Field of the Invention
The present invention relates to communications equipment and, more specifically but not exclusively, to antenna arrays for base stations in cellular communications networks.
Description of the Related Art
This section introduces aspects that may help facilitate a better understanding of the invention. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is prior art or what is not prior art.
Many modern base station antennas (BSAs) need to be multi-carrier and multi-operator and need to support different communication standards and different frequency ranges. One BSA can cover two or more relatively wide frequency bands (e.g., 698 MHz to 960 MHz plus 1710 MHz to 2690 MHz). To work with different standards and/or with different operators, a wideband BSA can be integrated with distributed filters.
Antenna arrays with distributed filters are known in the art. See, e.g., U.S. Pat. No. 6,208,299 B1 (the '299 patent). The advantage of the '299 patent is the possibility to obtain the same beamwidth for different frequency sub-bands. But the '299 patent does not allow independent beam tilt (or beam scanning) for its different sub-bands.
Antennas with distributed filters and independent (phased-array) beam tilt for each sub-band are known in the market. See, e.g., the Type No. 80010668 BSA with Adjustable Electronic Downtilt unit from Kathrein of Rosenheim, Germany.
Another disadvantage of prior-art antenna system 100 of
Other embodiments of the invention will become more fully apparent from the following detailed description, the appended claims, and the accompanying drawings in which like reference numerals identify similar or identical elements.
As shown in
In particular, each diplexing filter D in
Lastly, each phase shifter network PS1, PS2 is connected to a respective band-pass filter F1, F2 configured to the corresponding sub-band f1, f2. In one implementation, band-pass filter F1 passes signals in sub-band f1 and attenuates signals in sub-band f2 by about 30 dB, and analogously for band-pass filter F2 and sub-bands f2 and f1.
In antenna system 200, independent beam tilt is provided by using different phase shifter networks PS1 and PS2 for sub-bands f1 and f2. The same or similar beamwidth for both sub-bands f1, f2 is provided by using different numbers of antenna elements for the two sub-bands and different spacing (d1, d2, d1>d2) between the antenna elements. If the electrical lengths (in wavelengths) of (i) the antenna array containing elements A1 plus A2 and (ii) the array containing only elements A2 are the same, then the beamwidths for sub-bands f1 and f2 will be the same, even if the physical lengths are different.
For example, the most-desirable elevation beamwidth for DCS, IMT, and LTE2.6 bands in Europe is 6-7 degrees. This case can be realized in accordance with
By proper selection of the number, spacing, and beamwidths of elements A1 and A2, the sub-band beamwidths can be optimized not only in the elevation plane, but also in the azimuth plane. For elements A1, highly directive radiators can be used (e.g., Yagi style radiators) to keep the number of elements A1 relatively small and also provide a relatively narrow azimuth beamwidth (e.g., close to 60-65 degrees), which usually is desired (and not achieved with relatively wideband elements A2, which usually have an azimuth beamwidth of about 70 degrees at lower frequency).
Cost reduction can be obtained by using relatively simple/low-cost diplexing filters D near elements A2 (with relatively low isolation level 13-15 dB) instead of the more-expensive cavity diplexers CD of
Antenna parameters (such as return loss, gain, cross-polarization) for sub-band f1 also can be potentially improved, because relatively narrow-band radiating element A1 can be tuned for better performance compared to relatively wide-band radiating element A2.
In
Thus, antenna system 200 of
Although the disclosure has been described in the context of antenna systems supporting communications in two sub-bands, in general, antenna systems of the disclosure can be designed to support communications in two or more sub-bands.
As shown in
Lastly, each phase shifter network PS1, PS2, PS3 is connected to a respective band-pass filter F1, F2, F3 configured to the corresponding sub-band f1, f2, f3. In one implementation, band-pass filter F1 passes signals in sub-band f1 and attenuates signals in sub-bands f2 and f3 by about 30 dB, and analogously for band-pass filters F2 and F3.
In antenna system 400, independent beam tilt is provided by using different phase shifter networks PS1, PS2, PS3 for sub-bands f1, f2, f3. The same or similar beamwidth for all three sub-bands is provided by using different numbers of antenna elements for the three sub-bands and different spacing (d1>d2>d3) between the antenna elements. If the electrical lengths (in wavelengths) of the three groups of antenna elements A1+A2+A3, A2+A3, and A3 are the same for f1, f2, and f3, then the beamwidths for the three sub-bands will be the same, even if the physical lengths are different.
Analogous to
As used herein, the term “multiplexer” or “multiplexing filter” refers generally to filters, such as (without limitation) diplexing filters and triplexing filters, that combine multiple downlink signals having different frequency ranges for transmission and/or separate multiple received uplink signals having different frequency ranges. In the general case, multiplexers with up to N outputs can be used to provide independent beam tilt for each of N sub-bands with the same beamwidth, where N>1.
Although the disclosure has been described in the context of the linear or one-dimensional antenna (1-D) arrays of
Two-dimensional antenna system 500 can provide 2-D beam steering in any available directions with the same beamwidth for both sub-bands independently. 2-D antenna arrays can also be implemented using a diplexing filter and a single feed line as in
It should be appreciated by those of ordinary skill in the art that any block diagrams herein represent conceptual views of illustrative circuitry embodying the principles of the invention.
Unless explicitly stated otherwise, each numerical value and range should be interpreted as being approximate as if the word “about” or “approximately” preceded the value or range.
It will be further understood that various changes in the details, materials, and arrangements of the parts which have been described and illustrated in order to explain embodiments of this invention may be made by those skilled in the art without departing from embodiments of the invention encompassed by the following claims.
In this specification including any claims, the term “each” may be used to refer to one or more specified characteristics of a plurality of previously recited elements or steps. When used with the open-ended term “comprising,” the recitation of the term “each” does not exclude additional, unrecited elements or steps. Thus, it will be understood that an apparatus may have additional, unrecited elements and a method may have additional, unrecited steps, where the additional, unrecited elements or steps do not have the one or more specified characteristics.
The use of figure numbers and/or figure reference labels in the claims is intended to identify one or more possible embodiments of the claimed subject matter in order to facilitate the interpretation of the claims. Such use is not to be construed as necessarily limiting the scope of those claims to the embodiments shown in the corresponding figures.
It should be understood that the steps of the exemplary methods set forth herein are not necessarily required to be performed in the order described, and the order of the steps of such methods should be understood to be merely exemplary. Likewise, additional steps may be included in such methods, and certain steps may be omitted or combined, in methods consistent with various embodiments of the invention.
Although the elements in the following method claims, if any, are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence.
Reference herein to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments necessarily mutually exclusive of other embodiments. The same applies to the term “implementation.”
The embodiments covered by the claims in this application are limited to embodiments that (1) are enabled by this specification and (2) correspond to statutory subject matter. Non-enabled embodiments and embodiments that correspond to non-statutory subject matter are explicitly disclaimed even if they fall within the scope of the claims.
This application claims the benefit of the filing date of U.S. provisional application No. 61/986,166, filed on Apr. 30, 2014, the teachings of which are incorporated herein by reference in their entirety.
Number | Name | Date | Kind |
---|---|---|---|
4689627 | Lee et al. | Aug 1987 | A |
6208299 | Lindmark et al. | Mar 2001 | B1 |
20030109242 | Ohtaki | Jun 2003 | A1 |
20040166802 | McKay, Sr. | Aug 2004 | A1 |
20060208944 | Haskell | Sep 2006 | A1 |
20100151865 | Camp, Jr. | Jun 2010 | A1 |
20120243449 | He | Sep 2012 | A1 |
20130040581 | Alberth | Feb 2013 | A1 |
20130148636 | Lum | Jun 2013 | A1 |
20130207878 | Mital | Aug 2013 | A1 |
20130214973 | Veihl et al. | Aug 2013 | A1 |
20130235806 | Nilsson | Sep 2013 | A1 |
20130252671 | Liu | Sep 2013 | A1 |
20140242930 | Barker | Aug 2014 | A1 |
20150244072 | Harel | Aug 2015 | A1 |
20160365889 | Weissman | Dec 2016 | A1 |
Number | Date | Country |
---|---|---|
2706613 | Mar 2014 | EP |
Entry |
---|
“Dual-Bank Panel Dual Polarization Half-Power Beam Width Adjust. Electr. Downtilt,” Kathrein Antennen Electronic, Kathrein-Werks KG, Germany; 2014; pp. 1-2. |
International Search Report and Written Opinion; dated Jan. 16, 2015 for the corresponding PCT Application No. PCT/US2014/063620. |
Preliminary Report on Patentability and Written Opinion, corresponding to PCT/US2014/063620; dated Nov. 10, 2016, 8 pages. |
Number | Date | Country | |
---|---|---|---|
20150318876 A1 | Nov 2015 | US |
Number | Date | Country | |
---|---|---|---|
61986166 | Apr 2014 | US |