Single Slot Cavity Antenna Assembly

Abstract

A thin flexible wrap-around antenna assembly, particularly suitable for use in conjunction with a propelled vehicle such as a missile, is disclosed and generally includes a first or inner cylindrical thin conductor that can be flush-mounted on the skin of the propelled vehicle and a second concentrically positioned outer cylindrical thin conductor having an axial length which is equal to one-quarter wavelength at the anticipated operating frequency of the antenna. The conductors are electrically connected at adjacent transverse edges so as to define a one-quarter wavelength open-ended coaxial cavity which is connected to a transmitter or receiver by a combination electrical signal feed and impedance matching assembly.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to antennas and more particularly to an improved single slot cavity antenna assembly.

2. Description of the Prior Art

The use of antenna assemblies for both transmission and reception of radio signals is well known, and such antenna assemblies have taken many diverse dimensions and/or shapes to accomplish given objectives. Among such antennas known in the art are those useful in conjunction with propelled vehicles including missiles and more particularly missiles which carry instrument payloads for short term measurement of very high altitude environmental data, which data is transmitted from an antenna mounted on a missile to receiving stations on the ground, which stations are often ground tracking stations. However, monitoring has been found to be difficult due to signal nulls encountered as the vehicles assume different roll and aspect orientations.

Although the problem has been attacked in many ways, including the use of refined circuitry such as automatic gain control amplifiers which have to some effect alleviated the problem of antenna deficiencies, there still has been a need to improve the antennas so as to develop radiation patterns without signal lobes of varying strength. More particularly, the antenna should be characterized by an isotropic antenna radiation coverage, that is a pattern of constant relative power for any orientation of the antenna. As such, the pattern coverage is then relatively constant regardless of the roll or aspect orientation of the rocket, thereby facilitating data monitoring at a tracking station. The avoidance of signal nulls as a characteristic of the antenna eliminates an important deficiency that previously has caused temporary loss of signal information, and in the case of an unrecovered rocket, permanent loss thereof.

Although some previous attempts have been made to design antennas having patterns more nearly isotropic for use in rockets carrying environmental data sensors and associated instruments for telemetry purposes and the like, such antennas have not completely solved the problems in all cases due to one or more of such diverse reasons as failing to satisfy strict aerodynamic design requirements, exhibiting intolerable signal variations in the aspect patterns (the signal pattern measured about the missile in a plane containing the missile) and/or in the roll patterns (the signal pattern measured about the missile in a plane perpendicular to the missile axis), requiring complicated and often expensive components due to complex design requirements, and/or requiring excessive time and/or material in assembly so as to make antenna costs too high for at least some intended uses. For example, the aspect and roll radiation patterns in some antennas of recent design have been found to fluctuate as much as 30 db from isotropic radiation, while the required dimensions and/or costs inherent in other such antennas have made these antennas unusable, or at least undesirable, for many intended uses.

SUMMARY OF THE INVENTION

The present invention overcomes the aforementioned disadvantages, as well as other disadvantages, by providing an antenna which has an improved signal radiation pattern and which is both simple in design and economical to make. In addition, the antenna is particularly useful in airborne telemetry vehicles, which assume many orientations relative to any given tracking station, since it may be easily flush-mounted to the vehicle so as to provide a low profile and thereby avoid any substantial increase in air drag.

As will be seen hereinafter, a preferred embodiment of the antenna assembly according to the present invention generally comprises: first and second spaced-apart thin conductors; conductive means connecting a portion of the first conductor with a portion of the second conductor; electrical signal feed means, at least a part of which is constructed of thin ribbon-like conductive material, one portion of which terminates connected to said first conductor and a second portion of which terminates at a signal feed junction; and means for supporting said conductors and conductive material to thereby maintain the predetermined orientation therebetween. Constructed in this manner, the antenna not only exhibits an improved radiation pattern as will be seen hereinafter, but also is relatively simple in design and economical to produce.

Accordingly, an object of the present invention is to provide a new and improved antenna assembly having an improved signal radiation pattern.

Another object of the present invention is to provide a new and improved antenna assembly which is both simple in design and economical to manufacture.

Still another object of the present invention is to provide an antenna assembly having new and improved electrical signal feed means connected therewith.

A further object of the present invention is to provide an antenna of the last-mentioned type which has electrical signal feed means connected therewith requiring only one coaxial transmission line to be connected therewith.

Yet a further object of the present invention is to provide a new and improved antenna assembly integrally formed with an electrical signal feed assembly which is suitably dimensioned so as to simultaneously provide impedance matching to said antenna.

It is another object of the present invention to provide a new and improved thin flexible wrap-around antenna assembly which is readily adaptable for use with a propelled vehicle such as a missile.

Still another object of the present invention is to provide a new and improved cylindrical omnidirectional antenna having a reduced radiation pattern variation about the roll axis thereof.

Yet another object of the invention is to provide a new and improved cylindrical omnidirectional antenna having a reduced radiation pattern variation about the aspect axis thereof.

These and other objects and advantages will become apparent to those skilled in the art from the following description of a preferred embodiment of the present invention as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is an enlarged perspective view of a missile utilizing a wrap-around antenna assembly constructed in accordance with the present invention;

FIG. 2 is an enlarged perspective view of the antenna assembly separated from the missile of FIG. 1;

FIG. 3 is a cross-sectional view taken generally along line 3--3 in FIG. 2;

FIG. 4 is a partially broken-away enlarged sectional view taken generally along line 4--4 in FIG. 3;

FIG. 5 is an enlarged flattened-out view of the antenna assembly illustrated in FIG. 2, specifically displaying a portion of the electrical signal feed assembly used therewith; and

FIG. 6 is a graphic representation showing an experimental antenna gain radiation pattern utilizing the antenna of FIG. 2 mounted to the outer surface of the missile as illustrated in FIG. 1.

DETAILED DESCRIPTION

Turning now to the drawings, wherein like components are designated by like reference numerals throughout the various figures, a wrap-around antenna assembly 10, constructed in accordance with the present invention, is shown in FIG. 1 flush-mounted to a missile 12 having a metallic outer cylindrical body or skin 14 and a nose portion 15. As will be seen hereinafter, antenna assembly 10 is characterized by an isotropic antenna radiation coverage, that is, an omnidirectional pattern of constant relative power for any orientation of the antenna. As such, the pattern coverage is then relatively constant regardless of the roll or aspect orientation of missile 12 thereby facilitating data monitoring at a tracking station. For purposes of description, the antenna will be considered as a transmitting device, it being readily apparent to those skilled in the art that the same may be used for reception purposes also.

Turning to FIGS. 2 through 5, antenna assembly 10 is shown to include a thin inner cylindrical conductor 18, which is preferably constructed of copper. The conductor is adapted for flush mounting directly to and about the skin 14 of missile 12, as illustrated in FIG. 1, and thereby provides, in effect, a ground plane having an axial length equal to that of the missile. Antenna 10 further includes a second or outer cylindrical conductor 20, which is also preferably constructed of copper, and which has an axial length equal to or substantially equal to one-quarter wavelength at the anticipated operating frequency of the antenna. Conductor 20 is positioned concentrically about one end portion of conductor 18 and is radially spaced therefrom so as to define a one-quarter wavelength coaxial cavity 22, as illustrated best in FIG. 4.

While cavity 22 may be left void of material, for ease of construction a dielectric layer 24, preferably polytetrafluoroethylene (commercially available Teflon), and particularly Teflon-fiberglass, is positioned between and supports conductors 18 and 20. In this regard, it is to be noted that the actual length of coaxial cavity 22 must be corrected for the impedance producing effect of the dielectric layer. This may be accomplished by resorting to the relationship of effective wavelength .lambda..sub.c as a function of actual wavelength .lambda. , which relationship is:

.lambda..sub.c = .lambda./.sqroot..epsilon..sub.R

Wherein .lambda..sub.c is the corrected wavelength in a cavity filled with dielectric material, .lambda. is the actual wavelength in a cavity void of material and .epsilon..sub.R is the dielectric constant of the cavity filled material. By utilizing the above stated equation, the length of cavity 22 easily can be corrected so as to be "effectively" one-quarter wavelength. However, for purposes of clarity, only the term "one-quarter wavelength cavity" will be used hereinafter, it being understood that when the cavity is filled with dielectric material, such as material 24, an effective one-quarter wavelength cavity is contemplated.

Thus, for operation at a carrier frequency of, for example, 2.2 GHz and utilizing a dielectric such as polymerized tetrafluoroethylene, .lambda. is approximately equal to 5.4 inches and .epsilon..sub.R is approximately 2.5. Solving the aforestated equation yields a .lambda..sub.c of approximately 3.4 inches. Therefore, the effective one-quarter wavelength cavity of this example is slightly less than 1 inch in length.

Returning to FIG. 2, it can be seen that the entire left-hand transverse edge of inner conductor 18 is electrically shorted to the entire adjacent transverse edge of outer conductor 20. This can be accomplished in any suitable manner such as, for example, by the utilization of soldering material 26. In this way, the one-quarter wavelength coaxial cavity may be defined as a continuous open-ended cavity electrically shorted at one end, that is, at the soldering end 26, and having an open circuit defining a circumferential slot 28 a distance one-quarter wavelength therefrom.

Cavity 22 may be excited by signal energy produced at a source 30, as seen in FIG. 3, which may be located within missile 12 and which may be of conventional type such as, for example, a unit having an appropriate power source and radio frequency oscillator modulated in accordance with data signals from external environmental sensor devices. In this regard, an electrical signal feed assembly 32, operating in the TEM mode, is provided for coupling source 30 to inner and outer conductors 18 and 20.

Feed assembly 32 includes a coaxial transmission line 34 having outer and inner conductive cables 36 and 38 extending from within source 30 where they are connected to the appropriate components. The otherwise free end of outer conductive cable 36 is electrically connected to inner conductor 18 while the otherwise free end of inner conductive cable 38 is connected to the input of a combination multiple feed and impedance-matching network or assembly 40, which is a feature of the present invention and part of assembly 32 and which is to be described hereinafter.

The connections of the outer and inner conductive cables of transmission line 34 with conductor 18 and assembly 40, respectively, may be accomplished in any suitable manner, so long as the inner conductive cable is appropriately insulated from inner conductor 18. In this regard, a jack assembly, illustrated in FIG. 3, is provided and generally comprises an externally threaded female connector 42 having an integral shoulder 44 suitably mounted to the inner surface of conductor 18 and an internal insulating sleeve 46, the opening of which is axially aligned with an aperture 48 provided radially through antenna 10. Female connector 42 is adapted to receive a cooperating internally threaded male connector 50 mounted to the otherwise free end of conductive cable 36, as illustrated in FIG. 3. In this manner, the last-mentioned conductive cable is electrically connected to inner conductor 18. The inner conductive cable 38 of coaxial transmission line 34 is positioned through insulating sleeve 46 and aligned aperture 48 for connection to combination multiple feed and impedance-matching network 40.

Turning to FIG. 5, attention is directed to the combination multiple feed and impedance-matching network 40 which is supported on the exposed side of dielectric layer 24 and which comprises a plurality of thin ribbon-like leads constructed preferably of and displaying the same thinness as outer cylindrical conductor 20. In this regard, it has been found that the most favorable radiation patterns emanating from slot 28 of cavity 22 are developed when the cavity is excited in the TEM mode with a plurality of signals of uniform phase and amplitude provided at feed points generally designated by the reference numeral 53. These feed points are separated about the periphery of the slot 28 (on outer conductor 20) at intervals equal to or substantially equal to one wavelength (as corrected for the dielectric material 24 in cavity 22) at the aforestated anticipated operating frequency. Accordingly, assembly 40 includes a first plurality of leads 52, common ends of which are preferably integrally formed with, but in any case terminated at feed points 53.

Assembly 40 further includes a plurality of T-shaped leads 54, two of which are shown in FIG. 5, a third plurality of leads 56 and an input lead 58, all of which combine to connect the first plurality of leads 52 to the inner conductive cable 38 of coaxial transmission line 34 at a signal feed junction designated by the reference numeral 59. As illustrated in FIG. 5, the head of each T-shaped lead connects a pair of adjacent leads 52 while the leads 56 substantially form a partial band around dielectric layer 24 connecting the base of each T-shaped lead to input lead 58. In this regard, it is to be noted that dielectrical layer 24 maintains the predetermined orientation between the aforestated leads as well as the inner and outer conductor.

Leads 52, 54, 56, and 58 are suitably dimensioned (length, width and thickness) so as to provide continuous impedance-matching between coaxial transmission line 34 and open-ended cavity 22. With the impedance of coaxial transmission line 34 being appropriately chosen so as to match the impedance of source 30, it is readily apparent that there is substantially a perfect impedance match between the source and antenna 10 which, of course, provides for a more efficient antenna. In addition, the distance between input 58 or signal feed junction 59 and each feed point 53 is equal. In this manner, combination multiple feed and impedance-matching assembly 40 separates the input signal from coaxial transmission line 34 into a plurality of equal phase and amplitude signals and transfers the same to feed points 53 for exciting cavity 22 in the most favorable manner possible.

While assembly 40 is formed in the manner illustrated in FIG. 5 and includes four paths to conductor 20, it is to be understood that the invention, as contemplated, is not limited thereto. For example, there may be any number of feed points and paths depending upon the circumference of conductor 20. Accordingly, the paths between input 58 and feed points 53 may take on various dimensions and designs so long as the aforedescribed impedance matching and input signal separation functions are preserved. In this regard, the latter function is assured if the paths are of equal distances.

With antenna device 10 constructed in the aforedescribed manner, attention is now directed to a preferred method of making the same. As stated above, inner and outer cylindrical conductors 18 and 20 are preferably constructed of copper. More specifically, these conductors are preferably parts of a sheet of microstrip, that is, copper-clad layers supported by and on opposite sides of a sheet of dielectric material such as polytetrafluoro ethylene (commercially available Teflon), the dielectric sheet being dielectric material 24 illustrated in FIG. 2.

The method of making antenna 10 utilizing the aforedescribed sheet of microstrip includes the step of removing various portions of one of the copper-cladded layers from the intermediate dielectric insulating sheet so as to provide an integral configuration including outer conductor 20 and combination multiple feed and impedance matching network 40. This may be accomplished in any suitable manner, but is most preferably accomplished by resorting to conventional printed circuitboard techniques, that is, by photo-etching processes. Thereafter, adjacent transverse edges of the copper-cladded layers are electrically connected together such as, for example, by the utilization of solder 26 illustrated in FIG. 2, and aperture 48 is provided through the laminated material at the input or signal feed junction of network 40. A suitable jack assembly of the type described above, is then soldered or otherwise suitably mounted over the aperture and to the non-etched conductive layer in the manner illustrated in FIG. 3.

If the antenna assembly is to be used in the manner shown in FIG. 1, that is, as a wrap-around or cylindrical flush-mounted antenna, the longitudinal edges of the microstrip or laminated material are suitably connected together by any suitable means such as apertures 61 provided through opposite ends of the material as illustrated in FIG. 5. In this regard, construction of antenna device 10 is facilitated by connecting only the lengthwise edges of the intermediate dielectric layer 24 as illustrated by gaps 60 and 62 representing the unconnected lengthwise edges of inner and outer conductors 18 and 20, respectively. So long as these gaps are small relative to the operating wavelength of the antenna, they may be neglected as having no substantial effect on either the antenna impedance or radiation pattern. In this regard, the longitudinal edges of the laminated material may be connected together after the antenna assembly is wrapped around the body of the propelled vehicle or they may be initially connected together whereupon the assembly is then slid over and about the vehicle's body.

Having described the manner in which antenna assembly 10 is constructed, attention is now directed to the manner in which it operates in combination with missile 12, that is, with the inner cylindrical conductor 18 being flush mounted to and about missile skin 14 as illustrated in FIG. 1. As stated above, open-ended coaxial cavity 22 is excited in the TEM mode by a plurality of equal phase and amplitude signals (preferably radio frequency signals) originating from a source, such as source 30, mounted within the missile. Cavity 22, which is defined by one-quarter wavelength outer conductor 20 and inner conductor 18, has an impedance characteristic of effectively a one-quarter wavelength coaxial transmission line which is short-circuited at the end opposite feed points 53 by solder connection 26, the impedance characteristic being matched to that of source 30 by network 40.

In the case where the operating wavelength of antenna device 10 is much less than the circumference of missile 12, the cylindrical conductor 20 and the missile skin 14 (along with flush-mounted inner conductor 18) form a "fat" asymmetric dipole. Specifically, it has been found that the antenna of the present invention operates better as frequency increases and operates particularly well at frequencies within the VHF, UHF and microwave bands generally, and at the aforestated frequency of 2.2 GHz. In this regard, reference is made to a pending application of Robert E. Munson, Ser. No. 787,912, filed Dec. 30, 1968, which discloses a cavity antenna similar in operation to the present invention, but which structurally is entirely different. It should be apparent that the short circuit 26 at the forward end of cavity 22, as illustrated in FIG. 2, presents a negligible impedance which effectively transforms back as an open circuit at feed points 53 circumscribing antenna slot 28 or one-quarter wavelength from the short circuited end. The apparent open circuit is effectively in parallel with the radiation impedance of the "fat" asymmetrical dipole. Since the antenna 10 has a large diameter in terms of wavelength, the impedance across the asymmetrical dipole is real and divides between the feed points.

As stated above, FIG. 3 represents a broken-away sectional view of antenna assembly 10 illustrated in FIG. 2. Assuming the antenna is mounted to missile 12 in the manner shown in FIG. 1, dashed lines 64 illustrate the signal energy emanating from slot 28 and more particularly the approximate instantaneous direction of the electric field existing between conductor 20 and missile skin 14 making up the asymmetrical dipole. The direction of the field is reversed (not shown) at every half-wavelength from the rearward end of the cavity 22 in both the fore and aft directions of the missile since the polarity of cylindrical conductor 20 relative to the aft portion of skin 14 is constantly changing in accordance with the frequency of the oscillatory feed signal.

Referring to FIG. 6, an aspect radiation pattern developed by antenna assembly 10 utilized in the manner illustrated in FIG. 1 is shown wherein the axis of the missile was positioned substantially within the plane containing the pattern and wherein the assembly was operated at a frequency of 2.2 GHz. It is to be understood that this particular frequency is provided for illustrative purposes only and is not intended to limit the invention, the assembly operating equally well at other desired frequencies.

The pattern, representing the antenna gain relative to linear isotropic radiation, is substantially representative within one db of the infinite number of aspect radiation patterns which may be utilized to define a figure of revolution about the missile axis. More particularly, the radiation pattern of FIG. 6 is substantially representative of the pattern contained in any plane defining a cross-section through the figure of revolution produced by all aspect patterns containing the axis of the missile.

It readily may be appreciated that deep nulls exist only directly forwardly (0.degree.) and rearwardly (180.degree.) of the missile, that is, at the tip and tail thereof. As is well known, tip and tail pattern nulls in a telemetry missile are usually of little concern. As can also be seen from FIG. 6, the remainder of the signal pattern displays an average strength variation between signal peaks and nulls in the aspect plane of less that 5 db. Thus, the improved antenna device is highly favorable for receipt or transmission of electromagnetic signal energy to or from the missile without any appreciable loss in signal due to the vehicle orientation.

It is to be understood that while antenna assembly 10 has been described both operationally and in construction as a cylindrical flush mountable type antenna displaying an omnidirectional radiation pattern, the invention is not limited thereto. Specifically, antenna device 10 may be substantially flat or only partially curved so as to provide a more directional radiation pattern while retaining the various advantagous features recited above. In addition, although only one embodiment of the invention has been shown and described, various modifications as may appear to those skilled in the art are intended to be within the contemplation of the invention as defined in the scope of the claims.

Claims

What is claimed is:

1. A thin flexible wrap-around antenna assembly comprising: a first thin conductor; a second thin conductor spaced from said first conductor; conductive means connecting an edge portion of said first conductor with an edge portion of said second conductor; electrical signal feed means, at least a part of which is constructed of thin ribbon-like conductive material, one portion of which terminates connected to said first conductor and a second portion of which terminates at a signal feed junction spaced from said first conductor; and means for supporting said conductors and conductive material to thereby maintain a predetermined orientation therebetween, said means for supporting said conductors and conductive material including nonconductive means therebetween, and said first and second conductors, said conductive material and said nonconductive means each comprising part of a single sheet of dielectric material metallically cladded on opposite sides thereof.

2. A thin flexible wrap-around antenna assembly comprising: a first thin conductor; a second thin conductor spaced from said first conductor; conductive means connecting a portion of said first conductor with a portion of said second conductor; electrical signal feed means, at least a part of which is constructed of thin ribbon-like conductive material, one portion of which includes a plurality of leads connected to said first conductor and spaced apart at intervals substantially equal to one wavelength at a predetermined operating frequency of said antenna, and a second portion of which terminates at a signal feed junction spaced from said first conductor; and means for supporting said conductors and conductive material to thereby maintain a predetermined orientation therebetween.

3. A thin flexible wrap-around antenna assembly comprising: a first thin conductor; a second thin conductor spaced from said first conductor; conductive means connecting a portion of said first conductor with a portion of said second conductor; electrical signal feed means, at least a part of which is constructed of thin ribbon-like conductive material, one portion of which includes a plurality of leads connected to said first conductor and suitably dimensioned so as to transfer a plurality of substantially equal phase and amplitude signals to said first conductor and a second portion of which terminates at a signal feed junction spaced from said first conductor; and means for supporting said conductors and conductive material to thereby maintain a predetermined orientation therebetween.

4. A thin flexible wrap-around antenna assembly comprising: a thin conductor; electrical signal feed means, at least a part of which is constructed of thin ribbon-like conductive material, said electrical signal feed means including a plurality of leads one portion of each of which terminates connected to said conductor with said conductor connections being spaced apart at intervals substantially equal to one wavelength at a predetermined frequency of said antenna, and a second portion of each of which is connected with a signal feed junction, said conductive material being suitably dimensioned so as to provide impedance matching at the points of connection with said conductor; and means for supporting said conductor and conductive material to thereby maintain the predetermined orientation therebetween.

5. A thin flexible assembly adapted for use as a wrap-around antenna, said assembly comprising: a first thin cylindrical conductor the diameter of which is equal to a predetermined value; a second thin cylindrical conductor the diameter of which is equal to a value less than said predetermined value, said second conductor being positioned concentrically within said first conductor; conductive means connecting a portion of said first conductor with a portion of said second conductor; electrical signal feed means including a plurality of leads which terminate connected to said first conductor and which are spaced apart at intervals substantially equal to one wavelength at a predetermined operating frequency of said antenna, said leads being constructed of thin ribbon-like conductive material; and means for supporting said conductors and said leads to thereby maintain the predetermined orientation therebetween.

6. A thin flexible wrap-around antenna assembly comprising: a first cylindrical conductor the axial length of which is substantially equal to one-quarter wavelength at a predetermined operating frequency of said antenna; a second cylindrical conductor concentrically positioned within and radially spaced from said first conductor; conductive means connecting one transverse edge of said first conductor with an adjacent transverse edge of said second conductor so as to form a one-quarter wavelength open-ended coaxial cavity therebetween; electrical signal feed and impedance matching means including a plurality of leads terminating at and to said first conductor and circumferentially spaced apart at intervals substantially equal to one-wavelength at said predetermined frequency, said leads being constructed of thin ribbon-like material integral with said first conductor and suitably dimensioned so as to provide impedance matching at the points of connection with said first conductor.

7. An antenna according to claim 6 wherein said electrical signal feed means further includes a coaxial transmission line, the outer conductive cable of which is connected to said second conductor and the inner conductive cable of which is connected to said plurality of leads at a predetermined point spaced from said points of connection with said first conductor.

8. An antenna according to claim 7 wherein said leads are further suitably dimensioned so as to transfer a plurality of substantially equal phase and amplitude signals to said first conductor.

9. An impedance-matched antenna assembly comprising: a first conductor; a second conductor spaced from said first conductor; conductive means connecting a portion of said first conductor with a portion of said second conductor; electrical signal feed means, said feed means including a first plurality of thin ribbon-like conductive leads which terminate connected to said first conductor and which are suitably dimensioned so as to provide impedance matching at the points of connection with said first conductor and a second plurality of thin ribbon-like leads which terminate connected to said first plurality of leads and which are suitably dimensioned so as to provide impedance matching at the points of connection with said first plurality of leads; and means supporting said conductors and said first and second pluralities of leads to thereby maintain the predetermined orientation therebetween.

10. An impedance-matched antenna assembly comprising: a first conductor; a second conductor spaced from said first conductor; conductive means connecting a portion of said first conductor with a portion of said second conductor; electrical signal feed means; said feed means including a first plurality of thin ribbon-like conductive leads which terminate connected to said first conductor and which are suitably dimensioned so as to provide impedance matching at the points of connection with said first conductor, a second plurality of thin ribbon-like conductive leads each of which is connected to a pair of said first plurality of leads and suitably dimensioned so as to provide impedance matching at the points of connection with said first leads and a third plurality of thin ribbon-like conductive leads connected to said second plurality of leads and to a signal feed junction, said third plurality of leads being suitably dimensioned so as to provide impedance matching at the points of connection with said second leads; and means supporting said conductors and said first, second and third plurality of leads to thereby maintain the predetermined orientation therebetween.

11. An antenna according to claim 10 wherein the distances between said signal feed junction and the points of connection of said first conductive leads to said first conductor are substantially equal whereby to transfer a plurality of substantially equal phase and amplitude signals to said first conductor.

12. A method of making an antenna for a propelled vehicle such as, for example, a missile; said method comprising the steps of: providing a thin flexible support sheet; providing a thin flexible conductive layer on said support sheet; providing a thin flexible impedance matched electrical signal feed assembly on said support sheet; connecting said impedance matched electrical signal feed assembly to said conductive layer at a plurality of points spaced from one another a predetermined distance; fixing said conductive layer and said electrical signal feed assembly to said support sheet to thereby maintain a predetermined orientation therebetween; and positioning said thin flexible support sheet, conductive layer and said impedance matched electrical feed assembly circumferentially about and to the body of said vehicle.

13. A method according to claim 12 wherein said last-mentioned step includes the steps of wrapping said sheet about the body of said vehicle and thereafter connecting opposite ends of said sheet together.

14. A method according to claim 12 wherein said last-mentioned step includes the steps of connecting opposite ends of said sheet together and sliding the same about the body of said vehicle.