SURFACE MOUNTED BROADBAND ELEMENT

Abstract

The disclosed subject matter concerns an antenna which comprises a ground plane and at least a first and a second antenna element. Each antenna element comprises a feed point, a cavity, a main body, a tip and at least a first tapered portion and a second tapered portion. Each antenna element is arranged on the ground plane, where said first and second tapered portions extend along the antenna element from said tip towards the ground plane of the antenna element, and where each antenna element extends essentially perpendicularly to said ground plane along a centre axis of the antenna element. Each antenna element has at least a first leg and a second leg, where said first leg extends from said main body to the first feed point, where said feed point is located between the first leg and the ground plane, and where said second leg extends from said main body to the ground plane, and where said second leg is electrically connected to the ground plane.

Claims

1. An antenna comprising a ground plane and at least a first and a second antenna element, where each antenna element comprises a feed point, a cavity, a main body, a tip and at least a first tapered portion and a second tapered portion, where each antenna element is arranged on the ground plane, where said first and second tapered portions extend along the antenna element from said tip towards said ground plane of the antenna element, and where each antenna element extends essentially perpendicularly to said ground plane along a centre axis of the antenna element, where each antenna element has at least a first leg and a second leg, where said first leg extends from said main body to the first feed point, where said feed point is located between the first leg and the ground plane, and where said second leg extends from said main body to the ground plane, and where said second leg is electrically connected to the ground plane, where said main body and said first and second legs of each antenna element have a predefined thickness, where said cavity of each antenna element is formed in a space between said first and second legs, said main body and said ground plane of said antenna element, where the first and second antenna elements of the antenna are arranged in a first plane extending through the centre axes of said first and second antenna elements and adjacent each other such that a tapered slot is formed between the first tapered portion of the first antenna element and the second tapered portion of the second antenna element, and where said tapered slot tapers to said feed point.

2. An antenna according to claim 1, further comprising at least a further third and a fourth antenna element said third and fourth antenna elements corresponding to the first and second antenna elements, where the third antenna element is arranged such that the centre axis of the first antenna element is aligned with the centre axis of the third antenna element, whereby said first antenna element and said third antenna element form a dual-polarized antenna element, and where said third and fourth antenna elements are arranged in a second plane essentially perpendicular to the first plane and adjacent each other such that a tapered slot is formed between the first tapered portion of the third antenna element and the second tapered portion of the fourth antenna element.

3. Antenna according to claim 2, where said third antenna element is integral with said first antenna element to form the dual-polarized antenna element.

4. Antenna according to claim 3, where the main body of said first antenna element and said third antenna element of the dual-polarized antenna element together forms a tapered cone, and where the sum of the legs of the first antenna element and the third antenna element is at least four.

5. Antenna according to claim 1, further comprising a circuit board where one side of the circuit board constitutes the ground plane, and where the opposite side of the circuit board is equipped with at least one additional electrical component.

6. Antenna according to claim 5, where said circuit board is equipped with a via hole at the at least first feed point, where said via hole is running through said circuit board enabling an electrical connection of the feed point to an electrical component located on the opposite side of the circuit board.

7. Antenna according to claim 1, where said ground plane is equipped with a through-hole, in which a connector is arranged, where said feed point is connected to a centre conductor of said connector.

8. Antenna according to claim 1, where said antenna elements are manufactured by punching or milling a metal plate.

9. Antenna according to claim 1, where said antenna elements are manufactured by casting.

10. Antenna according to claim 1, where said antenna element is assembled to said ground plane using surface mount technology (SMT).

11. Antenna according to claim 1, where said antenna is assembled onto a printed-circuit board (PCB).

12. Antenna according to claim 1, where said antenna element is manufactured from a metallized plastic.

13. Antenna according to claim 1, where the tapered sections are formed in stepped sections.

14. Antenna according to claim 1, where the shape of said cavity is rounded.

15. Antenna according to claim 1, where the shape of said cavity is rectangular.

16. Antenna array comprising a plurality of antennas consisting of dual-polarised antenna elements according to claim 2.

17. Radar system comprising an antenna array according to claim 16.

18. Electronic warfare system comprising an antenna array according to claim 16.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 shows a side view of an antenna comprising a first and second antenna element according to the invention,

[0024] FIG. 2 shows a perspective view of a dual-polarized antenna element according to the invention,

[0025] FIG. 3 shows a perspective view of a dual-polarized antenna according to the invention, and

[0026] FIG. 4 shows a perspective view of an antenna array according to the invention.

DETAILED DESCRIPTION

[0027] Various aspects of the invention will hereinafter be described in conjunction with the appended drawings to illustrate and not to limit the invention, wherein like designations denote like elements, and variations of the described aspects are not restricted to the specifically shown embodiment, but are applicable on other variations of the invention.

[0028] FIG. 1 shows a side view of an antenna 10 according to the invention. The antenna comprises a first antenna element 11, and a second antenna element 12. The antenna further comprises a ground plane 15 on which the first and second antenna elements 11, 12 are arranged. Each antenna element has a centre axis 50 along which each respective antenna element extend perpendicular to said ground plane. Each of the first and second antenna elements 11, 12 comprise a tip 23 located at the end of the antenna element 11, 12 located farthest away from the ground plane 15. Each antenna element 11, 12 also comprise a main body 20 and a first tapered portion 21 and a second tapered portion 22. The antenna elements 11, 12 are substantially flat, with a predetermined thickness. The antenna elements are arranged in a first plane 51 extending through the centre axes 50 of each of the first and second antenna elements 11, 12. Each antenna element has a first leg 31 and a second leg 32. The legs 31, 32 are essentially integral with the main body of the antenna element. Each antenna element comprises a feed point 16 located between the ground plane and the first leg. The second leg is electrically connected to the ground plane. The first tapered portion extends from the tip of the antenna element along a side of the element to the end of the first leg at the feed point. The second tapered portion extends from the tip of the antenna element along a side of the element and along the second leg. In FIG. 1 the second tapered portion extends from the tip to the ground plane. Alternatively, the second tapered portion may end at a position on the second leg at the same distance from the ground plane as the distance between the first leg and the ground plane. In this case, the second leg is perpendicular for the remaining extension to the ground plane.

[0029] The first and second antenna elements 11, 12 are arranged adjacent to each other, such that a tapered slot 18 is formed between the first tapered portion 21 of the first antenna element 11 and the second tapered portion 22 of the second antenna element 12. Together, the first and second antenna elements 11, 12 thus form an antenna 10 capable of transmitting and/or receiving radio waves. Placing additional elements in series allows the forming of an antenna array 70 with a large number of antennas, where, in the same manner as the first and second elements, adjacent antenna elements form antennas. These antennas may then be arranged to transmit/receive on different amplitude and/or with different phase. While each antenna element has a feed point 16, the feed point of the antenna is in this case the feed point of the first antenna element 11. Should an additional antenna element be placed adjacent to the second antenna element 12 in the first plane on the opposite side from that of the first antenna element, the feed point of the second antenna element would be the feed point of the antenna formed by the tapered slot 18 between the additional antenna element and the second antenna element.

[0030] The feed point 16 is the electrical point which feeds the radio waves to the antenna 10 when transmitting or receiving the incoming radio waves incoming into the antenna. The antenna further comprises a circuit board 60 where one side of said circuit board constitutes the ground plane 15. The opposite side of the circuit board is equipped with electrical components 61. A via hole 62 runs through the circuit board providing an electrical connection between the feed point and an electrical component located on the opposite side of the circuit board. The immediate area surrounding the via hole is etched out such that there is no electrical contact between the ground plane and the via hole. The feed point is thus electrically connected to the components using the via hole in order to perform said transmitting or receiving of radio waves. It should be noted that a multi-layer circuit board could be used, and the via hole may be in connection with a layer.

[0031] Optionally, the ground plane 15 could be a solid metallic sheet with a connector arranged in a through-hole. The first leg 31 of the antenna element is then connected to this connector.

[0032] The antenna elements 11, 12, 13, 14 are produced using any of a multitude of suitable materials or methods. The elements can be metallic, metallized plastic or even plastic with metal strips arranged in suitable places. The method of production chosen may depend on the material used, but moulding, casting, milling or punching are examples of viable options. Laser or water cutting are also viable methods of production.

[0033] The details of the size of the antenna elements 11, 12, 13, 14 are subject to variations depending on the frequency band they are designed for. In general the width of the antenna elements (i.e. the extension in the first plane 51) is about λ/2, the length of the antenna elements (i.e. the extension along the centre line 50) varies from about λ/2 to several integer multiples of λ depending on the bandwidth. The thickness of each antenna element varies by the required impedance, but the values are usually smaller than λ/10.

[0034] While the cavity 17 shown in FIG. 1 is of a rectangular shape, a plurality of shapes are possible for the cavity as long as the shape of the cavity confers electromagnetic wave properties of the antenna 10 which allow for operation of said antenna. The cavity may for instance be rounded in shape or polygonal. One special case is where the cavity is shaped as a stub line, wherein the cavity is a narrow slotline, preferably with the same width as the distance between the first leg 31 and the ground plane 15. The stub line or slotline cavity then extends for a length along the ground plane about a quarter lambda or λ/4. The stub line or slotline cavity can be bent in different shapes as long as the length is correct. The stub line or slotline cavity may advantageously be soldered or glued using conductive glue onto a circuit board. Using a stub line or slotline cavity decreases the bandwidth of the antenna.

[0035] FIG. 2 shows a perspective view of a dual-polarized antenna element 40 according to the invention. The dual-polarized antenna element 40 is formed by a first 11 and a third 13 antenna element being integral with each other, their centre axes 50 being aligned, and one being arranged in a second plane 52 perpendicular to the first plane 51. By extension of this, the antenna elements are also essentially perpendicular to each other. The dual-polarized antenna element has two feed points 16 and two cavities 17 each belonging to their respective antenna elements, also applicable for the first and second legs 31, 32.

[0036] Shown in FIGS. 1 and 2 are antenna elements 11, 12, 13, 14 which are flat with a consistent thickness throughout. However, as long as the electrical properties conferred still make it applicable to antenna use, different shapes of the elements may be used. They may not necessarily be of even thickness, and when constructing the dual-polarized antenna element 40, the two antenna elements may have a shape and size such as to when integral with each other create a cone or spike shaped dual-polarized antenna element, so long as two adjacent dual-polarized antenna elements can still function together as an antenna. Additionally, the shape of the taper of the tapered sections 21, 22 may be different. Shown are tapers of a curved shape nearing perpendicular with the ground plane as the taper approaches the feed point. However the tapers may be entirely linear, or formed in stepped sections to create the tapered sections. Additionally, the taper ends at the feed point 16 on the first leg 31 at the first tapered portion, but the taper at the second tapered portion may either end at the same height from the ground plane, or continue tapering until the ground plane 15. Furthermore, the first and second legs 31, 32 are integral with the main body 20, tip 23, and first and second tapered sections 21, 22 of each antenna element 11, 12, 13, 14.

[0037] FIG. 3 shows a perspective view of a dual-polarized antenna 40 according to the invention. Shown are three dual-polarized antenna elements, each being similar in design to the one described previously and shown in FIG. 2. The antenna elements of the dual-polarized antenna elements form antennas 10 with an adjacent antenna element 11, 12, 13, 14 of a different dual-polarized antenna element located in the same plane 51, 52. The first antenna element 11 of the first dual-polarized antenna element forms a first antenna with the second antenna element 12 of the second-dual polarized antenna element. The third antenna element 13 of the first dual-polarized antenna element forms a second antenna with the fourth antenna element 14 of the third dual-polarized antenna element. The first and second antennas have different polarizations as they are arranged in the first and second planes 51, 52 respectively, where said planes are perpendicular to each other.

[0038] FIG. 4 shows a perspective view of an antenna array 70 according to the invention. The antenna array comprises a plurality of antennas 10 with different polarization formed between antenna elements 11, 12, 13, 14 of the dual-polarized antenna elements 40. The antenna array is thus composed of dual-polarized antenna elements arranged in the first and second planes 51, 52, and in further planes parallel and/or perpendicular to these planes, i.e. arranging the dual-polarized antenna elements in a grid like manner.

[0039] The antenna array 70, or individual antennas 10 may advantageously be covered in a protective foam cover which stabilizes the antenna elements and provides protection from shock, vibrations and other mechanical stresses. Other mechanically stabilising means can also be used to increase the stability of the antenna elements such as using a dielectric material as a support structure.

[0040] The antenna array 70 is suitable for use as an Active Electronically Scanned Array (AESA) and can act as both transmitter and/or receiver and in a radar system 90. The antenna array may also be used as part of other antenna systems e.g. as part of an Electronic Warfare (EW) system 100.

REFERENCE LIST

[0041] 10 Antenna [0042] 11 First antenna element [0043] 12 Second antenna element [0044] 13 Third antenna element [0045] 14 Fourth antenna element [0046] 15 Ground plane [0047] 16 Feed point [0048] 17 Cavity [0049] 18 Tapered slot [0050] 20 Main body [0051] 21 First tapered portion [0052] 22 Second tapered portion [0053] 23 Tip [0054] 31 First leg [0055] 32 Second leg [0056] 40 Dual-polarized antenna element [0057] 50 Centre axis [0058] 51 First plane [0059] 52 Second plane [0060] 60 Circuit board [0061] 61 Electrical component [0062] 62 Via hole [0063] 70 Antenna array [0064] 90 Radar system [0065] 100 Electronic warfare system