EP3454414B1

EP3454414B1 - Broadband low-profile dual-linearly polarized antenna for a onelte two-in-one platform

Info

Publication number: EP3454414B1
Application number: EP18193154.4A
Authority: EP
Inventors: Hong Xia XIAO; Chang Ming Ma
Original assignee: PCTel Inc
Current assignee: PCTel Inc
Priority date: 2017-09-08
Filing date: 2018-09-07
Publication date: 2020-05-27
Anticipated expiration: 2038-09-07
Also published as: EP3454414A1

Description

FIELD

The present application generally relates to a broadband low-profile dual-linearly polarized antenna and, more specifically, to a broadband low-profile dual-linearly polarized antenna for a OneLTE two-in-one platform.

BACKGROUND

Currently, OneLTE technology is rapidly emerging. OneLTE refers to simultaneously comprising both TD-LTE and LTE FDD wireless network access modes and a shared core network in an LTE network. The two wireless network access modes complement each other and cooperate with each other to achieve site-level convergence, network interoperability, and performance level integration on a network side, thereby maximizing overall network capacity and coverage. Operators can, thus, use all of their own spectrum, including TDD and FDD, to provide a unified 4G network experience.
However, existing dual-linearly polarized antennas for OneLTE typically include two radiating portions (i.e., 1.8 GHz for FDD and 2.6 GHz for TDD) because neither has sufficient bandwidth. For example, the dual-linearly polarized antenna disclosed by the U.S. Patent No. 3,740,754 , the first of its kind to describe a dual-linearly polarized antenna, just cannot meet the needs of a wide frequency band. Therefore, such antennas for OneLTE are bulky and do not meet requirements for miniaturization. Furthermore, in these antennas, there is a fairly obvious mutual coupling between the high and low frequency radiating portions, causing distortion of the radiation pattern of the radiating portions of the different frequency bands.
Although some two-in-one broadband antennas satisfying the 1.8GHz and 2.6GHz frequency bands of OneLTE have appeared in academic papers or industrial products, the thickness of these antennas is usually about 35mm, which cannot meet the requirements for smaller, lighter, broader, and greener antennas in the industrial design process of OneLTE base stations.
Therefore, it is desirable to overcome the defects and deficiencies in the prior art, by providing a broadband low-profile dual-linearly polarized antenna that satisfies miniaturization for a OneLTE two-in-one platform.
WO2016/133244A1 discloses a multi-band radiating element comprising: a first high frequency radiating element formed on the upper surface of a substrate; one or more first low frequency parasitic elements formed on the upper surface of the substrate and formed at a predetermined distance from the first high frequency radiating element in the direction of the outer edge of the substrate; one or more second low frequency parasitic elements formed on the upper surface of the substrate and formed at a predetermined distance from the first high frequency radiating element in the direction of the outer edge of the substrate; a second high frequency radiating element formed on the bottom surface of the substrate; and a reflector formed at a predetermined distance from the bottom surface of the substrate.

SUMMARY

The present invention is defined in independent claim 1, to which reference should now be made. Optional embodiments are defined in the dependent claims..
According to some embodiments, a broadband low-profile dual-linearly polarized antenna according to claim 1 is provided.
Furthermore, according to some embodiments, a broadband low-profile dual-linearly polarized antenna array device is provided that can include (1) a plurality of the above-described dual-linearly polarized antennas, (2) a feed network that can include a power divider for feeding the plurality of dual-linearly polarized antennas in equal amplitude and in same phase, wherein the feed network can include two feed ports for respectively exciting a ±45° polarization mode to feed each of the plurality of dual-linearly polarized antennas through the power divider, and (3) a bottom metal reflector.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation view of a broadband low-profile dual-linearly polarized antenna in accordance with disclosed embodiments;
FIG. 2 is a side view of a broadband low-profile dual-linearly polarized antenna in accordance with disclosed embodiments;
FIG. 3 is a top view of a radiating portion of a broadband low-profile dual-linearly polarized antenna in accordance with disclosed embodiments;
FIG. 4 is a bottom view of a radiating portion of a broadband low-profile dual-linearly polarized antenna in accordance with disclosed embodiments;
FIG. 5(a) is a side view of first and second baluns of a feed balun of a broadband low-profile dual-linearly polarized antenna in accordance with disclosed embodiments with portions thereof obscured;
FIG. 5(b) is a side view of the first and second baluns of the feed balun of the broadband low-profile dual-linearly polarized antenna that shows the portions obscured in FIG. 5(a);
FIG. 5(c) is a side view of first and second baluns of a feed balun of the broadband low-profile dual-linearly polarized antenna that shows the portions obscured in FIG. 5(a);
FIG. 6 is a view of a broadband low-profile antenna array device in accordance with disclosed embodiments that includes broadband low-profile dual-linearly polarized antennas as shown in FIG. 1 and FIG. 2;
FIG. 7(a) is a graph of a standing wave ratio curve of port A of the broadband low-profile antenna array device shown in FIG. 6;
FIG. 7(b) is a graph of a standing wave ratio curve of port B of the broadband low-profile antenna array device shown in FIG. 6;
FIG. 8 is a graph of an isolation curve of port A and port B of the broadband low-profile antenna array device shown in FIG. 6;
FIG. 9(a) is a graph of antenna performance for port A of the broadband low-profile antenna array device shown in FIG. 6 and illustrates the horizontal section radiation pattern;
FIG. 9(b) is a graph of antenna performance for port A of the broadband low-profile antenna array device shown in FIG. 6 and illustrates the vertical section radiation pattern;
FIG. 9(c) is a graph of antenna performance for port A of the broadband low-profile antenna array device shown in FIG. 6 and illustrates the gain curve;
FIG. 9(d) is a graph of antenna performance for port A of the broadband low-profile antenna array device shown in FIG. 6 and illustrates the efficiency curve;
FIG. 10(a) is a graph of antenna performance for port B of the broadband low-profile antenna array device shown in FIG. 6 and illustrates the horizontal section radiation pattern;
FIG. 10(b) is a graph of antenna performance for port B of the broadband low-profile antenna array device shown in FIG. 6 and illustrates the vertical section radiation pattern;
FIG. 10(c) is a graph of antenna performance for port B of the broadband low-profile antenna array device shown in FIG. 6 and illustrates the gain curve;
FIG. 10(d) is a graph of antenna performance for port B of the broadband low-profile antenna array device shown in FIG. 6 and illustrates the efficiency curve;
FIG. 11(a) is a graph of the horizontal section radiation patterns of main polarization and cross polarization for port A of the broadband low-profile antenna array device shown in FIG. 6; and
FIG. 11(b) is a graph of the horizontal section radiation patterns of main polarization and cross polarization for port B of the broadband low-profile antenna array device shown in FIG. 6.

DETAILED DESCRIPTION

The specific embodiments of the disclosed invention will be described in detail below with reference to the accompanying drawings in order to make the above objectives, features, and advantages of the disclosed invention clearer and more comprehensible.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the disclosed invention. However, the disclosed invention can be implemented in many other ways than those described herein, and a person skilled in the art can make a similar promotion without departing from the scope of the disclosed invention. Therefore, the disclosed invention is not limited by the specific embodiments disclosed below.
In some embodiments, a broadband low-profile dual-linearly polarized antenna as shown in FIG. 1 and FIG. 2 includes a radiating portion 1 and a feed balun 2. The radiating portion 1 can have a rectangular plate shape, and the feed balun 2 can be located at a center below the radiating portion 1. As shown in FIG. 1 and FIG. 2, the feed balun 2 can be placed on a feed circuit board 3.
The feed balun 2 can include a first balun 8 and a second balun 9 that are orthogonal to each other and can be connected to a lower surface of the radiating portion 1 to feed the radiating portion 1. Two plates of the feed balun 2 can be snapped together through a middle slot, wherein an upper end of a middle part of one of the two plates can have a short slot, and a lower end of a middle part of another of the two plates can have a long slot, thereby implementing the feed balun 2 through a mating connection of the long slot and the short slot.
As shown in FIG. 3 and FIG. 4, the radiation portion 1 includes a dielectric substrate, printed folded dipoles 7 spaced apart on an upper surface of the dielectric substrate, first coupled parasitic elements 4 on a lower surface of the dielectric substrate, and second coupled parasitic elements 5 on the upper surface of the dielectric substrate. The radiating portion 1 can be implemented on a printed circuit board by a printing process.
The printed folded dipoles 7 may be placed at equal or unequal intervals on the dielectric substrate. As shown in FIG. 3, a number of the printed folded dipoles 7 is four, and the printed folded dipoles 7 can be placed at equal intervals of 90 degrees. As further shown in FIG. 3, each of the printed folded dipoles 7 can have a respective T-shaped match and have a respective T-shaped slit inside to form a respective current path. In some embodiments, shapes of such T-shaped slits inside of the printed folded dipoles 7 need not be totally identical. For example, in some embodiments, a top of the T-shaped slits inside of upper and lower ones of the printed folded dipoles 7 can be narrower than a top of the T-shaped slits inside of left and right ones of the printed folded dipoles 7. Furthermore, in some embodiments, there can be a respective space between each of adjacent ones of the printed folded dipoles 7, and an inside of the respective space can be substantially square while an outside of the respective space can be a respective small opening. For the formation and principle of the printed folded dipoles 7 having a T-shaped match, reference may be made to the prior art, and details are not described herein again.
Each of the printed folded dipoles 7 includes a corresponding one of the first coupled parasitic elements 4 and a corresponding one of the second coupled parasitic elements 5 on either side, wherein the first coupled parasitic elements 4 are on the lower surface of the dielectric substrate, and the second coupled parasitic elements 5 are on the upper surface of the dielectric substrate. The first and second coupled parasitic elements 4, 5 can be used to expand bandwidth and reduce a profile of the broadband low-profile dual-linearly polarized antenna.
Each of the printed folded dipoles 7 can be non-electrically connected to the corresponding one of the first and second coupled parasitic elements 4, 5, but inductively induce current on the corresponding one of the first and second coupled parasitic elements 4, 5. Positions of the first and second coupled parasitic elements 4, 5 can be reasonably arranged according to requirements of inductive coupling. Accordingly, the specific shapes of the first and second coupled parasitic elements 4, 5 shown in FIG. 3 and FIG. 4 act only as an example, but not a limitation.
For example, as shown in FIG. 4, the first coupled parasitic elements 4 can be generally shaped as "┌", "┐", "└", and "┘", and each of the first coupled parasitic elements 4 is located between respective ones of the adjacent ones of the printed folded dipoles 7 with a respective notch facing inward. In some embodiments, each of the first coupled parasitic elements 4 can be located inside of respective outer contours of the respective ones of the adjacent ones of the printed folded dipoles 7, and in some embodiments, each of the first coupled parasitic elements 4 can be located right below respective inner sides of the respective small opening between the respective ones of the adjacent ones of the printed folded dipoles 7.
In some embodiments, each of the second coupled parasitic elements 5 can include two respective rectangular strips that need not be electrically connected in substantially the shape of the Chinese character "
" and is placed adjacent to respective neighboring portions of respective outer edges of the respective ones of the adjacent ones of the printed folded dipoles 7. In some embodiments, such rectangular strips can be different sizes, and a long side can be parallel to the respective outer edges of one of the printed folded dipoles 7.
Each of the printed folded dipoles 7 can have a corresponding feed point 6 located therein, and the feed balun 2 can feed each of the printed folded dipoles 7 through the corresponding feed point 6 in a manner of coupled feed.
FIG. 5(a) is a side view of portions of the first and second baluns 8, 9 of the feed balun 2 (other portions of the baluns 8, 9 are obscured). As shown in FIG. (a), a middle of the second balun 9 can include a recess to bypass the first balun 8 to avoid electrical connection (or, alternatively, to form a protrusion). FIG. 5(b) and FIG. 5(c) show the portions of the first and second baluns 8, 9 that are obscured in FIG. 5(a). As shown in FIG. 5(a), FIG. (b), and FIG. 5(c), shapes of the first and second baluns 8, 9 need not be the same, but both can be substantially "
" in shape and feed the radiating portion 1 at the top through a coupling manner.
The bottom of the feed balun 2 can be connected to a feed circuit. By way of example and not limitation, the feed circuit can be implemented using a microstrip circuit.
FIG. 6 is a view of a broadband low-profile dual-linearly polarized antenna array device in accordance with disclosed embodiments. FIG. 6 only shows two dual-linearly polarized antennas, but embodiments disclosed herein are not so limited, and such an antenna array device can include any number of dual-linearly polarized antennas as appropriate. As shown in FIG. 6, a feed network can feed the antenna array device. The feed network can include a one-to-two power divider so as to feed each of the dual-linearly polarized antennas with equal amplitude and same phase. The feed network can have two feed ports (i.e., port A and port B shown in FIG. 6) for respectively exciting two polarization modes of ±45° to feed each of the dual-linearly polarized antennas through the one-to-two power divider.
The antenna array device may also include a bottom metal reflector, and the feed network may be located above the bottom metal reflector. The bottom metal reflector can be made of a metal plate, such as a copper plate, and can have a metal flange.
In some embodiments, the antenna array device may include a radome.
By performing a performance test on the antenna array device shown in FIG. 6, the following test results and conclusions can be obtained.
As shown in FIG. 7(a) and FIG. 7(b), when frequency is around 1.8 GHz and 2.6 GHz, standing wave ratios can be 1.7 or less, regardless of port A or port B.
As shown in FIG. 8, when the frequency is around 1.8 GHz and 2.6 GHz, isolation of port A and port B can be kept below -25 dB.
As shown in FIG. 9(a), FIG. 9(b), FIG. 9(c), FIG. 9(d), FIG. 10(a), FIG. 10(b), FIG. 10(c), and FIG. 10(d), for port A or port B, an influence of frequency variation on radiation directivity of the broadband low-profile dual-linearly polarized antenna is not obvious, and radiant energy is mainly concentrated in the horizontal front. As further shown in FIG. 9(a), FIG. 9(b), FIG. 9(c), FIG. 9(d), FIG. 10(a), FIG. 10(b), FIG. 10(c), and FIG. 10(d), when the frequency is around 1.8 GHz and 2.6 GHz, gains of port A and port B can both be maintained above 10 dBi, and efficiencies can both be maintained above 80%.
As shown in FIG. 11(a) and FIG. 11(b), for port A or port B, radiation is dominated by a main polarization, and a high cross-polarization ratio is achieved.
In summary, the broadband low-profile dual-linearly polarized antenna and the antenna array device disclosed herein can effectively realize a low-profile (reducing antenna thickness of about 35 mm in conventional cross-polarized antennas to 19 mm), can implement a wide frequency band of 1700 MHz to 2700 MHz, and can achieve high gain, high efficiency, high cross-polarization ratio, and high isolation. Furthermore, the broadband low-profile dual-linearly polarized antenna and the antenna array device disclosed herein have such advantages as simple structure, neat appearance, easy engineering implementation, and suitability for mass production.
Although this disclosure has described specific embodiments and generally associated methods, modifications and replacements of these embodiments and methods will be apparent to those skilled in the art. Therefore, the above description of exemplary embodiments does not limit or constrain this disclosure.

Claims

A broadband low-profile dual-linearly polarized antenna comprising:
a radiating portion (1), wherein the radiating portion (1) comprises a dielectric substrate, four printed folded dipoles (7) spaced apart on an upper surface of the dielectric substrate, first coupled parasitic elements (4) on a lower surface of the dielectric substrate, and second coupled parasitic elements (5) on the upper surface of the dielectric substrate; and

a feed balun (2) for feeding the radiating portion (1),

wherein each of the four printed folded dipoles (7) includes a corresponding one of the first coupled parasitic elements (4) and a corresponding one of the second coupled parasitic elements (5);

wherein each of the first coupled parasitic elements (4) is located between and configured to be coupled to respective adjacent ones of the four printed folded dipoles (7), and

wherein each of the second coupled parasitic elements (5) is placed adjacent and configured to be coupled to respective neighboring portions of respective outer edges of the respective adjacent ones of the four printed folded dipoles (7).
The broadband low-profile dual-linearly polarized antenna according to claim 1, wherein each of the four printed folded dipoles (7) has a respective T-shaped match.
The broadband low-profile dual-linearly polarized antenna according to claim 1 or 2, wherein the first coupled parasitic elements (4) are generally shaped as Unicode hex character 250C "┌", Unicode hex character 2510 "┐", Unicode hex character 2514 "└", and Unicode hex character 2518 "┘", and wherein each of the first coupled parasitic elements (4) includes a respective notch facing inward.
The broadband low-profile dual-linearly polarized antenna according to claim 3, wherein each of the first coupled parasitic elements (4) is located inside of respective outer contours of the respective adjacent ones of the four printed folded dipoles.
The broadband low-profile dual-linearly polarized antenna according to claim 2, 3 or 4, wherein each of the second coupled parasitic elements (5) includes two respective rectangular strips that need not be electrically connected.
The broadband low-profile dual-linearly polarized antenna according to any one of claims 1 to 5, wherein the feed balun (2) comprises two orthogonal baluns (8, 9), and wherein each of the two orthogonal baluns (8, 9) is substantially shaped as Unicode hex character 220F "
".
The broadband low-profile dual-linearly polarized antenna according to any one of claims 1 to 6, wherein the feed balun (2) is configured to feed the radiating portion (1) in a manner of coupled feed.
The broadband low-profile dual-linearly polarized antenna according to any one of claims 1 to 7, wherein the four printed folded dipoles (7) are placed at equal or unequal intervals.
The broadband low-profile dual-linearly polarized antenna according to claim 8, wherein the four printed folded dipoles (7) are placed at the equal intervals of 90 degrees.
The broadband low-profiled dual-linearly polarized antenna according to any one of claims 1 to 9, wherein the radiating portion (1) is rectangular.
A broadband low-profile dual-linearly polarized antenna array device comprising:
a plurality of dual-linearly polarized antennas, wherein each of the plurality of dual-linearly polarized antennas includes the broadband low-profile dual-linearly polarized antenna of any one of claims 1 to 10;

a feed network comprising a power divider for feeding the plurality of dual-linearly polarized antennas in equal amplitude and in same phase, wherein the feed network has two feed ports for respectively exciting two polarization modes of ±45° to feed each of the plurality of dual-linearly polarized antenna through the power divider; and

a bottom metal reflector.
The broadband low-profile dual-linearly polarized antenna array device according to claim 11, wherein the plurality of dual-linearly polarized antennas has a number of two, and wherein the power divider is a one-to-two power divider.
The broadband low-profile dual-linearly polarization antenna array device according to claim 11 or 12, wherein the bottom metal reflector includes a metal flange.