U.S. patent number 3,845,490 [Application Number 05/357,029] was granted by the patent office on 1974-10-29 for stripline slotted balun dipole antenna.
This patent grant is currently assigned to General Electric Company. Invention is credited to Thomas E. Manwarren, Kenneth J. Scott.
United States Patent |
3,845,490 |
Manwarren , et al. |
October 29, 1974 |
STRIPLINE SLOTTED BALUN DIPOLE ANTENNA
Abstract
A stripline slotted balun dipole antenna, suitable for use as a
single antenna or as an array antenna element, is fabricated from
two metal-clad dielectric sheets, from which metal has been removed
in predetermined patterns, and then the sheets are sandwiched
together to form both the slotted balun dipole antenna and its
stripline feed. The metal remaining on the exterior of the
laminated structure constitutes a slotted balun dipole and the
metal remaining between the dielectric sheets constitutes the
center conductor of the stripline feed. The structure obviates the
need for metallic connections in the antenna area.
Inventors: |
Manwarren; Thomas E. (Pulaski,
NY), Scott; Kenneth J. (Baldwinsville, NY) |
Assignee: |
General Electric Company
(Syracuse, NY)
|
Family
ID: |
23403996 |
Appl.
No.: |
05/357,029 |
Filed: |
May 3, 1973 |
Current U.S.
Class: |
343/821; 333/26;
343/822; 333/238; 343/853 |
Current CPC
Class: |
H01Q
21/08 (20130101); H01Q 9/065 (20130101); H01P
5/1007 (20130101); H01Q 9/16 (20130101) |
Current International
Class: |
H01P
5/10 (20060101); H01Q 21/08 (20060101); H01Q
9/06 (20060101); H01Q 9/04 (20060101); H01Q
9/16 (20060101); H01q 009/16 (); H01q 021/08 ();
H01p 003/08 () |
Field of
Search: |
;343/793-795,812-816,821,820,853,822 ;333/84M,26 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lawrence; James W.
Assistant Examiner: Nussbaum; Marvin
Attorney, Agent or Firm: Baker; Carl W. Neuhauser; Frank L.
Waddell; Oscar B.
Claims
What is claimed as new and desired to be secured by Letters Patent
of the
1. An integral antenna and transmission line structure comprising
two sheets of dielectric material each partially covered with a
skin of electrically conducting material arranged in predetermined
pattern, said sheets being joined together in a laminated
structure, said laminated structure having an antenna portion
proximate one edge, the remainder of said structure constituting a
transmission line portion, said skin on the sides of said sheets
which form the exterior of said structure substantially covering
said transmission line portion and on said antenna portion defining
a T-shaped antenna dipole with the crossbar of the T adjacent an
edge of said structure and the stem of the T extending from the
center of the crossbar to said transmission line portion of the
structure, each said T portion of skin being slotted from the
center of the crossbar into the stem to divide the dipole defined
thereby into two separate arms each having a separate pillar of the
stem of the T, said skin on the sides of said sheets which have
been joined interiorly of said laminated structure constituting the
center conductor in the transmission
2. The structure of claim 1 wherein said stripline antenna feed
extends within one pillar of the stem of said T to its arm and has
a leg extending from that point to the remote end of the opposite
arm of the T whereby electrical connection of line and antenna is
accomplished by means of a virtual short at the base of said other
arm and whereby said structure constitutes a dipole antenna
connected to an unbalanced line by means of a
3. A dipole antenna and transmission line structure comprising:
a. two identically shaped exterior members of electrically
conducting material placed in spaced parallel overlapping
registering relationship; said members being T-shaped and slotted
from the exterior center of their cross bars to a point in their
stems to separate each said cross bar into distinct dipoles and to
cause both said members in cooperation to define a slotted balun
dipole antenna; the base of said stems beyond said slot
constituting one conductor of a transmission line;
b. an L-shaped antenna feed line piece of electrically conducting
material spaced intermediate said two members with its stem portion
parallel to the stem portions of said members to one side of the
slots and with its foot parallel to said cross bars extending from
one side of said slots to the remote end of the dipoles on the
opposite side of said slots, the base of said stem constituting a
second conductor of said transmission line; and
c. a dielectric material separating said piece from said members
whereby said piece and said members constitute an integral slotted
balun dipole
4. The dipole antenna and transmission line structure of claim 3
further comprising at least one additional set of members and piece
in a common plane with the first set with their stems parallel to
the first and with said foot and said cross bars in tandem with
those of said first set and having the bases of said stems
electrically connected in parallel to form
5. An integral antenna and transmission line structure comprising a
thin slab of dielectric material having two sides and a plurality
of edges; a sheet of electrically conducting material appliqued to
each side of said slab substantially coextensive with said slab
except for a border along one said edge, said sheets within said
border only partially covering said slab and defining a T-shaped
slotted balun dipole antenna with its radiator along said one edge
and its stem extending across said border; and a stratum of
electrically conducting material embedded in said slab generally
parallel with and electrically insulated from said sheets whereby
said stratum and sheets form a transmission line, said stratum
inside said border comprising an L-shaped conductor extending into
said antenna within one side of said stem and thence to the remote
end of the
6. The structure of claim 5 wherein there are a plurality of said
antennas
7. An integral antenna and transmission line structure comprising a
slab of dielectric material of substantial length and width when
compared with its thickness to cause said slab to have two sides
and a plurality of edges; a sheet of electrically conducting
material adhered to each side of said slab substantially
coextensive with said slab except for a border along one said edge,
said border constituting the antenna portion and the remainder
constituting the transmission line portion of said structure, said
sheets within said border only partially covering said slab and
defining a T-shaped slotted dipole antenna having a crossbar
portion contiguous to said edge and a stem portion connecting
between said crossbar and said sheet in said line portion, each
said crossbar and stem being slotted centrally from said one edge
toward the base of said stem to divide said T-shaped antenna into
two identical but reversed L-shaped portions; and an electrical
conductor embedded in said slab, said conductor constituting the
central conductor of the transmission line and extending into the
antenna portion of said structure between the stem portions of the
L portions on one side of said slot to near said edge and further
extending parallel to said edge across said dipole slot and
terminating at the remote end of the antenna whereby said structure
constitutes a dipole antenna connected to an unbalanced line by
means of a
8. The structure of claim 7 wherein said central conductor within
said
9. The structure of claim 8 wherein there are a plurality of
T-shaped antennas in said antenna portion and wherein said
stripline has a branch for each said antenna.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention pertains to microwave dipole antennas of a type
identified as "slot fed" and the means for connecting such antenna
to a transmission line generally referred to as stripline.
2. Description of the Prior Art
Slot fed dipole antennas have been constructed using various
techniques as, for example, weldments fabricated from tubing or rod
or in the form of castings. In addition, slot fed dipoles have been
used in phased array antennas using many different construction
techniques and in some instances in combination with stripline feed
systems. U.S. Pat. Nos. 3,056,925 Borck et al. and 3,496,566 Walter
et al. are examples of previous dipoles. Borck feeds a dipole by
means of a parallel conductor cable running through a dielectric
support structure. Walter discloses a dipole with associated baluns
made of hollow tubing through which is run a coaxial cable to the
dipole portion of the antenna where the conductors are individually
fastened to portions of the dipole structure. U.S. Pat. Nos.
3,518,579 to Hoffman and 3,573,831 to Forbes show the use of
microstrip structures as an antenna feed line. All of these
structures to some extent require individual spot connections of
conductors which require a degree of specialized labor in their
construction and in varying degrees these patents disclose the fact
that certain types of structural weaknesses have been almost
inherent in the art.
SUMMARY OF THE INVENTION
A principal object of this invention is to provide an integral
microwave dipole antenna and stripline feed which will be durable,
rugged and simple to construct. The structure is as readily
adaptable to use in arrays as to use as a single antenna. The
structure can be fabricated without the necessity for the physical
interconnection of electrical conductors which in other
constructions require a plurality of solder joints, brazes or
welds. Structural rigidity, particularly in arrays constructed
according to this invention, is provided by the fact that an entire
row of axially aligned dipoles is most easily fabricated in the
form of a single slab of fairly rigid material. Elimination of the
many electrical connections has been made possible by use of a
feeding arrangement which establishes a virtual short to the feed
center conductor at the base of one dipole arm at the edge of the
slot so that no actual physical connection is needed to permit the
current to excite the dipole. Similarly, the structure provides for
the connection of the unbalanced transmission line to the balanced
dipole without the use of solder joints, brazing, welding or
bolting.
Briefly, in accordance with this invention, there is a sheet of
dielectric material of which one edge defines the position of one
or the alignment of a plurality of dipole antennas. The antenna and
outer conductor of the transmission line are in the form of a
shaped metallic partial skin on each side of the dielectric sheet
with each antenna being a T-shape portion of skin adjacent to the
edge of the sheet and having the stem of each T extending away from
that edge to join to a portion of the metallic skin covering the
entire sheet except for the band proximate to the edge of the
dielectric sheet. Each T is slotted to separate the antenna into
two quarter wave radiating arms and to cause the legs of the T to
constitute a slotted balun connected to the dipole. The metal skins
remaining on the two sides of the sheet in identical configuration
are joined electrically at the base of the transmission line
portion of the sheet to constitute one side of the transmission
line. The other side of the transmission line is in the form of a
metallic conductor embedded in the dielectric sheet between the two
T shape sections. It is a conductor of finite dimensions running
off center and toward the propagating edge of the sheet between the
two parallel metallic skin portions of the leg of the T shape
portion to the intersection of balun and dipole and thence to
terminate one quarter wavelength from the center of the dipole
arms. This invention also contemplates the construction of such an
integral transmission line and antenna from prefabricated
dielectric sheets clad on both sides with a metal skin as for
example copper. The metal skin is partially removed from two clad
sheets to form the dipole and the sheets laminated together to form
the desired structure.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a partial planar view of an antenna array constructed
according to the invention showing a plurality of the individual
slotted balun dipole antennas;
FIG. 2 is a cross section of a portion of the antenna construction
taken along line 2--2 of FIG. 1;
FIG. 3 is a perspective view of a single dipole antenna according
to the invention;
FIG. 4 is an exploded view of a single dipole antenna according to
this invention which in part illustrates a preferred method of
construction of the invention;
FIG. 5 is an enlarged planar view of a single dipole antenna taken
from the antenna array of FIG. 1; and
FIG. 6 is a partial section of the antenna taken along the line 6-6
of FIG. 5.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment of this invention as illustrated in FIG. 1
constitutes an antenna array although the invention is also
suitable for implementation in single dipole constructions. FIG. 1
illustrates a portion of the radiating edge of an antenna array in
which there are a plurality of dipoles along the edge of the
structure excited from a single input line 31. The antenna
structure 1 is made up of two sheets of dielectric material 10 and
11 which are large sheets of a fairly rigid dielectric material
pre-clad with metallic copper or other electrically conducting
sheets 12 and 14. This structure is most easily fabricated from two
individual sheets 10 and 11, with 10 being pre-clad on both sides
and 11 clad on one side with sheets 12 and 14 from which portions
of the sheet have been cut away to leave dipoles 2 and striplines
3. By cutting away the electrically conducting sheets on each of
the two sheets of dielectric in mirror image fashion to form the
dipoles, and with the center conductor 3 being formed on the double
clad dielectric sheet, the two sheets can be laminated together so
that the total laminated antenna structure 1 includes the interior
striplines 3 and the dipole structures which are portions of the
electrically conducting sheets 12 and 14 comprising the exterior of
the laminated structure.
Each of the dipoles 2 is comprised of a T-shaped portion 20 of the
exterior electrical conducting sheets 12 and 14 of the laminated
structure. Each T-shaped antenna portion includes a dipole 21 and a
slotted balun 22. In addition, each antenna segment has been
partially separated by a slot 23 extending from the exterior center
of the dipole into the stem portion of the T. This slot defines the
balun and serves to isolate the dipole arms and to separate a
portion of the stem 22 into two stem portions 24 and 25. In each
instance, the dipole and the balun portions when functioning as an
antenna include the corresponding portion of the metallic sheet on
both exterior surfaces of the laminated structure. Each of the
dipoles has an edge contiguous with the edge of the dielectric
sheets so that the exterior edge in question can be referred to as
the radiating edge of the array. The dipole arms should have a
total length of one-half wavelength and the height of the T is on
the order of one-quarter wavelength. The end of the copper strip 33
is electrically one-quarter wavelength from slot 23, and is open
circuited at point A. It therefore reflects a short circuit between
the center conductor and the dipole arms at point B; thus, in
effect connecting the strip line center conductor to one side of
the dipole. The balun slot 23 presents a high impedance between the
dipole arms enabling a balanced potential difference to be applied
between the dipole arms.
Details of the construction to which this structure lends itself
will be more evident by reference to FIGS. 2, 3 and 4 wherein the
exploded view of FIG. 4 indicates the positional registry of the
dipoles on the two exterior surfaces of the laminated structure. It
is most obvious from these figures that the process of removal of
portions of the clad material permit construction without the
necessity of soldering, brazing, welding, or bolting of
electrically conducting materials. It is this feature that provides
minimum fabrication labor cost and eliminates all problems
concerning the physical joining of transmission line to radiator
which has been common to previous structures.
It is also possible, of course, to apply the present invention to
microstrip construction merely by the elimination of the
electrically conducting skin from one exterior surface of the
laminated antenna structure. It is also obvious that structures
according to the invention and generally in the configuration
accomplished by the Applicants and as illustrated in the drawings
might be produced by other methods of manufacture as for example,
molding. The configuration of the device makes the preferred simple
fabrication process possible which is to say that the particular
concept of the invention makes possible construction of antennas by
means of processes which are considerably less expensive,
particularly in the terms of labor hours, than was true of the
prior art. It is also obvious to those familiar with the microwave
art that the stripline center conductor may, after crossing the
slotted balun, be bent toward the base of the balun rather than
parallel to the dipole without interfering with the general
operation, and that moderate changes in the dipole, slot and other
dimensions may be incorporated without varying from the basic
configuration. Furthermore, the stripline feed 31 may have
quarter-wave transformers or other impedance matching devices
distributed throughout.
A further embodiment of the antenna invention is also possible
through use of air as the dielectric medium. In that configuration,
the metallic conductors would be thicker and nearly
self-supporting, requiring dielectric and metallic separators at
only appropriate positions throughout the feed line and in the
dipole-balun region.
Another embodiment of the structure is possible by stacking a
number of the above described rows of dipoles either horizontally
or vertically to form a planar array of dipoles.
* * * * *