The present application claims priority under 35 U.S.C. § 119 to Chinese Patent Application No. 201710376044.8, filed with the Chinese State Intellectual Property Office on May 24, 2017, the entire contents of which is incorporated by reference herein as if set forth in its entirety.
The present disclosure generally relates to antenna systems and, more particularly, to antenna systems having feed networks that include unshielded circuits.
Passive InterModulation (PIM) distortion is a form of electrical interference that may occur when two or more radio frequency (RF) signals encounter non-linear electrical junctions or materials along an RF transmission path. Such non-linearities may act like a mixer causing the RF signals to generate new RF signals at mathematical combinations of the original RF signals. These newly generated RF signals are referred to as “intermodulation products.” The newly generated RF signals may fall within the bandwidth of existing RF signals. This may occur, for example, when signals transmitted through a device generate intermodulation products that fall in the same bandwidth of signals that are received through the same device. If this occurs, the noise level experienced by the existing RF signals in the receiver bandwidth is increased. When the noise level is increased, it may be necessary to reduce the data rate and/or the quality of service. PIM distortion can be an important interconnection quality characteristic, as PIM distortion generated by a single low quality interconnection may degrade the electrical performance of the entire RF communications system. An unexpected current from an outer conductor of a cable in the antenna may increase PIM distortion levels and/or influence the isolation stability of the antenna.
The unexpected current may occur in an unshielded circuit that is included in a feed network of the antenna. The unshielded circuit may be, for example, any element made of microstrip or printed circuit board materials that is capable of radiating outwards.
For example, the unshielded circuit may be a power divider or a phase shifter. A plurality of cables may be attached to the unshielded circuit. For example, if the unshielded circuit is a phase shifter, an input cable and a plurality of several phase cables may be connected to the unshielded circuit. An unexpected current may appear on an outer conductor of one of these cables.
An unexpected current may also or additionally occur around a radiating element of the antenna. Usually, each radiating element is connected to a reflector of the antenna, which serves as a ground plane, and is also connected to an unshielded circuit via a cable. When performing service and maintenance work, technical personnel may separate the radiating element from the reflector, and thus the radiating element may no longer be connected to ground. In this situation, for example, the unexpected current may leak through the outer conductor of the connecting cable.
In view of above, the present disclosure proposes an antenna assembly, an unshielded circuit assembly for use in an antenna and a radiating unit assembly used with an antenna to eliminate the abovementioned unexpected current.
According to one aspect of the present disclosure, it is provided an antenna assembly. The antenna assembly includes a plurality of radiating elements; an unshielded circuit; and an input terminal. The plurality of radiating elements are connected to the unshielded circuit through respective ones of a plurality of additional cables, and the unshielded circuit is connected to the input terminal through an input cable; and at least one of the plurality of additional cables and the input cable is connected to a first open connect line.
In one implementation, a second open connect line is connected adjacent to a connection point between a first of the radiating elements and a first of the additional cables that is connected to the first of the radiating elements.
In one implementation, a length of the first open connect line and/or a length of the second open connect line is ¼ a wavelength corresponding to a center frequency of an operating frequency band of the antenna assembly.
In one implementation, at least one of the first open connect line and/or the second open connect line is L-shaped.
In one implementation, the at least one of the plurality of additional cables and the input cable is connected to the first open connect line via welding.
In one implementation, the second open connect line is connected adjacent to the connection point between the first of the radiating elements and the first of the additional cables via welding.
In one implementation, the input cable is connected to the first open connect line.
In one implementation, the at least one of the plurality of additional cables and the input cable is connected to the first open connect line adjacent the unshielded circuit.
In one implementation, the unshielded circuit includes a power divider or a phase shifter.
In one implementation, the radiating element includes a dipole.
According to another aspect of the present disclosure, it is provided an unshielded circuit assembly for use in an antenna. The unshielded circuit assembly includes an unshielded circuit; an input cable; and a plurality of additional cables The input cable and the plurality of additional cables are connected to the unshielded circuit, and at least one of the input cable and the plurality of additional cables is connected to an open connect line.
In one implementation, a length of the open connect line is ¼ of a wavelength corresponding to a center frequency of an operating frequency band of the antenna.
In one implementation, the open connect line is L-shaped.
In one implementation, the at least one of the input cable and the plurality of additional cables is connected to the open connect line via welding.
In one implementation, the input cable is connected to the open connect line.
In one implementation, the at least one of the input cable and the plurality of additional cables is connected to the open connect line adjacent to the unshielded circuit.
In one implementation, the unshielded circuit includes a power divider and a phase shifter.
According to a further aspect of the present disclosure, it is provided a radiating unit assembly used with an antenna. The radiating unit assembly includes a radiating element; and an unshielded circuit. The radiating element is connected to the unshielded circuit through a cable, and an open connect line is connected adjacent a connection point between the radiating element and the phase cable.
In one implementation, a length of the open connect line is ¼ of a wavelength corresponding to a center frequency of an operating frequency band of the antenna.
In one implementation, the open connect line is L-shaped.
In one implementation, the open connect line is connected adjacent the connection point between the radiating element and the cable via welding.
In one implementation, the radiating element includes a dipole.
According to the present disclosure, the unexpected current from the cable outer conductor of the cables in an unshielded circuit and/or in the radiating element area can be fully eliminated. The antenna PIM level and the isolation stability can be enhanced. Also, the common mode resonance can be eliminated.
The present disclosure will be understood better from the description of specific embodiments of the disclosure given in conjunction with the following figures, wherein:
In the figures, identical or similar reference numerals indicate identical or similar elements.
Example embodiments of the present disclosure will now be described in more detail in conjunction with accompanying figures. Although example embodiments are shown in the accompanying figures, it should be understood that the present disclosure can be embodied in various ways and is not limited to the embodiments depicted herein. Instead, the embodiments are provided herein to make the disclosure more thorough and complete and to convey the scope of the present disclosure to those skilled in this art.
The input cable 120 may carry RF signals from the radio to the phase shifter 100. The phase shifter 100 may split the input RF signal into a plurality of sub-components (three sub-components in the example of
Pursuant to embodiments of the present invention, open connect lines may be used to reduce or eliminate an unexpected current that may be carried, for example, on the outer conductor of one of the cables 120, 130, 140, 150. Referring again to
In another example embodiment, all of the cables can be connected to a respective open connect line 125, so as to reduce or eliminate any unexpected currents that are carried on the outer conductors of cables 120, 130, 140, 150.
In some embodiments, the open connect line 125 may be welded to its associated cable. It will be appreciated, however, that other connection methods may be used or that the open connect line 125 may be formed integrally with the remainder of the cable. In some embodiments, the cable may be connected to the open connect line 125 adjacent the unshielded circuit 100.
According to an embodiment of the present disclosure, a length of the open connect line 125 may be about ¼ wavelength of a center frequency of a frequency band of the antenna. With respect to signals that are at RF and microwave frequencies, connecting an open connect line 125 with a length of ¼ wavelength to the cable is equivalent to connecting the cable to a grounded element such as, for example, a reflector of the antenna system.
In one embodiment of the disclosure, the open connect line is L-shaped. However, the present disclosure is not limited thereto and the open connect line 125 can have any appropriate shape such as a straight line shape, etc.
In a typical phased array antenna, each radiating element 310 is connected to a reflector 320. The reflector may serve as a ground plane for the antenna and may be electrically grounded. However, when service and/or maintenance work are performed on the antenna, for example, technical personnel may separate the radiating element 310 from the reflector 320, and thus the radiating element 310 may no longer be connected to ground. Because of this, an unexpected current may leak through the outer conductor of the phase cable 330.
In order to reduce or eliminate this unexpected current, an open connect line 315 may be connected adjacent to a connection point between the radiating element 310 and the phase cable 330, as is illustrated in
According to an embodiment of the present disclosure, a length of the open connect line 315 may be about ¼ of a wavelength corresponding to a center frequency of a frequency band in which the radiating element 310 is configured to transmit and receive signals. At microwave and radio frequencies, using an open connect line 315 with a length of ¼ of a wavelength may be equivalent to connecting the phase cable 330 to an electrically grounded element such as, for example, the reflector 320 of the antenna.
As shown in
Therefore, in this embodiment, although the radiating element 310 does not actually touch the reflector 320 nor is it otherwise electrically connected to the reflector 320 to provide grounding, the current from the outer conductor of the phase cable 330 may still be reduced or eliminated, and thus a common mode resonance may also be reduced or eliminated. Additionally, the PIM level and the isolation stability of the antenna may be improved.
As shown in
One terminal of each of a plurality of phase cables 330, 130 and 150 (shown as three phase cables in
In order to eliminate the unexpected current in the unshielded circuit 10, an open connect line 125 can be connected to a cable that is connected to the unshielded circuit 100. In some embodiments, testing may be performed to identify the cables on which unexpected currents are detected and open connect lines 125 may then be attached to the identified cables. Thus, for example, if an unexpected current is detected on the input cable 120, then an open connect line 125 may be connected to the input cable 120 to eliminate this unexpected current, as shown in
Further, in order to eliminate an unexpected current in the radiating unit assembly 30, an open connect line 315 is connected adjacent a connection point between the radiating element 310 and the phase cable 330 to eliminate the unexpected current. Open connect lines 315 (not shown) may similarly be connected to the phase cables 130, 150 at the connections between the phase cables 130, 150 and their corresponding radiating elements 310.
According to an embodiment of the present disclosure, the length of the open connect line 125 and/or the length of the open connect line 315 may be about a ¼ wavelength of a center frequency of a frequency band of the antenna assembly/antenna. In one embodiment, the open connect lines 125/315 may be formed as L-shaped lines, as shown in
According to embodiments of the present disclosure, the open connect line 125/315 may be a rod made of metal or a rod with metal coating, such as a RF coaxial cable or a copper rod, etc. Under the common operating frequency of 600-2700 MHz, a general RF coaxial cable may be used as the open connect line.
The above depiction is provided to enable those skilled in the art to implement or use the present disclosure. For those skilled in the art, various modifications of the present disclosure are apparent, and the general principle defined herein may also be applied to other transformations without departing from the spirit and scope of the present disclosure. Thus, the present disclosure is not limited to the examples and designs as described herein, but should be consistent with the broadest scope of the principle and novel characteristics thereof.
Number | Date | Country | Kind |
---|---|---|---|
2017 1 0376044 | May 2017 | CN | national |
Number | Name | Date | Kind |
---|---|---|---|
20040046697 | Tai | Mar 2004 | A1 |
20090295642 | Nilsson | Dec 2009 | A1 |
20130265206 | Payne et al. | Oct 2013 | A1 |
20140266923 | Zhou | Sep 2014 | A1 |
20160043476 | Bi et al. | Feb 2016 | A1 |
20170093363 | Tabatabai | Mar 2017 | A1 |
Number | Date | Country |
---|---|---|
2010077574 | Jul 2010 | WO |
Entry |
---|
Extended European Search Report corresponding to European Application No. 18172600.1 (9 pages) (dated Oct. 9, 2018). |
Number | Date | Country | |
---|---|---|---|
20180342813 A1 | Nov 2018 | US |