U.S. patent number 3,641,578 [Application Number 05/056,830] was granted by the patent office on 1972-02-08 for discone antenna.
This patent grant is currently assigned to International Telephone and Telegraph Corporation. Invention is credited to Michael S. Polgar, William M. Spanos.
United States Patent |
3,641,578 |
Spanos , et al. |
February 8, 1972 |
DISCONE ANTENNA
Abstract
A multimode discone antenna providing simultaneously, without
interference, right- and left-hand circularly polarized
omnidirectional patterns and a vertically polarized omnidirectional
pattern. Four coaxial cables are disposed parallel to each other
with the outer conductors electrically coupled together. An
extension of the central conductor of each coaxial line is extended
downward from the upper end of and at a given angle less than
90.degree. to the associated one of the coaxial lines. This
arrangement, when the two pairs of diagonally disposed coaxial
lines are excited in a balanced relationship and the pairs are
excited orthogonally by first energy, provides simultaneously both
right- and left-hand circularly polarized omnidirectional patterns.
When a disc is electrically connected to the outer conductors of
the four coaxial lines and is physically supported in spaced and
orthogonal relation to the upper end of the four coaxial lines, the
antenna, in addition, simultaneously provides, when each of the
four coaxial lines are excited in phase by second energy, a
vertically polarized omnidirectional pattern. An embodiment of a
feed arrangement is disclosed enabling the four coaxial lines to be
excited in phase by the second energy and simultaneously to enable
each of the four coaxial lines to be excited by the different
orthogonally related first energy.
Inventors: |
Spanos; William M. (Wayne,
NJ), Polgar; Michael S. (Ocean Port, NJ) |
Assignee: |
International Telephone and
Telegraph Corporation (Nutley, NJ)
|
Family
ID: |
22006812 |
Appl.
No.: |
05/056,830 |
Filed: |
July 21, 1970 |
Current U.S.
Class: |
343/773; 333/117;
343/846; 342/365; 342/373 |
Current CPC
Class: |
H01Q
21/26 (20130101) |
Current International
Class: |
H01Q
21/24 (20060101); H01Q 21/26 (20060101); H01q
001/48 (); H01q 013/00 (); H01q 021/00 () |
Field of
Search: |
;343/796-802,806,846,808,809,850-865,773 ;333/11 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lieberman; Eli
Assistant Examiner: Nussbaum; Marvin
Claims
We claim:
1. A multimode vertically polarized omnidirectional pattern, a
right-hand circularly polarized omnidirectional pattern and a
left-hand circularly polarized omnidirectional pattern
comprising:
four coaxial transmission lines disposed in a parallel
relationship, each of said coaxial lines including an inner
conductor and an outer conductor;
first means to electrically and physically interconnect said outer
conductors of all said coaxial lines;
fourth first members each coupled to said center conductor of a
different one of said coaxial lines and extending downward from an
end of and at a given angle less than 90.degree. to the associated
one of said coaxial lines;
four second members each coupled to the free end of a different one
of said first members and extending downwardly and toward the
associated one of said coaxial lines at an angle less than
180.degree. and greater than 90.degree.;
a disc; and
second means to electrically connect said disc to said first means
and to physically support said disc spaced from said end of and
orthogonal to said coaxial lines.
2. An antenna according to claim 1, wherein:
each of said coaxial lines are excited by in-phase energy; and
simultaneously each of said coaxial lines are excited by different
orthogonally related energy.
3. An antenna according to claim 1, wherein:
said disc has a diameter approximately equal to 0.7 D at the
operating frequency of said antenna, where D is the distance
between the free ends of diagonally related ones of said first
members; and
each of said first and second members have a length greater than
one-quarter wavelength at said operating frequency.
4. An antenna according to claim 1, further including;
a first balanced hybrid having a first balanced port, a first
in-phase port, a first port coupled to said center conductor of a
first of said coaxial lines and a second port coupled to said
center conductor of a second of said coaxial lines diagonally
disposed with respect to said first of said coaxial lines, said
first port being responsive to first energy, said second port being
responsive to said first energy having a 180.degree. phase
relationship with said first energy at said first port and said
first and second ports simultaneously being responsive to in-phase
second energy;
a second balanced hybrid having a second balanced port, a second
in-phase port, a third port coupled to said center conductor of a
third of said coaxial lines and a fourth port coupled to said
center conductor of a fourth of said coaxial lines diagonally
disposed with respect to said third of said coaxial lines, said
third port being responsive to said first energy having a
-90.degree. phase relationship with said first energy at said first
port, said fourth port being responsive to said first energy having
a +90.degree. phase relationship with said first energy at said
first port and said third and fourth ports simultaneously being
responsive to said in-phase second energy;
third means interconnecting said first and second in-phase ports;
and
a quadrature hybrid having a fifth port, a sixth port, a 0.degree.
phase port coupled to said first balanced port and a 90.degree.
port coupled to said second balanced port.
5. A multimode discone antenna capable of having simultaneously a
vertically polarized omnidirectional pattern, a right-hand
circularly polarized omnidirectional pattern and a left-hand
circularly polarized omnidirectional pattern comprising:
four coaxial transmission lines disposed in a parallel
relationship, each of said coaxial lines including an inner
conductor and an outer conductor;
first means to electrically and physically interconnect said outer
conductors of all said coaxial lines;
four first members each coupled to said center conductor of a
different one of said coaxial lines and extending downward from and
end of and at a given angle less than 90.degree. to the associated
one of said coaxial lines;
a disc; and
second means to electrically connect said disc to said first means
and to physically support said disc spaced from said end of and
orthogonal to said coaxial lines.
6. An antenna according to claim 5, wherein:
each of said coaxial lines are excited by in-phase energy and
simultaneously each of said coaxial lines are excited by different
orthogonally related energy.
7. An antenna according to claim 5, wherein;
said disc has a diameter approximately equal to 0.7 D at the
operating frequency of said antenna, where D is the distance
between the free ends of diagonally related ones of said first
members; and
each of said first members have a length greater than one-quarter
wavelength at said operating frequency.
8. An antenna according to claim 5, further including:
a first balanced hybrid having a first balanced port, a first
in-phase port, a first port coupled to said center conductor of a
first of said coaxial lines and a second port coupled to said
center conductor of a second of said coaxial lines diagonally
disposed with respect to said first of said coaxial lines, said
first port being responsive to first energy, said second port being
responsive to said first energy having a 180.degree. phase
relationship with said first energy at said first port and said
first and second ports simultaneously being responsive to in-phase
second energy;
a second balanced hybrid having a second balanced port, a second
in-phase port, a third port coupled to said center conductor of a
third of said coaxial lines and a fourth port coupled to said
center conductor of a fourth of said coaxial lines diagonally
disposed with respect to said third of said coaxial lines, said
third port being responsive to said first energy having a
-90.degree. phase relationship with said first energy at said first
port, said fourth port being responsive to said first energy having
a +90.degree. phase relationship with said first energy at said
first port and said third and fourth ports simultaneously being
responsive to said in-phase second energy;
third means interconnecting said first and second in-phase ports;
and
a quadrant hybrid having a fifth port, a sixth port, a 0.degree.
phase port coupled to said first balanced port and a 90.degree.
port coupled to said second balanced port.
Description
BACKGROUND OF THE INVENTION
This invention relates to antennas and more particularly to discone
antennas.
Because of existing space limitations and a need for greater
numbers of antennas to provide radiating means for a multiplicity
of services, the trend in antenna design is toward compact
multipurpose radiators which provide more than one function. For
example, in mobile applications, requirements exist for providing
radio communications and navigation functions simultaneously in
either different frequency bands, or in the same frequency band.
The antenna radiation characteristics with respect to pattern
coverage and polarization are not necessarily identical. The advent
of communications and navigation systems which utilize satellites
have greatly complicated the design of common multipurpose antennas
because of requirements for pattern coverage and polarization which
differs from those for line-of-sight (LOS) ground-to-ground and
ground-to-air links. The satellite systems require circular
polarization and overhead coverage from ground base antennas,
necessitating different modes of excitation in the antenna from
those used for conventional systems.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a multimode
antenna suitable for utilization in satellite systems.
Another object of the present invention is to provide a multimode
discone antenna capable of having simultaneously a vertically
polarized omnidirectional pattern, a right-hand circularly
polarized omnidirectional pattern and a left-hand circularly
polarized omnidirectional pattern.
Still another object of the present invention is to provide a
multimode discone antenna capable of utilization with satellite
systems, LOS communication systems and/or navigation systems.
A feature of the present invention is the provision of a multimode
discone antenna capable of having simultaneously a vertically
polarized omnidirectional pattern, a right-hand circularly
polarized omnidirectional pattern and a left-hand circularly
polarized omnidirectional pattern comprising four coaxial
transmission lines disposed in a parallel relationship, each of the
coaxial lines including an inner conductor and an outer conductor;
first means to electrically and physically interconnect the outer
conductors of all the coaxial lines; and four first members each
coupled to the center conductor of a different one of a coaxial
line and extending downwardly from an end of, and at a given angle
less than 90.degree. to, the associated one of the coaxial
lines.
Another feature of the present invention is the provision of four
second members each coupled to the free end of a different one of
the above-mentioned first members and extending downwardly and
toward the associated one of the coaxial lines at an angle less
than 180.degree. and greater than 90.degree. .
A further feature of the present invention is the provision of a
disc and a second means to electrically connect the disc to the
above-mentioned first means and to physically support the disc
spaced from the end of, and orthogonal to, the above-mentioned
coaxial lines.
Still a further feature of this invention is the provision of a
multimode discone antenna as described above wherein each of the
four coaxial lines are excited by in-phase energy and
simultaneously each of the coaxial lines are excited by different
orthogonally related energy.
BRIEF DESCRIPTION OF THE DRAWING
The above-mentioned and other features and objects of this
invention will become more apparent by reference to the following
description taken in conjunction with the accompanying drawings, in
which:
FIG. 1 is a perspective view of a multimode discone antenna and its
feed arrangement in accordance with the principles of the present
invention;
FIG. 2 is a top view of FIG. 1;
FIG. 3 is a schematic illustration of the electric field and
current configuration for in-phase excitation of the coaxial lines
of FIGS. 1 and 2;
FIG. 4 is the elevational pattern resulting from the electric field
and current configuration as illustrated in FIG. 3;
FIG. 5 is a schematic illustration of the electric field and
current configuration when the four coaxial lines of FIGS. 1 and 2
are subjected to a balanced excitation; and
FIG. 6 illustrates the elevational pattern resulting from the
electric field and current configuration illustrated in FIG. 5.
DESCRIPTION OF THE PREFERRED EMBODIMENT
For purposes of explanation, let us consider a UHF (ultrahigh
frequency) line-of-sight (LOS) ground-to-ground communication, UHF
satellite communications and L-band DME (distance-measuring
equipment)/Tacan or RSB (Radar Safety Beacon)/IFF (Identification
Friend or Foe) applications wherein the following requirements
would exist for an antenna at a user terminal.
Function Polarization Frequency Pattern Coverage Band
__________________________________________________________________________
UHF LOS Vertical 225-400 MHz. Figure 8 in Communications elevation,
omnidirectional UHF Dual Circular 225-400 MHz. hemispherical
Satellite Communication DME/ Vertical 960-1,215 MHz. Figure 8 in
Tacan, elevation, RSB/IFF omnidirectional
__________________________________________________________________________
The term "dual circular" as presented in the above table refers to
right and left hand circularly polarized radiation. The term
"hemispherical" present in the above table has reference to a
right- and left-hand circularly polarized omnidirectional
pattern.
Referring to FIGS. 1 and 2, there is illustrated therein a
multimode discone antenna in accordance with the principles of the
present invention including four coaxial transmission lines 1-4,
each of which includes an outer conductor 5 and an inner conductor
6. The outer conductors 5 of coaxial lines 1-4 are interconnected
electrically and physically by members 7 and 8. To the center
conductors 6 at the upper end thereof is connected a member 9
extending downward from the upper end of coaxial lines 1-4 and at a
given angle less than 90.degree. to the associated one of coaxial
lines 1-4.
The structure just described provides a hemispherical antenna
pattern when each of the pairs of coaxial lines 1 and 4 and coaxial
lines 2 and 3 are excited in a balanced relationship and these
pairs of coaxial lines are orthogonally excited by a given energy
for transmission from the antenna structure, or when
hemispherically radiated energy is received by radiating elements
9. The radiating elements 9 in the form of wire or rods is
equivalent to the cone of a discone antenna and due to its
hemispherical antenna pattern provides the multifunction of
providing both right- and left-hand circular polarization with an
omnidirectional pattern. This arrangement as just described would
be suitable for UHF satellite communication as indicated in the
above table.
To aid in the producing of the desired shape of the antenna pattern
and also to adjust the impedance of the antenna structure, second
members 10 are coupled to the free end of each of the members 9 and
arranged to extend downwardly and toward the associated one of
coaxial lines 1-4 at an angle between members 9 and 10 less than
180.degree. and greater than 90.degree.. The angle between each of
the members 9 and 10 enables variation for space consideration and
also impedance considerations in the antenna structure as well as
the shape of the antenna pattern.
To provide vertical polarization for UHF LOS communications or
DME/Tacan, RSB/IFF applications, a disc 11 is disposed orthogonal
to the parallel coaxial lines 1-4. Disc 11 is electrically
connected to the outer conductors 5 of coaxial lines 1-4 by
physical connection to members 7 and 8 via feed member 12 which is
physically coupled to the center of disc 11. Feeder 12 also
provides an electrical connection between the outer conductors 5 of
coaxial lines 1-4 and disc 11. Current flows on outer conductor 5
of coaxial lines 1-4 due to inphase excitation thereof which could
cause the coaxial lines to radiate and disturb the desired
patterns. In accordance with this invention, a high impedance to
this current flow and, hence, elimination of the unwanted radiation
is provided by the one-quarter wavelength choke 19 having the end
20 thereof in electrical contact with outer conductor 5 of coaxial
lines 1-4.
Disc 11 has a diameter approximately equal to 0.7 D, where the
dimension D is illustrated in FIG. 2, at the operating frequency
while wires 9 and 10 each have a length greater than a quarter
wavelength. The lengths of wires 9 and 10, as well as the distance
D, controls the radiation patterns generated by the antenna of this
invention.
Another important dimension is the space between the ends of
coaxial lines 1-4 and disc 11 as provided by the length of member
12 and also the diameter of member 12. The spacing, as provided by
the length of member 12, and the diameter of member 12 may be
adjusted to control the impedance levels of the antenna structure
of this invention.
To provide transmission of vertically polarized omnidirectional
energy, coaxial lines 1-4 must each be energized by the desired
energy in-phase and upon reception of vertically polarized
omnidirectional energy coaxial transmission lines again will be
excited in-phase by the received energy.
FIG. 3 illustrates by virtue of the solid arrows the electrical
field configuration when the antenna structure and, particularly,
the coaxial lines 1-4 are excited in-phase. The dotted arrows
illustrated the current flow present in the diagonally related
members 9 and 10.
FIG. 4 illustrates the elevational antenna pattern resulting from
the electric field and current configuration as illustrated in FIG.
3.
FIG. 5 illustrates by the solid arrows the electric field
configuration when the antenna structure and, particularly, coaxial
lines 1 and 4 and coaxial lines 2 and 3 are excited in a balanced
relationship and these pairs are orthogonally excited through means
of quadrature hybrid 15 by the desired energy. The dotted arrows
illustrate the current flow present in diagonally related members 9
and 10 of FIG. 1.
FIG. 6 illustrates the elevational antenna pattern for the
circularly polarized portion of the antenna structure shown in
FIGS. 1 and 2.
The feed arrangement for the antenna structure of this invention as
shown in FIG. 1 used for both transmission and reception includes
two balanced hybrids 13 and 14 and a quadrature hybrid 15.
For transmission the feed arrangement operates as follows. The
energy to be transmitted with vertical polarization is applied to
port 16 and fed in common to the in-phase port of balanced hybrids
13 and 14. This results in an in-phase excitation of coaxial lines
1-4 as indicated by the (+) symbol applied to the ports of hybrids
13 and 14 connected to the center conductors of coaxial lines 1-4.
This inphase excitation of the coaxial lines 1-4 will result in the
figure-eight elevational antenna pattern provided by members 9 and
10 and disc 11.
The circular polarization pattern for transmission is
simultaneously provided by exciting port 17 of quadrature hybrid 15
with left-hand circularly polarized signal and port 18 of
quadrature hybrid 15 with right-hand circularly polarized signal.
This results in a 0.degree. phase shift for left-hand circularly
polarized signal (a 90.degree. phase shift for right-hand
circularly polarized signal) at port 21 of hybrid 15 which is
coupled to the balanced port of hybrid 13 and produces a 0.degree.
phase shift for left-hand circularly polarized signal (a
+90.degree. phase shift for right-hand circularly polarized signal)
for excitation of transmission line 4 and a 180.degree. phase shift
for left-hand circularly polarized signal (a -90.degree. phase
shift for right-hand circularly polarized signal) for excitation of
transmission line 1. Simultaneously, the energy applied to ports 17
and 18 is coupled from port 22 of hybrid 15 to the balanced port of
hybrid 14 resulting in a +90.degree. phase shift for left-hand
circularly polarized signal (a 0.degree. phase shift for right-hand
circularly polarized signal) for excitation of transmission line 3
and a -90.degree. phase shift for left-hand circularly polarized
signal (a 180.degree. phase shift for right-hand circularly
polarized signal) for excitation of transmission line 2. The
resultant excitation of coaxial lines 1-4 with different balanced
and orthogonal energy results in a circularly polarized signal
radiated from the antenna structure including members 9 and 10.
When the antenna structure of FIG. 1 is employed for receiving
left- and right-hand circularly polarized energy members 9 and 10
cause coaxial transmission lines 1-4 to be excited balanced and
in-phase quadrature and excite the ports of hybrids 13 and 14
identified as the 0.degree. (+90), 180.degree. (-90.degree.),
+90.degree. (0.degree.) and -90.degree. (180.degree.) ports. There
then will result at the output of ports 17 and 18, an output signal
transmitted by the circularly polarized signal. When the antenna
structure including members 9 and 10 and disc 11 receive vertically
polarized omnidirectional radiation, coaxial transmission lines 1-4
are excited by in-phase received signals as indicated by the (+)
ports of hybrids 13 and 14. The output from the in-phase ports of
hybrids 13 and 14 are coupled to port 16.
While we have described above the principles of our invention in
connection with specific apparatus, it is to be more clearly
understood that this description is made only by way of example and
not as a limitation to the scope of our invention as set forth in
the objects thereof and in the accompanying claims.
* * * * *