Patent Application
20130288632
This application claims priority to EP Application No. 12 165 712.6-2411 filed on Apr. 26, 2012, the disclosure of which is incorporated in its entirety by reference herein.
This invention relates to radio frequency antennas, specifically to a multiple antenna system which is capable of operating in multiple frequency ranges.
An antenna is usually connected to a transmitter or receiver by way of a feed line. Antennas for use at radio frequencies are effective over a limited frequency range. When operation is required over a wide frequency range it is common to use multiple antennas with each antenna optimized for a specific narrow band of frequencies. However, in such an antenna system for each antenna an individual feed line is to be provided so that such a system is costly, room consuming and heavy and, thus, less suitable for automotive applications.
Also common are systems in which multiple (active) antennas are connected to multiple receivers and/or transmitters via a single feed line. Signals of multiple antennas operated in different frequency ranges are combined by way of cross-over networks that superimpose signals in different frequency ranges to provide a broadband signal on a single feed line (e.g., multi-standard antenna systems), and signals of multiple antennas operated in the same frequency range (e.g., antenna diversity systems) are combined in a weighted fashion to provide an optimized signal in the particular frequency range which is to be transferred via the single feed line. However, if multi-standard antenna systems are arranged in a vehicle, in which usually receiving conditions vary strongly, the frequency response of the crossover networks may be either mismatched to the off air channel or the receiver may overloaded to the effect that the signals received are disturbed or the crossover networks produce too much noise due to little signal amplitudes.
Thus, there is a need to provide a multi-standard antenna/receiver system that overcomes the above-mentioned drawbacks.
An antenna system is disclosed herein which includes a frontend portion, a backend portion, a feed line for connecting the frontend portion and the backend portion with each other, and a control unit for controlling the frontend and/or the backend portion. The frontend portion includes multiple antennas that provide antenna signals and at least one combiner network that connects the antennas to the feed line. The backend portion includes multiple receivers and at least one splitter network that connects the feed line to the receivers. The control unit is configured to evaluate the reception quality and adjust the at least one combiner and/or splitter network dependent on the reception quality. The at least one combiner network combines the signals from at least two antennas in different, non-overlapping frequency ranges to form at least one combined signal thereof.
Various specific embodiments are described in more detail below based on the exemplary embodiments shown in the figures of the drawing. Unless stated otherwise, similar or identical components are labeled in all of the figures with the same reference numbers.
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
Referring to
The backend portion 2 includes a splitter network (e.g., crossover network) 5 that may have N bandpass filters BF1, BF2 . . . BFN whose inputs are connected with each other to form an input of the crossover network 5 that is connected to the feed line 3. The outputs of the bandpass filters BF1, BF2 . . . BFN are connected to N receiving paths established by receivers RCV1, RCV2 . . . RCVN that may be at least one of, for example, AM/FM, DAB, TV, DVB, CMMB and/or satellite receivers and that form part of a multi-standard receiver block 6. The backend portion 2 may be arranged in, for example, a head unit for automobiles.
A control unit 7 may be arranged in the frontend portion 1, the backend portion 2 or elsewhere, is connected to the antenna amplifiers V1, V2 . . . VN and/or the bandpass filters FF1, FF2 . . . FFN and/or the bandpass filters BF1, BF2 . . . BFN in order to control the same in at least one of, for example, gain and bias point, frequency range, insertion loss, band stop attenuation and bandwith. The control unit 7 may evaluate information provided by the multi-standard receiver block 6 or a dedicated evaluation circuit 8 that provides information based on own measurements performed on signals from the antennas A1, A2. . . AN and/or the antenna amplifiers V1, V2 . . . VN. Such information may be signal strength, band power, noise level, or the like.
Alternatively or additionally, further information may be such as Global Positioning Sensors (GPS) from a GPS sensor 9, broadcast information services such as the Radio Data System (RDS) or the Radio Broadcast Data System (RBDS), broadcast station maps etc. from the receivers RCV1, RCV2 . . . RCVN which may also supply information to the control unit 7 that represents, for example, the level of the signals received by the receivers RCV1, RCV2 . . . RCVN, the receiver standard, channel frequency, adjacent-channel interference channel noise level and/or the like. From the information received from any one or more of the antenna amplifiers V1, V2 . . . VN, the bandpass filters FF1, FF2 . . . FFN (BF1, BF2 . . . BFN), the receivers RCV1, RCV2 . . . RCVN, the dedicated evaluation circuitry 8, and the sensors 9, the control unit 7 generates control signals to control the antenna amplifiers V1, V2 . . . VN and/or the bandpass filters FF1, FF2 . . . FFN and, as the case may be of the bandpass filters BF1, BF2 . . . BFN in order to adjust one or more of the bias point, the gain of the antenna amplifiers V1, V2. . . VN, and/or the gain, the frequency range, the bandwidth, the insertion loss, and the stop band attenuation of the bandpass filters FF 1, FF2 . . . FFN and/or BF1, BF2 . . . BFN.
For instance, if the level of the signals to be received by one of the antennas A1, A2. . . AN is low, the bias point of the corresponding one of the antenna amplifiers V1, V2. . . VN, is adjusted in a manner that the noise produced by the amplifier is reduced. If the levels of the signals to be received by one of the antennas A1, A2. . . AN are too high or disturbing signals are received at a high level, the gain of the respective antenna amplifier V1, V2. . . VN may be reduced or the bandpass filters FF1, FF2 . . . FFN and/or BF1, BF2 . . . BFN may be tuned due to one or more of a change in the frequency range, in the bandwidth, the insertion loss, and the stop band attenuation.
In many situations it may be necessary to provide two (identical) antennas in the same frequency range (for the same standard) with, may be, different directivity. In such a case, both antennas may be evaluated and both may be controlled dependent on the assessment of one or more of the respective antenna, the amplifier, the bandpass filter, and the receiver. Referring now to FIG. 2, N pairs of antennas A1a, A2a. . . ANa, A1b, A2b. . . ANb and N pairs of amplifiers V1a, V2a. . . VNa; V1b, V2b. . . VNb are coupled via corresponding pairs of bandpass filters FF1a, FF2a. . . FFNa and FF1b, FF2b. . . FFNb in the frontend portion 1 and a pair of feed lines 3a and 3b with corresponding pairs of bandpass filters BF1a, BF2a. . . BFNa and BF1b, BF2b. . . BFNb arranged in the backend portion 2.
The cross-over networks 4 and 5 are connected upstream and downstream of the feed lines 3a and 3b. Pairs of receivers RCV1a, RCV2a . . . RCVNa; RCV1b, RCV2b . . . RCVNb are connected downstream of the pairs of filters BF1a, BF2a. . . BFNa and BF1b, BF2b. . . BFNb of the backend portion 2.
With a multiple standard system as described above with reference to
However, systems with partial antenna diversity may also be provided as described below with reference to
The individual frequency ranges AM, FM, DAB-L, TV−III+IV+V are non-overlapping. The outputs of amplifiers V1 and V5 are combined in a combiner CO1 to a single combined output signal that is transferred to a head unit HU via a feed line FL1. The outputs of amplifiers V2, V3 and V4 are combined (e.g., superimposed) in a combiner CO2 to a single combined output signal that is transferred to the head unit HU via a feed line FL2. The combiners CO1, CO2 may be crossover networks if the amplifiers A1 . . . A6 have essentially no impact on the frequency characteristic of the signals to be amplified. Alternatively, all amplifiers A1 . . . A6 may be operated only in a specified frequency range so that they additionally serve as bandpass filters. In this case, the combiners CO1, CO2 may simply be signal adders or the like. The head unit HU may include a triple FM/AM Tuner TU1 with phase diversity and a dual/triple multi-standard tuner TU2 with maximum ratio combining (MRC) technology. A splitter network SPN connects the splitter network SPN to the feedlines FL1, FL2, (FL3).
With a system according to the invention it is possible to connect, for example, two multi-standard receivers by way of only two feedlines to a multiplicity of antennas of a (partial) diversity system without causing any signal overdrive and large-signal problems. Thus, even in an antenna diversity system with a plurality of antennas the backend portion needs to be connected only by a small number of feedlines, for example 2 (or 3), and, accordingly, a small number of connectors are necessary so that the costs are kept small as well as room and weight is saved. This is achieved in that one or more of the frequency range, the bandwidth, the insertion loss, the stop band attenuation of the bandpass filters, and the gain of the amplifiers is controlled in order to address the receiving situation at a certain location. The control unit assesses the reception quality by evaluating information originating from the frontend portion, the backend portion or other arrangements including sensors, memories, wireless connections, etc. The control of the bandpass filters and/or the amplifiers may be adaptive to match their frequency response to the off air channel.
Although various examples of realizing the invention have been disclosed, it will be apparent to those skilled in the art that various changes and modifications can be made which will achieve some of the advantages of the invention with-out departing from the spirit and scope of the invention. It will be obvious to those reasonably skilled in the art that other components performing the same functions may be suitably substituted. Such modifications to the inventive concept are intended to be covered by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 12 165 712.6-2411 | Apr 2012 | EP | regional |
