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Патент USA US2412090

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Dec. 3, 1946.
P. J. KIBLER
2,412,090v
TURNSTILE ANTENNA
Filed Feb. 14, 1944
OR RECEIVER
TO TRANSMITTER
OR RECEIVER
INVENTOR
PAUL J. K|BLER_
ATTORNEY
2,412,090
Patented Dec. 3, 1946
UNITED STATES PATENT OFFICE
2,412,090
TURNSTILE ANTENNA
Paul J. Kibler, Fort Wayne, Ind., assignor to
Farnsworth Television and Radio Corporation,
a corporation of Delaware
Application February 14, 1944, Serial No. 522,323
7 Claims. (01. 250—33)
1
,
2
two oppositely disposed radiator elements and a
third terminal of the full Wave concentric line
particularly to impedance matching and phasing
located three-quarters of a wave length distant
means used in connection with antennas of ‘this
from one of the extreme terminals and a quarter
type.
‘
wave length distant from the other extreme ter
According to conventional practice turnstile
minal is connected to the apparatus to be used
antennas comprising a plurality of radiator ele
with the antenna.
ments symmetrically disposed with respect to one
For a better understanding of the invention,
another in the same plane are employed for radi
together with other and further objects thereof,
ating a rotating radio frequency ?eld having a
predetermined pattern. In order to establish such 10 reference is had to the following description,
taken in connection with the accompanying draw
a ?eld of substantially uniform intensity it is
necessary to supply substantially equal currents
ing, and its scope will be pointed out in the
to the respective radiator elements in a, prede
appended claims.
termined phase relation to one another. In the
In the drawing:
I
case of a turnstile antenna comprising four radi
Fig. 1 is a diagrammatic illustration of a four
ator elements, the elements are disposed at 90°
element turnstile antenna embodying the pres
angles with respect to one another and the ex
ent invention;
'
‘
citing currents are supplied thereto in time
Fig. 2 is a diagrammatic representation of a
quadrature. In order to equalize the exciting
concentric transmission .line for use with the an
currents it is necessary to match the impedances
tenna array of Fig. l; and,
of the radiator elements to the transmission
Fig. 3 is a schematic illustration of a network .
medium by which the currents are impressed
of lumped circuit elements also for use with the
upon the radiators. It also is necessary to couple
antennaarray of Fig. 1.
the current feeding transmission medium to the
Having reference now particularly to Fig. l of
radiator elements in such a manner that the ex
the drawing, there is shown a four-element turn
citing currents are impressed successively upon
stile antenna comprising a north radiator element
the respective radiator elements in proper phase.
N, an east radiator element E, a south radiator
In antennas of this character previously em
element S, and a west radiator element W. These
This invention relates to turnstile antennas and
ployed the impedance matching and phasing _
means have been of such characters that it has
not been possible to effect the required adjust
ments for each radiator element individually. It,
to one another.- The elements are of equal
lengths. In the illustrated embodiment of the
invention the radiator elements are each approxi
therefore, has been necessary to make these ad
justments only after complete assembly of the
antenna array.
mately equal to a quarter wave length which is
related to the radio‘frequency at which it is de
sired to establish the rotating ?eld. Connected
between the inner ends of each of the radiator
elements N, E, S and W are adjustable condensers
Then, because of the mutual
interdependence of the antenna components, the
adjustments are relatively dif?cult to make.
It is an object of this invention, therefore, to
provide a novel impedance matching and phasing
means for a turnstile antenna which will facili
tate the preliminary adjustment of the imped
ance matching and phasing means.
In accordance with the invention there is pro
vided a turnstile antenna having four equal
length radiator elements located in the same
radiator elements are all disposed in the same
plane and are located at 90° angles with respect
40
ll, I2, I 3V and M, respectively.‘ The opposite te'r—
minals of each of these condensers are connected
to ground. There also is connected betweenlthe
inner ends of the radiator elements N and W a
concentric transmission line l5, the effective
length of which is substantially equalto a quarter
wave length. Similarly, there is connected be
plane and disposed at 90° angles with respect to
tween the inner ends of the opposite pair of radi
one another. Associated with each of the radi
ator elements E and S a quarter Wave length
ator elements is an adjustable reactance device
concentric transmission line‘ IS. The inner ends
by means of which the radiator elements each
may be tuned for parallel resonance at the oper 50 of any two oppositely disposed‘ radiator elements
such as W and E constitute terminals A and B to
ating frequency. Adjacent tuned radiator ele
which there may be connected apparatus for sup
ments are connected to the respective ends of two
plying exciting currents of opposite phase to- the
quarter wave length concentric transmission lines.
antenna array. The outer conductors of the
The extreme terminals of a full wave concentric
transmission line are connected respectively to Gr Ul transmission-lines l5‘ and I6‘ are grounded, pref?
2,412,090
3
4
erably, adjacent the terminals A and B, respec
tively.
'
impedance of one of the radiator elements.
This impedance comprises the load connected
to the B terminal of the three-quarter wave
length line section IQ of the phasing line H.
In Fig. 2 there is illustrated one type of trans
mission medium suitable for connection to the
Inasmuch as it is characteristic of a three
antenna terminals A and B of Fig. l, as indicated
quarter wave length concentric transmission line
by corresponding characters of reference in the
two ?gures. This transmission medium com
to invert impedances at the terminals thereof,
the impedance looking into the three-quarter
prises a concentric transmission line I ‘I of full
Wave length section 1-9 from the point D also
wave length between the terminals A and B.
This concentric line- is divided into a quarter 10 is equal to twice the impedance of one of the
wave length section l8 and a three-quarter wave
tuned radiator elements.
length section I9. At the junction point of .
By connecting the phasing line sections l8
and 19 in parallel at the point D the impedance
these two line sections there is connected‘a
of the complete system looking toward the point
concentric transmission line 2| of whatever
length is required to couple the phasing trans 15 D from the connecting transmission line 2| is
equal to the impedance of one of the tuned
mission line I 1 to a circuit C such as a trans
radiator elements. Inasmuch as originally this
mitter for use in connection with the antenna
impedance was adjusted to correspond to the
array. The outer conductor of the transmis
sion line 2| is grounded and also connected to
characteristic impedance of a concentric trans
the transmission line I’! as shown.
_
20 mission line, a line of this character such as
Considering now the manner in which a turn
2| may be connected at the point D and there
stile antenna in accordance with the present in
by will be terminated in its characteristic im
vention is adjusted to‘ operate in the desired
pedance.
‘
Thus, by means of the described impedance
manner, reference will be made to Figs. 1 and 2.
Inasmuch as each of the radiator elements, such 25 matching arrangement the individual radiator
as the north radiator N, has a physical length
elements may be excited by currents of equal
equal to a quarter wave, the radiator element
magnitude. Also, by reason of the quarter wave
will exhibit a reactance at the related» fre_
length concentric line coupling between ad
quency which is slightly inductive. Consequent
jacentv radiator elements such as N and W, and
ly, the condenser II is adjusted suitably to pro 30 E and S, the exciting currents for the two radia
tors of each pair are in phase quadrature. Fin
vide the necessary capacitative reactance so that
ally, by means of the quarter wave length section
the radiator element is tuned for parallel reso
t8 and the three-quarter wave length section
nance at the radio frequency related to the
I9 of the phasing transmission line I1, exciting
length of the radiator element. Thus, the im_
pedance represented by the radiator element N 35 currents are supplied to the points A and B,
and the condenser Il may be made purely re
respectively, of the two pairs of radiator ele
sistive. Also, by suitable adjustment of the ef
ments in phase opposition. In this manner the
fective length of the radiator element, together
four radiator elements of the turnstile antenna
with a compensating adjustment of the tuning
are excited by currents of equal magnitude in
condenser, the effective impedance of the radia 40 phase quadrature.
tor may be made equal to the characteristic-im
Fig. 3 illustrates an alternative form of a phas
‘ pedance of a concentric transmission line.
Similarly to the described adjustment of con
denser l l, the condensers I2, l3 and I 4 are ad
justed so that the respective associated radiator
elements E, S and W have impedances, each
equal to the characteristic impedance of a con
ing transmission medium for supplying exciting
currents of opposite phase to the two pairs of ra
diator elements at the points A and B of Fig. 1.v
This medium comprises a balancing network
formed of condensers 22 and 23 between which
there is connected in series an inductor 24. The
reactances of the condenser 22 and the inductor
24 are made numerically equal to twice the react
ator elements N and W. are coupled by the con
centric line l5 and the radiator elements E and 50 ance of the condenser 23. The values of these re
actances will determine the effective impedance of
S are coupled by the concentric line !6, these
the network as seen from C. By suitably choosing
concentric lines are terminated at each end in
the values of these reactances, the network im
their characteristic impedances. In such a case
pedance may be matched properly to a transmis
then the radiators N and W are effectively con
nected in parallel by the quarter wave length Cr an sion medium connected thereto.
The condenser 22 is connected to the terminal
line l5. Similarly, the radiators E and S are
A of the antenna array of Fig. 1 and the junction
e?ectively connected in parallel by the quarter
point between the inductor 24 and the condenser
wave length line Hi. In such a case the im
23 is connected to the terminal B of the antenna
pedance of the pair of radiators N and W at
the point A and also the impedance of the pair 60 array. The condenser 23 is connected to ground,
as shown, and the junction point between the con
of radiators E and S at the point‘B is equal
denser 22 and the inductor 24 is connected to the
to one-half of the impedance of one of the tuned
apparatus with which the antenna array is to op
radiator elements. The impedance of the pair
erate.
>
of radiators N and W at the point A comprises
A network in accordance with that illustrated in
the load for the quarter wave length section l8
Fig. 3 is similar to one described by S. Frankel, in
of the phasing transmission line l1. Since it is
the Proceedings of the I. R. E, of September, 1941.
characteristic of the quarter wave length line
Such a network functions to impress currents de
to invert impedances, the impedance looking into
rived from the utilization circuit C upon the ter
the quarter wave length section l8 of the phas
minal points A and B in phase opposition and bal
ing line I‘! from the point D, therefore, is equal
anced with respect to ground. The antenna array
to twice the impedance of one of the radiator
as shown in Fig. 1 then functions in a manner
elements.
similar to that described to produce a rotating
In like manner, the impedance at the point
radio frequency ?eld of a substantially circular
B looking into the parallel arrangement of the
pattern.
~
.
radiator elements E and S is one-half of the
centric transmission line.
Thus, when the radi
2,412,090
5
6
In the foregoing description reference has been
phase coupling means for said antenna connect
made to feeding or supplying currents to an an
tenna array in accordance with this invention.
This is the case where the antenna is to be used
ed to two oppositely disposed radiator elements. ,
in conjunction with radiant energy transmitting
apparatus.‘ It is obvious, however, to those skilled
3. A turnstile antenna comprising, four equal
length radiator elements located in the same
UL plane and disposed at 90° angles. with respect to
one another, a pair of quarter wave length eon
centric transmission lines connected respectively
between adjacent radiator elements, a tuning
condenser connected to each of said radiator ele
ments to match the impedance of each element
to the characteristic impedance of one of said
cordingly, it is contemplated that the structures
transmission lines, and an opposed-phase cou
de?ned in the appended claims are suitable for use
pling medium for said antenna including a pair
either with transmitting or receiving apparatus.
of transmission lines of different lengths connect
Therefore, the ‘term “utilization circuit” used in
this speci?cation and in certain of the claims is 15 ed respectively to two oppositely disposed radiator
elements.
intended to de?ne a circuit associated with either
4. A turnstile antenna comprising, four equal
transmitting or receiving apparatus.
length radiator elements located in the same
It also will be obvious to those skilled in the
plane and disposed at 90° angles with respect to
art that the invention is not limited to use with
radiator elements substantially of quarter wave 20 one another, a pair of quarter Wave length con
centric transmission lines connected respectively
lengths. It is contemplated that the invention
between adjacent radiator elements, a variable
may be embodied in antennas having radiator ele"
tuning condenser connected to each of said ra
ments of substantially any desired lengths, pro
diator elements to match the impedance of each
vided that in any one antenna array all radiators
element to the characteristic impedance of one
are of the same length. In the case where the
of said transmission lines, and a coupling medium
radiator lengths are such that the radiator re
for said antenna, including a pair of concentric
actances at the operating frequency are capacita
transmission lines di?ering in length by a half
tive rather than inductive, as in the case de~
wave length connected respectively to two oppo
scribed, the matching reactances required for
sitely disposed radiator elements.
tuning will of necessity have to be inductive.
5. A turnstile antenna comprising, four equal
Hence, in place of the condensers H, l2, l3 and
length radiator elements located in the same
I4, corresponding adjustable inductors will be
plane and disposed at 90° angles with respect
in the art that such an antenna also is susceptible
of use with receiving apparatus, in which case the
radio frequency currents collected by the antenna
are transferred to the receiving apparatus. Ac
required,
From the foregoing description of one embodi
ment of this invention, it follows that there is
provided an antenna system, each radiator ele
ment of which is susceptible of individual pread
justment of its effective impedance, whereby after
complete assembly of the antenna array no fur
ther adjustments are required.
While there has been described what, at pres
ent, is considered the preferred embodiment of
the invention, it will be obvious to those skilled
to one another, a pair of quarter wave length
concentric transmission lines connected respec
tively between adjacent radiator elements, a vari
able condenser connected to each of said radi
ator elements to tune each element for parallel
resonance at the operating frequency and to
match the impedance of each element to the
characteristic impedance of one of said trans
mission lines, and a full wave concentric trans
mission line having its two extreme terminals
connected to two oppositely disposed radiator
in the art that various changes and modi?cations
elements and having a third terminal three quar
may be made therein without departing from the
ters of a wave length distant from one of said
invention, and therefore, it is aimed in the ap
extreme terminals and a quarter wave length
pended claims to cover all such changes and modi
distant from the other of said extreme terminals,
?cations as fall within the true spirit and scope
whereby currents of opposite phase may be apof the invention.
50 plied to said opposed radiator elements from a
What is claimed is:
source connected to said third terminal.
1. A turnstile antenna comprising, four equal
6. A turnstile antenna comprising, four equal
length radiator elements located in the same
length radiator elements located in the same
plane and disposed at 90° angles with respect to
plane and disposed at 90° angles with respect to
one another, a pair of quarter wave length trans
one another, a pair of quarter wave length trans
mission lines connected respectively between ad
mission lines connected respectively between ad
jacent radiator elements, individual means asso
jacent radiator elements, a tuning condenser con
ciated with each of said radiator elements to
nected to each of said radiator elements to match
match the impedance of each element to the
the impedance of each element to the character
characteristic impedance of one of said trans 60 istic impedance of one of said transmission lines,
mission lines separately and independently of the
and an opposed-phase coupling medium for said
other radiator elements, and means for coupling
antenna including a balancing network connect
two oppositely disposed radiator elements in
ed to two oppositely disposed radiator elements
phase opposition to a utilization circuit for said
and having an intermediate terminal connected
antenna.
to a utilization circuit for said antenna.
2. A turnstile antenna comprising, four equal
7. A turnstile antenna comprising, four equal
length radiator elements located in the same
length radiator elements located in the same
plane and disposed at 90° angles with respect to
plane and disposed at 90° angles with respect to
one another, a pair of quarter wave length con
one another, a pair of quarter Wave length con
centric transmission lines connected respectively 70 centric transmission lines connected respectively
between adjacent radiator elements. a reactance
between adjacent radiator elements, a variable
element associated with each of said radiator ele
condenser connected to each of said radiator ele
ments and adjustable to match the impedance of
ments to tune each element for parallel resonance
each element to the characteristic impedance of
and to match the impedance of each element to
one of said transmission lines, and opposed 75 the characteristic impedance of one of said trans
2,412,090
7
8
mission lines, and a coupling medium for said
0nd ‘condenser being connected to two oppositely
disposed radiator elements, and said second con
denser being connected to ground and-the Junc
antenna including a network comprising an in
ductor connected in series between a ?rst con
denser having a reactance numerically equal to
that of said inductor and a second condenser
having a reactance numerically equal to one-half
that of said inductor, said ?rst condenser and
the junction point of said inductor and said sec
tion point of said inductor and-said ?rst con-v
denser being connected to a utilization circuit for
'said antenna.
PAUL J. KIBLER.
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