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Патент USA US2126531

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Aug. 9, 1938.
P. s. CARTER~ '
2,126,531
ANTENNA
Filed lhflfrch 9, 1956
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INVENTOR/
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PHILIP S.CAR“FER
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ATTORNEY.
-
Aug- 9, 1938.
P. ,s. CARTER
2,126,531
ANTENNA
Filed March 9, 1936
2 Sheets-Sheet 2
1/195 v ‘
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900
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90"
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90"
7'0 TRANSMITTER
Fig.9
INVENTOR. ‘
PHILIP 5. CARTER‘
BY
’
ATTORNEY.
"
Patented Aug. 9, 1938
2,126,531
al
UNITED STATES
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7
PATENT =1 i‘OFFICE
2,126,531
_
d
‘f » ANTENNA "
V-Philip .sr-Carteryl’ort Je?'erson, N. Y; assignor to .
Radio Corporation of America, a corporation
’ of Delaware
Application March '9, 1936, .Serial ‘No. 67,785
‘
6 Claims.
This invention relates to an antenna system
(01. 250_3s)
for broadcasting vertically polarized waves. ‘
this ?gure of the drawings; then, if I is the
Heretoforein order to obtain a high latitudinal
‘concentration of radiation, ‘it has been usual to
employ an array of tall ‘radiators which reach
total‘ current in all the radiators the current in
one radiator is
I
considerable heights. An arrangement of this
sort is very costly, and ‘in most cases it is not
possible to obtain equal radiation in all horizontal
directions.
.
‘
'
radiators-‘nina circle of radius a, as shown in
»
The number of radiators within an angle d9 is
er
‘
The present invention provides an improved
antenna system wherein there is obtained sub
stantially equal radiation in all horizontal direc
tions and a great reduction in undesirable high
~angle radiation. In brief, the invention consists
are of concentric circular arrays of vertical radiators
‘spaced apart according to a de?nite mathemati
cal law, all of the vertical radiators in each cir
cular array ‘being of substantially equal length
and energized cophasally with equal currents
r1120 while adjacent circular arrays are fed either co
phasally or in opposition, depending upon the
lengths ‘of the radii of the arrays as measured
21F
Now consider that the ?eld Waves arrive.at
point P in this sketch, which point is at a su?i- '
cient distance from the circle for all paths to
be parallel. Let us now take as reference phase
the phase of a wave arriving from an element
on the reference axis 9:0. This wave has trav
elled a distance R. The Wave from the element
110 has travelled a distance r=R~a sin 9.
.
a sin 6
25
I have found that for a given ‘total current
the ?eld strength of the radiated wave ‘in the
.horizontal direction from .a circular array of a
where v is the velocity of light.
number of vertical radiators is proportional to
Jn(‘2wa/>\), where a is the radius of the circle
of reference phase by the real part of
‘
l
V
If .we represent the electric ?eld of the wave
30
I
‘wt
Kle'
of the ?rst kind with the argument. (ZTra/X).
It is thus apparent that for maximum radiation
horizontally, the radius must be such as to result
‘
.
v
21r
KI .
they
_,
KI .
21rd see
I ‘Regen/10+ v )d0—Re%61w<t+ )\ )cw
minimum. For this condition, J1 of (21ra/i) =0,
where J1 is the corresponding ?rst order Bessel
function of the ?rst kind. Hence the radii should
be roots ‘of the function J1(21ra/)\) .
.
d6
then the‘ ?eld from the element at 9 is
in the function Jo(21ra/)\) being a maximum or
‘
35
The total ?eld at P is then:
This results
‘in values approximately equal to 0.61, 1.12, 1.62,
2.12, 2.62 etc. wavelengths, wherein all radiators
‘in each circular array are fed cophasally, but
adjacent circular arrays are fed in phase oppo
_ sition.
The
di?erence in distance is asin 9, to which corre
sponds a distance in time
and J0(27rCL/7\) is the zero order Bessel function
“ 45
10
and the total current in these radiators is:
‘from a central point. These vertical radiators
.may either be dipoles or grounded vertical an
tennas.
Ul
n
‘
The invention is not limited to the arrange
ment already discussed. It is not necessary in
an array of circles to have radii corresponding
to all successive roots of the Bessel function
‘mentioned. For instance, it might be desirable
to use an array having radii of 0, 1.12, 2.12 etc.
wavelengths or 0.61, 1.62, 262 etc. wavelengths,
'40
‘where
.
1(7)
21ra
is the zero order Bessel function of the ?rst kind.
Now, for a given current the magnitude of the 45
?eld will be a maximum when
we
.is a maximum or a minimum.
1:111 radiators in the circles in either of these com
binations beingrfed cophasally. Another combi
nation might be with circles of radii .0, 1.62, 3.12
etc. wavelengths, where the radiators in adja
cent circles are fed in phase opposition.
1
,A' brief mathematical analysis of the theory
underlying the present invention will now be
given with particular reference to Fig. 10. Let
60 us assume that there are a large number of
JrT
is the first order Bessel function of the ?rst kind.
From the roots of this function we obtain the
relations given in the docket.
60
2
2,126,531
No radiation horizontally takes place when the
radius a is such that
or when a=0.382>\, 0.8801, etc.
A better understanding of the invention may
be had by referring to the following description
in conjunction with drawings wherein:
10
Figs. 1-4, inclusive, illustrate plan views of
antennas in accordance with the invention;
Figs. 5-8, inclusive, illustrate polar diagrams of
the ?eld distribution in any vertical plane of
various combinations of individual circular arrays
shown in Fig. 1;
Fig. 9 shows, by Way of example only, one way
of feeding the antenna arrays; and
Fig. 10 is a drawing given merely for the pur
pose of the theoretical explanation advanced
above.
systems shown, since other circular arrays may
be used which are suitably energized and have
as radii roots of the Bessel function named, with
out departing from the spirit and scope of the
invention.
What is claimed is:
1. An antenna comprising a plurality of con
centric circular antenna arrays each composed
of vertical radiators, the radius of each circular
array being such that the zero order Bessel func
tion of the ?rst kind, namely J 0(21ra/1) , with the
argument (21ra/A) , is a maximum or a minimum,
where a is the radius of the circular array, A the
wavelength, and high frequency apparatus for
energizing the radiators in each circular array 15
cophasally.
2. An antenna comprising a. plurality of con
centric circular antenna arrays each composed
of vertical radiators, the radii of successive cir
cular arrays multiplied by
In Fig. l is shown a plan View of one antenna
20
21r
arrangement in accordance with the invention,
comprising four concentric circular arrays 2, 3,
4, 5 of vertical radiators with a single radiator I
at the center. This system may be considered
the ?rst kind, J1(21ra/>\) with the argument 25
as consisting of ?ve circular arrays, the inner
most array consisting of single radiator I which
length, and high frequency apparatus for ener
is of zero radius. The radii from the central
radiator l to successive arrays are, as indicated,
30 equal to 0.61, 1.12, 1.62 and 2.12 wavelengths,
which are successive roots of the Bessel function
mentioned above. All the radiators in any one
circle are of equal length and energized cophasal
ly in any suitable manner and with equal cur
T
being successive roots of the Bessel function of
(21ra/A), where a is the radius and A the wave
gizing the radiators in each circular array co
phasally but out of phase with respect to the
radiators in the adjacent array.
30
3. An antenna comprising a plurality of con
centric circular antenna arrays each composed
of vertical radiators, the radii of successive cir
cular arrays multiplied by
to O1 rents, while radiators in adjacent circles are fed
are of sufficient number to produce an effect ap
proximating a current sheath. If desired, the
circular arrays may have currents of different
40 magnitude with respect to one another.
Figs. 2 and 3 show plan views of an antenna
system wherein the radii of successive arrays
correspond to alternate roots of the Bessel func
tion named. In both of these ?gures the adja
45 cent circular arrays are fed cophasally.
Fig. 4 shows, by way of example, another com
bination of circular arrays which may be used,
and wherein the radiators in adjacent circular
arrays are energized in phase opposition.
Fig. 5 is a polar diagram of the ?eld distribu
tion in any vertical plane for a single radiator.
Fig. 6 is a similar diagram for a circle of radia
tors having a radius of 0.61 wavelength.
Fig. '7 is a diagram resulting from the combi
55 nation of a circle of radiators having a radius
of 0.61 wavelength from a central point and a
single radiator at said central point.
Fig. 3 is a similar diagram for the system of
Fig. 1.
Fig. 9 shows one way of feeding all the ra
diators in any one circle by means of equal length
lines connecting with a main feeder. If the
radiators are dipoles, each line would comprise
a pair of wires. Similarly, other circular arrays
65 are also fed from the center.
To obtain phase
opposition or cophasal relation between any two
circular arrays, the central connection points of
the lines extending to the individual radiators
would be joined together by a proper length of
70 line to give the desired phase relation.
From the foregoing it will be understood that
the invention is not limited to the precise antenna
35
g
in phase opposition. The radiators in each circle
A
being alternate roots of the Bessel function of
the ?rst kind, J1(21ra/7\), with the argument
(21ra/A), where a is the radius, and 1 the wave
length, and high frequency apparatus for ener
gizing the radiators in all circular arrays co
phasally.
4. An antenna comprising a plurality of con
centric circular arrays each composed of ver
tical radiators, a single vertical radiator at the 45
center of said arrays, the radius of said ?rst
circular array as measured from said center be
ing approximately .6121, the radius of the second
circular array being approximately 1.121 and that
of the third array approximately 1.621, where A 50
is the wavelength, and high frequency apparatus
for energizing the radiators in each array co
phasally, but adjacent arrays out of phase.
5. An antenna comprising a plurality of con
centric circular arrays each composed of vertical 55
radiators, a single vertical radiator at the center
of said arrays, the radius of the ?rst of said ?rst
circular arrays as measured from said center
being approximately 1.121, the radius of said
second circular array being approximately 2.121,
where A is the wavelength, and high frequency
apparatus for energizing the radiators in all
arrays cophasally.
‘
6. An antenna comprising a plurality of con
centric circular arrays each composed of vertical
radiators, the radius of the ?rst of said arrays
as measured from the center being approximately
.611, and the radius of the second array being
approximately 1.621, where >\ is the wavelength,
and means for energizing all the radiators of all 70
arrays cophasally.
’
PHILIP S. CARTER.
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