Broadband filtering end-on-fire antenna

Abstract

The invention discloses a broadband filtering end-on-fire antenna. A top parasitic dipole, a middle parasitic dipole, a driving dipole and a bottom parasitic dipole act with the horizontal reverse current of an n-shaped dipole to form broadband low-fluctuation flat-top end-on-fire antenna. And the middle parasitic dipole, the bottom parasitic dipole, the driving dipole and the branch knots of the n-shaped dipole are utilized to form a filtering effect, so that broadband filtering and a broadband flat-top effect in an end-fire direction are realized, and loss, size and radiation efficiency can be considered at the same time.

Description

Technical Field

[0001] The invention relates to a microwave communication device, in particular to a broadband filtering end-fire antenna. Background Art

[0002] A filtered end-fire antenna is an antenna that has stable end-radiation within the operating frequency band, but rapidly decays outside the band. It is an antenna that integrates filtering and end-radiation functions, which helps reduce the size, cost and complexity of wireless systems. A broadband filtered end-fire antenna is an antenna that integrates filtering and end-radiation functions, and has a wide bandwidth that takes into account matching, gain and radiation form. Maintaining a specific radiation form over a wide frequency band is challenging and has practical application value.

[0003] There are two methods to implement the existing broadband filtered end-fire antenna: the first is to cascade the broadband filter with the end-fire antenna to form a broadband end-fire antenna with out-of-band suppression, but its radiation pattern is the more common pointed end-to-end radiation, and there are problems such as the broadband filter taking up extra size, high loss, and low radiation efficiency. The second is to use the reverse current between the arc-shaped reflector oscillator, the segmented director and the driving dipole to form a radiation zero point to achieve the filtering function, and at the same time have broadband matching, but its radiation pattern is still the more common pointed end-to-end radiation. In summary, the broadband radiation pattern of the existing broadband filtered end-fire antenna is reflected in the pointed end-to-end radiation, lacking the broadband flat-top radiation pattern. Summary of the invention

[0004] Purpose of the invention: In view of the above-mentioned prior art, a broadband filtered end-fire antenna is proposed to achieve a broadband flat-top effect in the end-fire direction, while taking into account loss, size and radiation efficiency.

[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 annular metal strip, a vertical metal strip, a bottom parasitic dipole at the bottom layer of the lower surface of the dielectric substrate, and a U-shaped metal ground; Along the radiation direction of the antenna, the top parasitic dipole is located in front of the Π-shaped dipole, the middle 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; The driving dipole, the coplanar coupling line, the step-shaped annular metal strip and the vertical metal strip are connected in sequence; the vertical metal strip, the step-shaped annular metal strip, the dielectric substrate and the U-shaped metal ground form a phase delay network.

[0006] Furthermore, the top parasitic dipole is arranged in parallel with the horizontal strips of the Π-shaped dipole; the middle parasitic dipole, the driven dipole and the bottom parasitic dipole are arranged in parallel in sequence, and their lengths increase in sequence.

[0007] Furthermore, the length of the horizontal strip of the Π-shaped dipole is between 1.32 and 1.36λ0, the length of the branches on both sides thereof is between 0.07λ0 and 0.11λ0, and the distance between the two branches is between 0.68λ0 and 0.72λ0.

[0008] Furthermore, the length of the top parasitic dipole is between 0.31λ0 and 0.35λ0, and the spacing between the top parasitic dipole and 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 spacing between the middle parasitic dipole and 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 spacing between the middle parasitic dipole and 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 spacing between the middle parasitic dipole and the driven dipole along the radiation direction of the antenna is between 0.023λ0 and 0.027λ0.

[0009] Beneficial effects: Existing broadband filtering end-fire antennas cannot achieve broadband flat-top effect in the end-fire direction, and there are also problems of large loss, large size or low radiation efficiency. The present invention uses the top parasitic dipole, the middle parasitic dipole, the driving dipole and the bottom parasitic dipole to interact with the horizontal reverse current of the π-shaped dipole to form broadband low-fluctuation flat-top radiation, and uses the branches of the middle parasitic dipole, the bottom parasitic dipole, the driving dipole and the π-shaped dipole to form a filtering effect, thereby achieving broadband filtering and broadband flat-top effect in the end-fire direction, and taking into account loss, size and radiation efficiency.

[0010] Specifically, the Π-shaped dipole is located between the driven dipole and the top parasitic dipole, the horizontal current in the middle is opposite to the horizontal currents on both sides, and the vertical currents on the two branches are also opposite. The horizontal reverse current is used to synthesize flat top lateral radiation, and the branches are used to increase the depth of the low-frequency radiation zero point.

[0011] The middle parasitic dipole, the driven dipole on the top layer and the bottom parasitic dipole on the bottom layer all present a quasi-half-wave distribution state within the working frequency band. On the one hand, they interact with the horizontal reverse current of the π-shaped dipole to form broadband flat top-end radiation. On the other hand, they interact with each other to form two radiation zero points located at the frequencies above and below the working frequency band, respectively, to achieve a broadband filtering effect.

[0012] The top parasitic dipole is located directly in front of the Π-shaped dipole and presents a quasi-half-wave current distribution. It can fill the beam depression of the broadband flat top directional radiation, form broadband low-fluctuation flat top directional radiation, and can improve the antenna gain and improve the sidelobe level. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the top view of the structure of the broadband filtering end-fire antenna of the present invention; Figure 2 It is a schematic diagram of the upward structure of the broadband filtering end-fire antenna of the present invention; Figure 3 Simulation of the embodiment of the present invention S Parameter response; Figure 4 is a simulation gain curve of an embodiment of the present invention; Figure 5 is a radiation efficiency simulation curve of an embodiment of the present invention; Figure 6 The embodiment of the present invention at 2.55 GHz E Surface simulation pattern; Figure 7 The embodiment of the present invention at 2.84 GHz E Surface simulation pattern; Figure 8 The embodiment of the present invention at 3.00 GHz E Surface simulation pattern. DETAILED DESCRIPTION

[0014] The present invention will be further explained below in conjunction with the accompanying drawings.

[0015] like Figure 1 , Figure 2 As shown, a broadband filtering end-fire antenna is composed of a top parasitic dipole 101, a Π-shaped dipole 102, a middle parasitic dipole 103, a driven dipole 104, a coplanar coupling line 105, a stepped annular metal strip 106, a vertical metal strip 107 located on the upper surface of a dielectric substrate 201, a bottom parasitic dipole 301 located at the bottom layer of the lower surface of the dielectric substrate 201, and a U-shaped metal ground 302.

[0016] Along the radiation direction of the antenna, 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. The top parasitic dipole 101 is arranged in parallel with the horizontal strips 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 sequence, and their lengths increase in sequence.

[0017] The driving dipole 104, the coplanar coupling line 105, the stepped annular metal strip 106, and the vertical metal strip 107 are connected in sequence. The U-shaped metal ground 302 is located behind the bottom parasitic dipole 301, which plays a role in reflecting electromagnetic waves.

[0018] The vertical metal strip 107 , the stepped annular metal strip 106 , the dielectric substrate 201 and the U-shaped metal ground 302 form a phase delay network.

[0019] The length of the horizontal strip of the Π-shaped dipole 102 is between 1.32 and 1.36λ0, the length of the branches on both sides is between 0.07λ0 and 0.11λ0, the spacing between the two branches is between 0.68λ0 and 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 and 0.35λ0, and the spacing between it and the horizontal strip of the Π-shaped dipole 102 is between 0.044λ0 and 0.048λ0; the length of the middle parasitic dipole 103 is between 0.32λ0 and 0.36λ0, and the spacing between it and 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 spacing between the driven dipole 104 and 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 spacing between it and the driven dipole 104 along the antenna radiation direction is between 0.023λ0 and 0.027λ0.

[0020] In the present invention, the signal is input through the phase delay network, excited and driven by the dipole 104 through the coplanar coupling line 105, 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 broadband filtered end-fire antenna with a broadband radiation pattern of flat-top radiation is realized.

[0021] In this process, the driving dipole 104, the top parasitic dipole 101, the middle parasitic dipole 103, and the bottom parasitic dipole 301 present a quasi-half-wave distribution state within the working frequency band, the middle horizontal current of the Π-shaped dipole 102 is opposite to the horizontal currents on both sides, and the vertical currents on the two branches are also in the 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 are synthesized with the horizontal current of the Π-shaped dipole to form a flat-top radiation end-fire effect that can cover a wider bandwidth, but due to the different spacing and coupling strength, it is easy to cause a depression in the middle area of ​​the flat-top beam within the wide band, reducing the flat-top performance, so it is necessary to further add the top parasitic dipole 101 to fill the beam depression, forming a broadband low-fluctuation flat top end radiation, and the top parasitic dipole 101 improves the gain of the antenna and improves the sidelobe level.

[0022] 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 frequencies above and below the working frequency band, forming a filtering effect. The branches of the Π-shaped dipole 102 can increase the depth of the low-frequency radiation zero point. Therefore, the overall antenna can achieve functions such as broadband flat top directional radiation and filtering, and since no filtering structure other than the radiator is used, the antenna can take into account loss, size and radiation efficiency.

[0023] The substrate used in this embodiment is Rogers RO4003C. The electrical size of the horizontal antenna only needs to be 1.33λ0. The simulated matching response is as follows: Figure 3 As shown in the figure, the -10-dB impedance matching bandwidth covers 2.54 -3.00 GHz, that is, the relative bandwidth can reach 16.6%. Figure 4 This is the gain simulation curve of this embodiment. The gain in the matching band is between 2.55-5dBi, there is a low-frequency radiation zero at 2.2GHz, and a high-frequency radiation zero at 3.3GHz. The out-of-band gain rolls off quickly, and the frequency selectivity calculated by the ratio of 3dB gain bandwidth to -10dB gain bandwidth can reach 0.8. Figure 5 The radiation efficiency simulation curve of this embodiment is shown. Within the working frequency band, the radiation efficiency is greater than 90%. Figures 6 to 8 The E-plane simulation patterns at three frequencies, 2.55 GHz, 2.84 GHz, and 3 GHz, are shown. Figure 6 It can be seen that the present invention has a good flat-top radiation effect within the working frequency band.

[0024] The present invention can simultaneously achieve broadband filtering and broadband flat-top effects in the end-fire direction, and can take into account loss, size and radiation efficiency.

[0025] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A broadband filtered end-fire antenna, characterized in that: It comprises a top parasitic dipole (101), a Π-shaped dipole (102), an intermediate parasitic dipole (103), a driving dipole (104), a coplanar coupling line (105), a stepped annular metal strip (106), a vertical metal strip (107) located on the upper surface of a dielectric substrate (201), a bottom parasitic dipole (301) located on the bottom layer of the lower surface of the dielectric substrate (201), and a U-shaped metal ground (302); Along the radiation direction of the antenna, 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 driving dipole (104), and the bottom parasitic dipole (301) is located behind the driving dipole; the U-shaped metal ground (302) is located behind the bottom parasitic dipole (301); The driving dipole (104), the coplanar coupling line (105), the stepped annular metal strip (106), and the vertical metal strip (107) are connected in sequence; the vertical metal strip (107), the stepped annular metal strip (106), the dielectric substrate (201), and the U-shaped metal ground (302) form a phase delay network.

2. The broadband filtering end-fire antenna according to claim 1, characterized in that: The top parasitic dipole (101) and the horizontal strips of the Π-shaped dipole (102) are arranged in parallel; the middle parasitic dipole (103), the driving dipole (104) and the bottom parasitic dipole (301) are arranged in parallel in sequence, and their lengths increase in sequence.

3. The broadband filtering end-fire antenna according to claim 1 or 2, characterized in that: The length of the horizontal strip of the Π-shaped dipole (102) is between 1.32 and 1.36λ0, the length of the branches on both sides thereof is between 0.07λ0 and 0.11λ0, and the distance between the two branches is between 0.68λ0 and 0.72λ0.

4. The broadband filtering end-fire antenna according to claim 3, characterized in that: The length of the top parasitic dipole (101) is between 0.31λ0 and 0.35λ0, and the spacing between the top parasitic dipole (101) and the horizontal strip of the Π-shaped dipole (102) is between 0.044λ0 and 0.048λ0; the length of the middle parasitic dipole (103) is between 0.32λ0 and 0.36λ0, and the spacing between the middle parasitic dipole (103) and 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 spacing between the middle parasitic dipole (103) and 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 spacing between the middle parasitic dipole (103) and the driven dipole (104) along the antenna radiation direction is between 0.023λ0 and 0.027λ0.

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