Patent Description:
Conventional base station antennas are known from <CIT>, <CIT>, amd <CIT>. An array that includes a plurality of closely spaced radiating element columns, for example, columns of +/-<NUM>° cross dipole radiating elements that are configured for beamforming, are mounted in some base station antennas such as beamforming base station antennas. Such arrays tend to have good cross-polarization performance parameters, for example, cross-polar discrimination, at small horizontal (i.e., azimuth plane) scanning angles, for example, a horizontal scanning angle close to <NUM>°, but have poorer cross-polarization performance parameters at larger horizontal scanning angles, for example, a horizontal scanning angle close to <NUM>°.

In order to improve cross-polarization performance parameters of the base station antenna at large horizontal scanning angles, in a solution of the prior art as shown in <FIG>, parasitic elements <NUM>' extending in a vertical direction V are usually used. Herein, a horizontal direction H corresponds to a row direction of the radiating elements in the array and the vertical direction V corresponds to the column direction of the radiating elements in the array. If the base station antenna is mounted for use without any downtilt in the elevation plane, the horizontal direction will be parallel to a plane defined by the horizon and the vertical direction will intersect the plane defined by the horizon at a right angle.

According to a first aspect of the present disclosure, a base station antenna is provided; the base station antenna comprises: a reflector; a plurality of first radiating elements arranged in a first column that extends in a vertical direction, where the first radiating elements extend in a forward direction from the reflector; a plurality of second radiating element arranged in a second column that extends in the vertical direction, where the second radiating elements extend in the forward direction from the reflector; and a plurality of parasitic elements, where the parasitic elements are arranged around the first radiating elements and/or second radiating elements; wherein, each parasitic element is configured as a rod-shaped metal part or comprises a rod-shaped metal body, where a longitudinal axis of the rod-shaped metal part or a longitudinal axis of the rod-shaped metal body extends at an angle of between <NUM>° to <NUM>° with respect to a plane defined by the reflector, and the parasitic elements are positioned in front of the reflector in and are electrically floating with respect to the reflector, and wherein the parasitic elements are arranged in a horizontal direction between adjacent ones of the first and second radiating elements.

In some embodiments, the longitudinal axis of the rod-shaped metal part or the longitudinal axis of the rod-shaped metal body basically extends perpendicularly to a plane defined by the reflector.

The base station antenna according to some embodiments of the present disclosure is capable of improving cross-polarization performance parameters, for example, cross-polar discrimination, at a large horizontal scanning angle and is capable of maintaining originally good cross-polarization performance parameters at a small horizontal scanning angle, or is capable of targetedly improving cross-polar discrimination at a small horizontal scanning angle. In addition, locating parasitic elements of the base station antenna in front of the reflector in a form of being electrically floated with the reflector according to some embodiments of the present disclosure has limited effects on current distribution of the base station antenna.

<FIG> is a schematic diagram of a base station antenna <NUM>' according to the prior art. <FIG> is a schematic diagram of equivalent active length of parasitic elements of the base station antenna of <FIG> at a small horizontal scanning angle and a large horizontal scanning angle, respectively.

As shown in <FIG>, the base station antenna <NUM>' may comprise a reflector <NUM>' and a plurality of columns <NUM>' of radiating elements <NUM>'. The radiating elements <NUM>' are mounted to extend forwardly of the reflector <NUM>'. Radiating elements <NUM>', for example, may be configured as +/-<NUM>° cross dipole radiating elements as shown in <FIG>. Such radiating elements <NUM>' basically have equal horizontal radiation component and vertical radiation component at small horizontal scanning angles AZ, for example, a horizontal scanning angle AZ of <NUM>°. In other words, it basically has balanced horizontal and vertical radiation components. Therefore, the base station antenna <NUM>' has good cross-polarization performance parameters, for example, cross-polar discrimination, at small horizontal scanning angles AZ. However, at large horizontal scanning angles AZ, for example, a horizontal scanning angle AZ of <NUM>°, the horizontal and vertical radiation components of radiating elements <NUM>' may change and may no longer be balanced. Therefore, as compared to a small horizontal scanning angle AZ, the base station antenna <NUM> has poorer cross-polarization performance parameters, for example, cross-polar discrimination, at a large horizontal scanning angle AZ.

In order to balance the radiation components of radiating elements <NUM>' at a large horizontal scanning angle AZ and thereby improve the cross-polarization performance parameters, the base station antenna <NUM>', as shown in <FIG>, includes metallic rod-shaped parasitic elements <NUM>' that extend in a vertical direction V that are installed around the radiating elements <NUM>'. Such metallic rod-shaped parasitic elements may also be referred to herein as parasitic pins. The working principle of parasitic elements <NUM>' is described in further detail with reference to <FIG>. As shown in <FIG>, at a large horizontal scanning angle AZ (AZ = <NUM>° in this example), the parasitic element <NUM>' has a first equivalent active length L1 in a vertical direction. The first equivalent active length L1 may be understood as the length of a first projection <NUM> of the parasitic element <NUM>' at a large horizontal scanning angle AZ on a base level (for example, the reflector). Similarly, at a small horizontal scanning angle AZ (AZ = <NUM>° in this example), parasitic element <NUM>' is provided with a second equivalent active length L2 in the vertical direction V. The parasitic element <NUM>' is capable of changing the radiation components of the radiating element <NUM> at a large horizontal scanning angle AZ to make the radiation components of the radiating element <NUM> more balanced, thereby improving the cross-polarization performance parameters of the base station antenna <NUM>' at a large horizontal scanning angle AZ. However, at a small horizontal scanning angle AZ, based on its first equivalent active length L1, the parasitic element <NUM>' also changes the radiation components of the radiating element <NUM>' with basically the same method. This causes originally balanced radiation components of the radiating element <NUM>' at small horizontal scanning angles AZ to possibly be imbalanced and may cause the originally good cross-polar discrimination of the base station antenna <NUM>' at small horizontal scanning angles AZ to become worse. In other words, such base station antenna <NUM>' is unable to obtain good cross-polar discrimination at both a large horizontal scanning angle AZ and a small horizontal scanning angle AZ.

In order to overcome the above drawback in the prior art, the present disclosure provides a new base station antenna <NUM>. A plurality of parasitic elements <NUM> are installed in the base station antenna <NUM> of the present disclosure and the parasitic elements may be configured as rod-shaped metal parts or elongated metal parts. Alternatively, the parasitic elements may comprise a rod-shaped metal body or an elongated metal body. In the present disclosure, "rod-shaped", or "elongated" should be understood as a dimension on a longitudinal axis of the rod-shaped metal part or rod-shaped metal body being larger, for example, <NUM> times or even <NUM> times larger than its transverse dimension, for example, transverse diameter. The longitudinal axis of the rod-shaped metal part or longitudinal axis of the rod-shaped metal body basically extends in a forward direction Z perpendicular to a plane defined by the reflector <NUM>.

In this way, the cross-polarization performance parameters, for example, cross-polar discrimination, of the base station antenna <NUM> at a large horizontal scanning angle AZ may be improved and the originally good cross-polarization performance parameters of the base station antenna <NUM> at a small horizontal scanning angle AZ may also be maintained. This shall be described below in further detail with reference to <FIG>.

<FIG> is a schematic diagram of a base station antenna according to some embodiments of the present disclosure. <FIG> is a schematic side view of the base station antenna in <FIG>. <FIG> is a schematic diagram of equivalent active lengths of a parasitic element of a base station antenna according to some embodiments of the present disclosure at a small horizontal scanning angle and a large horizontal scanning angle, respectively.

The base station antenna <NUM> in the various embodiments of the present disclosure, for example, may be a beamforming antenna. As shown in <FIG>, the base station antenna <NUM> comprises a reflector <NUM> and an array that comprises a plurality of columns <NUM> of radiating elements <NUM>. The reflector <NUM> may be used as a ground plane for the radiating elements <NUM>. The radiating elements <NUM> are mounted to extend in a forward direction Z from the reflector <NUM>. Each radiating element <NUM> may be a high-band radiating element, a mid-band radiating element, or a low-band radiating element. The low-band radiating element may be configured to operate, for example, in the <NUM> to <NUM> frequency range or one or more partial ranges thereof. The mid-band radiating element may be configured to operate, for example, in the <NUM> to <NUM> frequency range or one or more partial ranges thereof. The high-band radiating element may be configured to operate, for example, in the <NUM> to <NUM> frequency range or one or more partial ranges thereof.

In the embodiment of <FIG>, the base station antenna <NUM> may comprise a plurality of (three in this example) vertically extending radiating element <NUM> columns <NUM>. A first radiating element column <NUM> comprises a plurality of (four in this example) first radiating elements arranged in a vertical direction; a second radiating element column <NUM> comprises a plurality of (four in this example) second radiating elements arranged in a vertical direction; a third radiating element column <NUM> comprises a plurality of (four in this example) third radiating elements arranged in a vertical direction. The radiating elements <NUM> in the first radiating element column <NUM>, the second radiating element column <NUM> and the third radiating element column <NUM> define a plurality of pairs of horizontally aligned radiating elements <NUM>. Here, it should be understood that the antenna assembly <NUM> may comprise any number of vertically arranged radiating element <NUM> columns <NUM>, and each radiating element <NUM> column <NUM> may comprise any number of vertically arranged radiating elements <NUM>. Radiating elements <NUM>, for example, may be configured as +/-<NUM>° cross dipole radiating elements as shown in <FIG>, or configured as radiating elements with a rectangular or square contour, which are not shown.

As shown in <FIG>, the base station antenna <NUM> of the present disclosure is provided with a plurality of parasitic elements <NUM>. Each parasitic element <NUM> may be configured as a rod-shaped metal part, or comprise a rod-shaped metal body. The length L of the parasitic elements <NUM> along the longitudinal axis a of the parasitic element <NUM>, for example, may be set as a positive integer multiple of one-quarter of the corresponding center frequency wavelength of the operating frequency band of each radiating element <NUM>. In other words, the pre-determined length of the rod-shaped metal part or rod-shaped metal body may extend in a forward direction from the end close to the reflector, where the pre-determined length may be within the wavelength range of <NUM> to <NUM>, a wavelength range of <NUM> to <NUM>, or close to a wavelength of <NUM>. In other words, a length of each parasitic element is within a wavelength range of <NUM> to <NUM>, a wavelength range of <NUM> to <NUM>, or close to a wavelength of <NUM>. In some embodiments, as shown in <FIG>, the parasitic element <NUM> may extend further forward than the radiating element <NUM> from the reflector <NUM>. In some embodiments, the parasitic elements <NUM> are spaced apart from the reflector <NUM>, so that the parasitic elements <NUM> are adjacent to respective radiating arms of the radiating elements <NUM>.

Continuing to refer to <FIG>, the parasitic elements <NUM> are arranged around each radiating element <NUM>. The parasitic elements <NUM>, for example, are arranged in a horizontal direction H between adjacent radiating elements <NUM>. In some embodiments, the parasitic elements <NUM> may also be arranged at other locations in the base station antenna <NUM>. For example, they may be arranged in a vertical direction V between adjacent radiating elements <NUM> and/or arranged around the outside of the radiating element <NUM> columns.

It can be clearly seen in <FIG> that the parasitic element <NUM> may be configured as a rod-shaped metal part, where the longitudinal axis a of the rod-shaped metal part basically extends perpendicularly to the plane defined by the reflector <NUM>. In the present disclosure, "basically perpendicularly" may be understood as the longitudinal axis a of the parasitic element <NUM> extending at an angle of between <NUM> to <NUM>° (<NUM>° in this example) against the plane defined by the reflector <NUM>. In this case, as shown in <FIG>, at a large horizontal scanning angle AZ (AZ = <NUM>° in this example), the parasitic element <NUM> is provided with a third equivalent active length L3 in a vertical direction V. Therefore, the parasitic elements <NUM> of the present disclosure are similarly capable of improving the cross-polarization performance parameters, for example, cross-polar discrimination, of the base station antenna <NUM> at a large horizontal scanning angle AZ. However, at a small horizontal scanning angle AZ (AZ = <NUM>°) in this example, the parasitic elements <NUM> of the present disclosure are provided with a fourth equivalent active length L4 in a vertical direction V. As compared to the actual length L of the parasitic elements, the fourth equivalent active length L4 is shortened. As shown in <FIG>, when AZ = <NUM>°, the fourth equivalent active length L4 is shortened to be a point. Here, the "point" may be understood as a cross-section of the parasitic element in <FIG>. As compared to the length L or third equivalent active length L3 of the parasitic element, the fourth equivalent active length L4 is very small (it can be understood to be approximately <NUM> in this example). Therefore, such parasitic element <NUM> has very limited effects, and almost no effect, on the radiation components of the radiating element <NUM> at a small horizontal scanning angle AZ. Therefore, different from parasitic elements <NUM>' in the prior art, the parasitic elements <NUM> of the present disclosure are capable of better maintaining the originally balanced radiation components of radiating elements <NUM> at a small horizontal scanning angle AZ, thereby maintaining originally good cross-polarization performance parameters, for example, cross-polar discrimination. Therefore, the base station antenna <NUM> of the present disclosure is capable of achieving good cross-polarization performance parameters at a large horizontal scanning angle AZ and also at a small horizontal scanning angle AZ.

In some cases, for example, when radiating elements <NUM> have slightly imbalanced radiation components at a small horizontal scanning angle AZ, in order to change and balance the radiation components of radiating elements <NUM> at a small horizontal scanning angle AZ, the longitudinal axis a of parasitic elements <NUM> may extend at an inclination angle against the plane defined by the reflector <NUM>. The inclined angle, for example, may be a range of angles from <NUM> to <NUM>°, but this should not be understood as limiting the present disclosure. In this case, at a small horizontal scanning angle AZ, parasitic elements <NUM> may be provided with a fifth equivalent active length. The fifth equivalent active length may be between the second equivalent active length L2 and fourth equivalent active length L4, and may be changed by adjusting the above inclination angle according to actual needs. In this way, the parasitic elements <NUM> of the present disclosure are capable of targetedly changing the radiation components of radiating elements <NUM> at a small horizontal scanning angle AZ according to actual needs, thereby improving the cross-polarization performance parameters of radiating elements <NUM> at a small horizontal scanning angle AZ.

In some alternative embodiments, the parasitic elements <NUM> may also be configured as a L-shaped or T-shaped purely metallic components which comprise a rod-shaped metal body and a connecting section basically perpendicularly connected to the rod-shaped metal body, and the connecting section may be indirectly connected to the reflector by means of a dielectric element. The connecting section may be provided with a sixth equivalent active length at a small horizontal scanning angle AZ. The sixth equivalent active length may be adjusted by changing the length of the connecting section according to actual needs. Therefore, the L-shaped or T-shaped parasitic elements <NUM> are similarly capable of targetedly changing the radiation components of radiating elements <NUM> at a small horizontal scanning angle AZ, and are capable of improving the cross-polarization performance parameters of radiating elements <NUM> at a small horizontal scanning angle AZ.

In addition, to minimize the effects of current distribution on the reflector, the parasitic elements <NUM> are positioned in front of the reflector <NUM> and are electrically floating with respect to the reflector. In the present disclosure, "electrical suspension" may be understood as "having no galvanic connection between the parasitic elements <NUM> and reflector". As such, the parasitic elements <NUM> basically act as a separate electric field component, making the current distribution of the parasitic elements <NUM> purer.

In order to mount the parasitic elements <NUM> in front of the reflector <NUM> in a form of being electrically floating with respect to the reflector. As shown in <FIG>, the parasitic elements <NUM> may be arranged to be spaced apart from the reflector <NUM>. For this purpose, the parasitic elements <NUM> may be fixed onto the reflector <NUM> with a dielectric element, thereby preventing galvanic connection between the parasitic elements <NUM> and the reflector <NUM>. When the parasitic elements <NUM> are configured as separate rod-shaped metal parts, the end of the rod-shaped metal parts facing the reflector may be indirectly connected to the reflector <NUM> with a dielectric element. When the parasitic elements <NUM> are configured as L-shaped or T-shaped purely metallic components as described above, the connecting section of the L-shaped or T-shaped purely metallic components may be indirectly connected to the reflector <NUM> with a dielectric element. The dielectric element may be connected to the parasitic elements <NUM> and reflector <NUM> through various suitable connection methods, for example, bonding, plugging, snap-fitting, soldering, or rivet connection. In addition, the dielectric element may also be configured as a plug-in medium in a slot housed on the reflector <NUM>, and the parasitic elements <NUM> may be directly shape-fitted to and plugged into the medium.

<FIG> is a schematic perspective view of a base station antenna <NUM> according to some embodiments of the present disclosure. In order to reduce coupling interference between adjacent radiating elements <NUM>, in some embodiments of the present disclosure, apart from parasitic elements <NUM>', a plurality of vertically extending fence elements <NUM> may be additionally mounted onto the reflector <NUM>. Each fence element <NUM> may be a metallic element extending in a forward direction from the reflector <NUM> and mounted on the reflector <NUM>. Arranging fence elements <NUM> around the radiating elements <NUM> can reduce the coupling interference of corresponding radiating elements <NUM>, thereby further improving the radiation pattern of the base station antenna <NUM> and further improving the cross-polarization performance parameters of the base station antenna <NUM>. The fence elements <NUM> shown in <FIG> are arranged in a horizontal direction H between adjacent radiating elements <NUM>. It should be understood that the number and arrangement of the fence elements <NUM> may also be changed according to actual needs. For example, the antenna assembly <NUM> may further comprise a plurality of fence elements <NUM> extending in a horizontal direction H and the fence elements <NUM> are respectively arranged in a vertical direction between adjacent radiating elements <NUM>.

In the embodiment shown in <FIG>, in order to mount the parasitic elements <NUM>' in front of the reflector <NUM> so that they are electrically floating with respect to the reflector, the parasitic elements <NUM>' may be mounted on the fence elements <NUM> with a dielectric element, for example, a PCB substrate, and indirectly fixed onto the reflector <NUM>. The PCB substrate may be fixed on the fence elements <NUM> by, for example, a rivet connection. However, it may be conceived that the PCB substrate in <FIG> is not fixed onto the fence elements <NUM> but directly mounted on the reflector and extends in a forward direction from the reflector. Here, the PCB substrate may be plugged into the corresponding groove of the reflector <NUM>. In addition, the PCB substrate may also be mounted on a L-shaped plastic contact pin and indirectly fixed on the reflector <NUM>.

In the embodiment in <FIG>, the parasitic elements <NUM>' may be printed on the PCB substrate as printed traces, for example, on a first main surface and/or a second main surface of the PCB substrate. Printed traces acting as parasitic elements may be centrally printed on the PCB substrate and extend forwards a pre-determined length, for example, one quarter of a wavelength of corresponding to the center frequency of the operating frequency band of the radiating elements <NUM>, from the end close to the reflector.

<FIG> show radiation patterns of a base station antenna <NUM> before and after installing parasitic elements <NUM> at horizontal scanning angles AZ of <NUM>° and <NUM>°, in which, <FIG> shows a radiation pattern of the base station antenna <NUM> before installing parasitic elements <NUM> at a horizontal scanning angle AZ of <NUM>°; <FIG> shows a radiation pattern of the base station antenna <NUM> after installing parasitic elements <NUM> at a horizontal scanning angle AZ of <NUM>°; <FIG> shows a radiation pattern of the base station antenna <NUM> before installing parasitic elements <NUM> at a horizontal scanning angle AZ of <NUM>°; <FIG> shows a radiation pattern of the base station antenna <NUM> after installing parasitic elements <NUM> at a horizontal scanning angle AZ of <NUM>°. It can be clearly seen from <FIG> that the base station antenna <NUM> according to the present disclosure is capable of improving the peak cross-polar discrimination at a large horizontal scanning angle AZ (AZ = <NUM>° in this example) by at least <NUM> dB (<NUM> dB in this example) without causing the peak cross-polar discrimination at a small horizontal scanning angle AZ (AZ = <NUM>°) to drop by more than <NUM> dB (this is basically unchanged in this example). Therefore, it can be seen that the base station antenna <NUM> according to the present disclosure is capable of improving cross-polar discrimination at a large horizontal scanning angle AZ and is also capable of maintaining originally good cross-polar discrimination at a small horizontal scanning angle AZ.

The base station antenna <NUM> according to the present disclosure can bring one or more of the following advantages: first, the base station antenna <NUM> according to the present disclosure is capable of improving cross-polarization performance parameters, for example, cross-polar discrimination, at a large horizontal scanning angle AZ and is capable of maintaining originally good cross-polarization performance parameters, for example, cross-polar discrimination, at a small horizontal scanning angle AZ relatively as well; second, the parasitic elements <NUM> are positioned in front of the reflector so as to be electrically floating with respect to the reflector, and hence have almost no effect on the current distribution on the reflector or are hardly affected by the reflector; third, the parasitic elements <NUM> are capable of targetedly changing the radiation components of radiating elements <NUM> at a small horizontal scanning angle AZ according to actual needs, thereby improving the cross-polarization performance parameters of radiating elements <NUM> at a small horizontal scanning angle AZ.

Claim 1:
A base station antenna (<NUM>), comprising:
a reflector (<NUM>);
a plurality of first radiating elements (<NUM>) arranged in a first column (<NUM>) that extends in a vertical direction, where the first radiating elements extend in a forward direction from the reflector;
a plurality of second radiating elements (<NUM>) arranged in a second column (<NUM>) that extends in the vertical direction, where the second radiating elements extend in the forward direction from the reflector; and
a plurality of parasitic elements (<NUM>), where the parasitic elements are arranged around the first radiating elements and/or the second radiating elements;
wherein each parasitic element comprises a rod-shaped metal part, where a longitudinal axis of the rod-shaped metal part extends at an angle of between <NUM><NUM> to <NUM>° with respect to a plane defined by the reflector, and the parasitic elements are positioned in front of the reflector and are electrically floating with respect to the reflector, and
wherein the parasitic elements are arranged in a horizontal direction between adjacent ones of the first and second radiating elements.