MONOPOL WIRE HF ANTENNA, SYSTEM AND METHOD

Description

1 / 15 MONOPOL WIRE HF ANTENNA, SYSTEM AND METHOD BACKGROUND

[001] As is known in the art, monopole antennas can be used in a variety of applications. Some special monopoles, such as trapezoidal ring fractal monopoles, have bandwidths up to approximately 5:1 (2.2 to 10.8 GHz). Known monopoles may be limited by a planar design (such as microstrip), which is not practical for High Frequency (HF) applications that require monopoles to be tens of feet tall, as well as 16 to 35 feet (4.8 to 10.6 meters) tall. Some planar monopoles may require an electrically large vertical grounding plate (36 mm x 16 mm for 2.2-10.8 GHz), which is not feasible for HF array applications, which may require arrays on the order of 50 feet by 25 feet oriented horizontally under a vertically oriented monopole. Some planar monopoles may also be limited to single-element applications due to their large footprints, which prevent them from array applications.Furthermore, the use of distributed lumped elements, such as resistors, inductors, pin diodes, etc., in some monopole antennas, as well as antenna arrays, strategically positioned along the radiator to achieve broadband performance, reduces radiation efficiency, requires external DC biasing circuits, and increases costs. The loading of distributed lumped elements also limits high-power operation, for example, above 10 to 20 kW.

[002] Some known broadband antennas may have a wide-angle aperture with apex angles close to 85 degrees and are typically displacement wave antennas built on a radial ground screen to excite Transverse Electromagnetic Waves (TEM). Wide-angle aperture antennas Petition 870250105563, dated 11 / 18 / 2025, page 25 / 46 2 / 15 have such large footprints that they limit the ability to form either linear or 2D matrices without introducing grid lobes and increasing mutual coupling. SUMMARY

[003] Examples of disclosure embodiments provide methods and apparatus for multiple wire monopoles nested together to provide Ultra Wideband (UWB) RF performance for an HF antenna or HF array element. Example monopole antenna embodiments may provide extra resonant paths to partially fill monopole pattern nulls at higher frequencies. In some embodiments, a monopole antenna includes a small monopole that is clocked angle off from a large monopole. In some embodiments, a monopole antenna includes first and second monopoles aligned at clock angle and sharing part of their lower wires.

[004] Dissemination modalities include an HF antenna with nested wire monopoles to provide UWB RF performance covering 5 MHz to 45 MHz (9:1 bandwidth) for high power (up to 20 kW) in a narrow aperture using ground screen to provide image and not to excite TEM modes, which was never achieved.

[005] In one aspect, an antenna comprises: a first monopole having a first number of arms and an upper and a lower part, wherein the arms of the first monopole have curves; and a second monopole having a second number of arms, wherein the second monopole is at least partially nested within the first monopole.

[006] An antenna may also include one or more of the following features: the first monopole is offset by a clocking angle from the second monopole, the first and second monopoles Petition 870250105563, dated 11 / 18 / 2025, p. 26 / 46 3 / 15 are aligned at a clocking angle, the first and second number of arms is the same, the first number of arms is three, the second number of arms is between two and seven, the arms of the second monopole each have a curve, the respective curves form the first monopole in a diamond shape, the respective curves in the arms of the first monopole are located halfway up the antenna formed by the first and second monopoles, the curves in the arms of the first monopole define a width of the antenna, the antenna has a single feed for the first and second monopoles, a portion of the arms of the first monopole is shared by a portion of the arms of the second monopole, the arms of the first monopole have a diameter ranging from about 0.09 to 0.1λ, where λ is the wavelength of an average frequency of an operating band of the antenna, the antenna formed by the first and second monopoles does not include grouped elements.The antenna provides ultra-wideband performance covering more than 9:1 of bandwidth; the antenna is part of an over-the-horizon radar and / or low-band and high-band arrays formed from elements comprising nested first and second monopoles.

[007] In another aspect, a system comprises a means for radiating RF signals with first and second nested monopolar antennas.

[008] In a further aspect, a method comprises: radiating a signal with an antenna comprising nested first and second monopoles. A method may further include one or more of the following features: the first monopole is offset by clocking angle from the second monopole, the first and second monopoles are aligned by clocking angle, the first and second number of arms is the same, the first number of arms is three, the first number of arms is between two and seven, the arms of the second Petition 870250105563, dated 11 / 18 / 2025, p. 27 / 46 Each 4 / 15 monopole has a curve; the respective curves form the first monopole in a diamond shape. The respective curves on the arms of the first monopole are located halfway up the antenna formed by the first and second monopoles. The curves on the arms of the first monopole define the antenna's width. The antenna has a single feed for the first and second monopoles. A portion of the arms of the first monopole is shared by a portion of the arms of the second monopole. The arms of the first monopole have a diameter ranging from approximately 0.09 to 0.1λ, where λ is the wavelength of an average frequency of an operating band of the antenna. The antenna formed by the first and second monopoles does not include grouped elements. The antenna provides ultra-wideband performance covering more than 9:1 of bandwidth.The antenna is part of an over-the-horizon radar and / or low-band and high-band arrays formed from elements comprising nested first and second monopoles. BRIEF DESCRIPTION OF THE DRAWINGS

[009] The foregoing features of this invention, as well as the invention itself, can be more fully understood from the following description of the drawings in which: FIG. 1 shows an array of HF antennas from the prior art; FIG. 2 shows a duoconic monopole antenna of the prior art; FIG. 3A is a side view and FIG. 3B is a top view of a nested multiwire monopole antenna. FIG. 4A is a side view and FIG. 4B is a top view of a nested multiwire monopole antenna; FIG. 5A is a side view and FIG. 5B is a top view of a nested multiwire monopole antenna; Petition 870250105563, dated 11 / 18 / 2025, p. 28 / 46 5 / 15 FIG. 6A is a side view and FIG. 6B is a top view of a nested multiwire monopole antenna; FIG. 7 shows an example of performance for monopole antennas shown in FIG. 3, FIG. 4 and FIG. 5; FIG. 8A shows example dimensions for an illustrative monopole antenna; FIG. 8B shows a monopole antenna over a ground screen; and FIG. 9 is a schematic representation of an example of a two-row linear array having nested monopole antennas. DETAILED DESCRIPTION

[0010] Before describing examples of disclosure modalities in detail, some background information is provided. Monopole antennas refer to radio antennas that are typically straight conductors mounted on a conductive ground plane. Signals are transmitted and / or received along the length of the antenna. One side of the antenna feed line is connected to the lower end of the monopole and the other side is connected to the ground plane, with the ground plane situated on the Earth. Monopole antennas can operate as resonant antennas, where the antenna acts as a resonator for radio waves and oscillates with current waves traveling along its length, which corresponds to a wavelength of the transmitted and / or radio waves. A common antenna is called a quarter-wave monopole, which has a length of about one-quarter the wavelength of the operating radio waves.

[0011] Monopole antennas have an omnidirectional radiation pattern and radiate energy equally in all directions perpendicular to the antenna. A monopole radiates vertically polarized signals. The radiated energy varies with the elevation angle, with energy Petition 870250105563, dated 11 / 18 / 2025, p. 29 / 46 6 / 15 almost zero at the zenith. A monopole antenna situated on an infinite perfect electrical conductor (PEC) will have maximum energy very close to the horizon, while a monopole situated on a ground screen of finite size will have maximum energy at some elevation angle determined by the radius and conductivity of the ground screen.

[0012] FIG. 1 shows a prior art HF antenna array for an Over the Horizon (OTH) radar. A conventional OTH radar may have two separate transmission arrays, where the low-band array covers the lower half of the band and the high-band array covers the other half.

[0013] FIG. 2 shows a duoconical monopole antenna of the prior art of X.-L. Zhang et al: “An Optimum Design of Low-Profile Ultra-Wideband HF Skeletal Wire Duoconical Monopole Antenna with Parasitic Grounded Poles,” which is incorporated herein by reference.

[0014] FIG. 3A is a side view and FIG. 3B is a top view of a nested multiwire monopole antenna 300 according to example embodiments of the disclosure. The antenna 300 includes a first monopole 302 and a second monopole 304. In the illustrated embodiment, the second monopole 304 is nested within the first monopole 302. The first monopole 302 can be considered a large monopole and the second monopole 304 can be considered a small monopole.

[0015] It is understood that the nested monopole configuration requires analyzing interactions between each aperture to achieve broadband performance in the desired directions. Each monopole is analyzed separately, with the larger monopole designed for the lower frequency band and the smaller monopole designed for the higher frequency band. The antennas are then combined and tuned to remove resonances that occur near the overlap region of the two frequency bands. The optimization parameters Petition 870250105563, dated 11 / 18 / 2025, pp. 30 / 46 7 / 15 tuning includes determining the proper wire radius, determining ideal clock angles, and smoothing sharp corners to eliminate spark gaps and / or coronas.

[0016] In the illustrated embodiment, the first monopole 302 includes six equally spaced arms 306a-f extending from an upper part 308 of the antenna to a lower part 310. It should be noted that indicators for the UEV space are superimposed on the arms of the first and second monopoles 302, 304, as shown. Each of the arms 306 has a curve 312 extending a given radial distance from an axis 314 of the array. In the illustrated embodiment, the second monopole 304 includes six equally spaced arms 316a-f nested within the first monopole 302. Each of the arms 316 includes a curve 318. As can be seen, the arms 316 of the second monopole 304 are offset at the synchronization angle 318 of the arms 306 of the first monopole 302. The antenna is situated vertically above the ground.

[0017] FIG. 4A is a side view and FIG. 4B is a top view of a nested multiwire monopole antenna 400 according to example embodiments of the disclosure. In the illustrated embodiment, the antenna 400 includes a first monopole 402 and a second monopole 404. In the illustrated embodiment, the second monopole 404 is partially nested within the first monopole 402. The first monopole 402 has six equally spaced arms 406a-f and the second monopole 404 has six equally spaced arms 416a-f. As can be best seen in FIG. 4B, the arms 406a-f, 416a-f are aligned at a clocking angle so that they overlap in the vertical view.

[0018] In some embodiments, the respective arms 406, 416 of the first and second monopoles 402, 404 share the wire 407 of the respective curves 412, 418 up to the lower part 410 of the antenna. It must Petition 870250105563, dated 11 / 18 / 2025, p. 31 / 46 8 / 15 It should be noted that indicators for the uev space are shown for the first and second monopoles 402, 404, as shown.

[0019] FIG. 5A is a side view and FIG. 5B is a top view of a nested multiwire monopole antenna 500 according to example embodiments of the disclosure. In the illustrated embodiment, the antenna 500 includes a first monopole 502 and a second monopole 504 and a third monopole 505. In the illustrated embodiment, the second monopole 504 is partially nested within the first monopole 502, and the third monopole 505 is partially nested within the first and second monopoles. As can be seen, in the manner shown in FIGS. 3A and 3B, the first and second monopoles 502, 504 of the antenna 500 are offset by clocking angle and, in the manner shown in FIGS. 4A and 4B, the first and second monopoles 502, 504 share wires for arms 506, 516 of the monopoles.

[0020] FIG. 6A is a side view and FIG. 6B is a top view of a nested multiwire monopole antenna 600 according to example embodiments of the disclosure. In the illustrated embodiment, the antenna 600 includes a first monopole 602 and a second monopole 604, each with three equally spaced arms and a symmetrical clocking angle.

[0021] FIG. 7 shows an example of performance for the 300 monopole antenna of FIG. 3, the 400 monopole antenna of FIG. 4, the 500 monopole antenna of FIG. 5, and a conventional dual monopole antenna. As can be seen, the example nested monopole antennas 300, 400, and 500 provide ultra-wideband (UWB) RF performance for HF antennas and / or HF array elements. The 300 monopole (FIG. 3) provides a good balance between performance, complexity, and cost. The 400 monopole (FIG. 4) is simpler in construction than the 300 monopole but exhibits less gain and higher return loss. The 500 monopole (FIG. 5) has a wide bandwidth. Petition 870250105563, dated 11 / 18 / 2025, pp. 32 / 46 9 / 15 wider than monopoles 300 and 400, with added complexity.

[0022] Compared to conventional monopole antennas, example monopole modes provide additional resonant paths to partially fill monopole pattern nulls at higher frequencies. Example monopole modes provide ultra-wideband performance covering 5 to 45 MHz (9:1 bandwidth), which has never been achieved before.

[0023] Example embodiments of the disclosure provide an ultra-wideband HF antenna, a nested wire monopole having a diamond-shaped structure oriented perpendicular to the ground as well as perpendicular to the radial ground screen. The radial ground screen is located between the monopole and the ground and is oriented parallel to the ground. The polarization of the radiation is vertically electrical. The ground screen provides maximum directional gain at low elevation angles for radars above the horizon.

[0024] It is understood that any practical number of nested monopole antennas may be used. Although example embodiments show two nested monopoles, in other embodiments, three antennas are nested. Larger monopoles radiate closer to the lower end of the frequency band, while smaller (nested) antennas radiate closer to the upper end of the frequency band. Each of the nested antennas is designed separately and combined into an aperture with a single feed and further optimized to eliminate unwanted resonances.

[0025] It is understood that the monopole arms may comprise any suitable conductive material in any suitable shape. For example, monopole arms may be tubular, circular and / or square. In some embodiments, the diameter of the arms varies from about 0.09 - 0.1 λ based on the provision of stability. Petition 870250105563, dated 11 / 18 / 2025, pp. 33 / 46 10 / 15 structural without compromising performance, where λ is the wavelength corresponding to the average frequency of the operating band.

[0026] In some embodiments, smaller, nested antennas have the same number of arms as the larger antenna and may be staggered clockwise and symmetrically centered to fill the available space of the larger elements. In some embodiments, the curves of the arms, which define the width of the antenna, are located at or near the midpoint of the total height of the antenna. The intersection point of the arms is at the top and bottom of each radiator to form a junction that may be mounted as a pointed tip, a rounded cap, and / or grouped and fixed to a circular plate as a common connection platform. Electrical continuity must be maintained at this junction at all times. In some embodiments, the radial dimension of the circular plate should not exceed about 0.05 l, and the thickness of the plate should be greater than many skin depths.

[0027] In embodiments, the antenna has a single feed that feeds all the nested monopoles, located at the base. Balanced excitation is achieved with one connection made to the base and the other connection made to the radial ground screen, which is oriented parallel to the earth's surface. In one example embodiment, a feed may include a current balun with a 50 W coaxial cable input.

[0028] As an example, shown in FIGS. 8A (example dimensions) and 8B (ground-mounted and ground-mounted antenna), for HF applications between approximately 3 and 30 MHz (6:1 bandwidth) with three arms, the maximum antenna height is approximately 11 m, width approximately 7 m, and bend height approximately 5.5 m. The height of the nested inner monopole is approximately 7 m, the width approximately 2 m, and the bend height approximately 3.5 m. The wire diameter of Petition 870250105563, dated 11 / 18 / 2025, pp. 34 / 46 The 1 1 / 15 monopole is approximately 8 inches to allow for structural stability.

[0029] In example embodiments, the antenna is constructed using steel, aluminum, or similar electrically conductive materials with a suitable arm diameter, as described above. High-power applications up to about 20 kW are achieved with high efficiency, based on the thin layer depth of the material, where a layer depth is the depth of the metal thickness in which about 63% of the current flows. For arm diameters of about 0.09 - 0.1 λ, the material thickness is orders of magnitude thicker than a skin depth, therefore the radiation efficiency is high. In some embodiments, the antenna does not require distributed loads such as inductors, capacitors, or resistors, which reduce radiation efficiency at high power. High-power corona effects are minimized by eliminating sharp bends and sharp corners.

[0030] Wideband array applications (up to about 6:1) requiring high directional gain near the horizon (screen above ground), wide-angle scanning, and low mutual coupling may need to use two-dimensional (2D) arrays. Mixed narrowband spiral arrays, as well as nested ultrawide monopolar wire elements formed on a non-uniform spiral radius, have low grid lobes and low mutual coupling. Furthermore, spiral arrays with approximately constant unit cell size, arranged like the central structure of a sunflower plant, demonstrate very low grid lobes as well as very low mutual coupling. Rotational symmetry allows rotating the antenna with non-overlapping support cables to reduce mutual coupling for a fixed unit cell size.

[0031] Examples of ways of realizing a monopoly Petition 870250105563, dated 11 / 18 / 2025, pp. 35 / 46 12 / 15 antennas provide performance characteristics that have never been achieved before. For example, US Patent No. 6,608,598 to Mayes requires the use of strategically positioned concentrated elements (resistors, inductors, pin diodes, etc.) along the radiator to achieve broadband performance, which reduces radiation efficiency and requires external DC bias circuits.

[0032] In contrast, example modalities of an antenna Nested single-pole UWB systems do not require any grouped elements to achieve higher efficiency, and losses are based solely on the ohmic losses of the structure.

[0033] Furthermore, the distributed loading of concentrated elements in conventional arrays also limits high-power operation, where high power refers to up to 20 kW. The ability to form arrays for wide-aperture antennas that excite TEM modes is difficult, as the aperture angle expands to about 85 degrees and the unit cell size becomes too large.

[0034] FIG. 9 shows an example embodiment of a two-row linear array having nested monopole antennas according to illustrative embodiments of the disclosure. The two-row array may be suitable for OTH radar systems.

[0035] Various modalities of the concepts, systems, devices, structures, and techniques that are intended to be protected are described here with reference to the related drawings. It is possible to conceive of alternative modalities without departing from the scope of the concepts, systems, devices, structures, and techniques described here. Note that several connections and positional relationships (e.g., above, below, adjacent, etc.) are established between elements in the following description and in the drawings. These connections and / or positional relationships, unless Petition 870250105563, dated 11 / 18 / 2025, pages 36 / 46 13 / 15 as otherwise specified, can be direct or indirect, and the concepts, systems, devices, structures, and techniques described are not intended to be limiting in this respect. Therefore, an entity coupling can refer to a direct or indirect coupling, and a positional relationship between entities can be a direct or indirect positional relationship.

[0036] As an example of an indirect positional relationship, references in this description to the formation of layer A over layer B include situations in which one or more intermediate layers (e.g., layer C) are between layer A and layer B, provided that the relevant characteristics and functionalities of layer A and layer B are not substantially altered by the intermediate layer(s). The following definitions and abbreviations shall be used for the interpretation of the claims and the descriptive report. As used in this document, the terms includes, comprising, includes, including, has, having, contains or containing, or any other variation thereof, are intended to cover a non-exclusive inclusion.For example, a composition, a mixture, a process, a method, an article, or a device comprising a list of elements is not necessarily limited to those elements alone, but may include other elements not expressly listed or inherent to that composition, mixture, process, method, article, or device.

[0037] For the purposes of the following description, the terms top, bottom, right, left, vertical, horizontal, top, bottom and their derivatives shall refer to the structures and methods described, as directed in the figures of the drawings. The terms superimposed, on top, on top of, positioned on or positioned on top mean that a first element, such as a first structure, is present within a second element, such as a second structure, on Petition 870250105563, dated 11 / 18 / 2025, pp. 37 / 46 14 / 15 of intervening elements, such as an interface structure, may be present between the first element and the second element. The term direct contact means that a first element, as a first structure, and a second element, as a second structure, are connected without any intermediate conductive, insulating, or semiconducting layer at the interface of the two elements. It should be noted that the term selective for, such as, for example, a first element selective for a second element, means that the first element can be etched and the second element can act as an etching stop.

[0038] The use of ordinal terms such as first, second, third, etc., in claims to modify an element of the claim does not in itself denote any priority, precedence, or order of claim of one element over another or the temporal order in which the acts of a method are performed, but are used only as labels to distinguish an element of the claim with a given name from another element having the same name (except for use of the ordinal term) to distinguish the claimed elements.

[0039] The terms “approximately”, “substantially” and “about” mean within ±5% of a value, unless defined otherwise. For example, a first direction that is “substantially” perpendicular to a second direction refers to a first direction that is within ±5% of making a 90° angle with the second direction.

[0040] Having described exemplary embodiments of the invention, it will now become apparent to anyone with common knowledge of the art that other embodiments incorporating its concepts may also be used. The embodiments contained herein should not be limited to the embodiments disclosed, but rather should Petition 870250105563, dated 11 / 18 / 2025, pp. 38 / 46 15 / 15 being limited only by the spirit and scope of the appended claims. All publications and references cited in this document are incorporated by reference in their entirety.

[0041] Elements of different embodiments described herein may be combined to form other embodiments not specifically defined above. Several elements, which are described in the context of a single embodiment, may also be provided separately or in any suitable subcombination. Other embodiments not specifically described herein are also within the scope of the following claims. Petition 870250105563, dated 11 / 18 / 2025, pp. 39 / 46

Claims

1 / 3 CLAIMS 1. Antenna, characterized in that it comprises: a first monopole having a first number of arms and an upper and a lower part, wherein the arms of the first monopole have curves; and a second monopole having a second number of arms, wherein the second monopole has a height less than the height of the first monopole, and wherein the second monopole is at least partially nested within the first monopole.

2. Antenna, according to claim 1, characterized in that the first monopole is offset by a clocking angle from the second monopole.

3. Antenna, according to claim 1, characterized in that the first and second monopoles are aligned at a clocking angle.

4. Antenna, according to claim 1, characterized in that the first and second number of arms are the same.

5. Antenna, according to claim 1, characterized in that the first number of arms is three.

6. Antenna, according to claim 1, characterized in that the first number of arms is between two and seven.

7. Antenna, according to claim 1, characterized in that the arms of the second monopole have a curve.

8. Antenna, according to claim 7, characterized in that the curves in the arms of the first monopole form the first monopole into a diamond shape.

9. Antenna, according to claim 8, characterized in that the curves in the arms of the first monopole are located halfway up the antenna formed by the first and second monopoles.

10. Antenna, according to claim 9, characterized in that the curves in the arms of the first monopole define a width of the antenna.

11. Antenna, according to claim 1, characterized in that the antenna has a single feed for the first and second monopoles.

12. Antenna, according to claim 1, characterized in that portions of the arms of the first monopole are shared by portions of the arms of the second monopole.

13. Antenna, according to claim 1, characterized in that the arms of the first monopole have a diameter ranging from about 0.09 to 0.1λ, where λ is a wavelength of an average frequency of an operating band of the antenna.

14. Antenna, according to claim 1, characterized in that the antenna formed by the first and second monopoles does not include grouped elements.

15. Antenna, according to claim 1, characterized in that the antenna provides ultra-wideband performance covering more than 9:1 of bandwidth.

16. Antenna, according to claim 1, characterized in that the antenna forms part of an over-the-horizon radar.

17. Antenna, according to claim 16, characterized in that it further includes low-band and high-band arrays formed from elements comprising the first and second monopoles.

18. Antenna, according to claim 1, characterized in that it further comprises: a third monopole with a third number of arms, wherein the third monopole has a height less than the height of the second monopole and wherein the third monopole is at least partially nested within the second monopole.

19. System, characterized in that it comprises: a power line; a ground plane fixed to one side of the power line; and first and second monopoles coupled to the other side of the power line, the second monopole at least partially nested within the first monopole; wherein the first monopole has a first number of arms and an upper and a lower part, wherein the arms of the first monopole have curves; and wherein the second monopole has a second number of arms, wherein the second monopole has a height less than the height of the first monopole.

20. Method, characterized in that it comprises: transmitting a signal with an antenna comprising a first and a second monopole; wherein: the first monopole has a first number of arms and an upper and a lower part, wherein the arms of the first monopole have curves; and the second monopole has a second number of arms, wherein the second monopole has a height less than the height of the first monopole, and wherein the second monopole is at least partially nested within the first monopole. Petition 870250105563, dated 11 / 18 / 2025, p. 42 / 46

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