Compact multi-beam antenna with spherical luneberg lens enhancement

Abstract

An antenna is disclosed having a plurality of radiators arranged in a ring or circular arc around a dragon's eye lens. Each of the radiators (e.g., horn-shaped notch radiators) has a central axis of radiation intersecting the center of the dragon's eye lens. Each of the radiators radiates into the dragon's eye lens such that the dragon's eye lens substantially flattens the beam plane emitted by each of the radiators (at transmission) and focuses the incoming wavefront into the radiators (at reception). This not only enables a multitude of well-controlled individual beams, but also allows the consolidation of radiators to create well-defined sector beams with minimal sidelobes and fast roll-off.

Description

BACKGROUND

[0001] TECHNICAL FIELD

[0002] The present invention relates to wireless communications, and more specifically to compact multi-beam antennas.

[0003] BACKGROUND

[0004] There is a strong desire for compact antennas to provide multi-sector coverage with minimal gain pattern overlap between sectors. Side lobe overlap between sector gain patterns can result in severe inter-sector interference, which can severely degrade the SINR (signal to interference and noise ratio) of the antenna. The more compact the antenna, the more severe the inter-sector interference problem. Accordingly, mitigating the inter-sector interference problem typically involves increasing the size of the antenna.

[0005] Another deficiency of conventional multi-beam antennas is that their beam configuration is typically fixed. Accordingly, a given antenna can have three 120 degree sectors, or six 60 degree sectors, etc., but once fixed, cannot be reconfigured.

[0006] Accordingly, there is a need for a compact multi-beam antenna that substantially mitigates inter-sector interference, while also providing the ability to dynamically reconfigure itself for different numbers and angular ranges of sectors. SUMMARY

[0007] Accordingly, the present invention is directed to a spherical dragon's eye lens enhanced compact multi-beam antenna that addresses one or more of the problems due to limitations and disadvantages of the related art.

[0008] One aspect of the present invention relates to an antenna comprising a spherically symmetric gradient index lens and a first plurality of radiators disposed in a first annular configuration around the spherically symmetric gradient index lens, each of the first plurality of radiators having a central radiation axis pointing toward a center of the spherically symmetric gradient index lens.

[0009] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. BRIEF DESCRIPTION OF DRAWINGS

[0010] The accompanying drawings, which are incorporated herein and constitute part of the specification, illustrate a spherical dragon's eye lens enhanced compact multi-beam antenna. Together with the description, the drawings serve to explain the principles of the spherical dragon's eye lens enhanced compact multi-beam antenna described herein. In the drawings:

[0011] FIG. 1a illustrates an exemplary antenna according to the present disclosure.

[0012] Figure 1b illustrates an example horn notch radiators according to the present disclosure.

[0013] Figure 1c illustrates a portion of a radiators ring with multiple horn notch radiators.

[0014] Figure 1d illustrates an example antenna from an orientation perpendicular to the antenna elevation axis.

[0015] Figure 2 illustrates an example antenna with a radiators ring with steeper latitude orientation.

[0016] Figure 3 is a cross-sectional view of an example dragon lens according to the present disclosure.

[0017] Figure 4 is a top view of an example antenna according to the present disclosure providing a cross-sectional view of the concentric shells and central sphere within the dragon lens of the antenna and its radiators ring.

[0018] Figure 5 depicts an example antenna with one horn notch radiator 110 transmitting an RF signal, illustrating an example beam transmitted by the dragon lens.

[0019] Figure 6 illustrates an example gain pattern corresponding to six adjacent horn notch radiators 110 activated in unison, each with a 20 degree beamwidth to create a 120 degree sector.

[0020] Figure 7a illustrates a perspective view of an example antenna with two radiators rings.

[0021] Figure 7b illustrates another perspective view of an example antenna with two radiators rings.

[0022] Figure 8a illustrates an example antenna with a 180 degree partial circular arc radiators ring.

[0023] Figure 8b illustrates an example antenna with a 120 degree partial circular arc radiators ring.

[0024] Figure 9 illustrates an example antenna with vertical and horizontal polarized radiators according to the present disclosure. DETAILED DESCRIPTION

[0025] Reference will now be made in detail to embodiments of a spherical dragon lens enhanced compact multi-beam antenna according to the principles described herein, with reference to the accompanying drawings. The same reference numerals in different drawings can identify the same or similar elements.

[0026] Figure la shows an exemplary antenna 100 according to the present disclosure. The antenna 100 includes a radiator ring 105 comprising a plurality of horned notched radiators 110. The radiator ring 105 surrounds a spherically symmetric gradient index lens, such as a dragon lens 115. In the illustrated example, the radiator ring 110 has eighteen horned notched radiators (also known as Vivaldi radiators or tapered slot radiators). Further to this example, the antenna 100 is configured to operate in a frequency range of 1695 MHz to 4300 MHz; the dragon lens has a diameter of 400 mm; and each of the eighteen horned notched radiators 110 is configured to radiate with a gain pattern that is approximately 20 degrees wide. The radiator ring 105 can contain the dragon lens 115 centered about a sphere center 105 of the dragon lens, with an elevation axis 120 of the radiator ring 105 intersecting the sphere center 105 of the dragon lens such that the radiator ring 105 is disposed in an axially symmetric manner about the elevation axis 120.

[0027] The dragon lens 115 is a sphere with a concentric gradient index of refraction. They are known in the field of microwave engineering. The dragon lens 115 can have a continuous index of refraction profile from the sphere center to its outer surface. Alternatively, the dragon lens 115 can have an index of refraction step gradient. The dragon lens 115 serves to substantially focus and flatten the RF wavefront emitted by each horned notched radiator 110, whereby each horned notched radiator 110 radiates inwardly toward the sphere center of the dragon lens 115. As a receiver, the dragon lens 115 focuses a substantially flat wavefront into an aperture defined by a given horned notched radiator 110. The dragon lens 115 of the exemplary antenna 100 has a diameter of 400 mm, although varying diameters are possible and within the scope of the present disclosure. An exemplary dragon lens 115 is described in further detail below. The dragon lens can be made of any suitable material, including, for example, acrylonitrile butadiene styrene (ABS) which has a dielectric constant of 3 and a reasonable loss tangent. Other thermoplastic polymers can be used. The dragon lens can be made by 3D printing or other suitable methods.

[0028] Figure lb illustrates an exemplary horn notch radiators 110 according to the present disclosure. The horn notch radiators 110 have a conductive plate 112 with a cutout that defines a traveling wave slot 145, a slot line 150, and a slot line termination cavity 155. The horn notch radiators 110 also include a coaxial feed 130 having an outer conductor 132 and an inner conductor 134. As shown in Figure lb, the outer conductor 132 is coupled to the conductive plate 112 at the point where the conductive plate 112 and the coaxial feed 130 are matched. The inner conductor 134 passes through the conductive plate 112 at the point where the conductive plate 112 and the coaxial feed 130 are matched and through the slot line 150, the inner conductor being coated with a dielectric (not shown) on the other side of the slot line 150, and is coupled to the conductive plate 112.

[0029] The traveling wave slot 145 can define a central radiation axis 135 that substantially defines a central axis of a gain pattern of the horn notch radiators 110. The horn notch radiators 110 also have two front edges 140, each located on a side of the traveling wave slot 145. The front edges 140 define the portions of the horn notch radiators 110 that contact the outer surface of the dragon lens 115.

[0030] The horn notch radiators 110 can be of a conventional variety, with size parameters set according to the desired frequency and bandwidth.

[0031] The conductive plate 112 can be formed of copper, aluminum, brass, or other metals. In addition, the conductive plate 112 can be formed of sheet metal. Forming each horn notch radiator 110 (and the radiator ring 105) of sheet metal can reduce its interference with the gain patterns of the horn notch radiators 110 on the opposite side of the radiator ring 105 (on the other side of the dragon lens 115).

[0032] Figure lc illustrates a portion of the radiator ring 105 having a plurality of horn notch radiators 110. Their combined front edges 140, which contact the outer surface of the dragon lens 115 (not shown), and their respective central radiation axes 135, each of which can intersect the center of the sphere of the dragon lens 115, are shown.

[0033] Figure Id illustrates the example antenna 100 from an orientation that is perpendicular to the elevation axis 120. As shown, in the example antenna 100, the radiator ring 105 is oriented and disposed on the dragon's eye lens 115 such that it has a 4 degree latitude offset. Accordingly, each horn notch radiator 110 of the radiator ring 105 is oriented such that its central radiation axis 135 intersects the sphere center of the dragon's eye lens 115 from a 4 degree latitude offset. Further, the front edge 140 of each horn notch radiator 110 substantially contacts the dragon's eye lens 115 such that each front edge 140 contacts the dragon's eye lens 115 along a latitude plane that is located 4 degrees of latitude above the equatorial plane 125 of the dragon's eye lens 115, whereby the equatorial plane 125 of the dragon's eye lens 115 is orthogonal to the elevation axis 120.

[0034] The example 4 degree latitude offset of the radiator ring 105 causes each horn notch radiator 110 to aim its gain pattern downward at a 4 degree angle. As such, interference caused by the presence of horn notch radiators 110 on opposite sides of the radiator ring 105 (and the dragon's eye lens 115) is reduced. Further, in deployments where the antenna 100 is mounted above a user equipment (UE) in an intended coverage area, it can be advantageous to aim the gain pattern of the horn notch radiators 110 downward.

[0035] Figure 2 illustrates another example antenna 200 according to the present disclosure. The illustration of Figure 2 is in the same orientation as Figure Id, as the view is along the equatorial plane 125 and the elevation axis 120 is vertically oriented. The antenna 200 differs in that the radiator ring 205 is oriented such that the front edge 140 of the horn notch radiators 110 contacts the dragon's eye lens 115 along a latitude plane that is offset 10 degrees from the equatorial axis 125. The central radiation axis 135 of the horn notch radiators 110 thus intersects the sphere center of the dragon's eye lens 115 at an angle of 10 degrees relative to the equatorial plane 125 and at an angle of 80 degrees relative to the elevation axis 120.

[0036] As with the antenna 100, the example 10 degree latitude offset of the radiator ring 205 causes each horn notch radiator 110 to aim its gain pattern downward at a 10 degree angle, with the antenna 200 further aiming its respective gain patterns downward relative to the antenna 100. As such, the interference experienced by the antenna 200 caused by the presence of horn notch radiators 110 on opposite sides of the radiator ring 205 (and the dragon's eye lens 115) is also further reduced relative to the antenna 100. Similarly, in deployments where the antenna 100 is mounted above a UE in an intended coverage area, it can be more advantageous to aim the gain pattern of the horn notch radiators 110 downward. The complexity of the antenna 200 lies in that it can be more complex to manufacture a radiator ring 205 with a 10 degree latitude offset than a radiator ring with a 4 degree offset.

[0037] Variations of the antenna 100 / 200 are possible and within the scope of the present disclosure. For example, the radiator ring 105 can be flat and formed around the equatorial plane 125 of the Luneberg lens 115. This can make the radiator ring easier and less costly to manufacture. Although this can come at the expense of increased interference of the radiator pairs on opposite sides of the radiator ring 105 with each horn notch radiator 110, this can be tolerable, especially if the radiator ring 105 is formed from very thin metal. Further, the latitude angle of the radiator ring 105 can be greater than 10 degrees, depending on how the antenna 100 / 200 can be deployed and its intended coverage. There is a tradeoff in that as the latitude angle of the radiator ring 105 increases, the interference effects are diminished, but the space for the horn notch radiators 110 is reduced due to the reduced diameter of the radiator ring 105 with higher latitudes. Accordingly, a tradeoff can be made between reducing interference but reducing the horn notch radiators 110. It should be appreciated that such variations are possible and within the scope of the present disclosure.

[0038] FIG. 3 is a cross-sectional view of an example Luneberg lens 115 according to the present disclosure. The example Luneberg lens 115 can be made from a series of concentric shells 305 formed around a central sphere 310. In this embodiment, each individual shell 305 has a uniform and different index of refraction. The index of refraction of each shell 305 can be predetermined according to the following relationship, where ε r is the relative permittivity, R is the radius of the lens, and r is the radial distance from a given shell 305 to the center of the sphere of the Luneberg lens 115. In an example implementation, the Luneberg lens 115 can have an outer surface radius of 200 mm and be formed from 9 shells 305 formed around the central sphere 310. The relative permittivities of these shells can be as follows:

[0039]

[0040]

[0041] The example Luneberg lens 115 described above can provide sufficient focusing for well-defined beams with minimal side lobes for the antenna 100 / 200 to operate in the frequency range of 1695 MHz to 4300 MHz using eighteen horn notch radiators 110, each having a beam width of 20 degrees. It should be appreciated that variations of the Luneberg lens 115 are possible and within the scope of the present disclosure, as described above. For example, the Luneberg lens 115 can be formed from a gradient index sphere, involving 3D printed elements supported by a three-dimensional grid scaffold, and other techniques for forming a sphere with a gradient index of refraction having a maximum refractive index at the center and a minimum refractive index at the surface.

[0042] Figure 4 is a top view along the elevation axis 120 of the antenna 100 / 200, providing a cutaway view of the different shells 305 and center sphere 310 within the dragon lens 115 and the radiator ring 105 / 205.

[0043] Figure 5 depicts an example antenna 200 with one horn notch radiator 110 transmitting RF signals at 2650 MHz. In the illustration, the active horn notch radiator is obscured by the dragon lens 115, and thus is not shown in Figure 5. The focused beam 500 is transmitted through the side of the dragon lens 115 opposite the active horn notch radiator.

[0044] The antenna 100 / 200 can operate in different configurations to provide different beam widths and different numbers of independent beams. For example, if each horn notch radiator 110 operates independently, the antenna 100 / 200 can implement eighteen different sectors, each with a 20 degree beam width that overlaps minimally. Alternatively, different combinations of adjacent horn notch radiators 110 can be fed collectively, such that the antenna 100 / 200 can have fewer sectors and a wider coverage. Depending on the feed circuitry (not shown), the antenna 100 / 200 can be dynamically reconfigured to provide different sector coverage or beam scanning. For example, the antenna 100 / 200 can be configured such that the horn notch radiators 110 can be grouped into three circular arcs, each with 6 horn notch radiators. This forms a three sector antenna, each sector having a 120 degree coverage. Similarly, the antenna 100 / 200 can be fed to operate in six 60 degree coverage sectors or twelve 30 degree coverage sectors. It should be understood that such variations are possible and within the scope of the present disclosure.

[0045] Figure 6 shows an example gain pattern 600 corresponding to six adjacent horn notch radiators 110 activated together, each with a 20 degree beam width to create a 120 degree sector. As shown, the gain pattern 600 has minimal backlobe 605 and minimal overlap 610 (fast roll-off) with adjacent sectors. The beam shaping achieved by activating adjacent horn notch radiators 110 can provide a significant improvement in beam quality and minimal inter-sector interference.

[0046] Further to this example, when multiple adjacent horn notched radiators 110 are activated, each horn notched radiator 110 can be assigned a different power level, such that horn notched radiators 110 located at the center of a cluster of adjacent horn notched radiators can be fed with greater power, and horn notched radiators 110 disposed further away from the center horn notched radiator 110 can be fed with less power. This differential powering of activated horn notched radiators 110 can help improve beamforming. It should be understood that such variations are possible and within the scope of the present disclosure.

[0047] Figures 7a and 7b illustrate an example antenna 700, which can be substantially similar to antenna 100 / 200, but which has an additional ring of radiators 705. The latitude planes of the rings of radiators 105 and 705 can be set to provide two independent elevation sectors (along the elevation axis 120) and any number of combinations of azimuth sectors (around the elevation axis 120). The rings of radiators 105 and 705 can have the same number or a different number of horn notched radiators 110, depending on the radius of the ring of radiators 705. Further, the horn notched radiators 110 can be combined such that one radiator can be paired with a corresponding radiator in the other ring, up / down, to form a combined beam with improved beamforming and sectorization along the elevation axis as well as in azimuth. This can be implemented for a single 20 degree beam, a 60 degree sector, a 120 degree sector, etc.

[0048] Further to the example illustrated in Figures 7a and 7b, the example antenna 700 can have additional rings of radiators (not shown) disposed along higher latitudes. In this embodiment, the higher along the elevation axis the ring of radiators, the less interference from horn notched radiators 110 on opposite sides of the ring of radiators, the better the performance, although there can be fewer horn notched radiators 110 on rings of radiators at higher latitudes. For example, placement of a ring higher on the top of the lens results in a larger beam tilt angle below the lens, e.g., placement of a ring 30 degrees above the equator would result in a beam tilt angle 30 degrees below the equator. Another advantage of having more rings of radiators at increased latitudes is that it enables sectorization and beamforming in two dimensions: along the elevation axis as well as in azimuth. This can enable beamforming of multiple independent beams covering the entire substantially hemispherical coverage area of the antenna 700, and can provide multi-user MIMO capability within the coverage area. Further, horn notched radiators 110 of higher latitude rings of radiators can be provided with higher power relative to corresponding horn notched radiators 110 of rings of radiators closer to the equatorial plane of the dragon lens 115.

[0049] Figures 8a and 8b illustrate exemplary antennas 800a and 800b, respectively, both of which have partial circular arc radiator rings or "circular arc configurations." Antenna 800a has a radiator "ring" 805a, which can be a one-half circular arc of the radiator ring 105 of the antenna 100 / 200. The radiator ring 805a can have nine horn notched radiators 110, or can have more or fewer horn notched radiators, depending on the minimum beam width desired. Antenna 800a can be used for deployments where the intended coverage area is limited to 180 degrees. Similarly, antenna 800b has a radiator "ring" 805b, which has a one-third circular arc of the radiator ring 105 of the antenna 100 / 200. The radiator ring 805b can have six horn notched radiators 110, or can have more or fewer horn notched radiators, depending on the minimum beam width desired. Antenna 800b can be used for deployments where the intended coverage area is limited to 120 degrees. One advantage of the antennas 800a / 800b is that the horn notched radiators 110 are not interfered with by having horn notched radiators 110 on opposite sides of the dragon's breath lens 115. This is particularly true for the antenna 800b. Interference caused by the presence of horn notched radiators 110 on opposite sides of the dragon's breath lens 115 is most noticeable along the elevation axis (orthogonal to the plane defined by the conductive plates 112 of the horn notched radiators 110 and orthogonal to the central radiation axis 135), in which case side lobes can appear above and below the central radiation axis 135 of each horn notched radiator 110. Accordingly, the antenna 800b can be the least affected by this interference.

[0050] Figure 9 illustrates an exemplary antenna 900 according to the present disclosure. The horn notched radiators 110 of the above-described radiator ring 105 / 805a / 805b radiate energy with horizontal polarization (assuming the equatorial plane 125 is oriented horizontally). The antenna 900 can be substantially similar to the antennas 100 / 200 / 800a / 800b, but with vertically oriented horn notched radiators 912 disposed on the radiator ring 105 / 805a / 805b, forming a dual-polarized radiator ring 905. The addition of the vertically oriented horn notched radiators 912 enables the antenna 900 to radiate with vertical and horizontal polarization. This can improve the link quality between the antenna 900 and a given UE (by radiating a given signal in both polarization states), and also provide additional MIMO capability for the given UE (by radiating different signals in both polarization states). In one variant, the antenna 900 can have a partial circular arc radiator ring, such that the radiator ring 905 can cover a 180-degree or 120-degree circular arc, similar to the radiator rings 805a / 805b. Since interference from the horn notched radiators 110 present on opposite sides of the dragon lens 115 can cause side lobes in a direction orthogonal to the conductive plane 112 of the vertically oriented horn notched radiators 912 and in a direction orthogonal to the central axis of radiation 135 thereof, and since the vertically oriented horn notched radiators 912 are each arranged in a plane defined by each nearest neighboring vertically oriented horn notched radiator 912, this interference can have an increased impact.

[0051] In another variant, the antenna 900 can have multiple radiator rings, similar to the antennas 700a / 700b and variants thereof, each having vertically oriented horn notched radiators 912. These multiple radiator rings 905 can span the entire 360 degrees around the dragon lens 115, or can have a partial circular arc (e.g., 180 degrees or 120 degrees, etc.). It should be appreciated that such a variant is possible and within the scope of the present disclosure.

[0052] While the example radiator rings 105 / 205 / 705 / 805a / 805b / 905 have been described as having horn notched radiators 110 spaced apart at 20 degree intervals, each having a beamwidth of 20 degrees, it should be understood that variations thereto are possible and within the scope of the present disclosure. For example, by spacing the horn notched radiators 110 closer together, there can be an opportunity to combine more beams (one per horn notched radiator 110) together to form a given sector. More specifically, as shown in FIG. 6, six horn notched radiators 110 can be combined to form a 120 degree beam having superior beam shape and fast roll-off. By reducing the spacing between the horn notched radiators 110, more horn notched radiators can be combined to form a 120 degree beam (e.g., nine instead of six horn notched radiators 110), improving beamforming. Horn notched radiators 110 spaced more closely together can increase the side lobes in the gain pattern of each horn notched radiator 110. These are typically combined in the plane defined by the radiator ring 105 / 205 / 705 / 805a / 805b / 905, but not in the direction orthogonal to that plane (e.g., up / down).

[0053] While the above example antennas as described above cover 1695 MHz to 4300 MHz, it should be understood that variations are possible and within the scope of the present disclosure. For example, the antennas 100 / 200 / 700a / 700b / 800a / 800b / 900 (hereinafter "example antennas") can be scaled to operate in different frequency ranges. For example, a dragonchel 115 having a diameter of approximately 1 meter can provide all of the above capabilities for low band (LB) frequencies.

[0054] The relationship of the dragonchel 115 diameter to the intended frequency band can be described as follows. Given a desired minimum sector beamwidth, the diameter of the dragonchel 115 determines the lower limit of the frequencies at which the example antenna can operate. For example, if the desired minimum sector beamwidth is 60 degrees, one of two approaches is possible. First, if the diameter of the dragonchel 115 is fixed, there is a minimum frequency at which a single horn notched radiator 110 will provide a 60 degree beamwidth. In this case, there can be no opportunity for beamforming, as the sector beamwidth is completely defined by the single horn notched radiator 110. Second, if the minimum frequency is fixed, the diameter of the dragonchel 115 can be defined such that the beamwidth of a single horn notched radiator 110 is 60 degrees. Accordingly, if the lower limit of the required frequency range and the minimum sector beamwidth are known, the diameter of the dragonchel 115 can be set to the minimum diameter that satisfies these requirements.

[0055] While the diameter of the Luneberg lens 115 dictates the minimum operating frequency of the example antenna, the maximum operating frequency of the example antenna is determined by the integration of the Luneberg lens 115. For example, the example antenna is configured to operate in a frequency range of 1695 MHz to 4300 MHz. Depending on the horn notch radiators 110 employed, the maximum frequency of the example antenna can extend into the millimeter wave band. As the frequency increases, the beamwidth of each individual horn notch radiator 110 tightens into a narrower beam. The high end of the operating frequency is limited by the integration of the Luneberg lens 115, such that the higher the frequency, the more continuous and fine the index of refraction gradient needs to be. Accordingly, a Luneberg lens 115 composed of a series of concentric shells as described with respect to FIGS. 3 and 4 can not provide sufficient resolution to adequately focus high frequency beams. In such a case, a Luneberg lens 115 with a more finely grained index of refraction gradient can be required.

[0056] The example antenna can be scaled accordingly for different frequency ranges. For example, for an antenna operating at 24 GHz to 30 GHz, the example diameter of the Luneberg lens 115 can be between 25 mm to 50 mm if it is intended to use eighteen elements each with a 20 degree beamwidth. If a narrow beamwidth is desired, the diameter can be greater than 50 mm.

[0057] The example antenna described above generally refers to a wideband antenna. Wideband performance is typically achieved through the use of horn notch radiators 110. However, variations for narrowband antennas are also possible. In such a case, radiators other than horn notch radiators can be used, so long as the narrowband radiators have a radiating surface or edge that can abut the outer surface of the Luneberg lens 115. One example of this can include a log periodic radiator, such as a printed circuit log periodic radiator. Patch radiators can be used, though the angular range of the patch abutting the outer surface of the Luneberg lens 115 can inhibit the focusing action of the lens, resulting in a less than ideal beam shape.

[0058] While various embodiments of the present application have been described above, it should be understood that they have been presented by way of example only, and not limitation. None of the steps described need to be performed in the exact order described, nor need all of the steps be performed, to achieve desirable results. The various embodiments described can be combined in a variety of ways. Accordingly, the breadth and scope of the present application should not be limited by any of the above described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

1. An antenna comprising: a spherically symmetric gradient-index lens; and a first plurality of horn notched radiators disposed in a first circular arc configuration around the spherically symmetric gradient-index lens, each of the first plurality of horn notched radiators having a traveling wave slot defining a central radiation axis pointing towards a center of the spherically symmetric gradient-index lens and a front edge on either side of the traveling wave slot, wherein each front edge is in contact with an outer surface of the spherically symmetric gradient-index lens.

2. The antenna of claim 1, wherein the first circular arc configuration is disposed along an equatorial plane of the spherically symmetric gradient-index lens.

3. The antenna of claim 1, wherein the first circular arc configuration is disposed along a latitude plane of the spherically symmetric gradient-index lens.

4. The antenna of claim 3, wherein the latitude plane is at a latitude of 4 degrees.

5. The antenna of claim 3, wherein the latitude plane is at a latitude of 10 degrees.

6. The antenna of claim 1, wherein the first circular arc configuration comprises a 360 degree circular arc around an elevation axis of the spherically symmetric gradient-index lens.

7. The antenna of claim 6, wherein the first plurality of horn notched radiators comprises eighteen horn notched radiators.

8. The antenna of claim 1, wherein the first circular arc configuration comprises a 180 degree circular arc around an elevation axis of the spherically symmetric gradient-index lens.

9. The antenna of claim 8, wherein the first plurality of horn notched radiators comprises nine horn notched radiators.

10. The antenna of claim 1, wherein the first circular arc configuration comprises a 120 degree circular arc around an elevation axis of the spherically symmetric gradient-index lens.

11. The antenna of claim 10, wherein the first plurality of horn notched radiators comprises six horn notched radiators.

12. The antenna of claim 2, wherein each of the first plurality of horn notched radiators comprises a conductive plate having an edge, wherein the conductive plate contacts the spherically symmetric gradient-index lens along the edge parallel to the equatorial plane.

13. The antenna of claim 12, further comprising a second plurality of radiators disposed on the first circular arc configuration, each of the second plurality of radiators having a central radiation axis pointing towards a center of the spherically symmetric gradient-index lens, and each of the second plurality of radiators having a plane orthogonal to a conductive plane of a corresponding radiator of the first plurality of horn notched radiators.

14. The antenna of claim 3, further comprising a second plurality of radiators disposed in a second circular arc configuration around the spherically symmetric gradient-index lens, the second circular arc configuration disposed along a second latitude plane of the spherically symmetric gradient-index lens, each of the second plurality of radiators having a central radiation axis pointing towards a center of the spherically symmetric gradient-index lens.

15. The antenna of claim 1, wherein the first plurality of horn-shaped notched radiators comprises adjacent subsets of radiators coupled to a single RF feed.

16. The antenna of claim 15, wherein adjacent subsets of the radiators comprise: one or more center radiators of the subset of radiators; and two or more peripheral radiators of the subset of radiators, wherein the peripheral radiators are fed with signals attenuated relative to respective signals fed to the one or more center radiators.

17. The antenna of claim 1, wherein a diameter of the spherically symmetric gradient index lens is proportional to a minimum operating frequency of the antenna and a minimum sector beamwidth.

18. The antenna of claim 1, wherein the radiators are configured at 20 degrees.

19. The antenna of claim 1, wherein the radiators are spaced less than 20 degrees apart.

20. The antenna of claim 1, wherein the spherically symmetric gradient index lens is a Dragon Lens having a 1 m diameter.

21. The antenna of claim 1, wherein the spherically symmetric gradient index lens is a Dragon Lens having a diameter related to an operating frequency of the radiators.

22. The antenna of claim 1, wherein the spherically symmetric gradient index lens is a Dragon Lens having a fixed diameter.

23. A method of manipulating the antenna of claim 1, the method comprising: activating at least one of the radiators with RF power.

24. The method of claim 23, wherein activating comprises activating those radiators adjacent to the radiators with a common RF power.

25. The method of claim 23, wherein activating comprises activating those radiators adjacent to the radiators with different RF power levels.

26. A method of activating the antenna of claim 14, wherein the radiators of the first circular arc are activated with a different RF power level than the radiators of the second circular arc.

27. A method of activating the antenna of claim 14, wherein the radiators of the first circular arc and the radiators of the second circular arc are collectively powered to form a combined beam.

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