Modified ground plane to increase gain in geodesic antenna element patterns

Abstract

The geodesic antenna (100) includes an outer cone (105). The geodesic antenna also includes an inner cone (110) partially disposed within the outer cone and defining an electromagnetic waveguide with the outer cone. The geodesic antenna further includes a plurality of driven elements (150) configured to generate electromagnetic waves in a space between the outer and inner cones. The geodesic antenna further includes a ground plane (155, 155a, 155b, 155c, 155d) configured to reflect first ones of the generated electromagnetic waves (815, 865) back into the space between the outer and inner cones. The ground plane has a geometric design that prevents at least some second ones of the generated electromagnetic waves (825, 875) from reflecting off the ground plane and creating an interference pattern.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE

[0001] This disclosure relates generally to geodesic antennas. More specifically, this disclosure relates to modified ground planes to increase gain in element patterns of geodesic antennas. [Background technology]

[0002]

[0002] A geodesic antenna is an antenna in which antenna elements contribute to a beam pattern at all angles in azimuth. Some geodesic antennas include a cone that helps direct the electromagnetic energy, and the cone defines the lens aperture of the geodesic antenna. Geodesic lens apertures have many advantages, including simplicity of design. Due to their ease of construction and design, geodesic lens apertures are well suited for applications requiring 360° coverage in azimuth. However, electromagnetic energy is typically provided at one end of the cone, and some of the electromagnetic energy in the form of geodesic rays may couple at the other end of the cone, resulting in an interference pattern. This interference pattern can cause phase disturbances that complicate functions such as beam steering operations, resulting in beams with higher side lobes. Summary of the Invention

[0003]

[0003] The present disclosure provides a modified ground plane to increase gain in the element pattern of a geodesic antenna.

[0004]

[0004] In a first embodiment, the geodesic antenna includes an outer cone. The geodesic antenna also includes an inner cone disposed partially within the outer cone and defining an electromagnetic waveguide together with the outer cone. The geodesic antenna further includes a plurality of driven elements configured to generate electromagnetic waves in a space between the outer and inner cones. Additionally, the geodesic antenna includes a ground plate configured to reflect a first one of the generated electromagnetic waves back into the space between the outer and inner cones. The ground plate has a geometric design that prevents at least some of the second one of the generated electromagnetic waves from reflecting off the ground plate and creating an interference pattern.

[0005] In a second embodiment, a method includes generating electromagnetic waves in a space between an outer and inner cone of a geodesic antenna. The method also includes using a ground plane of the geodesic antenna to reflect a first one of the generated electromagnetic waves back into the space between the outer and inner cones. The ground plane has a geometric design that prevents at least some second one of the generated electromagnetic waves from reflecting off the ground plane and creating an interference pattern.

[0006]

[0006] Other technical features will be readily apparent to those skilled in the art from the following drawings, descriptions and claims. [Brief description of the drawings]

[0007]

[0007] For a more complete understanding of the present disclosure and its features, reference is made to the following description taken in conjunction with the accompanying drawings, in which: [Figure 1]

[0008] FIG. 1 illustrates an exemplary geodesic antenna according to the present disclosure. [Diagram 2] FIG. 2 illustrates an exemplary geodesic antenna according to the present disclosure. [Diagram 3] FIG. 3 illustrates an exemplary geodesic antenna according to the present disclosure. [Figure 4A]

[0009] FIG. 4A illustrates an exemplary modified ground plane for increasing gain in an element pattern of a geodesic antenna according to the present disclosure. [Figure 4B] FIG. 4B illustrates an exemplary modified ground plane for increasing gain in the element pattern of a geodesic antenna according to the present disclosure. [Figure 5A] FIG. 5A illustrates an exemplary modified ground plane for increasing gain in an element pattern of a geodesic antenna according to the present disclosure. [Figure 5B] FIG. 5B illustrates an exemplary modified ground plane for increasing gain in the element pattern of a geodesic antenna according to the present disclosure. [Figure 5C] FIG. 5C illustrates an exemplary modified ground plane for increasing gain in the element pattern of a geodesic antenna according to the present disclosure. [Figure 6A] FIG. 6A illustrates an exemplary modified ground plane for increasing gain in an element pattern of a geodesic antenna according to the present disclosure. [Figure 6B] FIG. 6B illustrates an exemplary modified ground plane for increasing gain in the element pattern of a geodesic antenna according to the present disclosure. [Figure 6C] FIG. 6C illustrates an exemplary modified ground plane for increasing gain in the element pattern of a geodesic antenna according to the present disclosure. [Figure 7A] FIG. 7A illustrates an exemplary modified ground plane for increasing gain in an element pattern of a geodesic antenna according to the present disclosure. [Figure 7B] FIG. 7B illustrates an exemplary modified ground plane for increasing gain in the element pattern of a geodesic antenna according to the present disclosure. [Figure 7C] FIG. 7C illustrates an exemplary modified ground plane for increasing gain in the element pattern of a geodesic antenna according to the present disclosure. [Figure 8A]

[0010] FIG. 8A illustrates an example of the operation of a geodesic antenna having a modified ground plane according to the present disclosure. [Figure 8B] FIG. 8B illustrates an example of the operation of a geodesic antenna having a modified ground plane according to the present disclosure. [Figure 9A]

[0011] FIG. 9A shows an example of the benefit obtained using a modified ground plane to increase the gain in the element pattern of a geodesic antenna in accordance with the present disclosure. [Figure 9B] FIG. 9B shows an example of the benefit obtained using a modified ground plane in accordance with the present disclosure to increase the gain in the element pattern of a geodesic antenna. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008]

[0012] 1-9B described below, and the various embodiments used herein to illustrate the principles of the present invention, are for illustrative purposes only and should not be construed in any manner to limit the scope of the invention. Those skilled in the art will understand that the principles of the present invention may be implemented in any type of suitably arranged device or system.

[0009]

[0013] As mentioned above, some geodesic antennas include a cone that helps direct the electromagnetic energy, the cone defining the lens aperture of the geodesic antenna. However, the electromagnetic energy is typically provided at one end of the cone, and some of the electromagnetic energy in the form of a geodesic electromagnetic wave can couple at the other end of the cone, resulting in an interference pattern. This interference pattern can cause phase disturbances that complicate functions such as beam steering operations, resulting in the formation of beams with higher side lobes.

[0010]

[0014] The present disclosure provides various modified ground planes that can be used in geodesic antennas. As described in more detail below, each modified ground plane reflects electromagnetic energy generated by the geodesic antenna. Using geometric manipulation of the ground plane, the electromagnetic energy can be reflected or trapped at a steeper angle relative to the scan angle of the geodesic antenna (steeper angles of reflection also help trap the electromagnetic energy). As a result, this electromagnetic energy has a reduced or minimized impact and does not contribute significantly to the overall output beam generated by the geodesic antenna. In this manner, the interference pattern of the geodesic antenna can be reduced, which helps increase the gain in the element pattern of the geodesic antenna. This can also help limit the phase ripple of the geodesic antenna, simplifying the phase calculations of the geodesic antenna. This also helps lower the side lobes when forming the output beam. Furthermore, processing such as beam steering calculations can be simplified since there is no need to consider secondary effects of interference.

[0011]

[0015] Figures 1-3 illustrate an exemplary geodesic antenna 100 in accordance with the present disclosure. More specifically, Figure 1 illustrates a perspective view of geodesic antenna 100, Figure 2 illustrates an exploded view of geodesic antenna 100, and Figure 3 illustrates a cross-sectional view of geodesic antenna 100. The embodiment of geodesic antenna 100 in Figures 1-3 is for illustration only, and geodesic antenna 100 may have any other suitable element pattern.

[0012]

[0016] As shown in FIGS. 1-3, the geodesic antenna 100 is formed using nested geodesic lens antennas (GLA), referred to as "cones." In the exemplary embodiment of FIGS. 1-3, the geodesic antenna 100 includes an outer cone 105 and an inner cone 110. The outer cone 105 and the inner cone 110 are concentric to function as a parallel plate waveguide. Although more than two cones can be used in the geodesic antenna 100, for simplicity, the relationship between the outer cone 105 and the inner cone 110 is described, and the relationship between the outer cone 105 and the inner cone 110 can be extended to more than two cones. For example, additional outer cones can be concentric with the inner cone 110 and the outer cone 105 to function as a parallel plate waveguide.

[0013]

[0017] The outer cone 105 is configured to receive a portion of the inner cone 110 within an interior space of the outer cone 105. The outer cone 105 may be formed from any suitable conductive material, such as one or more metals. The outer cone 105 may be formed by any suitable method, such as casting, injection molding, metal spinning, metal turning, etc. Additionally, the outer cone 105 may have any suitable size, shape, and dimensions. In this example, the outer cone 105 is formed as a hollow, generally cylindrical structure 115 that is at least partially enclosed at one end. The periphery of the opposite end of the outer cone 105 has a flared portion 120 that projects radially from a central axis of the outer cone 105. The surface of the flared portion 120 is at a reflex angle (greater than 180°) from an inner surface 125 of the outer cone 105.

[0014]

[0018] A portion of the inner cone 110 is inserted into the outer cone 105, and another portion of the inner cone 110 extends above the outer cone 105. The inner cone 110 may be formed from any suitable conductive material, such as one or more metals. The conductive material of the inner cone 110 may be the same or different than the conductive material of the outer cone 105. Additionally, the inner cone 110 may be formed by any suitable method, such as casting, injection molding, metal spinning, or metal turning. Additionally, the inner cone 110 may have any suitable size, shape, and dimensions. In this example, the inner cone 110 is formed as a hollow, generally cylindrical structure 130, at least a portion of which is received within the outer cone 105. Insertion of the inner cone 110 into the outer cone 105 forms an annulus 135 between the inner surface 125 of the outer cone 105 and the outer surface 140 of the inner cone 110. The circumferential portion at the opposite end of the inner cone 110 has a flare 145 that projects radially from the central axis of the inner cone 110. The surface of the flare 145 is at an oblique angle (less than or greater than 90°) relative to the outer surface 140 of the inner cone 110.

[0015]

[0019] The outer cone 105 and the inner cone 110 form a geodesic parallel plate waveguide as conformal structures such as a pair of conical sections. The inner cone 110 is joined within the outer cone 105 to form a parallel waveguide that is formed between the inner surface 125 of the outer cone 105 and the outer surface 140 of the inner cone 110. The inner surface 125 of the outer cone 105 and the outer surface 140 of the inner cone 110 represent the opposing plates of the waveguide. It should be noted that although the inner cone 110 and the outer cone 105 are both described as having the same shape (generally a hollow cylinder with flared ends), the shapes of the outer cone 105 and the inner cone 110 may differ.

[0016]

[0020] As previously mentioned, the flare portion 120 of the outer cone 105 may extend at an oblique angle from the apex of the inner surface 125 of the outer cone 105, and the flare portion 145 of the inner cone 110 may extend at an oblique angle from the apex of the outer surface 140 of the inner cone 110. The flare portion 120 of the outer cone 105 and the flare portion 145 of the inner cone 110 allow for focusing of the resulting waveguide radiating element pattern. The configuration of the flare portions 120 and 145 allows for an omni-directional waveguide radiating element pattern.

[0017]

[0021] Each of the plurality of driven elements 150 is coupled to the outer cone 105 and extends into the annulus 135 between the inner surface 125 of the outer cone 105 and the outer surface 140 of the inner cone 110. Each driven element 150 is connected to a transmitter or receiver, such as by using a transmission line. When the driven elements 150 are implemented in a transmitting geodesic antenna 100, the driven elements 150 are driven by a radio frequency (RF) signal from the transmitter, which causes the driven elements 150 to generate electromagnetic energy in the form of RF waves in the annulus 135. The phase of the RF signal provided to each driven element 150 can be varied depending on the desired direction of the output beam transmitted by the geodesic antenna 100. When the driven elements 150 are implemented in a receiving geodesic antenna 100, the driven elements 150 convert the electromagnetic energy in the form of RF waves collected in the annulus 135 into an electric current, which is provided to the receiver. Each driven element 150 may represent a quarter wavelength feed probe or other feed probe.

[0018]

[0022] At least one driving element 150 may be configured to generate at least one primary geodesic electromagnetic ray. The primary geodesic electromagnetic ray from the driving element 150 may generally be focused outward of the outer cone 105. However, secondary geodesic rays may be generated as a side effect of the primary geodesic electromagnetic ray interacting with the outer surface 140 of the inner cone 110 and the inner surface 125 of the outer cone 105. The secondary geodesic electromagnetic ray may also be generated based on the general dispersion of the beam. At least one driving element 150 may act as a monopole and generate electromagnetic waves in the opposite direction toward the ground plate 155. The ground plate 155 may be implemented as a base inside the outer cone 105 or may be formed separately from the outer cone 105 and coupled to the outer cone 105.

[0019]

[0023] The ground plane 155 reflects the electromagnetic waves from one or more of the driven elements 150, and the reflected electromagnetic waves increase the gain of the primary geodesic electromagnetic waves. The ground plane 155 represents a parasitic element that is electromagnetically coupled to the driven element 150. The primary geodesic electromagnetic waves from one or more of the driven elements 150 can contribute to a pointing angle within the scan angle of the geodesic antenna 100. For example, the primary geodesic electromagnetic waves can form an element pattern suitable for a particular application of the geodesic antenna 100. The outer cone 105 and the inner cone 110 can be designed with a desired scan angle that affects the gain and size of the geodesic antenna 100. A smaller scan angle results in a larger gain, but may require the geodesic antenna 100 to be higher. A larger scan angle results in a smaller gain, but allows for a smaller and more compact geodesic antenna 100.

[0020]

[0024] However, without some type of modification, the secondary geodesic electromagnetic waves can wrap around within the annulus 135 between the inner cone 110 and the outer cone 105 and interfere with both the primary geodesic electromagnetic waves generated by the driving element 150 and other secondary geodesic electromagnetic waves. This can create interference patterns that can cause phase disturbances that can complicate functions such as beam steering operations and can result in beam forming with higher side lobes. It is necessary and desirable to reduce or minimize the interference patterns to improve the operation of the geodesic antenna 100.

[0021]

[0025] As described in more detail below, the ground plane 155 is designed to help significantly reduce interference patterns associated with the geodesic antenna 100. This is accomplished by designing the ground plane 155 to more effectively trap electromagnetic energy that may form secondary geodesic electromagnetic waves. In some embodiments, the ground plane 155 includes holes that allow electromagnetic waves to pass through the ground plane 155 and be trapped beneath the ground plane 155. In other embodiments, the ground plane 155 includes a prism or other angled surface that reflects electromagnetic waves at a steeper angle compared to a simple, flat ground plane. Either approach helps to more effectively trap secondary geodesic electromagnetic waves within the geodesic antenna 100, which helps to reduce interference patterns of the geodesic antenna 100. Exemplary embodiments of the ground plane 155 are described below. The ground plane 155 can be formed from any suitable conductive material, such as one or more metals. The ground plane 155 can also be formed by any suitable method, such as machining. Furthermore, the main plate 155 may have any suitable size, shape, and dimensions.

[0022]

[0026] In this example, the base 160 represents the bottom of the geodesic antenna 100 and serves to connect the various components of the geodesic antenna 100 together. For example, the base 160 connects to the outer cone 105 and the inner cone 110 while also securing the ground plate 155 within the geodesic antenna 100. In this particular example, various bolts or other connectors 165 can pass through the base 160 and into the outer cone 105, thereby securing the outer cone 105 to the base 160. Similarly, various bolts or other connectors 170 can pass through the base 160 and into the inner cone 110, thereby securing the inner cone 110 to the base 160. Additionally, as described below, at least some of the connectors 165 or 170 can pass through openings in the ground plate 155 and be secured to the ground plate 155 in position between the base 160 and the outer and inner cones 105, 110. In some embodiments, base 160 may implement an RF trap that captures and terminates electromagnetic waves that enter base 160 through ground plane 155. Base 160 may be formed from any suitable material and in any suitable manner. Base 160 may also have any suitable size, shape, and dimensions.

[0023]

[0027] It should be noted that in some embodiments, removing the base 160 from the geodesic antenna 100 and replacing the ground plate 155 may be a relatively simple operation. For example, an operator may only need to remove the connectors 165 and 170, lift the base 160 and current ground plate 155 from the outer and inner cones 105, 110, replace the current ground plate 155 with another ground plate 155, and reattach the base 160 and other ground plate 155 to the outer and inner cones 105, 110 using the connectors 165 and 170. In particular, an operator may be able to modify the ground plate used in the geodesic antenna 100 as needed or desired, such as to change the performance of the antenna or to adapt the performance of the antenna to a desired application. However, the ability to modify the ground plate 155 of the geodesic antenna 100 is optional and may or may not be supported in any particular implementation of the geodesic antenna 100.

[0024]

[0028] Geodesic antenna 100 and its individual components may have any suitable size, shape, and dimensions. For example, in some embodiments, geodesic antenna 100 has a total diameter of about 9 inches and a total height of about 7 inches. However, the design of geodesic antenna 100 can be readily scaled to meet the specific requirements of any particular application. Geodesic antenna 100 can also provide 360° coverage in azimuth and support desired beam steering or other beam related functions. Geodesic antenna 100 herein can be used in any suitable manner, such as in defense-related or covert applications where 360° in azimuth is required or desired.

[0025]

[0029] 1-3 illustrate an example geodesic antenna 100, although various modifications may be made to Figures 1-3. For example, geodesic antenna 100 may have multiple outer cones 105, each having a driven element 150. Geodesic antenna 100 may also be used in combination with any suitable number and type of external components and systems.

[0026]

[0030] Figures 4A through 7C illustrate exemplary modified ground planes 155a-155d for increasing gain in the element pattern of a geodesic antenna in accordance with the present disclosure. For ease of explanation, the ground planes 155a-155d illustrated in Figures 4A through 7C are described as being used with the geodesic antenna 100 of Figures 1 through 3. However, the ground planes 155a-155d illustrated in Figures 4A through 7C may be used with other suitable geodesic antennas.

[0027]

[0031] 4A and 4B, a first exemplary embodiment of the ground plate 155a represents a substantially planar annular structure, where the ground plate 155a is formed as an annular ring 405 that surrounds an open space 410 within the ring 405. The open space 410 allows, for example, a portion of the base 160 to pass through the ground plate 155a and couple to and support the inner cone 110. The ring 405 includes various openings 415, where each opening 415 passes completely through the ground plate 155a. The openings 415 allow a portion of the electromagnetic waves directed towards the ground plate 155a to pass through the ground plate 155a and be trapped using the base 160.

[0028]

[0032] In some embodiments, when the ground plate 155a is secured to the outer and inner cones 105, 110 by the base 160, each opening 415 can be positioned such that it is substantially equidistant or centered between the two drive elements 150. This may, for example, allow for more effective capture of electromagnetic waves that may otherwise wrap around the annular portion 135 and form secondary geodesic electromagnetic waves. In these embodiments, the number of openings 415 and the positions of the openings 415 may vary based on the number and positions of the drive elements 150. However, any other suitable number and positions of openings 415 may be used herein. In this particular example, each opening 415 is formed as a generally triangular structure with rounded corners and slightly curved short sides. However, each opening 415 may have any other suitable shape.

[0029]

[0033] Various protrusions 420 extend from the outer periphery of the ring 405, with each protrusion 420 including an opening 425. Each opening 425 allows one of the connectors 165 to pass through the associated protrusion 420, which allows the base 160 to be attached to the outer cone 105 and serves to secure the main plate 155a in place. However, it should be noted that any other suitable mechanism may be used to secure the main plate 155a in place.

[0030]

[0034] As shown in FIGS. 5A-5C, the second exemplary embodiment of the ground plate 155b is similar to the ground plate 155a in some respects. For example, the ground plate 155b is formed using an annular ring 505 that surrounds an empty space 510 within the ring 505. The ring 505 includes various openings 515, where each opening 515 completely penetrates the ground plate 155b. The openings 515 allow a portion of the electromagnetic waves directed toward the ground plate 155b to pass through the ground plate 155b and be trapped using the base 160. In some embodiments, when the ground plate 155b is secured to the outer and inner cones 105, 110 by the base 160, each opening 515 can be positioned such that it is substantially equidistant or centered between the two drive elements 150, and the number of openings 515 and the location of the openings 515 can vary based on the number and location of the drive elements 150. However, any other suitable number and location of the openings 515 can be used in the present case. In this particular example, each opening 515 is formed as a generally triangular structure with rounded corners and slightly curved short sides. However, each opening 515 could have any other suitable shape. Various protrusions 520 extend from the outer periphery of the ring 505, each protrusion 520 including an opening 525. Each opening 525 allows one of the connectors 165 to pass through the associated protrusion 520, which allows the base 160 to be attached to the outer cone 105 and helps secure the main plate 155b in place. However, it should be noted that any other suitable mechanism may be used to secure the main plate 155b in place.

[0031]

[0035] Additionally, ground plate 155b includes various raised walls 530 that extend upward or away from ring 505. In this example, two walls 530 are disposed on opposite sides of each opening 515. The walls 530 may serve to reflect electromagnetic energy into openings 515 and / or at steeper angles compared to flat ground plate 155a. Either mechanism may serve to trap electromagnetic energy within geodesic antenna 100 that may otherwise form secondary geodesic electromagnetic waves.

[0032]

[0036] It should be noted that each wall 530 may be integrally formed with the ring 505 or may be formed separately from the ring 505 and attached to the ring 505. For example, the ring 505 and walls 530 may be formed by machining a single piece of material or by using an additive manufacturing process, in which case the walls 530 would be integral with the ring 505. In other cases, the ring 505 and walls 530 may be formed separately and the walls 530 may be welded, glued, or otherwise attached to the ring 505. It should also be noted that while the walls 530 here are shown as having a uniform height and extending completely across the annular width of the ring 505, other configurations of the walls 530 may be used. For example, the walls 530 may have a tapered height that descends toward the outer or inner edge of the ring 505, or other non-uniform height, or the walls 530 may extend partially (but not completely) across the annular width of the ring 505.

[0033]

[0037] As shown in FIGS. 6A-6C, the third exemplary embodiment of the ground plate 155c is similar to the ground plates 155a and 155b in some respects. For example, the ground plate 155c is formed using an annular ring 605 that surrounds an open space 610 within the ring 605. The ring 605 includes various openings 615, where each opening 615 completely penetrates the ground plate 155c. The openings 615 allow a portion of the electromagnetic waves directed toward the ground plate 155c to pass through the ground plate 155c and be trapped using the base 160. In some embodiments, when the ground plate 155c is fixed to the outer and inner cones 105, 110 by the base 160, each opening 615 can be positioned such that it is substantially equidistant or centered between the two drive elements 150, and the number of openings 615 and the location of the openings 615 can vary based on the number and location of the drive elements 150. However, any other suitable number and location of the openings 615 can be used in the present case. In this particular example, each opening 615 is formed as a generally triangular structure with rounded corners and slightly curved short sides. However, each opening 615 could have any other suitable shape. Various protrusions 620 extend from the outer periphery of the ring 605, each protrusion 620 including an opening 625. Each opening 625 allows one of the connectors 165 to pass through the associated protrusion 620, which allows the base 160 to be attached to the outer cone 105 and helps secure the main plate 155c in place. However, it should be noted that any other suitable mechanism may be used to secure the main plate 155c in place.

[0034]

[0038] Additionally, ground plate 155c includes various raised walls 630 that extend upwardly or away from ring 605. In this example, each wall 630 completely surrounds or encircles an associated one of openings 615. Walls 630 may serve to reflect electromagnetic energy into openings 615 and / or at steeper angles compared to flat ground plate 155a. Either mechanism may serve to trap electromagnetic energy within geodesic antenna 100 that may otherwise form secondary geodesic electromagnetic waves.

[0035]

[0039] It should be noted that each wall 630 may be integrally formed with the ring 605 or may be formed separately from the ring 605 and attached to the ring 605. For example, the ring 505 and the walls 530 may be formed by machining a single piece of material or by using an additive manufacturing process, in which case the walls 630 would be integral with the ring 605. In other cases, the ring 605 and the walls 630 may be formed separately and the walls 630 may be welded, glued, or otherwise attached to the ring 605. It should also be noted that while the walls 630 here are shown as having a uniform height and extending entirely around the associated opening 615, other forms of walls 630 may be used. For example, the walls 630 may have a tapered height that descends toward the outer or inner edge of the ring 605 or other non-uniform height, or the walls 630 may extend partially (but not completely) around the associated opening 615.

[0036]

[0040] As shown in Figures 7A-7C, the fourth exemplary embodiment of the base plate 155d is similar to the base plates 155a-155c in some respects. For example, the base plate 155d is formed using an annular ring 705 that surrounds an open space 710 within the ring 705. Various protrusions 720 extend from the outer periphery of the ring 705, each of the protrusions 720 including an opening 725. Each opening 725 allows one of the connectors 165 to pass through the associated protrusion 720, which allows the base 160 to be attached to the outer cone 105 and helps to secure the base plate 155d in place. However, it should be noted that any other suitable mechanism may be used to secure the base plate 155d in place.

[0037]

[0041] Rather than using holes, the ring 705 here includes various prisms 715, each of which includes multiple reflective surfaces 716. In some cases, the reflective surfaces 716 can reflect electromagnetic energy at a steeper angle relative to the flat ground plane 155a. This can help trap electromagnetic energy within the geodesic antenna 100 that might otherwise form secondary geodesic electromagnetic waves. Alternatively or in the alternative, the reflective surfaces 716 can reflect electromagnetic energy that would otherwise form secondary geodesic electromagnetic waves in a desired direction that helps increase the gain of one or more primary geodesic electromagnetic waves. In some embodiments, when the ground plate 155d is secured to the outer and inner cones 105, 110 by the base 160, each prism 715 can be positioned such that it is substantially equidistant or centered between the two drive elements 150, and the number of prisms 715 and the positions of the prisms 715 can vary based on the number and positions of the drive elements 150. However, any other suitable number and positions of prisms 715 can be used herein. In this particular example, each prism 715 is formed as a generally triangular prism structure with rounded corners and slightly curved short sides. However, each prism 715 can have any other suitable shape.

[0038]

[0042] It should be noted that each prism 715 may be integrally formed with the ring 705 or may be formed separately from the ring 705 and attached to the ring 705. For example, the ring 705 and prism 715 may be formed by machining a single piece of material or by using an additive manufacturing process, in which case the prism 715 would be integral with the ring 705. In another case, the ring 705 and prism 715 may be formed separately and the prism 715 may be welded, glued, or otherwise attached to the ring 705. It should also be noted that although the prism 715 here is shown having two primary reflective surfaces 716, other configurations for the prism 715 may be used, such as having more than two reflective surfaces 716. Also, each individual prism 715 may be replaced with multiple separated angled reflective surfaces.

[0039]

[0043] Although Figures 4A-7C show examples of modified ground planes 155a-155d that increase the gain in the element pattern of the geodesic antenna, various modifications may be made to Figures 4A-7C. Any combination of features of two or more of the ground planes 155a-155d may be used in one ground plane, such as when both prisms on the annular ring and apertures in the annular ring are used in the ground plane. Also, the ground planes 155a-155d shown herein are intended to represent only examples of ground planes that are geometrically modified (compared to simply flat annular ground planes) to suppress the generation of secondary geodesic electromagnetic waves that may cause interference patterns or otherwise cause problems for the geodesic antenna. Other suitable ground planes may be formed using other suitable geometric modifications and still fall within the scope of the present disclosure.

[0040]

[0044] 8A and 8B show examples of operation of a geodesic antenna with a ground plane modified in accordance with the present disclosure. More specifically, FIG. 8A shows an example of operation of a geodesic antenna 100 with a ground plane 155a, and FIG. 8B shows an example of operation of a geodesic antenna 100 with a ground plane 155d. For ease of explanation, the operation shown in FIG. 8A and FIG. 8B is described as including the geodesic antenna 100 of FIG. 1-3. However, the ground planes 155a-155d or other ground planes designed in accordance with the present disclosure can be used in any other suitable geodesic antenna.

[0041]

[0045] 8A, the driven element 150 may generate a primary geodesic electromagnetic wave 805, which may have a maximum scan angle 810 relative to a vertical axis through the driven element 150. The driven element 150 may also generate a secondary geodesic electromagnetic wave 815, which may be reflected from a planar portion of the ground plane 155a as a secondary geodesic electromagnetic wave 820, where the secondary geodesic electromagnetic wave 820 is oriented in the same or similar direction as the primary geodesic electromagnetic wave 805, which may be desirable and may help increase the gain of the geodesic antenna 100.

[0042]

[0046] The driven element 150 may also generate an additional secondary electromagnetic wave 825, which may represent an undesirable electromagnetic wave, as it may lead to interference patterns or other problems. Here, the secondary electromagnetic wave 825 passes through one of the openings 415 in the ground plate 155a and into the space 830 defined between the ground plate 155a and the base 160. This secondary electromagnetic wave 825 may be reflected one or more times and ideally terminated. This may then help reduce the interference pattern of the geodesic antenna 100 using the ground plate 155a.

[0043]

[0047] 8B, the driven element 150 can generate a primary geodesic electromagnetic wave 855, which can have a maximum scan angle 860 relative to a vertical axis through the driven element 150. The driven element 150 can also generate a secondary geodesic electromagnetic wave 865, which can be reflected from a planar portion of the ground plane 155d as a secondary geodesic electromagnetic wave 870. Here, the secondary geodesic electromagnetic wave 820 is oriented in the same or similar direction as the primary geodesic electromagnetic wave 805, which may be desirable and help increase the gain of the geodesic antenna 100.

[0044]

[0048] The driven element 150 may also generate additional secondary electromagnetic waves 875, which may represent undesirable electromagnetic waves as they may lead to interference patterns or other problems. Here, the secondary electromagnetic waves 875 reflect off the prism 715 on the ground plate 155d as secondary geodesic electromagnetic waves 880. Depending on the angle of reflection, the secondary geodesic electromagnetic waves 880 may be directed in the same or similar direction as the primary geodesic electromagnetic waves 855 (which may be desirable and may help increase the gain of the geodesic antenna 100), or at an angle steeper than the scan angle. As a result, this helps reduce the interference patterns of the geodesic antenna 100 using the ground plate 155d.

[0045]

[0049] 8A and 8B show an example of the operation of geodesic antenna 100 using modified ground plates 155a, 155d, although various modifications may be made to Figures 8A and 8B. For example, the operation of geodesic antenna 100 is simplified here to illustrate how ground plates 155a, 155d may be used to show how to increase the gain of the element pattern of geodesic antenna 100. As a specific example, driven element 150 is capable of generating multiple electromagnetic waves in various directions.

[0046]

[0050] 9A and 9B show an example of the benefit obtained using a modified ground plane to increase the gain in the element pattern of a geodesic antenna according to the present disclosure. More specifically, FIG 9A shows an example normalized gain plot 900 illustrating the side lobe performance of a geodesic antenna 100 using a modified ground plane, and FIG 9B shows an example gain plot 950 of a geodesic antenna 100 using a modified ground plane.

[0047]

[0051] 9A, line 905 represents the normalized gain of a geodesic antenna using a conventional flat annular ground plane, and line 910 represents the normalized gain of geodesic antenna 100 using one of the modified ground planes described above. As seen in region 915 of plot 900, the use of the modified ground plane serves to improve the gain seen in the side lobes of the output beam produced by geodesic antenna 100. In this particular example, the gain improvement may be approximately 1 decibel, although other improvements may be obtained based on the design of the ground plane (among other things) used in geodesic antenna 100.

[0048]

[0052] 9B, line 955 represents the gain of a geodesic antenna using a conventional flat annular ground plane, and line 960 represents the gain of geodesic antenna 100 using one of the modified ground planes described above. As seen in region 965 of plot 950, the use of the modified ground plane serves to improve the gain of the output beam generated by geodesic antenna 100. In this particular example, the gain improvement may be approximately 1 decibel, although other improvements may be obtained based on the design of the ground plane (among other things) used in geodesic antenna 100.

[0049]

[0053] Although Figures 9A and 9B show examples of benefits that may be obtained using a modified ground plane to increase the gain of an element pattern of a geodesic antenna, various modifications may be made to Figures 9A and 9B. For example, the benefits shown in Figures 9A and 9B are for illustrative purposes only and are meant only to identify exemplary types of benefits that may be obtained using a modified ground plane to increase the gain of an element pattern of a geodesic antenna. The actual benefits obtained for any particular geodesic antenna using any particular ground plane may vary based on many factors.

[0050]

[0054] It may be helpful to provide definitions of certain words and phrases used throughout this patent document. The terms "include" and "comprise" and their derivatives mean inclusion without limitation. The term "or" is inclusive and means "and / or." The phrase "related to" and its derivatives may mean including, contained within, interconnected with, containing, contained within, connected to or with, coupled to or with, communicable with, cooperate with, interleaved with, juxtaposed with, adjacent to, bound by, having, having the nature of, having a relationship to or with, and the like. The phrase "at least one," when used in conjunction with a list of items, means that various combinations of one or more of the listed items may be used and that only one item in the list may be required. For example, "at least one of A, B, and C" includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C.

[0051]

[0055] The description of the present application should not be construed to imply that any particular element, step, or function is an essential or critical element that must be included in the scope of the claims. The scope of patented subject matter is defined solely by the allowed claims. Moreover, no claim shall invoke 35 U.S.C. § 112(f) with respect to any of the appended claims or claim elements, unless the precise words "means for" or "step for" are used in a particular claim and are followed by a participial phrase that identifies the function. The use of terms such as "mechanism," "module," "device," "unit," "component," "element," "member," "apparatus," "machine," "system," "processor," or "controller" in the claims is understood and intended to refer to structures known to those skilled in the art that are further modified or improved by the features of the claims themselves, and is not intended to invoke 35 U.S.C. § 112(f).

[0052]

[0056] While this disclosure has described certain embodiments and generally associated methods, modifications and permutations of these embodiments and methods will be apparent to those skilled in the art. Thus, the above description of exemplary embodiments is not intended to limit or restrict this disclosure. Other modifications, substitutions, and alterations are possible without departing from the spirit and scope of this disclosure, as defined by the following claims.

Claims

1. A geodesic antenna comprising: Outer cone; an inner cone disposed partially within said outer cone and defining, together with said outer cone, an electromagnetic waveguide; A plurality of drive elements configured to generate electromagnetic waves in a space between the outer cone and the inner cone; and a ground plate configured to reflect a first one of the generated electromagnetic waves back into a space between the outer cone and the inner cone, the ground plate having a geometric design that prevents a second one of the generated electromagnetic waves from reflecting off the ground plate and creating an interference pattern; A geodesic antenna including:

2. 2. The geodesic antenna of claim 1, wherein the ground plane comprises: an annular ring; and a plurality of apertures disposed along and extending through said annular ring; A geodesic antenna, including:

3. 3. A geodesic antenna as claimed in claim 2, wherein the plurality of apertures are arranged along the annular ring such that each aperture is positioned to directly receive each of the two electromagnetic waves generated by the two driven elements.

4. 3. The geodesic antenna of claim 2, wherein the ground plane further comprises a plurality of raised walls extending from the annular ring.

5. 5. The geodesic antenna of claim 4, wherein the plurality of raised walls includes two raised walls disposed on opposite sides of each opening.

6. 5. The geodesic antenna of claim 4, wherein the plurality of raised walls includes a raised wall surrounding each aperture.

7. 3. The geodesic antenna of claim 2, comprising: A geodesic antenna further comprising a base configured to secure the ground plate to the outer cone and the inner cone, the base also configured to receive and terminate the second electromagnetic wave passing through an opening in the ground plate.

8. 2. The geodesic antenna of claim 1, wherein the ground plane comprises: a planar portion configured to reflect the first electromagnetic wave back into a space between the outer cone and the inner cone; and a plurality of angled surfaces configured to reflect the second electromagnetic wave back into a space between the outer cone and the inner cone; A geodesic antenna, including:

9. 9. The geodesic antenna of claim 8, wherein the ground plane includes a plurality of prisms that form the inclined surface.

10. The geodesic antenna of claim 9, comprising: the base plate includes an annular ring; and A geodesic antenna, wherein the prisms are disposed along the annular ring.

11. 11. A geodesic antenna as claimed in claim 10, wherein the plurality of prisms are arranged along the annular ring such that each prism is positioned to directly receive each of the two electromagnetic waves generated by the two driven elements.

12. 9. The geodesic antenna of claim 8, wherein the plurality of sloping surfaces are configured to reflect the second electromagnetic wave in the same direction as the first electromagnetic wave.

13. 9. The geodesic antenna of claim 8, wherein the plurality of sloping surfaces are configured to reflect the second electromagnetic wave at an angle steeper than a scan angle of the geodesic antenna.

14. 2. The geodesic antenna of claim 1, comprising: A geodesic antenna further comprising a base configured to secure the ground plate to the outer cone and the inner cone, the base also configured to be detachable from the outer cone and the inner cone, allowing the ground plate to be replaced with another ground plate having a different geometric design.

15. 15. The geodesic antenna of claim 14, wherein the ground plate includes a central aperture configured to allow a portion of the base to pass through the ground plate.

16. generating electromagnetic waves in a space between an outer cone and an inner cone of a geodesic antenna; and using a ground plane of the geodesic antenna to reflect a first one of the generated electromagnetic waves back into a space between the outer cone and the inner cone, the ground plane having a geometric design that prevents a second one of the generated electromagnetic waves from reflecting off the ground plane and creating an interference pattern; The method includes:

17. 17. The method of claim 16, the ground plane includes a plurality of openings that allow the second electromagnetic wave to pass through the ground plane; and A base of the geodesic antenna terminates the second electromagnetic wave passing through the ground plane.

18. 18. The method of claim 17, The base plate further includes a plurality of walls at least partially surrounding the opening; and The wall may include: reflecting the second electromagnetic wave into the aperture; and reflecting the second electromagnetic wave at an angle steeper than a scan angle of the geodesic antenna; The method is configured for at least one of:

19. 17. The method of claim 16, the ground plane includes a plurality of angled surfaces that reflect the second electromagnetic wave back into a space between the outer cone and the inner cone.

20. 20. The method of claim 19, wherein the ground plate includes a plurality of prisms that form the tilted surface.

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