Antenna element and antenna array

Abstract

An antenna element having: a feed line for feeding in electrical power; and a first multiplicity of radiating elements situated on a first side of the feed line, and a second multiplicity of radiating elements situated on a second side of the feed line, the radiating elements being coupled in series to the feed line, being fed with electrical power by the feed line, and being designed to transmit electromagnetic radiation; the first multiplicity of radiating elements differing from the second multiplicity of radiating elements in a distribution of spatial dimensions of the radiating elements and/or in a distribution of distances of adjacent radiating elements.

Claims

1. An antenna element, comprising: a feed line configured to feed in electrical power; a first multiplicity of radiating elements situated on a substrate on a first side of the feed line; and a second multiplicity of radiating elements situated on the substrate a second side of the feed line; wherein: the first and second multiplicity of radiating elements are coupled in series to the feed line, are fed with electrical power by the feed line, and are configured to transmit electromagnetic radiation; and so that a radiated maximum of the transmitted electromagnetic radiation occurs non-perpendicularly to the substrate: distances between immediately adjacent radiating elements of the first multiplicity of radiating elements are distributed with a Dolph-Chebyshev distribution; and distances between immediately adjacent radiating elements of the second multiplicity of radiating elements are distributed with a binomial distribution, so that the distances of the second multiplicity are distributed differently than the distances of the first multiplicity.

2. The antenna element as recited in claim 1, wherein radiating elements of the first multiplicity of radiating elements and/or radiating elements of the second multiplicity of radiating elements are slotted patches.

3. The antenna element as recited in claim 1, wherein the first and second multiplicity of radiating elements are coupled to the feed line via striplines, and/or capacitive couplings, and/or slot couplings.

4. The antenna element as recited in claim 1, wherein the antenna element is a dipole antenna element.

5. The antenna element as recited in claim 1, wherein the feed line and the first and second multiplicities of radiating elements are formed as strip elements.

6. The antenna element as recited in claim 1, wherein the first multiplicity of radiating elements and the second multiplicity of radiating elements are arranged alternatingly along the feed line, and the first multiplicity of radiating elements are arranged so as to be offset relative to the second multiplicity of radiating elements along the feed line.

7. The antenna element as recited in claim 1, wherein at least one radiating element of the first multiplicity of radiating elements differs from all radiating elements of the second multiplicity of radiating elements in the width and/or in a distance to an adjacent radiating element of the first multiplicity of radiating elements.

8. The antenna element as recited in claim 1, wherein the feed line extends in a first direction, the first multiplicity of radiating elements extend in a second direction that is perpendicular to the first direction, and the second multiplicity of radiating elements extend in a third direction that is perpendicular to the first direction.

9. The antenna element as recited in claim 1, wherein the first multiplicity of radiating elements and the second multiplicity of radiating elements are distributed along a same segment of the feed line so that at least one radiating element of the first multiplicity of radiating elements (a) is closer to a first end of the feed line than at least one radiating element of the second multiplicity of radiating elements and (b) is further to the first end of the feed line than at least one other radiating element of the second multiplicity of radiating elements.

10. The antenna element as recited in claim 1, wherein the substrate is a radiofrequency substrate.

11. An antenna array, comprising: a multiplicity of antenna elements, each of the antenna elements including: a feed line configured to feed in electrical power; a first multiplicity of radiating elements situated on a substrate on a first side of the feed line; and a second multiplicity of radiating elements situated on the substrate a second side of the feed line; wherein: the first and second multiplicity of radiating elements are coupled in series to the feed line, are fed with electrical power by the feed line, and are configured to transmit electromagnetic radiation; and so that a radiated maximum of the transmitted electromagnetic radiation occurs non-perpendicularly to the substrate: distances between immediately adjacent radiating elements of the first multiplicity of radiating elements are distributed with a Dolph-Chebyshev distribution; and distances between immediately adjacent radiating elements of the second multiplicity of radiating elements are distributed with a binomial distribution, so that the distances of the second multiplicity are distributed differently than the distances of the first multiplicity.

12. An antenna element, comprising: a feed line configured to feed in electrical power; a first multiplicity of radiating elements situated on a substrate on a first side of the feed line; and a second multiplicity of radiating elements situated on the substrate a second side of the feed line; wherein: the first and second multiplicity of radiating elements are coupled in series to the feed line, are fed with electrical power by the feed line, and are configured to transmit electromagnetic radiation; the first multiplicity of radiating elements differ from the second multiplicity of radiating elements in a distribution of spatial dimensions of radiating elements and/or in a distribution of distances of adjacent radiating elements such that a radiated maximum of the transmitted electromagnetic radiation occurs non-perpendicularly to the substrate; the distribution of the spatial dimensions and/or of the distances of at least one of the first and second multiplicities of radiating elements include a Dolph-Chebyshev distribution and/or a binomial distribution; and the distribution of distances of the first multiplicity of radiating elements is such that respective distances of respective pairs of immediately adjacent ones of the radiating elements of the first multiplicity of radiating elements differ from one another, each of the respective distances being a distance separating between the respective radiating elements of the respective pair.

13. The antenna element as recited in claim 12, wherein the distances separating between immediately adjacent radiating elements of the first multiplicity of radiating elements differ from the distances separating between immediately adjacent radiating elements of the second multiplicity of radiating elements.

14. The antenna element as recited in claim 12, wherein the distribution of distances of the first multiplicity of radiating elements is the Dolph-Chebyshev distribution.

15. The antenna element as recited in claim 14, wherein the distribution of distances of the second multiplicity of radiating elements is the binomial distribution by which respective distances of respective pairs of immediately adjacent ones of the radiating elements of the second multiplicity of radiating elements differ from one another, each of the respective distances being a distance separating between the respective radiating elements of the respective pair.

16. The antenna element as recited in claim 12, wherein the distribution of the spatial dimensions of the at least one of the first and second multiplicities of radiating elements includes the binomial distribution.

17. The antenna element as recited in claim 12, wherein the distribution of distances of the at least one of the first and second multiplicities of radiating elements includes the binomial distribution.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic top view of an antenna element according to a specific embodiment of the present invention.

(2) FIG. 2 shows an illustration of the radiated power as a function of the angle of radiation for the antenna element shown in FIG. 1.

(3) FIG. 3 shows a schematic top view of an antenna element according to a further specific embodiment of the present invention.

(4) FIG. 4 shows a schematic top view of an antenna array according to a specific embodiment of the present invention.

(5) FIG. 5 shows an illustration of the radiated power as a function of the angle of radiation for the antenna array shown in FIG. 4.

(6) In all Figures, identical or functionally identical elements and devices are provided with the same reference characters.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(7) FIG. 1 illustrates an example of an antenna element 1a in accordance with an example embodiment of the present invention. Antenna element 1a is realized as a panel antenna element that is fashioned on a substrate (not shown). Antenna element 1a can be realized as a radar transmitter device or as a radar receiver device. Antenna element 1a can also be an element of an antenna array.

(8) Antenna element 1a has a feed line 2 that runs in a straight line, realized as a stripline. However, the present invention is not limited to this. Thus, feed line 2 need not necessarily run in a straight line.

(9) Feed line 2, planar in design, has radiating elements 31 to 36 and 41 to 46 situated on a first, or left, side of feed line 2 and on a second, or right, side of feed line 2. Radiating elements 31 to 36 and 41 to 46 are realized as patches that are connected or coupled directly to feed line 2.

(10) However, the present invention is not limited to such an embodiment. Thus, radiating elements 31 to 36 and 41 to 46 can be coupled to the feed line via coupling elements, such as strip elements connected to feed line 2. According to further specific embodiments, radiating elements 31 to 36 and 41 to 46 can also be coupled to feed line 2 via capacitive couplings and/or slot couplings.

(11) Electrical power is fed to radiating elements 31 to 36 and 41 to 46 via feed line 2. Radiating elements 31 to 36 and 41 to 46 are in this way excited so as to transmit electromagnetic waves, preferably radar radiation. In particular, antenna element 1a can be designed to transmit radar waves in the gigahertz range, in particular for operation in the 77 gigahertz frequency band, which is widely used in automotive applications.

(12) Radiating elements 31 to 36 and 41 to 46 can be subdivided into a first multiplicity 3 of radiating elements 31 to 36 on the left, or first, side of feed line 2 and a second multiplicity 4 of radiating elements 41 to 46 on the right, or second, side of feed line 2. In each case, the first multiplicity 3 of radiating elements 31 to 36, or the second multiplicity 4 of radiating elements 41 to 46, are coupled in series to feed line 2.

(13) In the embodiment shown in FIG. 1, first multiplicity 3 of radiating elements 31 to 36 differs from second multiplicity 4 of radiating elements 41 to 46 in the distribution of the widths of radiating elements 31 to 36 and 41 to 46. Both radiating elements 31 to 36 of first multiplicity 3 of radiating elements 31 to 36 and radiating elements 41 to 46 of second multiplicity 4 of radiating elements 41 to 46 are realized in rectangular fashion and have identical length z, which is measured orthogonally to feed line 2. In addition, the distances x between successive radiating elements 31 to 36 and 41 to 46 are identical in each case. The distances x preferably correspond to the wavelength of the transmitted radar radiation.

(14) Widths D of radiating elements 31 to 36 of first multiplicity 3 of radiating elements 31 to 36 are fixed in each case. Here, widths D are measured parallel to feed line 2. First multiplicity 3 of radiating elements 31 to 36 thus has a uniform distribution of the widths.

(15) Widths D1 to D6 of radiating elements 41 to 46 of second multiplicity 4 of radiating elements 41 to 46 follow a Dolph-Chebyschev distribution. The ratio of widths D1 to D6 thus corresponds to the ratio of Chebyschev polynomials. According to a further specific embodiment, widths D1 to D6 can follow any other distribution, for example a binomial distribution. The radiation characteristic of antenna element 1a can be set via the choice of suitable distributions.

(16) According to further specific embodiments, in addition or alternatively the lengths z of radiating elements 31 to 36 and 41 to 46 can vary. Preferably, the distribution of the lengths z of first multiplicity 3 of radiating elements 31 to 36 differs from the distribution of the lengths z of second multiplicity 4 of radiating elements 41 to 46.

(17) According to further specific embodiments, in addition or alternatively the distances x between successive radiating elements 31 to 36 and 41 to 46 can vary. Preferably, the distribution of the distances x of first multiplicity 3 of radiating elements 31 to 36 differs from the distribution of the distances x of second multiplicity 4 of radiating elements 41 to 46.

(18) FIG. 2 illustrates a radiated power of antenna element 1a, shown in FIG. 1, as a function of an azimuth angle θ. It will be seen that the radiation characteristic has a maximum at an angle that differs from 0°, i.e., the main direction of radiation does not run perpendicular to the substrate. As a result, antenna element 1a is particularly well-suited for applications in the automotive area, for example in the front or rear edge or corner region.

(19) As FIG. 2 shows, a main direction of radiation can be achieved at an azimuth angle of approximately 25°. In addition, a high degree of stability of the radiation pattern can be achieved, such that the direction of radiation and the radiated power remain substantially constant in a bandwidth of approximately 3 gigahertz. In addition, a high radiated power can be achieved in a large angular range having a width of approximately 90° even after changing the direction of radiation. In addition, a good side lobe level can be achieved in the elevation plane, such that, in a band 3 gigahertz in width around a frequency of 76.5 gigahertz, substantially no change occurs in the main direction of radiation.

(20) FIG. 3 shows an antenna element 1b according to a further specific embodiment of the present invention. Antenna element 1b has a first multiplicity 8 of radiating elements 81 to 84, where the widths v1 to v4 of radiating elements 81 to 84 follow a binomial distribution. Radiating elements 81 to 84 are each realized as slot radiating elements. In addition, antenna element 1b has a second multiplicity 9 of radiating elements 91 to 95, where widths u1 to u5 follow a Dolph-Chebyschev distribution. The distances x between successive radiating elements 81 to 84 and 91 to 95 are constant in each case.

(21) The radiating elements of first multiplicity 8 and second multiplicity 9 are configured slightly offset to one another due to the different widths, in order to correspondingly adjust the phase.

(22) Preferably, the width of the radiating elements decreases in each case towards the edge of feed line 2, as is illustrated for second multiplicity 4 of radiating elements 41 to 46 of antenna element 1a shown in FIG. 1, and for first multiplicity 8 and second multiplicity 9 of radiating elements of antenna element 1b shown in FIG. 3.

(23) FIG. 4 illustrates an example antenna array 7 according to the present invention. The antenna array has six antenna elements 1c, each having a first multiplicity 5 of radiating elements 51 to 56 having binomially distributed widths d1 to d6, and a second multiplicity 6 of radiating elements 61 to 65 having constant widths d.

(24) Antenna elements 1c are each connected in pairs, via first to sixth striplines 21 to 26, to seventh and eighth striplines 27, 28, which are coupled to a ninth stripline 29. Electrical energy can be coupled into the respective striplines 2 of individual antenna elements 1c via ninth stripline 29. Phase differences between the individual antenna elements 1c can be achieved via differently selected lengths of first to sixth striplines 21 to 26, and in this way a suitable radiation characteristic can be achieved.

(25) Instead of antenna elements 1c shown in FIG. 4, any antenna elements having unequally distributed radiating elements can be used, in particular antenna elements 1a, 1b shown in FIGS. 1 and 3.

(26) FIG. 5 illustrates the radiated power of antenna array 7, shown in FIG. 4, as a function of the azimuth angle θ. The radiation characteristic has a maximum at a value of −45°. The achievable maximum is in addition significantly more pronounced than would be the case with the use of antenna elements having equally distributed radiating elements.