
2
pG
R
P
S
a
a
+=
ηθ
π
( 2 )
In (2) G – an enna gain in di ec ion o maximum
adia ion,
Analysis o pulsed elec omagne ic ields adia ed by powe ul sou ces 293
(
Θ
º) – an enna’s pa e n o di ec i i y in e ical
ele a ion plane (dependence o elec ic ield in ensi y
om angle
Θ
º ),
η
- e iciency ac o o an enna and wa eguide,
less han one,
p – coe icien o elec omagne ic wa es
e lec ion om g ound,
R- dis ance AB (Fig.1) be ween phase cen e o
an enna A and obse a ional poin B.
E iciency o pa abolic an ennas is
η
<0,7. This
pa ame e is in ol ed usually in expe imen ally
measu ed pa e n o di ec i i y. Choosing o di e en
alues o angle
Θ
º pe mi s o calcula e S
a
and o
d aw powe densi y dependence on dis ance.
Dis ance L can be ound by:
L = ( h
1
– h
2
)/ g
Θ
º. ( 3 )
As inal esul , dependence S
a
om dis ance
be ween an enna and poin B can be d awn. I can be
used o inding o sani a y p o ec ion zone. In his
zone elec omagne ic ield powe lux densi y S
a
is a
g ea e han pe mi ed.
Radius o calcula ed sani a y zone depends on:
P
peak
- powe o ada ’s adia ed impulse,
G - an enna gain,
α
º
3dB,
Θ
º
3dB
– wid h o an enna’s pa e n o
di ec i i y on le el 3 dB in ho izon al and e ical
plane espec i ely,
Θ
º
max
– angle o an enna’s maximum adia ion in
e ical plane,
h
1
– an enna’s phase cen e high abo e g ound
su ace.
Di ec ion o maximum adia ion
Θ
º
max
and high o
an ennas ins alla ion h
1
can be chosen only and hey
es ima e sani a y p o ec ion zone adius R
san
Inc easing o h
1
bid up a cos o an enna’s ins alla ion
and he ise
Θ
º
max
wo sen de ec ion o down lying
ai c a s.
3. PERMITTED LEVEL OF
ELECTROMAGNETIC RADIATION
Hygiene no ma i e [3] desc ibes pe mi ed le el
o elec omagne ic adia ion o s a iona y elec onic
sys ems in li ing and wo k places in Li huania
epublic. In equencies band o e 300 MHz o
con inuous oscilla ion he powe lux densi y canno
be g ea e han 10.0

W/cm
2
. In Eu opean s anda d
[4] he pe mi ed le el o powe lux densi y is
same. In Li huanian no ma i e [3] he sa e a e age
le el o powe lux densi y in case o pulse adia ion
named 20.0

W/cm
2
because adia ion hea s he
human body du ing sho pulse ime and he body is
u ning cold du ing a long pause be ween pulses.
Russia has he simila no ma i e [2] o e alua ion
adia ion o me eo ological ada s. I adia ed
wa eleng h 10 cm ± 15%, he pe mi ed le el o
a e age powe lux densi y is acc edi ed 20.0

W/cm
2
on 2 m abo e g ound su ace.
Sepa a e desc ip ion o pe mi ed le els o
elec omagne ic adia ion is p oposed o people
wo king places. In equencies band 300 MHz-300
GHz he pe mi ed lux densi y depends on exposi ion
ime [3]. I exposi ion du a ion is 5 min, he
no ma i e is he g ea es – 1000

W/cm
2
. The
minimal no ma i e 25.0

W/cm
2
is o wo ke s
exposi ion du ing 8 hou s and mo e.
4. RADAR RADIATION LEVEL EVALUATION
The e a e age powe lux densi y calcula ions
ha e been made o Thomson ada which is used in
Li huania. P ima y ada da a o calcula ion is aken
om echnical documen a ion:
- equency o oscilla ions in adia ed adio
pulses - = 2900 MHz (
λ
= 10,34 cm ),
- peak powe o ansmi ed impulses P
peak
= 600
kW,
- du a ion o pulse
τ
= 1
µ
s.
- pe iod o pulses epe i ion Tp = 1000
µ
s.
Cha ac e is ics o p ima y ada an enna AC 316
a e he ollowing:
- ho izon al size o pa abolic an enna D = 4,12
m,
- e ical size H = 3,3 m,
- he g ea es gain o an enna G = 34,9 dB in
maximum di ec ion 3°,
- wid h o an enna di ec i i y pa e n in
ho izon al plane on 3 dB le el is
α
º
3dB
= 1.5°. Side
lobes a e 25 dB less han he main lobe,
- an enna pa e n o di ec i i y in e ical plane
has he shape cosec
2

up o
Θ
º= 50°. Gain alues in
dependence on
Θ
º a e aken in Tab.1.
- o a ion equency o an enna – 0.4 Hz.
Calcula ion p ocess.
An enna’s adia ion in es iga ion was made o
ins alla ion heigh : h
1
=5m and 22m. Powe lux
densi y alues we e ound a heigh h
2
= 2 m o e he
g ound su ace. P
peak
= 600 kW,
τ
= 1
µ
s, Tp =
1000
µ
s and
α
º
3dB
= 1.5° we e aken in o (1) and
ound a e age powe P
a
= 2.5 W. Only pa o pa e n
di ec i i y in e ical plane wi h nega i e alues o
angle
Θ
º om –0.5º ill -10º e e y 0.5º we e used
because only adia ion down was in e es ing. So 20
alues o -
Θ
º and adequa e alues o gain G(
Θ
º) in
dB we e ead om he pa e n (Tab.1). In equa ion
(2) G(
Θ
º) will co espond G·
2
(
Θ
º) ·
η
se in imes
ins ead o G in dB. The conc e e alues o
Θ
º we e
ecalcula ed in o dis ance L acco ding (3) (see
Fig.1). In equa ion (2) mul iplie (1-p
2
) was inse ed
co esponding o e lec ion o elec omagne ic wa es
om g ound (Fig.1). Acco ding o ecommenda ions
om li e a u e [2] (1-p
2
) = 1.5 on equency 2900
MHz. I is necessa y o no e ha his alue in eali y
is smalle han 1.5 because e lec ed wa e wi h
di ec wa e adds oge he no essen ially in phase.
294 Ad ances in Elec ical and Elec onic Enginee ing
Tab. 1. Da a o ada an enna’s pa e n o di ec i i y in
e ical plane and a e age adia ed powe lux densi y
dependence on dis ance
-

° G
2
(

°)

,
dB G
2
(

°)

L,m S
a
,

W/cm
2
0.5 27.6 575 113 0.0095
1 25.3 339 119 0.0088
1.5 22.9 195 126 0.0059
2 20.0 100 133 0.0041
2.5 17.9 61.7 142 0.0052
3 15.8 38 151 0.0056
3.5 13.9 24.5 162 0.0058
4 12.1 16.2 175 0.0051
4.5 10.5 11.2 190 0.0051
5 10.0 10.0 208 0.0054
5.5 8.9 7.76 229 0.0058
6 7.9 6.17 255 0.0052
6.5 7.2 5.25 286 0.006
7 7.1 5.13 327 0.0069
7.5 6.4 4.37 382 0.0079
8 5.5 3.55 457 0.0089
8.5 3.9 2.45 573 0.0092
9 5.0 3.16 763 0.0101
9.5 6.3 4.27 1145 0.0078
10 6.2 4.17 2291 0.0033
The esul s o calcula ion acco ding (2) o a e age
powe lux densi y depending on dis ance in Tab. 1
ha e maximum he 0.0101

W/cm
2
a dis ance 763
m. This alue is many imes smalle han he
pe mi ed le el 20.0

W/cm
2
. So i is possible o
educe heigh o an enna and o win in i s p ice.
Dependence o a e age powe lux densi y on
dis ance in case o heigh 5 m is shown on Fig. 2.
Cu e has a maximum o wo ac o s. Powe lux
densi y dec eases o ene gy dissipa ion in eceding
om ada an enna acco ding law 1/ R
2
. On ano he
hand adia ion inc eases wi h dis ance because in
an enna’s pa e n o di ec i i y in e ical plane a
le el o adia ion is g ea e . Fu he he lux densi y a
e y as dec eases a e maximum. Maximal go
powe lux densi y 0.45

W/cm
2
a dis ance 115 m is
smalle hen he pe mi ed le el acco ding no ma i e
- 20,0

W/cm
2
. In his case sani a y p o ec ion zone
absen and elec omagne ic adia ion o ada ’s
an enna is no dange ous o popula ion.
0 200 400 600 800 1000 1200 1400
0.0
0.1
0.2
0.3
0.4
0.5
A e age powe lux densi y S
a e
,
µ
W/cm
2
Dis ance L, m
Fig. 2. G aphical p esen a ion o he a e age powe lux
densi y om dis ance a an enna heigh 5 m
5. CONCLUSIONS
1.
P oposed e alua ion me hod o ada s
an enna’s mic owa e adia ion uses in calcula ions
a e age alue o adia ed powe densi y, which is
compa ed wi h pe mi ed le el acco ding no ma i e.
2.
Li huania and Eu ope Union ha e he same
no ma i e in equencies band 300 MHz - 300 GHz
o pe mi ed le els o elec omagne ic ield powe
lux densi y - 10,0

W/cm
2
i adia ion is con inuous
and in case o impulse adia ion - 20,0

W/cm
2
.
3.
I phase cen e o ada an enna is on heigh
5 m, he adia ed powe lux densi y is 40 imes
smalle han pe mi ed le el and is no dange ous o
popula ion. I an enna is equipped highe , he
maximum o adia ion in ensi y is u he bu wi h
many imes smalle ampli ude.
REFERENCES
[1]
Me hodical guidelines o diagnosis and
no malisa ion o elec omagne ic si ua ion in
me eo ological ada s places. USSR Minis y o
Heal h Ca e, 1985.
[2]
Maceika K. No ma i e o pe missible
elec omagne ic ields le el. P oc. o XI In .
Con e ence on Elec omagne ic Dis u bances,
Bialys ok BTU, pp.641-642.
[3]
Hygiene’s no ma i e HN 80:2000:
Elec omagne ic ield in wo k places and
esiden ial a ea. Pe mi ed alues and
measu emen equi emen s in 10 kHz-300 GHz
equencies. Minis y o Heal h Ca e o Republic
Li huania, Vilnius, 2000.
[4]
S anda d EN 50364: 2001: Limi a ion o human
exposu e o elec omagne ic ields om de ices
ope a ing in he equency ange 0 Hz o 10 GHz,
used in Elec onic A icle Su eillance (EAS),
Radio F equency Iden i ica ion (RFID) and
simila applica ions.
[5]
Skolnik M.I.: In oduc ion o Rada Sys ems.
McG aw-Hill, 2001.