WO2019223318A1 - 室内基站及其pifa天线 - Google Patents

室内基站及其pifa天线 Download PDF

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Publication number
WO2019223318A1
WO2019223318A1 PCT/CN2018/125515 CN2018125515W WO2019223318A1 WO 2019223318 A1 WO2019223318 A1 WO 2019223318A1 CN 2018125515 W CN2018125515 W CN 2018125515W WO 2019223318 A1 WO2019223318 A1 WO 2019223318A1
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WIPO (PCT)
Prior art keywords
short
pifa antenna
feeding
metal plate
plate body
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PCT/CN2018/125515
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English (en)
French (fr)
Inventor
高霞
郑耀华
刘建祥
蔡鑫荣
Original Assignee
京信通信系统（中国）有限公司
京信通信系统（广州）有限公司
京信通信技术(广州)有限公司
天津京信通信系统有限公司
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Publication of WO2019223318A1 publication Critical patent/WO2019223318A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/007—Details of, or arrangements associated with, antennas specially adapted for indoor communication
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/12—Supports; Mounting means
    • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
    • H01Q1/24—Supports; Mounting means by structural association with other equipment or articles with receiving set
    • H01Q1/241—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM
    • H01Q1/246—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for base stations
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/36—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/48—Earthing means; Earth screens; Counterpoises
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/50—Structural association of antennas with earthing switches, lead-in devices or lightning protectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • H01Q15/14—Reflecting surfaces; Equivalent structures

Definitions

  • the present invention relates to the field of mobile communication technology, and in particular, to an indoor base station and its PIFA antenna.
  • the demand for indoor low-power hotspot coverage has increased dramatically, so the demand for indoor base stations with small size, low cost, and good performance is also increasing.
  • the most critical component elements involved in indoor base stations include base station antennas, and currently the base station antennas commonly used for indoor base stations are PIFA (Planar Inverted F) antennas.
  • PIFA Planar Inverted F
  • the widely used frequency band of indoor base stations is mainly 1710 ⁇ 2690MHz, and the frequency band is relatively wide.
  • the frequency range covered by common PIFA antennas is relatively narrow, so a single PIFA antenna cannot meet the full frequency band coverage requirements of indoor base stations. Therefore, multiple PIFA antennas can only be integrated to enable indoor base stations to achieve wide-band coverage.
  • a PIFA antenna includes:
  • the reflective floor has a bearing surface, and the bearing surface is provided with mutually spaced feeding areas and short-circuit areas;
  • a power feeding network disposed in the power feeding area and electrically connected to the reflective floor;
  • a radiating unit includes a metal plate body, a feeding part, an open circuit branch and a short circuit branch, which are arranged in parallel and spaced from the bearing surface, the metal plate body has a feeding end and a short circuit end, and the metal plate body is formed on the metal plate body.
  • One end of the feeding part is electrically connected to the feeding end, the other end is electrically connected to the feeding network, one end of the open branch is electrically connected to the feeding end, and the other end is connected to the reflection
  • the floor is arranged at intervals, one end of the short-circuited branch is electrically connected to the short-circuited end, and the other end is electrically connected to the short-circuited area.
  • the reflective floor is a double-sided PCB, and a plurality of metalized vias are formed on the reflective floor.
  • the distribution density of the metalized vias in the feeding area and the short-circuit area is greater than the distribution density in the remaining areas of the reflective floor.
  • the feeding network is a coplanar waveguide feeding network.
  • the feeding portion, the open branch and the short branch are all L-shaped.
  • the power feeding portion, the open branch and the short branch are all vertically connected to the metal plate body.
  • the edge of the short-circuited branch is provided with a gap.
  • the hollow portion is located at an edge of the metal plate body, so that the edge of the metal plate body is jagged.
  • the radiating unit is an axisymmetric structure, and the feeding portion is symmetrical with respect to the symmetric axis of the radiating unit.
  • the impedance bandwidth of the above PIFA antenna is related to the distance between the reflective floor and the metal plate, and the settings of the open and short branches are helpful to optimize the impedance matching. Further, the setting of the hollow portion makes the current form a curve on the metal plate Current, so the current path becomes longer. Moreover, the short-circuited branches can form a loop between the short-circuited end and the feeding end, which can further extend the current path. Due to the extension of the current path, the frequency of the signal that can be transmitted and received by the radiating unit also changes, which reduces the operating frequency band of the radiating unit. It can be seen that the above-mentioned PIFA antenna can reduce the volume while expanding the coverage frequency band, so it is conducive to the miniaturization of indoor base stations.
  • an indoor base station including:
  • the PIFA antenna according to any one of the above preferred embodiments.
  • the signal transmitting and receiving device is communicatively connected with the PIFA base station antenna.
  • the above PIFA antenna can reduce the volume while expanding the coverage frequency band. Therefore, when the above-mentioned PIFA antenna is applied to an indoor base station, the number of integrated PIFA antennas can be reduced. Or, the number of integrations does not change, due to the significant reduction in volume of a single PIFA antenna. Therefore, the indoor base station can be miniaturized.
  • FIG. 1 is a schematic structural diagram of a PIFA antenna in a preferred embodiment of the present invention
  • FIG. 2 is a schematic structural diagram of a reflective floor in the PIFA antenna shown in FIG. 1;
  • FIG. 3 is a schematic structural diagram of a radiating unit in the PIFA antenna shown in FIG. 1;
  • FIG. 4 is a plan development view of the radiation unit shown in FIG. 3;
  • FIG. 5 is a simulation diagram of the reflection coefficient and gain of the PIFA antenna shown in FIG. 1; FIG.
  • FIG. 6 is a schematic diagram of the input impedance simulation of the PIFA antenna shown in FIG. 1;
  • FIG. 7 is a radiation pattern of the PIFA antenna shown in FIG. 1 at a two-dimensional plane at 1.7 GHz, 2.3 GHz, and 2.7 GHz;
  • FIG. 8 is a radiation pattern of the PIFA antenna shown in FIG. 1 at a two-dimensional plane at 1.7 GHz, 2.3 GHz, and 2.7 GHz;
  • FIG. 9 is a radiation pattern at a frequency of 1.7 GHz, 2.3 GHz, and 2.7 GHz in a two-dimensional plane.
  • the invention provides an indoor base station and a PIFA antenna.
  • the indoor base station includes the above-mentioned PIFA antenna, and a signal transceiving device which is communicatively connected with the above-mentioned PIFA antenna.
  • the signal transceiving device is used to convert an electrical signal into an electromagnetic wave signal, and the electromagnetic wave signal can be transmitted to the antenna and radiated into space by the PIFA antenna.
  • the signal transceiving device can convert the electromagnetic wave signal received by the PIFA antenna into an electrical signal.
  • the PIFA antenna 100 in the preferred embodiment of the present invention includes a reflective floor 110, a feeding network 120, and a radiating unit 130.
  • the reflective floor 110 mainly plays a role of reflecting and enhancing electromagnetic wave signals, and generally has a metal plate structure.
  • the reflective floor 110 may be in a strip shape, a circle or a rectangle.
  • the reflective floor 110 has a bearing surface 111.
  • the bearing surface 111 is provided with a power feeding region 1112 and a short-circuit region 1114 spaced apart from each other.
  • the reflective floor 110 is a double-sided PCB, and a plurality of metallized vias 113 are formed on the reflective floor 110.
  • the reflective floor 110 is composed of a dielectric substrate and copper layers covering opposite sides of the dielectric substrate.
  • the metalized via 113 refers to a solidified metal inside the through hole, so that the through hole is electrically conductive.
  • the metalized vias 113 are used to electrically connect the copper layers on both sides, so that the two sides of 110 are connected and grounded.
  • a hole can be drilled on the reflective floor 110, and then a liquid metal (such as copper) is injected into the hole and solidified to form a metalized via hole 113.
  • the dielectric substrate is a FR-4 dielectric (FR-4 is a code of a flame-resistant material grade), the dielectric constant is 4.4, and the thickness is 1.6 mm.
  • the reflective floor 110 is a double-layer PCB board
  • the reflective floor 110 can be used not only to match the impedance and reflected electromagnetic waves of the PIFA antenna 100, but also to design the feeding network 120.
  • radio frequency or digital circuits can be added to the surface of the double-layer PCB board, which is beneficial to the miniaturization design of the PIFA antenna 100.
  • the feeding network 120 is disposed in the feeding area 1112 and is electrically connected to the reflective floor 110.
  • the radiating unit 130 is electrically connected to the feeding network 120, and the feeding network 120 is configured to feed a current to the radiating unit 130.
  • the feeding network 120 is a coplanar waveguide (CPW) type feeding network.
  • the coplanar waveguide has the characteristics of simple process and wide frequency band, so it is beneficial to expand the frequency band width of the PIFA antenna 100.
  • the feeding mode of the coplanar waveguide can weld the coaxial feeder in the same plane, which is convenient for processing.
  • the radiation unit 130 is used for receiving and radiating electromagnetic wave signals. Please refer to FIG. 3 and FIG. 4 together.
  • the radiation unit 130 includes a metal plate 131, a power feeding portion 133, an open branch 135 and a short branch 137.
  • the metal plate body 131 is disposed parallel to and spaced from the bearing surface 111.
  • the metal plate body 131 can be formed of a good conductor such as copper or silver.
  • the radiating unit 130 is a one-piece structure, and the metal plate body 131, the power feeding portion 133, the open branch 135, and the short-circuit branch 137 can be obtained by punching, bending, and punching the metal plate.
  • the radiating unit 130 is made of white copper.
  • the metal plate body 131 has a feeding end (not shown) and a short-circuiting end (not shown).
  • the outer contour of the metal plate body 131 may be various shapes such as a circle, a rectangle, and the feeding end and the short-circuit end are located at different ends of the metal plate body 110.
  • the metal plate body 131 has two edges that are parallel and opposite to each other, and the feeding end and the short-circuit are located on the two edges, respectively.
  • the power feeding portion 133, the open branch 135, and the short branch 137 may have a long plate-like structure.
  • One end of the feeding portion 133 is electrically connected to the feeding end, and the other end is electrically connected to the feeding network 120.
  • One end of the open branch 135 is electrically connected to the feeding end, and the other end is spaced from the reflective floor 110.
  • One end of the short-circuit branch 137 is electrically connected to the short-circuit terminal, and the other end is electrically connected to the short-circuit region.
  • a steel mesh is laid in the power feeding area and the short-circuit area, and the power feeding portion 133 and the short-circuit branch 137 are respectively electrically connected to the power feeding area and the short-circuit area of the reflective floor 110 by furnace welding. Compared with the traditional manual welding and riveting, the reliability and processing efficiency of the connection can be effectively improved.
  • the radiation unit 130 is an axisymmetric structure, and the feeding portion 133 is symmetrical with respect to the axis of symmetry of the radiation unit 130.
  • the current entered by the power feeding portion 133 can flow uniformly along both sides of the metal plate body 110, thereby ensuring the symmetry of the signal radiation, which is beneficial to improving the symmetry of the radiation pattern of the PIFA antenna 100.
  • the electric signal enters the radiating unit 130 through the feeding network 120 from the feeding portion 133.
  • a current flows from the feeding portion 133 to the open branch 135 and the short branch 137.
  • the open branch 135 and the short branch 137 will optimize the impedance bandwidth of the radiating unit 130 so that the PIFA antenna has a wider impedance bandwidth.
  • the feeding network 120 has a strong current distribution, that is, a strong inductivity.
  • the open branch 135 is a capacitive load. By optimizing the size of the open branch 135, the inductive reactance generated by the feeding network 120 can be eliminated.
  • the shorting branch 137 converts the open circuit (high input impedance) of the conventional PIFA antenna into a short circuit (low input impedance).
  • the shorting branches 137 of different widths can adjust and optimize the input impedance of the antenna.
  • the antenna will resonate and achieve a wide impedance bandwidth.
  • the impedance of the radiating unit 130 needs to match the impedance of the feeder.
  • the resonance point and impedance of the PIFA antenna 100 are tuned by its height (the distance between the reflective floor 100 and the metal plate 131). Therefore, in order to ensure better impedance matching in general PIFA antennas, a higher height must be set, which leads to a high profile. Since the impedance matching of the open branch 135 and the short branch 137 is optimized, the height of the radiation unit 130 can be reduced while the impedance matching is satisfied, so that the PIFA antenna 100 has a low profile.
  • a hollow portion 1312 is formed on the metal plate body 131.
  • the hollow portion 1312 may be a structure such as a hole or a slot opened in the metal plate body 131. Further, the hollow portion 1312 is provided, so that a meandering flow is formed during the current flowing from the feeding end to the short-circuiting end, so the current path becomes longer.
  • the short-circuit branch 137 can form a complete loop between the short-circuit terminal and the feeding terminal, so the current path can be further extended. Due to the extension of the current path, the frequency of the signal that can be transmitted and received by the radiating unit 130 changes accordingly, so that the working frequency band of the radiating unit 130 becomes wider.
  • the width of the radiating unit 130 when the width of the radiating unit 130 is unchanged (the distance from the feeding end to the short-circuiting end), the width of the frequency band covered by it can be significantly expanded. Alternatively, without changing the width of the frequency band covered by the radiation unit 130, its width can be significantly reduced.
  • the PIFA antenna 100 including the radiating unit 130 can also widen the working frequency band or reduce the volume. Therefore, when the above-mentioned PIFA antenna 100 is applied to an indoor base station, the number of integrated PIFA antennas 100 can be reduced, which is beneficial to miniaturization of the indoor base station. Alternatively, in the case where the number of integrations is not changed, since the volume of a single PIFA antenna 100 is significantly reduced, miniaturization of an indoor base station can also be achieved.
  • the reflective floor 110 is a rectangular plate-like structure with a length of 180 mm, a width of 180 mm, and a thickness of 1.6 mm.
  • the thickness of the radiation unit 130 is 0.5 mm, and its size is 45 mm in length, 39 mm in width, and 18 mm in height.
  • the width refers to the distance from the short-circuited end to the feeding end.
  • the length is a dimension perpendicular to the width direction, and the height is the distance between the metal plate body 110 and the reflection 2110.
  • FIG. 5 shows the reflection coefficient and gain of the PIFA antenna 100.
  • the impedance bandwidth of the PIFA antenna 100 (S 11 ⁇ -10dB is 1650-2760MHz, and the gain is about 4.8-6.2dBi.
  • the gain of the PIFA antenna 100 changes less than 1.4dB. It can be seen that the PIFA antenna Realize better impedance matching in the working frequency band of common indoor base stations.
  • the height of the PIFA antenna 100 is approximately 19 mm, which is approximately equal to 0.14 ⁇ g ( ⁇ g is a free-space wavelength corresponding to a center frequency of 2.2 GHz). In the existing PIFA antenna, its height is generally 0.25 ⁇ g . It can be seen that, while satisfying the same impedance matching requirement, the height of the PIFA antenna 100 described above is effectively reduced significantly, thereby having good low-profile characteristics.
  • FIG. 6 shows the input impedance of the PIFA antenna 100.
  • the PIFA antenna 100 has relatively small changes in its resistance and reactance values around 50 ohms and 0 ohms in the 1650-2760MHz frequency band. It can be seen that the PIFA antenna 100 also has a wide frequency band characteristic, and its working frequency band covers a common frequency band of an indoor base station. When applied to indoor base stations, it can effectively reduce the number of antennas (only one is needed), reduce material and labor costs, and also achieve miniaturization of indoor base stations.
  • the PIFA antenna 100 also has a low directivity, and the PIFA antenna 100 has a monopole radiation characteristic, that is, a low directivity. among them.
  • the radiation pattern of the PIFA antenna 100 is conical, and the antenna gain is about 4.8 to 6.2dBi, so that it can achieve all-round indoor coverage.
  • the PIFA antenna 100 are radiation patterns of the PIFA antenna 100 at the frequency points of 1.7 GHz, 2.3 GHz, and 2.7 GHz, respectively, and the radiation patterns are conical.
  • the PIFA antenna 100 has an asymmetric structure, so as the frequency increases, the antenna radiation directivity becomes stronger.
  • the cross polarization ratio of the PIFA antenna 100 is less than -30dB.
  • the PIFA antenna 100 has good symmetry. However, as the frequency increases, the value of E ⁇ becomes larger and larger. At 2.7 GHz, the value of E ⁇ is greater than the value of E ⁇ .
  • the PIFA antenna 100 has good out-of-roundness at low frequencies, and is 1.3 dB and 1.9 dB at 1.7 GHz and 2.3 GHz, respectively.
  • the distribution density of the metalized vias 113 in the feeding area and the short-circuit area is greater than the distribution density in the remaining areas of the reflective floor 110.
  • the radiation unit 130 is connected to the reflective floor 110 in a feeding area and a short-circuit area. Since the reflective floor 100 in this embodiment is a double-layer PCB board, the copper layers on both sides are communicated through the metalized vias 113. Therefore, setting more metalized vias 113 in the feeding area and the short-circuit area can further improve the reliability of the electrical connection between the radiating unit 130 and the metal floor 110 and the feeding network 120 and the metal floor 110, thereby ensuring the effective transmission of electromagnetic waves. .
  • the power feeding portion 133, the open branch 135, and the short branch 137 are all L-shaped.
  • the power feeding portion 133 includes a main body 1332 and a bent portion 1334 bent with respect to the main body 1332.
  • the bent portion 1334 is welded to the feeding area of the metal base plate 110, thereby increasing the contact area of the feeding portion 133 with the metal base plate 110 and the feeding network 120, and improving the signal transmission effect.
  • the structure of the open branch 135 and the short-circuited branch 137 is similar to the power feeding portion 133, and the contact area between the short-circuited branch 137 and the metal floor 110 is also increased.
  • the power feeding portion 133, the open branch 135 and the short branch 137 are all vertically connected to the metal plate body 131.
  • a portion of the feeding portion 133, the open branch 135, and the short branch 137 connected to the metal plate body 131 is perpendicular to the metal plate body 131.
  • the main body 1332 is perpendicular to the surface of the metal plate body 131
  • the bent portion 1334 is parallel to the metal plate body 131.
  • the overall width of the radiating unit 130 can be reduced; on the other hand, the bent portion 1334 is also parallel to the bearing surface 111, so it fits tighter with the metal base plate 110.
  • a notch 1372 is defined in an edge of the short-circuit branch 137.
  • the notches 1372 have the same function as the hollow portions 1312, and the notches 1372 may be symmetrically distributed on the edges of both sides of the shorting branch 137.
  • the presence of the notch 1372 will cause a meandering flow, thereby further extending the current path, and further expanding the impedance bandwidth of the radiation unit 130.
  • the hollow portion 1312 is located on the edge of the metal plate body 131, so that the edge of the metal plate body 131 is sawtooth-shaped.
  • the hollow portion 1312 is located at the edge of the metal plate body 131, and the current needs to flow to the edge first and then bypass the hollow portion 1312 during transmission, and the meandering effect is better. It can be understood that the hollow portion 1312 may also be a through hole located in the middle of the metal floor 110.
  • the impedance bandwidth of the PIFA antenna 100 is related to the distance between the reflective floor 100 and the metal plate 131, and the setting of the open branch 135 and the short branch 137 is beneficial to optimize the impedance matching. Further, the arrangement of the hollow portion 1312 causes the current to form a meandering flow on the metal plate body 131, so the current path becomes longer. In addition, the short-circuit branch 137 can form a loop between the short-circuit terminal and the feeding terminal, which can further extend the current path. Due to the extension of the current path, the frequency of the signal that can be transmitted and received by the radiating unit 130 changes accordingly, which reduces the operating frequency band of the radiating unit 130. It can be seen that the above-mentioned PIFA antenna 100 can reduce the volume while expanding the coverage frequency band, so it is beneficial to the miniaturization of indoor base stations.

Abstract

本发明涉及一种室内基站及其PIFA天线。PIFA天线包括反射地板、馈电网络及辐射单元。辐射单元包括金属板体、馈电部分、开路枝节及短路枝节，金属板体具有馈电端及短路端，且金属板体上形成有镂空部。PIFA天线的阻抗带宽与反射地板与金属板体之间的距离相关，而开路枝节和短路枝节的设置有利于优化阻抗匹配，进一步的，镂空部的设置使得电流在金属板体上形成曲流，故电流路径变长。而且，短路枝节可在短路端及馈电端之间形成回路，能进一步延长电流路径。由于电流路径延长，辐射单元可收发的信号频率也随之改变，使得辐射单元的工作频段降低。可见，上述PIFA天线可在展开覆盖频段的同时减小体积，故有利于实现室内基站的小型化。

Description

室内基站及其PIFA天线 技术领域
本发明涉及移动通讯技术领域，特别涉及一种室内基站及其PIFA天线。
背景技术
随着移动通信网络的发展，室内小功率热点覆盖的需求急剧增长，故对小体积、低成本、性能良好的室内基站的需求也越来越多。其中，室内基站涉及到的最关键的组成元件包括基站天线，而目前室内基站常用的基站天线为PIFA(平面倒F形)天线。
室内基站应用较广的频段主要是1710～2690MHz,频带较宽。但是，常见的PIFA天线所覆盖的频带范围较窄，故单个PIFA天线无法满足室内基站全部频段覆盖的需求。因此，只能将多个PIFA天线进行集成，以使室内基站实现宽频段的覆盖。
然而，多个PIFA天线进行集成势必会提升室内基站结构的复杂程度，并显著增大体积，故不利于室内基站的小型化。
发明内容
基于此，有必要针对现有室内基站体积较大的问题，提供一种有利于室内基站小型化的PIFA天线。
一种PIFA天线，包括：
反射地板，具有承载面，所述承载面上设置有相互间隔的馈电区域及短路区域；
馈电网络，设置于所述馈电区域，并与所述反射地板电连接；及
辐射单元，包括与所述承载面平行且间隔设置的金属板体、馈电部分、开路枝节及短路枝节，所述金属板体具有馈电端及短路端，且所述金属板体上形成有镂空部；
其中，所述馈电部分的一端与所述馈电端电连接，另一端与所述馈电网络 电连接，所述开路枝节的一端与所述馈电端电连接，另一端与所述反射地板间隔设置，所述短路枝节的一端与所述短路端电连接，另一端与所述短路区域电连接。
在其中一个实施例中，所述反射地板为双面PCB板，且所述反射地板上形成有多个金属化过孔。
在其中一个实施例中，所述金属化过孔在所述馈电区域及所述短路区域的分布密度大于在所述反射地板其余区域的分布密度。
在其中一个实施例中，所述馈电网络为共面波导式馈电网络。
在其中一个实施例中，所述馈电部分、所述开路枝节及所述短路枝节均呈L形。
在其中一个实施例中，所述馈电部分、所述开路枝节及所述短路枝节均垂直连接于所述金属板体。
在其中一个实施例中，所述短路枝节的边缘开设有缺口。
在其中一个实施例中，所述镂空部位于所述金属板体的边缘，以使所述金属板体的边缘呈锯齿状。
在其中一个实施例中，所述辐射单元为轴对称结构，且所述馈电部分相对于所述辐射单元的对称轴对称。
上述PIFA天线，其阻抗带宽与反射地板与金属板体之间的距离相关，而开路枝节和短路枝节的设置有利于优化阻抗匹配，进一步的，镂空部的设置使得电流在金属板体上形成曲流，故电流路径变长。而且，短路枝节可在短路端及馈电端之间形成回路，能进一步延长电流路径。由于电流路径延长，辐射单元可收发的信号频率也随之改变，使得辐射单元的工作频段降低。可见，上述PIFA天线可在展开覆盖频段的同时减小体积，故有利于实现室内基站的小型化。
此外，本发明还提供一种室内基站，包括：
如上述优选实施例中任一项所述的PIFA天线；及
信号收发装置，与所述PIFA基站天线通讯连接。
由于上述PIFA天线可在展开覆盖频段的同时减小体积。因此，将上述PIFA天线应用于室内基站时，可以减少PIFA天线的集成数量。或者，在集成数量不 变的情况下，由于单个PIFA天线的体积显著缩小。因此，上述室内基站可实现小型化。
附图说明
图1为本发明较佳实施例中PIFA天线的的结构示意图；
图2为图1所示PIFA天线中反射地板的结构示意图；
图3为图1所示PIFA天线中辐射单元的结构示意图；
图4为图3所示辐射单元的平面展开图；
图5为图1所示PIFA天线的反射系数与增益仿真示意图；
图6为图1所示PIFA天线的输入阻抗仿真示意图；
图7为图1所示PIFA天线在一个二维平面1.7GHz、2.3GHz、2.7GHz频点的辐射方向图；
图8为图1所示PIFA天线在一个二维平面1.7GHz、2.3GHz、2.7GHz频点的辐射方向图；
图9为在一个二维平面1.7GHz、2.3GHz、2.7GHz频点的辐射方向图。
具体实施方式
为了便于理解本发明，下面将参照相关附图对本发明进行更全面的描述。附图中给出了本发明的较佳的实施例。但是，本发明可以以许多不同的形式来实现，并不限于本文所描述的实施例。相反地，提供这些实施例的目的是使对本发明的公开内容的理解更加透彻全面。
需要说明的是，当元件被称为“固定于”另一个元件，它可以直接在另一个元件上或者也可以存在居中的元件。当一个元件被认为是“连接”另一个元件，它可以是直接连接到另一个元件或者可能同时存在居中元件。本文所使用的术语“垂直的”、“水平的”、“左”、“右”以及类似的表述只是为了说明的目的。
除非另有定义，本文所使用的所有的技术和科学术语与属于本发明的技术领域的技术人员通常理解的含义相同。本文中在本发明的说明书中所使用的术 语只是为了描述具体的实施例的目的，不是旨在于限制本发明。本文所使用的术语“及/或”包括一个或多个相关的所列项目的任意的和所有的组合。
本发明提供了一种室内基站及PIFA天线。其中，室内基站包括上述PIFA天线，以及与上述PIFA天线通讯连接的信号收发装置。信号收发装置用于将电信号转化成电磁波信号，电磁波信号可传输至天线并由PIFA天线向空间辐射。而且，信号收发装置还可将PIFA天线接收到的电磁波信号转化成电信号。
请参阅图1及图2，本发明较佳实施例中的PIFA天线100包括反射地板110、馈电网络120及辐射单元130。
反射地板110主要起到反射及增强电磁波信号的作用，一般为金属板状结构。其中，反射地板110可以呈长条形、圆形或矩形。进一步的，反射地板110具有承载面111。而且，承载面111上设置有相互间隔的馈电区域1112及短路区域1114。
在本实施例中，反射地板110为双面PCB板，且反射地板110上形成有多个金属化过孔113。
具体的，反射地板110由介质基材及覆设于介质基材相对两侧的铜层构成。金属化过孔113是指通孔内部固化有金属，从而使得通孔实现导电。金属化过孔113用于电连接两侧的铜层，从而使得110两侧实现连通及接地。其中，可先在反射地板110上钻孔，再向孔内注入液态金属(如铜)并凝固，以形成金属化过孔113。优选的，介质基材为FR-4介质(FR-4为耐燃材料等级的代号)，介电常数是4.4，厚度是1.6毫米。
由于反射地板110为双层PCB板，故反射地板110不仅可以用于匹配PIFA天线100的阻抗和反射电磁波，还可以用于馈电网络120的设计。同时，双层PCB板的表面可添加射频或数字电路，有利于实现PIFA天线100的小型化设计。
馈电网络120设置于馈电区域1112，并与反射地板110电连接。其中，辐射单元130与馈电网络120电连接，馈电网络120用于向辐射单元130馈送电流。
具体在本实施例中，馈电网络120为共面波导(CPW)式馈电网络。共面波导具有工艺简单及宽频带的特性，故有利于扩大PIFA天线100的频带宽度。 而且，共面波导的馈电方式可使同轴馈线的同一平面内焊接，便于加工。
辐射单元130用于接收及辐射电磁波信号。请一并参阅图3及图4，辐射单元130包括金属板体131、馈电部分133、开路枝节135及短路枝节137。
金属板体131与承载面111平行且间隔设置。金属板体131可由铜、银等良导体成型。具体在本实施例中，辐射单元130为一体成型的结构，可通过对金属板材进行冲压、弯折、冲铣以分别得到金属板体131、馈电部分133、开路枝节135及短路枝节137。优选的，辐射单元130为洋白铜材质。
金属板体131具有馈电端(图未标)及短路端(图未标)。金属板体131的外部轮廓可以为圆形、矩形等多种形状，而馈电端及短路端则位于金属板体110不同的两端。具体在本实施例中，金属板体131具有平行且相对的两个边缘，馈电端及短路则分别位于上述两个边缘。
馈电部分133、开路枝节135及短路枝节137可以呈长条形的板状结构。其中，馈电部分133的一端与馈电端电连接，另一端与馈电网络120电连接。开路枝节135的一端与馈电端电连接，另一端与反射地板110间隔设置。短路枝节137的一端与述短路端电连接，另一端与短路区域电连接。
具体在本实施例中，馈电区域及短路区域铺设钢网，馈电部分133及短路枝节137通过过炉焊接方式分别与反射地板110的馈电区域及短路区域实现电连接。与传统的手动焊接、铆接相比，可使得连接的可靠性及加工效率得到有效地提升。
如图3所示，本实施例中的开路枝节135为两个，且分别位于馈电部分133的两侧。在本实施例中，辐射单元130为轴对称结构，且馈电部分133相对于辐射单元130的对称轴对称。
因此，由馈电部分133进入的电流则可沿金属板体110的两侧均匀流动，从而保证信号辐射的对称，进而有利于提升PIFA天线100辐射方向图的对称性。
电信号经馈电网络120由馈电部分133进入辐射单元130内。而且，电流会从馈电部分133向开路枝节135及短路枝节137流动。开路枝节135和短路枝节137将会对辐射单元130的阻抗带宽实现优化，使PIFA天线具有较宽的阻抗带宽。馈电网络120具有较强的电流分布，即感性较强。开路枝节135属于 容性加载，通过开路枝节135尺寸的优化，可消除由馈电网络120产生的感性电抗。短路枝节137将传统PIFA天线的开路(高输入阻抗)转变为短路(低输入阻抗)，不同宽度的短路枝节137可调整与优化天线的输入阻抗。当天线的输入阻抗的实部接近50欧姆，虚部接近0欧姆时，天线会谐振，并实现宽的阻抗带宽。
在无线通信领域，为了实现PIFA天线100与馈线匹配，辐射单元130的阻抗须要与馈线的阻抗匹配。而PIFA天线100谐振点及阻抗由其高度(反射地板100与金属板体131之间的距离)实现调谐。因此，一般的PIFA天线中为了保证较好阻抗匹配，则必须设置较高的高度，进而导致其具有高剖面。而由于开路枝节135和短路枝节137对阻抗匹配实现了优化，故可在满足阻抗匹配的同时降低辐射单元130的高度，以使上述PIFA天线100具有低剖面。
此外，金属板体131上形成有镂空部1312。镂空部1312可以是开设于金属板体131上的孔、槽等结构。进一步的，镂空部1312的设置，使得电流由馈电端向短路端流动的过程中形成曲流，故电流路径变长。而且，短路枝节137可在短路端及馈电端之间形成完整的回路，故能进一步延长电流路径。由于电流路径延长，辐射单元130可收发的信号频率也随之改变，使得辐射单元130的工作频段变宽。因此，在辐射单元130宽度不变的情况下(馈电端到短路端之间的距离)，其覆盖的频段宽度可显著的扩宽。或者，在不改变辐射单元130覆盖的频段宽度情况下，其宽度可显著缩小。
显然，包括辐射单元130的PIFA天线100也可实现工作频段的扩宽，或者体积缩小。因此，将上述PIFA天线100应用于室内基站时，可以减少PIFA天线100的集成数量，有利于实现室内基站的小型化。或者，在集成数量不变的情况下，由于单个PIFA天线100的体积显著缩小，故也能实现室内基站的小型化。
以下将结合本实施例中PIFA天线100的一个具体尺寸进行说明。其中，反射地板110为长180mm、宽180mm、厚1.6mm的矩形板状结构；辐射单元130的厚度为0.5mm，其尺寸是长45mm、宽39mm、高18mm。宽指的是短路端到馈电端之间的距离，长为垂直于宽度方向上的尺寸，高为金属板体110与反射 2110之间的距离。
图5为PIFA天线100的反射系数与增益。由图可知，PIFA天线100的阻抗带宽(S 11≤-10dB为是1650～2760MHz，增益约4.8～6.2dBi。在宽频带范围内，PIFA天线100的增益变化小于1.4dB。可见，PIFA天线在常见的室内基站的工作频段内实现较好的阻抗匹配。
然而，此时PIFA天线100的高度大约为19mm,约等于0.14λ g(λ g为中心频点2.2GHz对应的自由空间波长)。而在现有的PIFA天线中，其高度一般为0.25λ g。可见，在满足相同的阻抗匹配需求的同时，上述PIFA天线100的高度有效显著降低，从而具有良好的低剖面特性。
图6为PIFA天线100的输入阻抗。由图可知，PIFA天线100在1650～2760MHz频段内，其电阻和电抗值在50欧姆和0欧姆附近变化相对较小。可见，PIFA天线100还具有宽频带特性，其工作频段覆盖室内基站的常用频段。应用于室内基站时，可以有效降低天线的数量(只需1个)，减小物料和人工成本，同时还能实现室内基站的小型化。
此外，PIFA天线100还具有较低的方向性，PIFA天线100具有单极子的辐射特性，即低方向性。其中。PIFA天线100的辐射方向图是圆锥形，天线增益约4.8～6.2dBi，从而能实现室内的全方位的覆盖。
图7至图9为PIFA天线100分别在1.7GHz、2.3GHz、2.7GHz频点的辐射方向图，其辐射方向图呈圆锥形。
如图7所示，在垂直面φ＝0°的二维方向上，PIFA天线100具有不对称结构，故随着频率的增加，天线辐射定向性变强。其中，PIFA天线100交叉极化比小于-30dB。
如图8所示，在垂直面φ＝90°的二维方向上，PIFA天线100具有良好的对称性。但随着频率的增加，E φ值越来越大。在2.7GHz频点，E φ值大于E θ的值。
如图9所示，在水平面θ＝90°的二维方向上，PIFA天线100在低频具有良好的不圆度，在1.7GHz和2.3GHz频点，分别为1.3dB和1.9dB。
在本实施例中，金属化过孔113在馈电区域及短路区域的分布密度大于在反射地板110其余区域的分布密度。
具体的，辐射单元130在馈电区域及短路区域与反射地板110实现连接。由于本实施例中的反射地板100为双层PCB板，而两侧的铜层通过金属化过孔113连通。因此，在馈电区域及短路区域设置较多的金属化过孔113则能进一步提升辐射单元130与金属地板110以及馈电网络120与金属地板110电连接的可靠性，从而确保电磁波的有效传输。
在本实施例中，馈电部分133、开路枝节135及短路枝节137均呈L形。
以馈电部分133为例，包括主体1332及相对于主体1332弯折的弯折部1334。其中，弯折部1334焊接于金属底板110的馈电区域，从而增大馈电部分133与金属底板110以及馈电网络120的接触面积，提升信号传输的效果。
同理，开路枝节135及短路枝节137的结构与馈电部分133近似，短路枝节137与金属地板110的接触面积也增大。
进一步的，在本实施例中，馈电部分133、开路枝节135及短路枝节137均垂直连接于金属板体131。
具体的，馈电部分133、开路枝节135及短路枝节137与金属板体131连接的部分垂直于金属板体131。以馈电部分133为例，主体1332垂直于金属板体131的表面，而弯折部1334则平行于金属板体131。一方面，可以缩小辐射单元130整体的宽度；另一方面，弯折部1334与承载面111也平行，故与金属底板110贴合更紧。
在本实施例中，短路枝节137的边缘开设有缺口1372。
具体的，缺口1372与镂空部1312的作用相同，缺口1372可对称分布于短路枝节137两侧的边缘。当电流经短路枝节137流向反射地板110形成回路时，由于缺口1372的存在将导致形成曲流，从而进一步延长电流路径，从而进一步展宽辐射单元130的阻抗带宽。
在本实施例中，镂空部1312位于金属板体131的边缘，以使金属板体131的边缘呈锯齿状。
具体的，镂空部1312位于金属板体131的边缘，则电流在传输过程中需要先流向边缘再绕过镂空部1312，曲流效果更好。可以理解，镂空部1312也可以是位于金属地板110中部的通孔。
上述PIFA天线100，其阻抗带宽与反射地板100与金属板体131之间的距离相关，而开路枝节135和短路枝节137的设置有利于优化阻抗匹配。进一步的，镂空部1312的设置使得电流在金属板体131上形成曲流，故电流路径变长。而且，短路枝节137可在短路端及馈电端之间形成回路，能进一步延长电流路径。由于电流路径延长，辐射单元130可收发的信号频率也随之改变，使得辐射单元130的工作频段降低。可见，上述PIFA天线100可在展开覆盖频段的同时减小体积，，故有利于实现室内基站的小型化。
以上所述实施例的各技术特征可以进行任意的组合，为使描述简洁，未对上述实施例中的各个技术特征所有可能的组合都进行描述，然而，只要这些技术特征的组合不存在矛盾，都应当认为是本说明书记载的范围。
以上所述实施例仅表达了本发明的几种实施方式，其描述较为具体和详细，但并不能因此而理解为对发明专利范围的限制。应当指出的是，对于本领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干变形和改进，这些都属于本发明的保护范围。因此，本发明专利的保护范围应以所附权利要求为准。

Claims (10)

  1. 一种PIFA天线，其特征在于，包括：
    反射地板，具有承载面，所述承载面上设置有相互间隔的馈电区域及短路区域；
    馈电网络，设置于所述馈电区域，并与所述反射地板电连接；及
    辐射单元，包括与所述承载面平行且间隔设置的金属板体、馈电部分、开路枝节及短路枝节，所述金属板体具有馈电端及短路端，且所述金属板体上形成有镂空部；
    其中，所述馈电部分的一端与所述馈电端电连接，另一端与所述馈电网络电连接，所述开路枝节的一端与所述馈电端电连接，另一端与所述反射地板间隔设置，所述短路枝节的一端与所述短路端电连接，另一端与所述短路区域电连接。
  2. 根据权利要求1所述的PIFA天线，其特征在于，所述反射地板为双面PCB板，且所述反射地板上形成有多个金属化过孔。
  3. 根据权利要求2所述的PIFA天线，其特征在于，所述金属化过孔在所述馈电区域及所述短路区域的分布密度大于在所述反射地板其余区域的分布密度。
  4. 根据权利要求1所述的PIFA天线，其特征在于，所述馈电网络为共面波导式馈电网络。
  5. 根据权利要求1所述的PIFA天线，其特征在于，所述馈电部分、所述开路枝节及所述短路枝节均呈L形。
  6. 根据权利要求5所述的PIFA天线，其特征在于，所述馈电部分、所述开路枝节及所述短路枝节均垂直连接于所述金属板体。
  7. 根据权利要求1所述的PIFA天线，其特征在于，所述短路枝节的边缘开设有缺口。
  8. 根据权利要求1所述的PIFA天线，其特征在于，所述镂空部位于所述金属板体的边缘，以使所述金属板体的边缘呈锯齿状。
  9. 根据权利要求1至8任一项所述的PIFA天线，其特征在于，所述辐射单元为轴对称结构，且所述馈电部分相对于所述辐射单元的对称轴对称。
  10. 一种室内基站，其特征在于，包括：
    如上述权利要求1至9任一项所述的PIFA天线；及信号收发装置，与所述PIFA基站天线通讯连接。
PCT/CN2018/125515 2018-05-22 2018-12-29 室内基站及其pifa天线 WO2019223318A1 (zh)

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CN108493588B (zh) * 2018-05-22 2020-07-28 京信通信系统（中国）有限公司 室内基站及其pifa天线
CN110768005A (zh) * 2019-10-29 2020-02-07 上海安费诺永亿通讯电子有限公司 一种双极化天线振子
CN114079152A (zh) * 2020-08-19 2022-02-22 昆山睿翔讯通通信技术有限公司 一种小型化低频天线
CN113300086B (zh) * 2021-05-18 2023-07-14 北京有竹居网络技术有限公司 指环

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