A broadband filtering end-fire antenna

Abstract

The application discloses a broadband filtering end-fire antenna, which is characterized in that a top parasitic dipole, a middle parasitic dipole, a driven dipole, a bottom parasitic dipole and a horizontal reverse current of a Pi-shaped dipole are combined to form a broadband low-fluctuation flat-top end-fire radiation, and branches of the middle parasitic dipole, the bottom parasitic dipole, the driven dipole and the Pi-shaped dipole are used to form a filtering effect, so that the broadband filtering and the broadband flat-top effect of the end-fire direction are realized, and the loss, the size and the radiation efficiency can be considered.

Description

TECHNICAL FIELD

[0001] The present application relates to a microwave communication device, in particular to a broadband filtering end-fire antenna. BACKGROUND

[0002] The filtering end-fire antenna refers to the stable end-fire radiation in the working frequency band, and the rapid decline of the gain outside the band, that is, the antenna integrates the filtering function and the end-fire radiation function, which is beneficial to reduce the size, cost and complexity of the wireless system. The broadband filtering end-fire antenna refers to the integration of filtering and end-fire radiation functions, while also having a wide bandwidth that takes into account matching, gain and radiation form, and maintaining a specific radiation form in a wide frequency band has certain challenges and practical application value.

[0003] There are two implementation methods for the existing broadband filtering end-fire antenna: the first method is to cascade a broadband filter and an end-fire antenna to form a broadband end-fire antenna with out-of-band suppression, but its radiation form is a common sharp end-fire radiation, and there are problems such as additional size occupied by the broadband filter, high loss, and low radiation efficiency. The second method is to use the reverse current between the arc-shaped reflector, the segmented director and the driven dipole to form a radiation zero point to realize the filtering function, while having a wideband matching, but its radiation form is still a common sharp end-fire radiation. In summary, the wideband radiation form of the existing broadband filtering end-fire antenna is a sharp end-fire radiation, which lacks a wideband flat-top radiation form. SUMMARY

[0004] The present application relates to a microwave communication device, in particular to a a broadband filtering end-fire antenna.

[0005] Technical solution: A broadband filtering end-fire antenna, comprising a top parasitic dipole, a Π-shaped dipole, an intermediate parasitic dipole, a driven dipole, a coplanar coupling line, a stepped ring-shaped metal strip, a vertical metal strip on the upper surface of the dielectric substrate, a bottom parasitic dipole on the lower surface of the dielectric substrate, and a U-shaped metal ground;

[0006] Along the radiation direction of the antenna, the top parasitic dipole is located in front of the Π-shaped dipole, the intermediate parasitic dipole is located between the Π-shaped dipole and the driven dipole, and the bottom parasitic dipole is located behind the driven dipole; the U-shaped metal ground is located behind the bottom parasitic dipole;

[0007] The driven dipole, the coplanar coupling line, the stepped ring-shaped metal strip, and the vertical metal strip are connected in sequence; the vertical metal strip, the stepped ring-shaped metal strip, the dielectric substrate, and the U-shaped metal ground form a phase delay network.

[0008] Further, the top parasitic dipole is arranged in parallel with the horizontal strip of the Π-shaped dipole; the middle parasitic dipole, the driven dipole and the bottom parasitic dipole are arranged in parallel in sequence, and the lengths are increased in sequence.

[0009] Further, the length of the horizontal strip of the Π-shaped dipole is between 1.32λ0 and 1.36λ0, the length of the two side branches is between 0.07λ0 and 0.11λ0, and the interval between the two branches is between 0.68λ0 and 0.72λ0.

[0010] Further, the length of the top parasitic dipole is between 0.31λ0 and 0.35λ0, and the interval with the horizontal strip of the Π-shaped dipole is between 0.044λ0 and 0.048λ0; the length of the middle parasitic dipole is between 0.32λ0 and 0.36λ0, and the interval with the driven dipole is between 0.025λ0 and 0.029λ0; the length of the driven dipole is between 0.38λ0 and 0.42λ0, and the interval with the horizontal strip of the Π-shaped dipole is between 0.072λ0 and 0.076λ0; the length of the bottom parasitic dipole is between 0.42λ0 and 0.46λ0, and the interval with the driven dipole along the radiation direction of the antenna is between 0.023λ0 and 0.027λ0.

[0011] Beneficial effects: the existing wideband filtering end-fire antenna cannot realize the wideband flat-top effect of the end-fire direction, and also has problems of large loss, large size or low radiation efficiency. The top parasitic dipole, the middle parasitic dipole, the driven dipole and the bottom parasitic dipole are used to interact with the horizontal reverse current of the Π-shaped dipole to form a wideband low fluctuation flat-top end-fire radiation, and the branches of the middle parasitic dipole, the bottom parasitic dipole, the driven dipole and the Π-shaped dipole are used to form a filtering effect, so as to realize the wideband filtering and the wideband flat-top effect of the end-fire direction, and also to consider the loss, size and radiation efficiency.

[0012] Specifically, the Π-shaped dipole is located between the driven dipole and the top parasitic dipole, the middle horizontal current and the two side horizontal currents are reversed, and the vertical currents on the two branches are also reversed, wherein the horizontal reverse current is used to synthesize a flat-top end-fire radiation, and the branches are used to improve the depth of the low-frequency radiation zero point.

[0013] The middle parasitic dipole of the top layer, the driven dipole and the bottom parasitic dipole of the bottom layer all present a quasi-half-wave distribution state in the working frequency band, on the one hand, interact with the horizontal reverse current of the Π-shaped dipole to form a wideband flat-top end-fire radiation, and on the other hand, interact to form two radiation zeros respectively at frequencies above and below the working frequency band, to realize a wideband filtering effect.

[0014] The top parasitic dipole is located in front of the Π-shaped dipole, presents quasi-half-wave current distribution, can fill the beam depression of the wideband flat top end-fire radiation, form wideband low fluctuation flat top end-fire radiation, and can improve the antenna gain and improve the sidelobe level. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a top view structural schematic diagram of the wideband filtering end-fire antenna of the present application;

[0016] Figure 2 is a bottom view structural schematic diagram of the wideband filtering end-fire antenna of the present application;

[0017] Figure 3 is a simulation of the embodiment of the present application S Parameter response;

[0018] Figure 4 is a simulation gain curve of the embodiment of the present application;

[0019] Figure 5 is a radiation efficiency simulation curve of the embodiment of the present application;

[0020] Figure 6 is a surface simulation pattern of the embodiment of the present application at 2.55 GHz; E

[0021] is a surface simulation pattern of the embodiment of the present application at 2.84 GHz; Figure 7 E is a surface simulation pattern of the embodiment of the present application at 3.00 GHz.

[0022] Figure 8 E DETAILED DESCRIPTION

[0023] The present application will be further explained below in conjunction with the drawings.

[0024] As shown in Figure 1 ,a wideband filtering end-fire antenna, which is composed of a top parasitic dipole 101, a Π-shaped dipole 102, an intermediate parasitic dipole 103, a driven dipole 104, a coplanar coupling line 105, a stepped loop metal strip 106, a vertical metal strip 107, a bottom parasitic dipole 301 and a U-shaped metal ground 302 located on the lower surface of a dielectric substrate 201. Figure 2

[0025] ​​​Along the antenna radiation direction, the top parasitic dipole 101 is located in front of the Π-shaped dipole 102, the middle parasitic dipole 103 is located between the Π-shaped dipole 102 and the driven dipole 104, and the bottom parasitic dipole 301 is located behind the driven dipole. Among them, the top parasitic dipole 101 is arranged in parallel with the horizontal strip of the Π-shaped dipole 102. The middle parasitic dipole 103, the driven dipole 104 and the bottom parasitic dipole 301 are arranged in parallel in turn, and the lengths are increased in turn.

[0026] The driven dipole 104, the coplanar coupling line 105, the stepped loop metal strip 106 and the vertical metal strip 107 are connected in turn. The U-shaped metal ground 302 is located behind the bottom parasitic dipole 301, which plays a role of reflecting electromagnetic waves.

[0027] The vertical metal strip 107, the stepped loop metal strip 106, the dielectric substrate 201 and the U-shaped metal ground 302 constitute a phase delay network.

[0028] Among them, the length of the horizontal strip of the Π-shaped dipole 102 is between 1.32~1.36λ0, the length of the two side branches is between 0.07λ0~0.11λ0, the interval between the two branches is between 0.68λ0~0.72λ0, and λ0 is the air wavelength corresponding to the center frequency. The length of the top parasitic dipole 101 is between 0.31λ0~0.35λ0, and the interval between the top parasitic dipole 101 and the horizontal strip of the Π-shaped dipole 102 is between 0.044λ0~0.048λ0; the length of the middle parasitic dipole 103 is between 0.32λ0~0.36λ0, and the interval between the middle parasitic dipole 103 and the driven dipole is between 0.025λ0~0.029λ0; the length of the driven dipole 104 is between 0.38λ0~0.42λ0, and the interval between the driven dipole 104 and the horizontal strip of the Π-shaped dipole 102 is between 0.072λ0~0.076λ0; the length of the bottom parasitic dipole 301 is between 0.42λ0~0.46λ0, and the interval between the bottom parasitic dipole 301 and the driven dipole 104 along the antenna radiation direction is between 0.023λ0~0.027λ0.

[0029] In the present application, the signal is input through the phase delay network, excited by the coplanar coupling line 105 to the driven dipole 104, and further coupled to the bottom parasitic dipole 301, the middle parasitic dipole 103, the Π-shaped dipole 102 and the top parasitic dipole 101. Under the action of the overall structure, a wideband filtering end-fire antenna with flat-top radiation is realized.

[0030] In the process, the driving dipole 104, the top parasitic dipole 101, the middle parasitic dipole 103, the bottom parasitic dipole 301 present quasi-half-wave distribution state in the working frequency band, the middle horizontal current of the Π-shaped dipole 102 and the horizontal currents on both sides are opposite, and the vertical currents on both branches are also in opposite state. Among them, the quasi-half-wave currents of the driving dipole 104, the middle parasitic dipole 103 and the bottom parasitic dipole 301 and the horizontal currents of the Π-shaped dipole combine to form a flat-top radiation end-fire effect that can cover a wide bandwidth, but due to different distances and coupling strengths, it is easy to cause the middle region of the flat-top beam in the wide frequency band to be concave, which reduces the flat-top performance, so the top parasitic dipole 101 is needed to fill the beam concave to form a wideband low fluctuation flat-top end-fire, and the top parasitic dipole 101 improves the gain of the antenna and improves the sidelobe level.

[0031] At the same time, the middle parasitic dipole 103 and the bottom parasitic dipole 301 can form a radiation zero point with the driving dipole 104, respectively, at the frequency above and below the working frequency band, forming a filtering effect. The branches of the Π-shaped dipole 102 can improve the depth of the low-frequency radiation zero point. Therefore, the overall antenna can realize wideband flat-top end-fire, filtering and other functions, and because no filtering structure other than the radiator is used, the antenna can balance the loss, size and radiation efficiency.

[0032] The substrate used in this embodiment is Rogers RO4003C, and the horizontal antenna electric size only needs 1.33λ0. The simulated matching response is as shown in Figure 3 The -10-dB impedance matching frequency width covers 2.54-3.00GHz, that is, the relative bandwidth can reach 16.6%. Figure 4 The gain simulation curve of this embodiment is shown in the figure, the gain in the matching frequency band is between 2.55-5dBi, there is a low-frequency radiation zero point at 2.2GHz and a high-frequency radiation zero point at 3.3GHz, the out-of-band gain rapidly rolls off, and the frequency selectivity calculated by the ratio of 3dB gain bandwidth to -10dB gain bandwidth is 0.8. Figure 5 The radiation efficiency simulation curve of this embodiment is shown in the figure, in the working frequency band, the radiation efficiency is greater than 90%. Figure 6 to Figure 8 The E-plane simulation patterns at 2.55GHz, 2.84GHz and 3GHz are shown in the figures, from Figure 6 It can be seen that the present application has good flat-top radiation effect in the working frequency band.

[0033] The present application can simultaneously realize wideband filtering and wideband flat-top effect of end-fire direction, and can balance the loss, size and radiation efficiency.

[0034] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the protection scope of the present application.

Claims

1. A broadband filtered end-fire antenna, characterized by, The antenna comprises a top parasitic dipole (101) on the upper surface of a dielectric substrate (201), a Π-shaped dipole (102), an intermediate parasitic dipole (103), a driven dipole (104), a coplanar coupling line (105), a stepped loop metal strip (106), a vertical metal strip (107), a bottom parasitic dipole (301) on the lower surface of the dielectric substrate (201), and a U-shaped metal ground (302). In the radiation direction of the antenna, the top parasitic dipole (101) is located in front of the Π-shaped dipole (102), the intermediate parasitic dipole (103) is located between the Π-shaped dipole (102) and the driven dipole (104), and the bottom parasitic dipole (301) is located behind the driven dipole; the U-shaped metal ground (302) is located behind the bottom parasitic dipole (301). The driven dipole (104), the coplanar coupling line (105), the stepped loop metal strip (106), and the vertical metal strip (107) are sequentially connected behind the driven dipole (104); the vertical metal strip (107), the stepped loop metal strip (106), the dielectric substrate (201), and the U-shaped metal ground (302) form a phase delay network. The top parasitic dipole (101) is parallel to the horizontal strip of the Π-shaped dipole (102); the intermediate parasitic dipole (103), the driven dipole (104), and the bottom parasitic dipole (301) are sequentially and parallelly arranged, and their lengths are sequentially increased.

2. The wideband filtered end-fire antenna of claim 1, wherein, The length of the horizontal strip of the Π-shaped dipole (102) is between 1.32λ0 and 1.36λ0, the lengths of the two side branches are between 0.07λ0 and 0.11λ0, the distance between the two branches is between 0.68λ0 and 0.72λ0, and λ0 is the air wavelength corresponding to the center frequency.

3. The wideband filtered end-fire antenna of claim 2, wherein, The length of the top parasitic dipole (101) is between 0.31λ0 and 0.35λ0, and the interval with the horizontal strip of the Π-shaped dipole (102) is between 0.044λ0 and 0.048λ0; the length of the intermediate parasitic dipole (103) is between 0.32λ0 and 0.36λ0, and the interval with the driven dipole is between 0.025λ0 and 0.029λ0; the length of the driven dipole (104) is between 0.38λ0 and 0.42λ0, and the distance between the horizontal strip of the Π-shaped dipole (102) is between 0.072λ0 and 0.076λ0; the length of the bottom parasitic dipole (301) is between 0.42λ0 and 0.46λ0, and the interval with the driven dipole (104) in the radiation direction of the antenna is between 0.023λ0 and 0.027λ0.

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