Antenna with uniform radiation for ultra-wide bandwidth

Abstract

An antenna element includes an outer conductor and an inner conductor. The outer conductor forms a perimeter of the antenna element. The inner conductor is physically and electrically connected to the outer conductor only at an intermediate connection at an inner portion of the outer conductor. The outer conductor and the inner conductor are arranged to form a slot therebetween. The slot extends around the inner conductor such that each end of the slot is adjacent to the intermediate connection.

Claims

1. An antenna element, comprising an outer conductor forming a perimeter of the antenna element; an inner conductor physically and electrically connected to the outer conductor only at an intermediate connection at an inner portion of the outer conductor; and a planar portion that at least forms the perimeter of the antenna element, and a protruding section that protrudes from the planar portion, wherein the outer conductor and the inner conductor are arranged to form a slot therebetween, the slot extends around the inner conductor such that each end of the slot is adjacent to the intermediate connection, and the protruding section includes a dome shape, the inner conductor includes a feed point adapted to receive an electrical connection distal to the intermediate connection, and the intermediate connection is adpated to be angled towards a ground plane due to the dome shape of the protruding section.

2. The antenna element of claim 1, wherein the inner conductor includes a feed point adapted to receive an electrical connection distal to the intermediate connection.

3. The antenna element of claim 1, wherein the perimeter of the outer conductor includes a cylindrical shape.

4. The antenna element of claim 1, wherein the perimeter of the antenna element is within ten percent of a wavelength from half of the wavelength that the antenna element is adapted to receive.

5. The antenna element of claim 1, wherein the slot meanders on each side of the inner conductor such that the slot includes a length that is within ten percent of a wavelength from half of the wavelength that the antenna element is adapted to receive.

6. The antenna element of claim 1, further comprising circuitry configured to cause operation of the antenna element with a substantially uniform radiation pattern.

7. The antenna element of claim 1, wherein the circuitry is configured to utilize the antenna element to determine a distance to a device.

8. An electronic device, comprising circuitry communicatively coupled to an antenna element, wherein the antenna element includes an outer conductor forming a perimeter of the antenna element; an inner conductor physically and electrically connected to the outer conductor only at an intermediate connection at an inner portion of the outer conductor; and a planar portion that at least forms the perimeter of the antenna element, and a protruding section that protrudes from the planar portion, wherein the outer conductor and the inner conductor are arranged to form a slot therebetween, the slot extends around the inner conductor such that each end of the slot is adjacent to the intermediate connection, and the protruding section includes a dome shape, the inner conductor includes a feed point adapted to receive an electrical connection distal to the intermediate connection, and the intermediate connection is adapted to be angled towards a ground plane due to the dome shape of the protruding section.

9. The electronic device of claim 8, wherein the inner conductor includes a feed point adapted to receive an electrical connection distal to the intermediate connection.

10. The electronic device of claim 8, wherein the perimeter of the outer conductor includes a cylindrical shape.

11. The electronic device of claim 8, wherein the perimeter of the antenna element is within ten percent of a wavelength from half of the wavelength that the antenna element is adapted to receive.

12. The electronic device of claim 8, wherein the slot meanders on each side of the inner conductor such that the slot includes a length that is within ten percent of a wavelength from half of the wavelength that the antenna element is adapted to receive.

13. The electronic device of claim 8, wherein the circuitry is configured to cause operation of the antenna element with a substantially uniform radiation pattern.

14. The electronic device of claim 8, wherein the circuitry is configured to utilize the antenna element to determine a distance to another device.

15. A method comprising providing an antenna element that includes: an outer conductor forming a perimeter of the antenna element; an inner conductor physically and electrically connected to the outer conductor only at an intermediate connection at an inner portion of the outer conductor; and a planar portion that at least forms the perimeter of the antenna element, and a protruding section that protrudes from the planar portion, wherein the outer conductor and the inner conductor are arranged to form a slot therebetween, the slot extends around the inner conductor such that each end of the slot is adjacent to the intermediate connection, and the protruding section includes a dome shape, the inner conductor includes a feed point adapted to receive an electrical connection distal to the intermediate connection, and the intermediate connection is adapted to be angled towards a ground plane due to the dome shape of the protruding section.

16. The method of claim 15, wherein the inner conductor includes a feed point adapted to receive an electrical connection distal to the intermediate connection.

17. The method of claim 15, wherein the perimeter of the outer conductor includes a cylindrical shape.

18. The method of claim 15, wherein the perimeter of the antenna element is within ten percent of a wavelength from half of the wavelength that the antenna element is adapted to receive.

19. The method of claim 15, wherein the slot meanders on each side of the inner conductor such that the slot includes a length that is within ten percent of a wavelength from half of the wavelength that the antenna element is adapted to receive.

20. The method of claim 15, further comprising operating the antenna element with a substantially uniform radiation pattern.

21. The method of claim 15, further comprising utilizing the antenna element to determine a distance to a device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present disclosure is illustrated and described herein with reference to the various drawings, in which like reference numbers are used to denote like system components/method steps, as appropriate, and in which:

(2) FIG. 1 is a schematic illustration of a first UWB device, positioned relative to a second UWB device and a third UWB device, with a polar plot illustrating a typical radiation pattern relative to the first antenna of the first UWB device;

(3) FIG. 2 is a schematic illustration of a first UWB device, positioned relative to a second UWB device and a third UWB device, with a polar plot illustrating an optimal radiation pattern relative to the first antenna of the first UWB device;

(4) FIG. 3 is a perspective diagram of a slotted patch antenna;

(5) FIG. 4 is a perspective diagram of the slotted patch antenna of FIG. 3 from an alternate view;

(6) FIG. 5 is a side perspective diagram of the slotted patch antenna of FIGS. 3-4;

(7) FIG. 6 is a top perspective diagram of the slotted patch antenna of FIGS. 3-5;

(8) FIG. 7 is a perspective diagram of an embodiment of a single slotted patch antenna of FIGS. 3-6 connected to a mounting bracket;

(9) FIG. 8 is a perspective diagram of an embodiment of two slotted patch antenna of FIGS. 3-6 connected to a mounting bracket;

(10) FIG. 9 is a schematic illustration and representation of the currents flowing in the slotted patch antenna of FIGS. 3-6;

(11) FIG. 10 is a schematic illustration and representation of the voltages of the slotted patch antenna of FIGS. 3-6;

(12) FIG. 11 is a schematic illustration and representation of the currents flowing, the voltages across the slot, and the equivalent magnetic currents of the slotted patch antenna of FIGS. 3-6;

(13) FIG. 12 is a schematic illustration and representation of the resulting radiation patterns from the currents and voltages of the slotted patch antenna of FIGS. 3-6;

(14) FIG. 13 is a polar plot illustrating a comparison of a radiation pattern for an embodiment of the slotted patch antenna and a radiation pattern for a classical IFA antenna; and

(15) FIG. 14 is a Cartesian plot of the comparison of FIG. 13.

DETAILED DESCRIPTION OF THE DISCLOSURE

(16) In various embodiments, the present disclosure relates to systems and methods for generating a uniform radiation pattern with a slotted patch antenna. The slotted patch antenna includes vertical short walls that position the slotted patch antenna above the ground plane and mechanically support the antenna element. The antenna element includes a long slot that separates an outer conducting element from an inner conducting element except at an intermediate connection between the outer and inner conducting elements that is distal to a feed point on the inner conductor. The outer and inner conducting elements and the slot therebetween are adapted to generate two complementary radiation sources that are orthogonal to each other such that the two radiation sources compensate for dips in the radiation pattern of the other radiation source, which results in a more uniform overall radiation pattern of the slotted patch antenna.

(17) FIG. 3 is a perspective diagram of a slotted patch antenna 100. FIG. 4 is a perspective diagram of the slotted patch antenna 100 of FIG. 3 from an alternate view. FIG. 5 is a side perspective diagram of the slotted patch antenna 100 of FIGS. 3-4. FIG. 6 is a top perspective diagram of the slotted patch antenna 100 of FIGS. 3-5. Referring to FIGS. 3-6, the slotted patch antenna 100 includes short walls 110 and an antenna element 120. The short walls 110 are adapted to physically and electronically connect the antenna element 120 to a ground plane 105 and are adapted to act as vertical grounding walls/pins. The short walls 110 provide matching vias adding shunt inductance to the ground. As shown in FIG. 4, the short walls 110 are adapted to maintain a gap 115 between the antenna element 120 and the ground plane 105. In embodiments, the short walls 110 are adapted such that the gap 115 is smaller than at least one of a length, width, and height of the antenna element 120 so that the slotted patch antenna 100 has a low profile relative to the ground plane 105. In the embodiment illustrated, the slotted patch antenna 100 includes two short walls 110 positioned on the same side of the antenna element 120 and are spaced apart. In some embodiments, the gap 115 is from 1-2 millimeters.

(18) In some embodiments, the short walls 110 are vias that extend through a Printed Circuit Board (“PCB”) to the ground plane 105 at the bottom of the PCB, allowing the antenna element 120 to rest on the dielectric material.

(19) The antenna element 120 includes an outer conductor 122, an inner conductor 124, and a slot 125. The outer conductor 122 is adapted to form a perimeter of the antenna element 120 (this length is the fully enclosed perimeter, including across the slot, between the short walls 110). In embodiments, the perimeter has a length of approximately half of the wavelength that the antenna element 120 is configured to receive.

(20) In some embodiments, the perimeter of the antenna element 120 is within ten percent of the wavelength from half of the wavelength, such as from forty percent to 60 percent of the wavelength. For example, a UWB channel is centered at 6.5 GHz, where the wavelength in free space is approximately 46 millimeters. In these embodiments, the perimeter is within ten percent of half of 46 millimeters, or in other words, within plus or minus 4.6 millimeters of 23 millimeters. In one embodiment, the perimeter is 27 millimeters.

(21) In some embodiments, the perimeter is within 5 millimeters of half of the wavelength. In the embodiment illustrated, the perimeter includes a circular shape, such as a cylindrical shape. In some embodiments, the cylindrical shape includes a radius from 3 millimeters to 4.5 millimeters.

(22) The outer conductor 122 connects to the short walls 110. In embodiments, the outer conductor 122 includes two adjacent ends on the same side of the antenna element 120, each connected to a short wall 110. The outer conductor 122 then extends around the inner conductor 124, forming the perimeter of the antenna element, while maintaining a gap directly between the two adjacent ends. In embodiments with the circular/cylindrical shape, the circular/cylindrical shape is formed with an opening opposite the intermediate connection 123.

(23) The inner conductor 124 physically and electrically connects to the outer conductor 122 at an intermediate connection 123 that is at an inner portion of the outer conductor 122 and a side of the antenna element 120 opposite the short walls 110. The inner conductor 124 extends from the intermediate connection 123 generally toward the short walls to a feed point 126 that is proximal to the short walls 110 and distal to the intermediate connection 123. In embodiments, the feed point 126 is positioned between the ends of the outer conductor 122 that are connected to the short walls 110. In embodiments with the circular/cylindrical shape, the feed point 126 is positioned between the ends defining the opening therein.

(24) The inner conductor 124 and the outer conductor 122 are adapted to form a slot 125 therebetween. Referring to FIG. 6, the ends of the slot 125 are each adjacent to the intermediate connection 123, and the slot 125 extends from one end of the slot 125, along the inner conductor 124, around the feed point 126, and back along the inner conductor 124 to the other end of the slot 125. While the slot 125 appears to be open between the ends of the outer conductor 122 and the short walls 110, the slot 125 can be considered enclosed by short walls 110 and the ground plane 105 at that end of the antenna element 120, which provides continuity of conductive material, such as metal, around the entire slot structure.

(25) In embodiments, the slot 125 meanders to increase a length of the slot 125, such that each half of the slot, extending along each side of the inner conductor 124, has a length longer than at least one of a length and a width of the antenna element 120. In the embodiment illustrated, each half of the slot 125 is longer than a diameter of the cylindrical shape of the perimeter of the outer conductor 122. In some embodiments, the length of the slot 125, measured from one end of the slot 125 adjacent to the intermediate connection around the inner conductor to the other end of the slot 125 adjacent to the intermediate connection 123, is approximately half of the wavelength that the antenna element 120 is configured to receive.

(26) In some embodiments, the length of the slot 125 of the antenna element 120 is within ten percent of the wavelength from half of the wavelength, such as from forty percent to 60 percent of the wavelength. For example, a UWB channel is centered at 6.5 GHz, where the wavelength in free space is approximately 46 millimeters. In these embodiments, the length of the slot 125 is within ten percent of half of 46 millimeters, or in other words, within plus or minus 4.6 millimeters of 23 millimeters. In one embodiment, the length of the slot is 20 millimeters. In some embodiments, the length of the slot 125 is within 5 millimeters of half the wavelength.

(27) In embodiments, the meandering path is in the form of one or more curves that benefit the radiation pattern. In the embodiment illustrated, the slot 125 is symmetrical, with each half of the slot 125 circumferentially diverging from the intermediate connection 123 before converging towards the other half of the slot 125, after which each half of the slot 125 extends parallel to the other towards the feed point 126 and the short walls 110. This meandering results in an inner conductor with a thicker, semicircular/wedge-like shape adjoining the intermediate connection with a stem-like shape extending therefrom and to the feed point 126. As discussed in greater detail below, the meandering slot 125 produces an approximate of a magnetic dipole that is orthogonal to an approximate electric monopole produced by the antenna element 120.

(28) A width of the slot 125 is selected to control a voltage across the slot 125. In embodiments, a width of the slot 125 is less than a width of the portion of the inner conductor 124 with the stem-like shape. In embodiments, the slot 125 is narrow relative to the length and width of the antenna element 120. In some embodiments, the slot is approximately 1 millimeter, such as within a predetermined tolerance of 1 millimeter. However, other widths are also contemplated. As the slot 125 is relatively narrow, the bandwidth resulting therefrom is sufficient, the mechanical integrity of the antenna element 120 is maintained, and the resulting volume of the antenna element 120 is minimized.

(29) The antenna element 120 includes a plate-like shape. In embodiments, the plate-like shape is one of a flat plate and a planar portion 128 with a protruding section 129 therein. In some embodiments, the protruding section 129 raises away from the ground plane 105, and in other embodiments, the protruding section 129 lowers towards the ground plane 105. In the embodiment illustrated in FIGS. 3-6, the protruding section 129 includes a dome shape, such as a hollow spherical cap and hollow hemisphere, with the planar portion 128 at the base thereof, where the planar portion 128 includes an annular shape, such as a hollow right circular cylinder. As a minimum portion section of the radiation pattern can result due to the direction that the protruding section 129 extends, the direction of the protruding section 129 extending away from or towards the ground plane 105 may be selected based off of a direction in which a dip in the radiation pattern can be tolerated the most.

(30) In some embodiments, a maximum height 127 of the protruding section 129 relative to the planar portion 128 is from 1/15 to 1/10 of the wavelength, such as from 3 millimeters to 5 millimeters.

(31) In embodiments, the slot 125 extends primarily within the protruding section 129, such that the outer conductor 122 includes the planar portion 128 and outer portions of the protruding section 129, while the inner conductor 124 primarily includes an inner portion of the protruding section 129.

(32) In the embodiment illustrated in FIGS. 3-6, the slotted patch antenna 100, including the short walls 110 and the antenna element 120, is a unitary structure that is a single structurally formed entity. In embodiments, the slotted patch antenna 100 is stamped sheet metal. In other embodiments, the slotted patch antenna 100 is cast.

(33) In further embodiments, the slotted patch antenna 100 is integrated into a PCB. In particular, the antenna element 120 is planar and printed on a PCB. In some embodiments, the antenna element 120 is formed using traces on top of the PCB. With ground at a backside of the PCB, the short walls 110 are vias extending through the PCB to the ground. In some embodiments, the slot 125 and the perimeter are defined by printed shapes on the surface of the PCB. In some embodiments, multiple antenna elements 120 are printed on the PCB, each being connected to the ground by short walls 110 that are vias.

(34) In yet further embodiments, the slotted patch antenna 100 is printed on a carrier with metalized plastic, such as LDS, printed metal on plastic, and a metal pattern on a flex material. The antenna element 120 and the carrier are mounted as a unit to a device.

(35) FIG. 7 is a perspective diagram of an embodiment of a single slotted patch antenna 100 of FIGS. 3-6 connected to a mounting bracket. FIG. 8 is a perspective diagram of an embodiment of two slotted patch antennas 100 of FIGS. 3-6 connected to a mounting bracket. Referring to FIGS. 7 and 8, one or more single slotted patch antennas 100 can be connected to a mounting bracket, where the mounting bracket is a ground plane 105.

(36) In the embodiments illustrated in FIGS. 7 and 8, the mounting bracket includes bracket arms 104 that connect the short walls 110 to the mounting bracket. The mounting bracket also includes first bores 106 and second bores 108 for securing the mounting bracket within an electronic device. The first and second bores 106 and 108 can be formed in a body of the mounting bracket, separate bracket supports 107, and the like. In some embodiments, the mounting bracket also includes clips 109 for securing the slotted patch antennas 100 in place within the electronic device.

(37) In embodiments with two or more slotted patch antennas 100, an angle of arrival and relative phases can be determined, and in embodiments with at least three slotted patch antennas 100, a position of an electronic device sending the signal can be determined using triangulation. The spacing between the multiple slotted patch antennas 100 is selected to work across a full range of UWB frequencies. In some embodiments, the spacing between multiple slotted patch antennas 100 is different such that good spacing for varying UWB frequencies is achieved. In embodiments with multiple slotted patch antennas 100, the antenna elements 120 are positioned within a device with known distances and angles therebetween for finding relative phases and angles of incoming signals from other devices.

(38) Again, the structure of the slotted patch antenna 100 is formed such that two complimentary radiation sources are generated. The two complimentary radiation sources are orthogonal to each other such that the two radiation sources compensate for dips in the radiation pattern of the other radiation source to generate a more uniform overall radiation pattern of the slotted patch antenna 100.

(39) FIG. 9 is a schematic illustration and representation of the currents 93, 94 flowing in the slotted patch antenna 100 of FIGS. 3-6. The current flows in FIG. 9 are illustrated with arrows where the larger arrows are the stronger electric currents. Referring to FIG. 9, most of the electric currents and the strongest electric currents flow from the electric feed 91 and ground 92 towards an opposing end of the slotted patch antenna, the opposing end including the intermediate connection 123. The strong electric currents across the inner conductor 124 and around an edge of the outer conductor 122 are a first source of radiation. As illustrated in FIG. 9, the first source of radiation flowing in a direction from the electric feed 91 and ground 92 have a similar flow to that of an electric monopole 80. Furthermore, in embodiments with a protruding section 129, such as with a domed shape, currents at the end of the inner conductor 124 and traversing the intermediate connection 123 are moving at least partially towards the ground plate 105. As the radiation patterns of monopoles and dipoles can be weak in the direction of the current flow, bending the current towards the ground tilts a weak portion of the radiation towards the ground, which results in a more uniform pattern of the overall radiation pattern.

(40) FIG. 10 is a schematic illustration and representation of the voltages 95, 96, 97 of the slotted patch antenna of FIGS. 3-6. FIG. 11 is a schematic illustration and representation of the currents 93, 94 flowing, the voltages 95, 96 across the slot, and the equivalent magnetic currents 98 of the slotted patch antenna 100 of FIGS. 3-6. Referring to FIGS. 10 and 11, the currents 93, 94 flowing around the slot form a voltage 95, 96 across the slot 125 with the maximum voltage 95 adjoining the feed point 126, while the minimum voltage 96 adjoins the intermediate connection 123, which produces a second source of radiation. Note that a fringe field voltage 97 is also created between the ground plane 105 and the perimeter of the antenna element 120, which contributes to the radiation.

(41) With the currents 93, 94 flowing around the slot 125, an equivalent magnetic current 98 is produced that is the equivalent to a magnetic dipole 83. FIG. 12 is a schematic illustration and representation of the resulting electric fields from the approximations of the electric monopole 80 and the magnetic dipole 83 produced from the currents 93, 94 and voltages 95, 96, 97 of the slotted patch antenna 100 of FIGS. 3-6. As illustrated in FIG. 12, the approximated electric monopole 80 resulting from the electric currents flowing across the slotted patch antenna 100 has a minimum electric field 82 in the direction of the approximated electric monopole 80, with a maximum electric field orthogonal thereto. Complementarily, the approximated magnetic dipole 83 is orthogonal to the approximated electric monopole 80 and has a minimum electric field 85 in the direction thereof, and a maximum electric field 86 orthogonal thereto. Thus, the two sources are complementary due to the radiation pattern resulting from the combined electric fields that result from the orthogonal nature of the maximum electric fields 81 and 84, which results in a combined electric field that is more uniform in all angular directions.

(42) Thus, since the inner conductor 124, the edge of the outer conductor 122, and the slot 125 each radiate, and the resulting patterns are orthogonal, the inner conductor 124 and edge of the outer conductor 122 compensate for the dips in the radiation pattern produced by the slot 125 and vice versa.

(43) FIG. 13 is a polar plot 70 illustrating a comparison of a radiation pattern 72 for an embodiment of the slotted patch antenna 100 and a radiation pattern 73 for a classical IFA antenna. FIG. 14 is a Cartesian plot 71 of the comparison of FIG. 13. As shown in FIGS. 13 and 14, the radiation pattern 72 for the embodiment of the slotted patch antenna 100 has a generally uniform radiation pattern with a variation range that is only about 6 dB. In contrast, the classical IFA antenna has a non-uniform radiation pattern with a variation range that is significantly larger, at about 20 dB.

(44) With a generally uniform pattern in all angular directions, such as the radiation pattern 72 illustrated in FIGS. 13 and 14, a more accurate determination of a distance a device is from an electronic device with one or more slotted patch antennas and a more accurate determination of whether a device (and therefore the user) is moving towards or moving away from the electronic device that includes the one or more slotted patch antennas 100, no matter the angular direction is achievable. Further, with multiple slotted patch antennas 100, triangulation can be used to track a device within range thereof. Such tracking can be used to track the location of the device, movement of the device, identify devices that are coming/going from the location, and the like. Indeed, the more uniform the radiation pattern, the more accurately each of the above can be determined. Such tracking can be used for wellness, such as ensuring the elderly is moving, not on the floor (such as detecting that the device is on the floor) and still at the location, energy management (based on a number of devices detected and the location of those devices), and security, such as turning alarms on/off, detecting whether an unknown person is approaching, identifying the person approaching, which direction a person is approaching from, and the like.

(45) Although the present disclosure has been illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples may perform similar functions and/or achieve like results. All such equivalent embodiments and examples are within the spirit and scope of the present disclosure, are contemplated thereby, and are intended to be covered by the following claims.