WO2015063036A1

WO2015063036A1 - Flat multi-frequency antenna

Info

Publication number: WO2015063036A1
Application number: PCT/EP2014/073021
Authority: WO
Inventors: Michael Heiss
Original assignee: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Priority date: 2013-10-30
Filing date: 2014-10-27
Publication date: 2015-05-07
Also published as: DE102013222139A1

Abstract

A flat multi-frequency antenna (10) comprising a first radiating electrode (12) which comprises a first surface (A₁) and at least one second radiating electrode (16) which has a second surface (A₂). The first surface (A₁) has at least one opening (14), and the second radiating electrode (16) is disposed in the opening (14) in spaced relation to the first radiating electrode (12). The first radiating electrode (12) and the second radiating electrode (16) are in a common metallisation layer (18).

Description

Planar multi-frequency antenna

DESCRIPTION Embodiments of the present invention relate to a planar multi-frequency antenna having a first and at least a second radiation electrode. Further embodiments relate to a method for feeding such a multi-frequency antenna. A Mehrfreuqenzantenne is an antenna in which the radiation and electrical properties (radiation pattern, polarization, impedance, etc.) are not dependent on the frequency or at several frequencies are good or at least satisfactory. Thus, such an antenna can be operated at several frequencies. Furthermore, antennas are also referred to as multi-frequency antennas in which the properties are the same or good or satisfactory only at certain discrete frequencies.

A planar antenna is constructed, for example, from a ground plane and at least one conductive surface (layer). In this case, at least one conductive surface (layer) is fed at least one point. This arrangement often has only a small bandwidth, so there is a need to design the planar antenna for the function in multiple frequency bands.

In planar antennas (microstrip antennas), a multi-frequency antenna can be achieved by using multiple metallic layers [1, 2], by slits in a patch [3] or by short circuits. Also special shapes of the surfaces [4] or a loading of the surfaces (with parasitic elements) [5] can be used. The present invention is therefore based on the object to provide a concept that makes it possible to create a compact planar multi-frequency antenna. The object is achieved by a device according to claim 1 and a method according to claim 24.

Embodiments of the present invention provide a planar multi-frequency antenna comprising a first radiation electrode having a first surface and at least one second radiation electrode having a second surface. The first surface has at least one opening, wherein the second radiation electrode is arranged in the opening, spaced from the first radiation electrode. In this case, the first radiation electrode and the second radiation electrode are in a common metallization.

Furthermore, a method is provided. The method includes feeding the planar multi-frequency antenna with an electrical signal. The present invention utilizes the effect that the antenna can be operated as a multi-frequency antenna by arranging a plurality of radiant electrodes of planar design. The arrangement of the second radiation electrode in the first radiation electrode enables a compact construction of the multi-frequency antenna. In addition, such planar multi-frequency antennas offer great design possibilities with regard to the design of the area, as a result of which the antenna can be tuned to the frequency bands in which it is to be operated. Since the antenna is mounted on a solid support, the antennas are robust against mechanical influences and at the same time inexpensive to manufacture.

In the planar multi-frequency antenna, all the radiation electrodes of the multi-frequency antenna can be in the common metallization layer. This results in a simple and compact design for the multi-frequency antenna. The single-layer design also reduces the emission of surface waves.

The first radiation electrode may be configured in the planar multi-frequency antenna for the lowest frequency band. Because the lowest frequency band is the has the longest wavelength and the wavelength is preferably tuned to the length of the antenna in order to optimize the gain, preferably the largest radiation electrode for the lowest frequency band is designed and operated in this lowest frequency band.

The planar multi-frequency antenna may include a feed network electrically connecting a feed point and at least one of the radiation electrodes. In this case, the feed network can be arranged in the opening and can connect at least the first radiation electrode and the second radiation electrode to one another. The feed network may be configured to provide individual impedance matching for the first radiation electrode and the second radiation electrode. It can be formed on at least one of the radiation electrodes and a plurality of feeding points. Feeding the radiation electrodes via a feed point simplifies the layout of the planar multi-frequency antenna. By arranging the feeding point in the opening, in addition, the multi-frequency antenna can be made more compact. The feed network allows individual impedance matching between the feed point and the radiation electrodes. By an individual impedance matching of the feed network between the feed point and the radiation electrode, the adaptation of the antenna can be optimized.

In embodiments, the opening or the radiation electrodes can be formed as a rectangle. The second radiation electrode may be placed centrally in the opening. An opening formed as a rectangle or radiation electrodes formed as a rectangle allow a simple construction and calculation of the configuration of the multi-frequency antenna. In this case, a rectangular area has hardly any negative effects on the radiation behavior of the radiation electrode. The central placement of the second radiation electrode typically improves a radiation characteristic of the multi-frequency antenna.

The opening may be completely within one half of the area of the first radiation electrode. By the arrangement of the opening in one half the area results in a higher gain or better emission characteristics of the multi-frequency antenna.

In embodiments, the opening may not extend beyond two straight lines that extend through a centroid and bound one quarter of the total area of the first radiation electrode. Through the lines, the opening is limited to at most a quarter of the area of the first radiation electrode. The limitation of the opening in the radiation electrode to a quarter of the area of the first radiation electrode increases the gain of Mehrfrequenenzantenne or additionally improves their radiation properties.

In embodiments, the first radiation electrode may be designed such that a distance (A) between an outer boundary of the first radiation electrode and the opening amounts to at least 0.25% of a maximum extent of the first radiation electrode. Furthermore, the second radiation electrode may have a distance (B) from the first radiation electrode which corresponds to at least 0.5% of a maximum extension of the first radiation electrode. Further, the area of the second radiation electrode may have a size smaller than 40% of the area of the first radiation electrode. The spacing of the radiation electrodes precludes conductive connections and thus short circuits between the radiation electrodes. The described design rules can also optimize the gain or the emission characteristics of the planar multi-frequency antenna. Furthermore, in further embodiments, a plurality of radiation electrodes may be arranged in the opening, wherein the radiation electrodes have a distance (C) from each other. The distance (C) between the radiation electrodes in the opening may be at least 0.5% of a largest dimension, the largest of the second radiation electrodes. By arranging a plurality of radiation electrodes in the opening, the multi-frequency antenna can be tuned to a plurality of frequency bands. The profit can be increased in the individual frequency bands and for the entire antenna. In embodiments, the second radiation electrode may have a further opening in which a third radiation electrode is arranged. By arranging a third radiation electrode in a further opening of the second radiation electrode, the same effects arise as by arranging the second radiation electrode in an opening of the first radiation electrode. Thus, a compact planar multi-frequency antenna can be operated over several frequency bands, which has a good profit.

In a second metallization layer, a ground plane may be arranged plane-parallel to the first radiation electrode. In this case, the ground plane should not project beyond an outer circumference of the first radiation electrode. A ground plane provides a solid reference area under the radiation electrode which enhances the radiation performance of the multi-frequency antenna. In embodiments, at least one electrical component can be integrated in the opening or at least one slot can be made in at least one of the radiation electrodes. By integrating at least one component in the opening, a compact design of the radiation electrode is achieved. The at least one component can serve, for example, to tune the feed network. The introduction of slots in the radiation electrodes serves to tune the radiation electrodes to a specific frequency band and allows, for example, a circular polarization of the antenna.

Embodiments of the present invention will be explained with reference to the accompanying figures. Show it:

Fig. 1 is a perspective view of an embodiment planar multi-frequency antenna; 2 shows an embodiment of a multi-frequency antenna with a feed network. 3 shows an embodiment of a multi-frequency antenna having a plurality of second radiation electrodes;

4 shows an embodiment of a multi-frequency antenna having a plurality of second radiation electrodes and a plurality of feed points;

5 shows an embodiment of a multi-frequency antenna, in which the second radiation electrode has a further opening in which a third radiation electrode is arranged;

6 shows an embodiment of a multi-frequency antenna, with a third radiation electrode and a plurality of feed points.

7 shows a further embodiment of a multi-frequency antenna with a feed network;

8a shows an embodiment of a multi-frequency antenna, wherein the opening is arranged completely in one half of the first surface of the first radiation electrode;

8b shows an embodiment of a multi-frequency antenna, wherein the opening is arranged in a quarter of the first radiation electrode.

9 shows a further embodiment of a multi-frequency antenna, with a plurality of second radiation electrodes;

10 is a side view of an embodiment of a planar multi-frequency antenna. In the following description of the embodiments of the invention, the same or equivalent elements in the figures are given the same reference numerals, so that their description in the different embodiments are interchangeable. Fig. 1 shows a perspective view of a planar multi-frequency antenna 10, according to an embodiment of the present invention. The multi-frequency antenna is designated in its entirety by 10. The planar Mehrfrequenantenne 10 includes a first radiation electrode 12 having a first surface Ai, wherein the first surface Ai has an opening 14. In the opening 14, spaced from the first radiation electrode 12, a second radiation electrode 16 having a second surface A _{2 is} arranged. The first radiation electrode 12 and the second radiation electrode 16 lie in a common metallization layer 18.

The first radiation electrode 12 and the second radiation electrode 16 are, for example, planar conductive electrodes, which may also be referred to as a patch. Planar refers to the spatial arrangement of points in a plane. The points are then plan, if they lie in a plane. However, the radiation electrodes 12, 16 can also lie in a curved plane and, for example, form a section of a lateral surface of a circular cylinder.

The radiation electrodes 12, 16 are essentially formed as rectangles. The radiation electrodes 12, 16 may be designed to allow the radiation of a dual or circularly polarized electromagnetic wave. The radiation electrodes 12, 16 (patches) may have any shape in some embodiments. Frequently used are: Rectangles, circles, triangles, hexagons, octagons, fractals and flush-filling curves ("Space-Filling") [7]. In the embodiment shown, the first and second radiation electrodes 12, 16 are rectangular. But it can also be used, for example, rectangular radiation electrodes, in which, for example, at least one corner is "cut off", d. H. the 90 ° angle of the corner has been replaced by two 135 ° angles.

The first radiation electrode 12 comprises, as mentioned, the area Ai. The surface Ai has an opening 14. The opening 14 represents a region enclosed by the surface A1, in which no electrically conductive material, the first Radiation electrode 12 is present. The opening 14 lies in the same plane, ie in the same metallization layer 18 as the first radiation electrode 12. The opening 14 may be formed as a rectangle. However, other forms for the design of the opening 14 are possible. For example, the opening 14 may be formed as a circle, triangle, hexagon, octagon or fractal. The formation of the opening 14 depends on the frequency band in which the multi-frequency antenna 10 is operated and other factors.

In the plane or in the same metal tuning position 18 as the first radiation electrode 12, a second radiation electrode 16 can be arranged in the opening 14. The second radiation electrode 16 may be spaced from the first radiation electrode 12. As a result of the spacing, the first radiation electrode 12 and the second first radiation electrode 16 are electrically insulated from one another. Thus, no conductive signal exchange between the two radiation electrodes 12, 16 take place. The spacing allows the use of the two radiation electrodes 12, 16 in different frequency bands. The different frequency bands can be offset in time or used simultaneously. A plane in which patches, electrodes or conductor surfaces are arranged is designated as metallization layer 18 in the planar multi-frequency antenna 10. In exemplary embodiments, all the radiation electrodes 12, 16 may lie in a common metallization layer 18. In this case, all the radiation electrodes 12, 16 are arranged in one layer in a common metallization layer 18. As a result, a simple and compact construction of the planar multi-frequency antenna 10 is made possible. The single-layer structure of the multi-frequency antenna 10, for example, surface waves can be reduced or even completely prevented. By reducing the surface waves, the gain of the multi-frequency antenna 10 is increased, or the efficiency is improved.

The gain or antenna gain includes the directivity and efficiency of an antenna. The profit thus denotes the ratio of the radiated radiant power density, compared with a lossless reference antenna with the same power supply, which usually has a non-directional radiant intensity. The first radiation electrode may be designed for the lowest frequency band. The first radiation electrode 12 has the greater extent with respect to the second radiation electrode 16. For the operation of the antenna, a frequency band should be used whose wavelength λ corresponds approximately to twice a side length of the areas Ai or A ₂ , ie the longitudinal side of the first or second radiation electrode 12, 16 has a length of approximately K / 2 on. The wavelength λ is greater the lower the frequency. As a result, the larger the size of the antenna, the lower the frequency at which the antenna can be operated optimally. The antenna shown in embodiments (multi-frequency antenna) consists of a patch antenna (first radiation electrode 12) for the lowest frequency band. At least one opening (14) is introduced into the patch (first radiation electrode 12) of the antenna (multi-frequency antenna 10). In each introduced opening 14, a further patch (second radiation electrode 16) for a higher frequency can now be introduced. This creates a structure in which there is a patch (radiation electrode) in another patch (radiation electrode).

FIG. 2 shows another embodiment of the planar multi-frequency antenna 10 with the first radiation electrode 12 and the second radiation electrode 16, which is arranged in the opening 14 of the first radiation electrode 12. The multi-frequency antenna (patch antenna) is designed for two frequencies. The lower frequency radiation electrode (patch) is housed in the aperture 14 of a higher frequency radiation electrode (patches). The position and size of the radiation electrodes 12, 16 (patches) and the openings 14 is arbitrary. The multi-frequency antenna 10 further comprises a feed network 20 which connects a feed point 22 and at least one of the radiation electrodes 12, 16 electrical. In embodiments of the multi-frequency antenna, at least the first radiation electrodes 12 and the second radiation electrodes 16 are connected to each other, wherein the feed network 20 is designed to provide individual impedance matching for the first radiation electrode and the second radiation electrode. The electrical connection between the feeding point 22 and the radiation electrodes 12, 16 can be effected directly, as shown in FIG. 2, or via electrical elements with specific electrical properties. By way of example, the electrical elements can have capacitive or inductive conduction characteristics and can be designed, for example, as capacitors or coils. By way of example, the electrical elements can be used to adapt the impedance, for example, between a signal source and one of the radiation electrodes 12, 16. Due to the feed network 20 (the matching circuit), however, the introduced patch (second radiation electrode 16) will only have a small size.

Via the feed point 22, electrical signals can be transmitted from a signal source to the multi-frequency antenna 10. The feeding point 22 may be, for example, a circular surface or a different shaped structure to which a connection of the feed network 20 is contacted, for example, by means of a needle tip or to which a coaxial cable is connected to the feed point. The feeding point 22 may also comprise a coupling element, such as a plug, with which the electrical signal of the signal source is transmitted to the multi-frequency antenna. Any source suitable for the operation of a planar multi-frequency antenna may be used as the signal source. In this case, the signal source generates an electromagnetic signal which is preferably transmitted via an electrical current conductive connection to the feed point.

The multi-frequency antenna 10 shown in embodiments can also be used as a planar multi-frequency antenna 10 for receiving electrical signals. In this case, electromagnetic signals from the multi-frequency antenna 10th received and led over the feed network 20 to the feed point 22. At the feed point 22, the signals can be tapped and forwarded to a receiving unit. The receiving unit may be, for example, a tuner or a comparable signal processor. It is also possible to use the multi-frequency antenna, at the same time or in short offset intervals, both as a transmitter and as a receiver of electromagnetic waves or signals.

In embodiments, the feed network may be located in the opening. As shown in FIG. 2, the feed network 20 may be disposed in the opening 14 between the first radiation electrode 12 and the second radiation electrode 16. In this case, the feed network 20 may be arranged to feed both the first radiation electrode 12 and the second radiation electrode 14 from a common feed point 22. The feed point 22 can preferably be arranged centrally between the first 12 and the second radiation electrode 16 or, as shown in FIG. 2, asymmetrically between the two radiation electrodes 12, 16.

3 shows a further exemplary embodiment of the planar multi-frequency antenna 10 with the first radiation electrode 12 and the opening 14 in the area A _{1 of} the first radiation electrode 12. A plurality of second radiation electrodes 16 can be arranged in the opening 14. The patch antenna (multi-frequency antenna 10) is suitable for multiple frequencies. There are several (different or equal) second radiation electrodes (patches) in the opening 14 of the first radiation electrodes 12 (the larger patch) housed. The position and size of the radiation electrodes 12, 16 (patches) and the openings 14 are arbitrary.

In embodiments, the multi-frequency antenna 10 can have up to n second radiation electrodes 16i to 16 _n, where n is a natural number greater than or equal to one, n>. 1 In FIG. 3, for example, three second radiation electrodes 16 - ₁ , 16 ₂ , 16 3 are arranged in the opening 14. The first radiation electrode 12 and the second radiation electrodes 16 ₁ , 16 ₂ , 16 ₃ can be fed via the feed network 20 are fed by a common feed point 22. The feed point 22 can be arranged centrally in the feed network 20. Thus, a good supply of all radiation electrodes 12, 16 can be achieved with little effort and space requirement.

4 shows a further exemplary embodiment of the planar multi-frequency antenna 10. The first radiation electrode 12 with the surface Ai has the opening 14. In the opening 14, three second radiation electrodes 16ι, 16 ₂ , I 63, spaced from the first radiation electrode 12, are arranged. The second radiation electrodes 16 ^ 16 ₂ , 16 ₃ can be connected to a signal source via a feed network 20, for example. The feed network 20 has a plurality of feed points 22. The feeding points 22 are electrically connected to the radiation electrode 12, 16 ₁ , 16 ₂ , 16 ₃ . The feeding points 22 may be located 16 ₃ on one of the radiation electrodes 12, 61 I, 16 _2,. The Speisungs- points 22 may also be in the opening 14 of the first radiation electrode be located 12 and via electrically conductive connections to the radiation electrodes 12, 61 I, 16 _2, be connected I6. ₃ For example, to various signals to the radiation electrodes 12, I 61, 16 ₂ to output 16 ₃ or to receive from these, are shown in Figure 4 embodiment of the radiation electrodes 12, I 61, 16 _2, 16 ₃ or in Feeding network 20 a plurality of feed points 22 formed. Through the feed points 22 can be electrically transmitted signals from a signal source to the multi-frequency antenna 10 or received by this. Each patch (radiation _electrodes 12, 16 _Ί , 16 ₂ , 16 ₃ ) can be provided with its own supply or all patches (radiation electrodes 12, I 61, 16 ₂ , 16 ₃ ) can be connected to each other via a feed network. Likewise, a dual or circular polarization can be achieved with each patch (radiation electrodes 12, I 61, 16 ₂ , 16 ₃ ) and a corresponding feed (eg several feed positions). One possible feed is to use a coaxial contact (sample) for each patch (radiation electrode 12, 161, 16 ₂ , 16 ₃ ). Also, the use of a connected to the outermost patch (first radiation electrode 12) coaxial line with connections to the smaller Patches (second radiation electrodes 16i, 16 ₂ , 16 ₃ ) and / or in combination with the coaxial terminals for the smaller patches (second radiation electrodes 16 1, 16 ₂ , 16 ₃ ) is possible. Different methods of feeding the radiation electrodes are possible. The radiation electrodes can be powered separately as shown in Figures 4 and 6, or the radiation electrodes (patches) are fed together, as shown in Figure 3. Different feeds are possible, for example the first radiation electrode (outermost patch) could be provided with a microstrip line (microstrip line) and a second radiation electrode (inner patch) with a conical slot feed (Taperd-Siot feed). Furthermore, any combination of different feeds is possible.

5 shows an exemplary embodiment of the planar multi-frequency antenna 10, in which the second radiation electrode 16 has a further opening 24 in which a third radiation electrode 26 is arranged. The second radiation electrode 16 may also have a plurality of further openings 24, in each of which at least one third radiation electrode 26 may be arranged (not shown in FIG. 5). Furthermore, it is possible in further exemplary embodiments that the multi-frequency antenna 10 has, for example, a plurality of second radiation electrodes 16. The further opening 24, like the opening 14 in the first radiation electrode 12, can have any desired shape and have the same functions and advantages as the opening 14 in the first radiation electrode 12. Several patches (radiation electrodes 12, 16, 26) can also be interleaved become. In this case, the variants of Figure 3 and Figure 5 can be combined as desired.

In the further opening 24, at least one third radiation electrode 26, spaced from the second radiation electrode 16 may be arranged. The third radiation electrode 26 may be configured in shape and material as the first or second radiation electrode 12, 16 and also have the same functions and advantages as the first 12 or second radiation electrode 16. Die One or more third radiation electrodes 26 are preferably designed for a higher frequency band than the second radiation electrode 16.

Furthermore, in embodiments of the multi-frequency antenna 10 by at least one opening in the third radiation electrode further nesting of radiation electrodes of the multi-frequency antenna 10 is possible. Corresponding interleaves through openings in the radiation electrodes can be continued as desired. 6 shows an exemplary embodiment of the multi-frequency antenna 10, in which the second radiation electrode 16 has a further opening 24 in which the third radiation electrode 26 is arranged. In addition, the embodiment comprises feed points 22 which are arranged on the first radiation electrode 12, the second radiation electrode 16, and the third radiation electrode 26. The arrangement of the feed points 22 directly on each of the radiation electrodes 12, 16, 26, no feed network, which is arranged in one of the openings 14, 24, necessary. Thus, no additional connections between the radiation electrodes 12, 16, 26 and the feed points 22 are necessary.

FIG. 7 shows a further exemplary embodiment of the multi-frequency antenna 10. The first surface of the first radiation electrode 12 has the opening 14. The opening 14 has the shape of two adjacent rectangles. In the opening 14, the second radiation electrode 16, from the first radiation electrode 12 spaced apart, arranged. In addition, an embodiment of the feed network 20 is arranged in the opening. The food network 20 may have a feed point 22 and an electrical connection between the feed point 22 and the first and second radiation electrodes 12, 16. Via the feed network 20, the first and second radiation electrodes 12, 16 can be connected, for example, to an electrical signal source. In this case, the feed network 20 can be designed to effect individual impedance adjustments for the first radiation electrode 12 and the second radiation electrode 16 or to tune or set signal launching distances. influences. Due to the configuration of the feed network 20, for example, an adaptation of the line impedance to the multi-frequency antenna 10 or an adjustment of the impedance of the feed to the impedance of the radiation electrode can be carried out.

FIG. 8 a shows an exemplary embodiment of the multi-frequency antenna 10, wherein the opening 14 is arranged completely in one half of the first surface A-1 of the first radiation electrode 12. The second radiation electrode 16, with the second surface A ₂ , is disposed in the opening, spaced from the first radiation electrode 12. The opening 14 may be located entirely within one half of the first surface A1 of the first radiation electrode 12. For example, half of the first area Ai can be determined by a straight line which is laid through a centroid of the first radiation electrode 12. By arranging the opening 14 in one half of the radiation electrode 12, the gain of the multi-frequency antenna can be increased or favorable emission properties can be achieved.

FIG. 8 b shows an exemplary embodiment of a multi-frequency antenna 10, wherein the opening 14 is arranged in a quarter of the first radiation electrode 12. In this case, the opening 14 in the first radiation electrode 12 does not extend beyond two straight lines, which run through a centroid, and which delimit a quarter of the total area Ai of the first radiation electrode 12. As a result, the opening 14 is limited to at most a quarter of the area Ai of the first radiation electrode 12. In the opening 14, the second Strahlungselekt- is arranged 16 with the surface A ₂ . By the arrangement of the opening 14 in a quarter of the area Ai of the first radiation electrode 12, the gain of the multi-frequency antenna 10 can be additionally increased or favorable radiation properties can be achieved. For the exemplary embodiment according to FIG. 8b, a few details for the dimensioning of the multi-frequency antenna 10 are shown below. In this case, the first radiation electrode 12 can be designed such that a distance (A) between an outer boundary of the first radiation electrode 12 and the opening 14 is at least 0.25% of a maximum extension of the first radiation electrode. In a rectangular configuration of the first and second radiation electrodes 12, 16 and the opening 14, the distance (A) on the first radiation electrodes 12 (the large patch) can be at least 0.5% of the longer side length of the first radiation electrode 12 (of the largest patch ) amount.

Furthermore, the second radiation electrode 16 has a distance B from the first radiation electrode 12. The distance B should correspond to at least 0.5% of the largest extent of the first radiation electrode 12. In a rectangular configuration of the first and second radiation electrodes 12, 16 and the opening 14, the distance to the first radiation electrode 12 (large patch) should be at least 1% of the largest side length of the first radiation electrode 12 (of the largest patch). The feed points 22 shown in FIGS. 8A and 8B are arranged, for example, centrally on a longitudinal side of the first radiation electrode 12 or on a longitudinal side of the second radiation electrode 16.

In one embodiment of the planar multi-frequency antenna 10, the area A _{2 of} the second radiation electrode 16 may have a size smaller than 40% of the area Ai of the first radiation electrode 12. By an aforementioned area division, a good gain of the multi-frequency antenna 10 results Good multi-frequency characteristics. The second radiation electrode 16 may be placed centrally in the opening 14 in one embodiment of the planar multi-frequency antenna 10. This results in an optimized radiation behavior of the multi-frequency antenna 10.

9 shows another embodiment of the planar multi-frequency antenna 10, wherein a plurality of second radiation electrodes 16 are arranged in the opening 14. The second radiation electrodes 16i, 16 _{2 in} this case have a distance C to each other. The distance C is a distance between any two second radiation electrodes 16 i to 16 _n at an arbitrary distance. 4 073021 bigen location of the second radiation electrodes 16i to 16 _n . The distance C between the second radiation electrodes 16 i to 16 _n in the opening 14 should amount to at least 0.5% of a largest dimension, the largest of the second radiation electrodes 16. In a rectangular configuration of the first and second radiation electrodes 12, 16 and the opening 14 (as shown for example in FIG. 9), the distance of the individual second radiation electrodes should, for example, 16i, 16 ₂ (patches) be at least 1% of the largest of the second radiation electrodes 16 (of the largest patch). Additionally, in embodiments of the planar multi-frequency antenna in a second metallization plane, a ground plane may be arranged plane-parallel to the first radiation electrode. In a preferred embodiment, the ground plane does not project beyond an outer periphery of the first radiation electrode. The ground plane can have all sorts of shapes, commonly used are: rectangles, circles, triangles, hexagons, octagons, fractals, and space-filling curves [7].

In embodiments of the planar multi-frequency antenna, different matching circuits can be integrated in the opening of the largest patch (first radiation electrode). Furthermore, in another exemplary embodiment of the planar multi-frequency antenna, at least one electrical component can be integrated in one of the openings of the radiation electrodes. Thus, e.g. an RFID transponder with a microstrip antenna (microstrip antenna or planar multi-frequency antenna) can be used for several frequencies. The electrical component can also be used for example for balancing or for impedance matching of the feed network. As a result, the radiation behavior of the planar multi-frequency antenna can be optimized.

In one embodiment, at least one slot may be introduced in at least one of the radiation electrodes (patches). This results, for example in the operation of the multi-frequency antenna with circularly polarized electromagnetic waves, an additional gain or it is possible to emit a circularly polarized electromagnetic wave. Various methods of feeding the radiation electrodes are possible. The radiation electrodes can be fed separately, as shown in FIGS. 4 and 6, or the radiation electrodes (patches) are fed together, as shown in FIG. Different feeds are possible, for example the first radiation electrode (the outermost patch) could be provided with a microstrip line (microstrip line) and a second radiation electrode (inner patch) with a conical slot feed (Taperd-Siot feed). Furthermore, any combination of different feeds is possible. Each type of power supply can, as shown in FIG. 7, be provided with any desired matching circuit.

One of the key features of the embodiments is the creation of a planar multi-frequency antenna (multi-frequency patch antenna) which integrates the radiation patches for the higher frequency bands into the radiation electrode (patch) for the lowest frequency band.

To adapt the multi-frequency antenna, e.g. Microstrip lines (microstrip lines), load (loading) of the patch or slots are used. The planar multi-frequency antenna can also work in several frequency bands at the same time.

The points mentioned in the exemplary embodiments can be arbitrarily combined with other types of antenna construction, such as using a plurality of radiation electrodes (patches) one above the other, wherein single-layered multi-frequency antennas are typically superior. Figure 10 shows a microstrip antenna (microstrip antenna), wherein a multi-frequency antenna is achieved by using a plurality of metallic layers. The planar multi-frequency antenna (patch antenna) is composed of a ground plane 28 and at least one conductive layer 30. It is also possible in embodiments to use openings for the loading of the radiation electrodes (patches). Likewise, in embodiments by two radiation electrodes (patches) side by side [6] a planar multi-frequency antenna (mother frequency patch antenna) are created.

In the embodiments of the planar multi-frequency antenna, the use of only two metallic layers (ground plane or ground plane and metallization layer or plane with the radiation electrodes or patches) was in the foreground. In this case, the multi-frequency antenna (antenna) should not be larger than the first radiation electrode (the largest patch) for the lowest frequency. If the opening is made larger than shown in particular in the embodiments of Figures 8a and 8b, a reduction of the antenna gain takes place. If this does not affect the application, the opening can be made larger than shown in Figures 8a and 8b. literature

[1] F. Croq, D. M. Pozar, "Multifrequency Operation of Microstrip Antennas Using Aperture Coupled Parallel Resonators", IEEE Transaction on Antennas and Propagation, vol. 40, n. 11, pp. 1367-1374, Nov. 1992 [2] J. Anguera, C. Puente, C. Borja, "A Procedure to Design Stacked Microstrip Patch Antennas Based on a Simple Network Model", Microwave and Opt. Tech. Letters, vol. 3, Wiley, Jun. 2001

[3] I. Sarkar, P.P. Sarkar, S.K. Chowdhury, "A Novel Compact, Microstrip Antenna With Multifrequency Operation," International Seminar / Workshop on

Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) 2009, pp. 147-151, Sept. 2009

[4] Y. Pang, B. Gao, "Novel Compact Multi-frequency Microstrip Patch Antenna", 2003 IEEE Antennas and Propagation Society International Symposium, vol. 4, pp. 166-169, Jun. 2003 [5] J. Montero-de-Paz, E. Ugarte-unoz, FJ Herraiz-Martinez, D. Segovia-Vargas, "Multifrequency Single Patch Antennas Loadad with Split Ring Resonators" Proceedings of the Fourth European Conference on Antennas and Propagation ( EuCAP), 2010

[6] Z.-J. Tang, Y. G. He, "Broadband microstrip antenna with U and T slots for 2.45 / 2.41 GHz RFID tag", Electronics Letters, vol. 45, issue: 18, pp. 926-928, Aug. 2009 [7] S.R. Anoop, K.K. Ajayan, M.R. Baijul, V. Krishnakumar. V, "Multiband Behavioral Analysis of a Higher Order Fractal Patch Antenna", International Congress on Ultra Modern Telecommunications and Control Systems and Workshops (ICUMT) 2010, p. 823-827, Oct. Although some aspects have been described in the context of a device, it will be understood that these aspects also constitute a description of the corresponding method such that a block or device of a device is also to be understood as a corresponding method step or feature of a method step. Similarly, aspects described in connection with or as a method step also represent a description of a corresponding block or detail or feature of a corresponding device. Some or all of the method steps may be performed by a hardware device (or using a hardware device). Apparatus), such as a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, some or more of the most important method steps may be performed by such an apparatus.

The embodiments described above are merely illustrative of the principles of the present invention. It will be understood that modifications and variations of the arrangements and details described herein will be apparent to others of ordinary skill in the art. Therefore, it is intended that the invention be limited only by the scope of the following claims and is not limited by the specific details presented with reference to the description and explanation of the embodiments herein.

Claims

claims

A planar multi-frequency antenna (10) comprising:

- A first radiation electrode (12) having a first surface (A-i), wherein the first surface (A1) has at least one opening (14), and

at least one second radiation electrode (16) having a second surface (A2), wherein the second radiation electrode (16) is disposed in the opening (14) spaced from the first radiation electrode (12), and wherein the first radiation electrode (12) and the second radiation electrode (16) lie in a common metallization layer (18).

A planar multi-frequency antenna (10) according to claim 1, wherein all the radiation electrodes (12, 16, 26) of the planar multi-frequency antenna (10) lie in the common metallization layer (18).

A planar multi-frequency antenna (10) according to claim 1 or 2, wherein the first radiation electrode (12) is designed for the lowest frequency band.

A planar multi-frequency antenna (10) according to any one of claims 1 to 3, wherein the planar multi-frequency antenna (10) comprises a feed network (20) electrically connecting a feed point (22) and at least one of the radiation electrodes (12, 16, 26).

A planar multi-frequency antenna (10) according to claim 4, wherein at least said first radiation electrode (12) and said second radiation electrode (16) are interconnected, and wherein said feed network (20) is arranged to effect individual impedance adjustments for the first radiation electrode (12) and the second radiation electrode (16).

Planar multi-frequency antenna (10) according to one of claims 4 or 5, wherein at least one of the radiation electrodes (12, 16, 26), a plurality of feed points (22) is formed.

A planar multi-frequency antenna (10) according to any one of claims 4 or 5, wherein the feed network (20) is disposed in the aperture (14, 24).

The planar multi-frequency antenna (10) of claim 7, wherein the feed network (22) is disposed in the opening (14, 24) between the first radiation electrode (12) and the second radiation electrode (16), the feed network (20) being arranged to both the first radiation electrode (12) and the second radiation electrode (16) to be fed from a common feed point (22).

9. A planar multi-frequency antenna (10) according to any one of claims 1 to 8, wherein the opening (14, 24) is formed as a rectangle.

A multi-frequency planar antenna (10) according to any one of claims 1 to 9, wherein the aperture (14) is located entirely within one half of the first surface (Ai) of the first radiation electrode (12). 1 1. The planar multi-frequency antenna (10) of claim 9, wherein the aperture (14) does not extend beyond two straight lines passing through a centroid and bordering a quarter of the total area (Ai) of the first radiation electrode (12), such that the aperture (14) is limited to at most a quarter of the area (Ai) of the first radiation electrode (12).

12. A planar multi-frequency antenna (10) according to any one of claims 1 to 1 1, wherein the radiation electrodes (12, 16, 24) are formed as a rectangle. 13. A planar multi-frequency antenna (10) according to any one of claims 1 to 12, wherein the second radiation electrode (16) is placed centrally in the opening (14).

14. A planar multi-frequency antenna (10) according to any one of claims 1 to 12, wherein the first radiation electrode (12) is designed such that a distance

(A) between an outer boundary of the first radiation electrode (12) and the opening (14) is at least 0.25% of a maximum extension of the first radiation electrode (12).

A planar multi-frequency antenna (10) according to any one of claims 1 to 14, wherein the second radiation electrode (16) to the first radiation electrode (12) has a distance (B) corresponding to at least 0.5% of a maximum extension of the first radiation electrode (12) ,

Planar multi-frequency antenna (10) according to any one of claims 1 to 15, wherein the surface (A ₂ ) of the second radiation electrode (16) has a size which is smaller than 40% of the area (Α-ι) of the first radiation electrode (12).

Planar multi-frequency antenna (10) according to any one of claims 1 to 16, wherein a plurality of radiation electrodes (16i, to 16 _n) in the opening (14) are arranged, wherein the radiation electrode (16i, to 16 _n) spaced apart a distance (C) exhibit.

A planar multi-frequency antenna (10) according to claim 17, wherein the distance (C) between the radiation electrodes (16, 26) in the opening (14) is at least 0.5% of a largest dimension, the largest of the second radiation electrodes (16).

Planar multi-frequency antenna (10) according to one of claims 1 to 18, wherein the second radiation electrode (16), a further opening (24), in which a third radiation electrode (26) is arranged. Planar multi-frequency antenna (10) according to one of claims 1 to 18, wherein in a second metallization layer (18), a ground plane is arranged plane-parallel to the first radiation electrode (12).

The planar multi-frequency antenna (10) of claim 20, wherein the ground plane (G) does not protrude beyond an outer periphery of the first radiation electrode (12).

Planar multi-frequency antenna (10) according to one of claims 1 to 21, wherein in the opening (14) at least one electrical component is integrated.

Planar multi-frequency antenna (10) according to one of claims 1 to 22, wherein in at least one of the radiation electrodes (12, 16, 26) at least one slot is introduced.

A method of operating a multi-frequency piano antenna (10), the multi-frequency piano antenna (10):

- A first radiation electrode (12) having a first surface (Ai), wherein the first surface (Ai) has at least one opening (14), and

at least one second radiation electrode (16) having a second surface (A ₂ ), wherein the second radiation electrode (16) is disposed in the opening (14) spaced from the first radiation electrode (12), and wherein the first radiation electrode (12 ) and the second radiation electrode (16) lie in a common metallization layer (18); and wherein the method comprises feeding the multi-frequency piano antenna (10) with an electrical signal. 25. The method of claim 24, wherein the planar multi-frequency antenna (10) is energized to emit a dual polarized or a circularly polarized electromagnetic wave.

26. A planar multi-frequency antenna (10) comprising:

- A first radiation electrode (12) having a first surface (Ai), wherein the first surface (A1) has at least one opening (14), and

at least one second radiation electrode (16) having a second surface (A ₂ ), wherein the second radiation electrode (16) is disposed in the opening (14) spaced from the first radiation electrode (12), the first radiation electrode (12) and the second radiation electrode (16) lie in a common metallization layer (18); and wherein a plurality of radiation electrodes (16i, to 16 _n) are arranged in the opening (14), wherein the radiation electrode (16i, to 16 _n) spaced apart a distance (C).

27. A planar multi-frequency antenna (10) comprising:

- At least a second radiation electrode (16) having a second surface (A ₂ ), wherein the second radiation electrode (16) in the opening (14), from the first radiation electrode (12) spaced, is arranged all the radiation electrodes (12, 16, 26) of the planar multi-frequency antenna (10) lie in a common metallization layer (18); wherein the first radiation electrode (12) is designed for the lowest frequency band; and wherein the planar multi-frequency antenna (10) comprises a feed network (20) electrically connecting a feed point (22) and at least one of the radiation electrodes (12, 16, 26).