WO2002007254A1

WO2002007254A1 - Antenna for multi-frequency operation

Info

Publication number: WO2002007254A1
Application number: PCT/EP2001/008078
Authority: WO
Inventors: Roland Gabriel; Maximilian GÖTTL
Original assignee: Kathrein-Werke Kg
Priority date: 2000-07-18
Filing date: 2001-07-12
Publication date: 2002-01-24
Also published as: AU8760801A; CN2514507Y; DE10034911A1

Abstract

An improved antenna comprising at least two individual radiators (1, 2) can be operated in at least two frequency bands (f1, f2, ..., fn). The antenna is improved by the following measures: each output of the individual radiators (1), which can be operated in at least two frequency bands (f1, f2, ..., fn), or the output of a group of corresponding individual radiators (1) is assigned to a frequency separating filter (21), whereby the frequency band provided on the connection, which is located on the radiator, is separately provided in at least two partial frequency bands (f1, f2, ..., fn) on connections, which are located on the supply system. A supply system (7) is constructed in such a manner that the supply-side connections (23.1, 23.2) on the frequency separating filter (21) are interconnected with a predeterminable or variably adjustable phase and/or amplitude for the respective partial frequency band for forming beams and, in particular, for variably setting the lowering angle of the main lobe.

Description

Antenna for multi-frequency operation

The invention relates to an antenna for multi-frequency operation according to the preamble of claim 1.

It is important for a network operator in the mobile radio sector to be able to use antennas for the different frequencies at the same time. However, since different requirements are placed on the service area or network planning for the different services, different radiation characteristics, in particular different vertical drop angles, are also required for the vertical characteristic. Different vertical drop angles for the main lobe for the different frequencies would be ideal. However, this is not possible with the previously known solutions for closely adjacent frequencies.

Therefore, only solutions are known which use different radiators for the different frequency ranges. These can consist, for example, of nested dipoles, as is described, for example, in DE-Al 198 23 749 for dual-polarized multi-polarization. antenna can be seen. The disadvantage here, however, is that, due to the geometry of the arrangement, the frequency bands cannot be directly adjacent, but rather must have a ratio of 1: 2.

In addition, from the publication "Electronic Letters", August 1999, Vol. 35, No. 17, pp. 1399-1400, by Yeunjeong, Kim, Wansuk Yun and Youngjoong Yoon a dual band patch antenna is known which has different connections for two different frequencies. However, the connections for the other frequency are polarized orthogonally to each other. A solution for two polarizations and several frequencies cannot be found. Another disadvantage here is the complex layer structure with four different dielectric layers lying one on top of the other.

In contrast, broadband antennas can also be operated in neighboring frequency ranges or over a very broad frequency band. However, no different, in particular variably adjustable, radiation characteristics can be achieved for the different frequency ranges. In the previous publication "Electronic Letters", March 2000, Vol. 36, No. 6, pp. 487-488 are from the publication of D.H. Werner and D. Lee known "Design of dual-polarized multiband frequency selective surfaces using fractal elements" dual-polarized fractal antenna structures that can be operated in a large frequency band. However, these antenna structures do not include separately adjustable radiation patterns.

A transmitting / receiving antenna is known from WO 98/43315. knows, which provides for a first polarization on the individual radiators of the antenna array duplex filter to thereby divide the antenna array for the receive frequency range (Rx) and for the transmit frequency range (Tx) into different inputs and outputs. If the different frequencies (Rx - Tx) are not decoupled via the orthogonal polarization, then at least one isolating amplifier in one of the two frequency bands at the duplex filter inputs and outputs is disadvantageously necessary. Isolation amplifiers are also required since adequate decoupling between the frequency bands (Rx and Tx) cannot be achieved. Furthermore, there is no suggestion for generating different lowering angles for different frequency ranges.

Finally, a two-band antenna array with broadband single radiators is known from WO 84/04855 AI. It comprises several single radiators that can be operated in two frequency bands. Each output of the individual radiators which can be operated in two frequency bands is assigned to a crossover network, the frequency band present at the radiator-side connection being present separately in at least two sub-frequency bands at the supply network-side connections. The feed network is constructed in such a way that the connections on the feeder network side on the crossover for the respective sub-frequency band for beam shaping and in particular for different setting of the lowering angle of the main lobe can be interconnected with a predefinable and changeable adjustable phase and / or amplitude.

With antenna arrays of this type, however, it proves to be difficult and complex to to implement damping between the individual frequency bands.

It is therefore an object of the present invention to provide an antenna arrangement which, when operating in different frequency bands, preferably realizes a different, in particular independently adjustable, radiation characteristic without additional active components with a high overall decoupling between the two frequency bands, and this with comparable Little effort.

The object is achieved according to the features specified in claim 1. Advantageous refinements of the invention are specified in the subclaims.

It must be described as surprising that the antenna device according to the invention can be independently set with a very low filter effort

Beam pattern enables. Almost independent radiation characteristics can be achieved with a blocking attenuation of the crossovers of even less than approx. 15 dB, e.g. B. from 8 to 12 dB can be realized. It is now provided in accordance with the invention that the overall required blocking damping is multi-stage, i.e. to build up at least in two stages, the cheapest way is to carry out an additional filter arrangement in the feeder network connection itself, upstream or downstream, i.e. at least in the feed line section in front of a branch point and / or provided phase shifters.

What is particularly surprising here is that filter structures can be used, which allow the interconnection by means of a passive feed network and at the same time have a sufficiently high decoupling between the different frequency bands for each polarization.

According to the invention, this can be achieved by means of crossovers in the form of a frequency-selective filter structure, which preferably allows a frequency band to be divided into two sub-frequency bands with sufficient blocking attenuation. The use of a fixed feed network or preferably a variably designed feed network using phase shifters now allows the individual emitters to be interconnected in such a way that the desired radiation diagram setting can be made for the respective frequency range, i.e. that in particular the vertical lowering angle can preferably be set separately according to the wishes and necessities.

Finally, since a low blocking attenuation is sufficient for the shaping of the diagram, but nevertheless high decoupling values of, for example, 30 dB and more are required, it results in accordance with a particularly preferred embodiment of the invention to put an additional filter effort at the feed inlet. This enables that only one additional filter is required per polarization to increase the decoupling. In this way, highly selective additional filters provided for each dipole or each dipole group can be avoided.

The invention is explained in more detail below on the basis of exemplary embodiments. The following show in detail: Figure 1: a first embodiment of an antenna array with four dipoles, which are interconnected with a fixed feed network;

FIG. 2: an exemplary embodiment modified from FIG. 1, in which the interconnection for a frequency range is carried out variably by means of a fixed interconnection and the interconnection for a second frequency range is carried out variably by means of phase shifters;

FIG. 2a: an enlarged section from FIG. 2 to illustrate a phase shifter;

FIG. 3: a further exemplary embodiment in which the interconnection is carried out variably via phase shifters for both frequency ranges;

Figure 4: an antenna array with dual polarized

Radiators and two frequency ranges, in which for each polarization for each

Frequency range the interconnection takes place by means of phase shifters;

FIG. 5: an exemplary embodiment for a dual-band antenna, in which the second band is frequency-selectively divided into a frequency band f2 and f3 and thus a three-range antenna results; and FIG. 6: an exemplary embodiment modified from FIG. 2 to clarify that a crossover can also be assigned to a group of at least two individual radiators.

The first exemplary embodiment according to FIG. 1 is discussed below. The antenna array shown schematically therein comprises four individual radiators 1, in the exemplary embodiment shown in the manner of dipoles 1 ', which are usually arranged in front of a reflector which is arranged vertically, for example in the vertical direction.

The individual radiators 1 are fed via feed connections 5.1 and 5.2 via a fixed or hard-wired feed network 7. Depending on the number of individual radiators 1, there is a multiple branching of the feed lines 9 starting from each feed connection 5.1 or 5.2, namely from the feed connection 5.1 via the feed line 9 and a branching point 11 into the feed branch lines 9.1 and via the respective subsequent branch point 13 to the subsequent feed branch line 9.2 , The same applies to the further 'supply connection 5.2 with the feed line 109, the branch point 111, the feed branch lines 109.1, the branch points 113 and the feed branch lines 109.2. The feed lines also contain impedance transformers, which are not shown for the sake of simplicity.

The individual radiators 1 are each connected via their respective output 17a via a line 17 to a radiator-side connection 19 of a crossover 21, which in turn is connected to two connections on the supply network side. Conclusions 23.1 and 23.2 is connected, specifically frequency-selective for a first frequency band fl and a second frequency band f2. The crossovers 21 can be constructed by a frequency-selective filter structure.

The respective feed branch lines 9.2 and 109.2 are connected to the connections 23.1 and 23.2 on the supply network side, so that all the individual radiators 1 are frequency-selectively connected to the supply connection 5.1 for the first frequency band fl and the supply connection 5.2 for the second frequency band f2.

The crossovers 21 are with sufficient blocking attenuation of z. B. 15 dB or even less than 10 dB in the at least two sub-frequency bands. The interconnection can be carried out in such a way that the setting of the radiation diagram is preset differently for the respective frequency band. The presetting can take place in such a way that, for example, the vertical drop angles are different for both frequency bands.

Finally, in the exemplary embodiment according to FIG. 1 (as will be explained in greater detail in the exemplary embodiment according to FIG. 6), an additional filter 121 is connected to the two connections 5.1 and 5.2 on the supply network side in order to increase the total blocking attenuation. As a result, the crossovers 21 can be designed such that they themselves have only a low blocking attenuation.

The exemplary embodiment according to FIG. 2 largely corresponds to that according to FIG. 1, but with the lower decided that for the one frequency band f2 there is no fixed interconnection at the branching points 113, but that in each case variably adjustable phase shifters 27 are provided. The phase shifters can be constructed in such a way as is basically known from WO 98/21779. In other words, a one-piece member 31 which is adjustable about a pivot axis 29 is provided and is connected to the feed connection 5.2 via a line 109 and 109.1. This one-piece member 31 is connected, for example, galvanically or capacitively to a part-circular contact or coupling element 33, which is electrically connected at its opposite end regions to phase shifter connections 35, from which the connection to the supply network-side connections 23.2 at the frequency ranges is established via subsequent feed branch lines 109.2 21 takes place. The so-called partially circular contact or coupling element 33 in the exemplary embodiment shown is preferably constructed using stripline or micro-stripline technology, specifically on a base plate 28 (ground plate).

The radiation diagram for the first frequency band fl thus takes place via the fixed feed network part, as a result of which a specific radiation diagram is predefined. Via the variably adjustable phase shifter elements 27, however, the radiation diagram is set with respect to the second frequency band f2 via a variable feed network, so that the radiation shaping and thus in particular the radiation reduction, ie the angle of reduction for the main lobe, can be set differently within the frequency band f2. The exemplary embodiment according to FIG. 3 is modified compared to that according to FIG. 2 insofar as a feed network 7 is provided for both frequency bands fl and f2, which provides for a corresponding beam shaping in both frequency bands fl and f2 and thus in particular a vertically adjustable and / or changeable variable Allows lowering of the main legs.

In the exemplary embodiment according to FIG. 4, an antenna array is now used which does not consist of single radiators 1, but of dual-polarized radiators 2. These dual-polarized radiators 2 can be composed, for example, of a dipole square or a dipole cross, that is to say using single dipole radiators 1. Correspondingly, each dipole single radiator of a dual-polarized dipole cross 2 (or, for example in the case of a dipole square, two dipole radiators each arranged in parallel) is connected to a crossover 21 via a common line 17 or 17 '. Thus, as can be seen from FIG. 4, two lines 17, 17 'proceed from each of the four dipole radiators, each of which leads to the radiator-side connection 19 of the crossovers 21. With four dual-polarized dipole radiators 2, eight crossovers are thus provided. In general, 2 n crossovers 21 are therefore required in this exemplary embodiment with n dual-polarized dipole radiators. In FIG. 5, the connection 5.1 at the top for the frequency fl is assigned to the polarization + 45 °, the connection 5.1 ′ for the frequency fl at the bottom being assigned to the negative polarization -45 ° in FIG

Figure 4 shown and assembled into a dipole cross dipole radiator are arranged in a + 45 ° / -45 ° orientation. The dipoles la and lb of the dual-polarized dipole emitters 2, which are aligned in parallel to one another, are brought together frequency-selectively via two downstream feed networks, in the exemplary embodiment according to FIG set and / or change a first as for a second frequency fl and f2 separately for each polarization.

Finally, reference is made to the exemplary embodiment according to FIG. 5. FIG. 5 shows an arrangement likewise for a dual-polarized antenna 2, each of the dual-polarized antennas 2 provided according to FIG. 5 comprising a cross dipole 2 ′ and a dipole square 2 ″ surrounding the cross dipole 2 ′.

The individual radiators la or lb of the dipole square 2 ", which are respectively arranged parallel to one another, are connected via a variable feed network 7, the respective radiating individual radiators la of a radiator arrangement 2", which are arranged parallel to one another, being paired with the individual radiators arranged in the same parallel orientation la a second radiator arrangement 2 "are connected together via a phase shifter 27, and the feed connection-side connections of the phase shifters 27 then in turn lead via a branching point 211 to a common feed connection 5.3. The same applies to the second polarization of this dipole square arrangement, in which via the feed connection 5.3 'A connection via the downstream branch point 211' to the phase shifters 27 and via the two outputs in each case to the two parallel dipole radiators lb of a relevant radiator arrangement 2 ".

The connections 5.3 and 5.3 'thus serve to receive or transmit a third frequency band with a first and a second polarization. The frequency band f3 can e.g. are at 824 to 960 MHz.

With respect to the cross dipoles 10 'arranged in the interior of the dipole squares, on the other hand, there is a frequency-selective division into two frequency bands fl and f2, the outputs on the supply connection side then in turn for each of the two polarizations in accordance with the exemplary embodiment according to FIG. 4 via phase shifters 27 with the two supply connections for fl and f2 are interconnected. The frequency band fl can e.g. 1920 to 2170 MHz and the second frequency band f2 cover a range from 1710 to 1880 MHz.

FIG. 5 thus shows a dual-polarized antenna with three band ranges, the radiation diagram and in particular the angle of attenuation for all three frequency bands and both orthogonal polarizations being adjustable differently.

Deviating from the last-mentioned example, a frequency-selective band division could of course also be provided for the third frequency band. In the same way, if required for a single frequency band, a fixed interconnection without an individually adjustable lowering angle could be implemented, as is shown schematically, for example, in FIG. 2.

In all exemplary embodiments, the crossovers can preferably be implemented by filter structures, which can also be integrated in particular in the housing of the antenna. The filter structures can also consist of shielded stripline structures or triplate structures.

Alternatively or partially alternatively and additionally, the filter structures can also be formed from coaxial filters.

It can be seen from the exemplary embodiments explained that the corresponding antennas comprise at least two individual radiators. However, it is also possible to provide more than two individual radiators which belong to a common group. Only one group of single radiators is possible, but also several groups of single radiators, as described for example in the case of dual-polarized antennas.

To achieve good decoupling, the crossovers should have a minimum blocking attenuation of at least 6 dB, 8dB or 10 dB compared to the other frequency range. This value should preferably be at least 15 dB, in particular at least 20 dB.

In order to additionally increase the blocking attenuation in the other frequency band, additional filters can be provided in the output of the antenna after the interconnection by means of the feed network mentioned. An improvement in heat dissipation can finally also be achieved in that the filters are attached to the reflector plate. The filters on the refector plate can be mechanically stacked on top of each other be stacked.

A modification is shown on the basis of FIG. 6, which can in principle be used for all the exemplary embodiments explained in accordance with FIGS. 1 to 5.

In the exemplary embodiment according to FIG. 6, it is made clear that, for example, deviations from FIG. 2, e.g. a group 100 with two individual radiators 1 is assigned to a crossover 21. The group 100 of individual emitters 1 can not only have two individual emitters 1, 1 ', but also, for example, several individual emitters 1, 1', e.g. comprise three individual radiators, which can be assigned to an input of a crossover 21, for example via a common summing point and a downstream line.

With reference to FIG. 6, it is additionally shown what can also be used in all other exemplary embodiments that additional filters 121 can be provided, which are preferably assigned in the output of an antenna after interconnection by means of the feed network 7, and are preferably attached to the reflector plate can. By setting up these additional filters 121, the blocking effect of the filters 21 for the downstream individual radiators can be further improved in a cost-effective and simple manner.

Claims

claims;

1. Antenna array for at least two frequency bands with the following features

with at least two individual radiators (1, 2), the at least two individual radiators (1, 2) can be operated in two frequency bands (fl, f2),

- Each output (17a) of the individual radiators (1, 2) which can be operated in two frequency bands is assigned a crossover (22), the frequency band present at the radiator-side connection (17a) being present separately in at least two sub-frequency bands at connections (5.1, 5.2) on the supply network side,

- An intended feed network is constructed in such a way that the connections (23.1, 23.2) on the feeder network (21) for the respective sub-frequency band (fl, f2) for beam shaping and in particular for different setting of the lowering angle of the main lobe are adjustable and / or adjustable Phase and / or amplitude are interconnected, characterized by the following further features

a multi-stage filter structure is provided in order to achieve sufficient blocking attenuation with respect to the respective other frequency band range, - In addition to the crossovers (21), which form a first filter structure to achieve the blocking attenuation, additional filters (121) are provided, which are connected to the respective feed network connection (5.1, 5.2) or upstream or in one of the feed network connection (5.1, 5.2) Downstream feed line section (109) are arranged, which leads to a first crossover (21, 27) viewed on the feed network side.

2. Antenna according to claim 1, characterized in that a crossover network (21) is assigned to a group (100) of at least two individual radiators (1, 1 ').

3. Antenna according to one of claims 1 or 2, characterized in that at least with respect to a frequency band (fl, f2, ..., fn) the outputs (23.1, 23.2) of the crossovers (21) via assigned phase shifters (27) at least indirectly are connected to the respective feed network connection (5.1, 5.2, ..., 5.n).

4. Antenna according to one of claims 1 to 3, characterized in that all individual radiators (1, 2) or groups

(2, 2 ', 2 ") of individual radiators (1, 2) via the assigned crossovers (21) and assigned phase shifters

(27) are interconnected with the assigned feed network connections (5.1, 5.2, ..., 5.n) in such a way that the radiation diagram and, in particular, the setting of the lowering angle of the main lobe can be set differently for all frequency bands.

5. Antenna according to one of claims 1 to 4, characterized in that at least two dual polarized radiation leranrangements (1, 2) are provided.

6. Antenna according to one of claims 1 to 5, characterized in that the radiator arrangements (1, 2) comprise dual-polarized individual radiators (1, 2) which radiate for each of the polarizations in two different frequency bands, at least for one polarization Frequency band splitting is provided via a fixed or a variable feed network (7) using phase shifters (27).

7. Antenna according to one of claims 1 to 6, characterized in that the crossovers (21) are formed from filter structures, which in particular comprise shielded stripline or triplate structures.

8. Antenna according to one of claims 1 to 7, characterized in that the crossovers (21) are formed from filter structures which comprise coaxial filters.

9. Antenna according to one of claims 1 to 8, characterized in that the crossovers (21) have a minimal blocking attenuation with respect to the other frequency band of at least 6, 8 or 10 dB, in particular at least 15 dB, preferably at least 20 dB.

10. Antenna according to one of claims 1 to 9, characterized in that the portion of the blocking attenuation of the crossover is below about 15 dB, preferably below 10 dB, for example by 8 to 12 dB, the total

Decoupling preferably has 30 dB and more.

11. Antenna according to one of claims 1 to 10, characterized characterized in that the interconnection of the crossovers (21) in two frequency bands (fl, f2) takes place by means of differently adjustable phase shifters (27).

12. Antenna according to one of claims 1 to 11, characterized in that the interconnection of the crossovers (27) for at least one frequency band is fixed and for at least one further frequency band by means of phase shifters (27) is provided variably. '-

13. Antenna according to one of claims 1 to 12, characterized in that at least further independent individual radiators (2 ') are provided for at least one further frequency band (f3), so that the antenna in at least three frequency bands (fl, f2,. .., fn) is operable.

14. Antenna according to one of claims 1 to 13, characterized in that the feed network (7) is constructed using filter switches (21) so that a division into more than two frequency bands is provided.

Antenna according to one of claims 1 to 14, characterized in that the filters, i.e. the filter switches (21) and / or the additionally provided filters (121) are attached to the reflector plate.

16. Antenna according to claim 15, characterized in that the additional filters (121) are mechanically stacked on the reflector plate.

17. Antenna according to one of claims 1 to 16, characterized in that the filter structures in the housing the antenna are integrated.