Flat-top radiation quasi-yagi antenna based on dipole mode superposition

Abstract

The invention discloses a flat-top radiation quasi-yagi antenna based on dipole mode superposition, the overall structure is bilaterally symmetrical, and the flat-top radiation quasi-yagi antenna comprises a dielectric substrate, a long dipole, a short dipole, a coplanar coupling line and a parallel metal strip which are located on the upper surface of the dielectric substrate, and a rectangular metal ground located on the lower surface of the dielectric substrate. The long dipole is located in front of the short dipole and is parallel to the short dipole; the short dipole, the coplanar coupling line and the parallel metal strip are connected in sequence; the parallel metal strips, the dielectric substrate and the rectangular metal ground form a coupling microstrip line. A long dipole working in a three-half-wave current distribution mode, a short dipole working in a half-wave current distribution mode and a rectangular metal ground are sequentially arranged in the axial direction of the structure, the amplitude ratio of the long dipole and the short dipole is controlled through a gap between the long dipole and the short dipole, and then overlapping of the two modes in an E-plane far-field area is influenced; in addition, the antenna has the advantages of being small in size, simple in structure and low in loss.

Description

Technical Field

[0001] The invention relates to a microwave communication device, in particular to a flat-top radiation quasi-Yagi antenna. Background Art

[0002] Quasi-Yagi antennas usually radiate along the antenna axis, and have the advantages of simple structure, planarization, low cost, and easy integration with RF circuits. The radiation pattern of traditional quasi-Yagi antennas is pointed top radiation, that is, the gain is maximum in the axial direction and decreases when it deviates from the axial direction, so the gain is uneven within the main beam range, and its beam width statistics are 3dB beam width. When the flat-top radiating quasi-Yagi antenna radiates, 1dB beam width is usually used as a measurement method, that is, there is a beam range with stable gain, and the gain decays rapidly outside the 1dB beam width. Therefore, the flat-top radiating quasi-Yagi antenna is more suitable for systems such as electronic toll collection and wireless power transmission that require stable and uniform signals, and is also suitable for systems with high interference requirements for adjacent equipment.

[0003] The existing quasi-Yagi antennas are all pointed-top single-beam radiation. There is no quasi-Yagi antenna with flat-top radiation at present, and there is only one flat-top radiation omnidirectional antenna based on dipole. The dipole flat-top radiation omnidirectional antenna is realized by folding the seventh-order harmonic resonant dipole. The flat-top effect is adjusted by adjusting the compression coefficient to realize the omnidirectional antenna with flat-top radiation. It has the advantages of simple structure and low loss, but has the problems of large size, large gain fluctuation within the flat-top range, and non-end-fire antenna. Therefore, it is necessary to propose a flat-top radiation quasi-Yagi antenna based on dipole, which can not only realize the flat-top directional radiation, but also take into account the gain fluctuation, size, simple structure and low loss of flat-top radiation. Summary of the invention

[0004] Purpose of the invention: In view of the above-mentioned prior art, a flat-top radiating quasi-Yagi antenna based on dipole mode superposition is proposed to achieve flat-top directional radiation, and can take into account low gain fluctuation, small size, simple structure and low loss.

[0005] Technical solution: A flat-top radiating quasi-Yagi antenna based on dipole mode superposition, with an overall bilaterally symmetrical structure, comprising: a dielectric substrate, a long dipole, a short dipole, a coplanar coupling line, and parallel metal strips located on the upper surface of the dielectric substrate, and a rectangular metal ground located on the lower surface of the dielectric substrate; the long dipole is located in front of the short dipole, and the two are parallel to each other; the short dipole, the coplanar coupling line, and the parallel metal strips are connected in sequence; the parallel metal strips, the dielectric substrate, and the rectangular metal ground constitute a coupled microstrip line.

[0006] Furthermore, the gap between the long dipole and the short dipole is between 0.08λ0 and 0.12λ0, the length of the long dipole is between 1.33λ0 and 1.37λ0, the length of the short dipole is between 0.38λ0 and 0.42λ0, and λ0 is the air wavelength corresponding to the center frequency.

[0007] Furthermore, the length of the coplanar coupling line is between 0.10λ0 and 0.14λ0.

[0008] Furthermore, the upper and lower sides of the rectangular metal ground are flush with the upper and lower ends of the parallel metal strips.

[0009] Beneficial effects: The existing quasi-Yagi antenna does not achieve flat-top directional radiation, and the dipole flat-top radiating omnidirectional antenna has the problems of large gain fluctuation within the flat-top range, non-end-directional radiation, and large size. The present invention arranges a long dipole working in a three-half-wave current distribution mode, a short dipole working in a half-wave current distribution mode, and a rectangular metal ground in sequence in the axial direction of the structure, and uses the gap between the long and short dipoles to control the amplitude ratio of the two, thereby affecting the two modes in E The far-field regions of the two surfaces overlap, producing a flat top-end radiation effect with low gain fluctuation, and it has the characteristics of small size, simple structure and low loss.

[0010] Specifically, the electrical length of the long dipole is between 1.33λ0 and 1.37λ0, showing a three-half-wave current distribution mode with periodic inversion. When the gap with the short dipole is between 0.08λ0 and 0.12λ0, the appropriate mode current amplitude can be obtained, thus forming a half-wave mode with the short dipole. E The far field is superimposed to achieve a flat-top radiation pattern. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the structure of the quasi-Yagi antenna based on the dipole mode superposition flat-top radiation; Figure 2 Simulation of the embodiment of the present invention S parameter response plots; Figure 3 is the embodiment of the present invention at the center frequency (2.82 GHz) E Surface simulation pattern. DETAILED DESCRIPTION

[0012] The present invention will be further explained below in conjunction with the accompanying drawings.

[0013] like Figure 1As shown, a flat-top radiating quasi-Yagi antenna based on dipole mode superposition is composed of a long dipole 101, a short dipole 102, a coplanar coupling line 103, a parallel metal strip 104 on the top layer, a dielectric substrate 201 on the middle layer, and a rectangular metal ground 301 on the bottom layer. The overall structure is bilaterally symmetrical.

[0014] The long dipole 101, the short dipole 102, the coplanar coupling line 103, and the parallel metal strips 104 are all located on the upper surface of the dielectric substrate 201. The long dipole 101 is located in front of the short dipole 102, and the two are parallel to each other, and the gap between them is between 0.08λ0 and 0.12λ0, and the length of the long dipole 101 is between 1.33λ0 and 1.37λ0, the length of the short dipole 102 is between 0.38λ0 and 0.42λ0, and the length of the coplanar coupling line 103 is between 0.10λ0 and 0.14λ0, and λ0 is the air wavelength corresponding to the center frequency.

[0015] The two arms of the short dipole 102 are connected to one end of the coplanar coupling line 103 near the middle disconnection, and the other end of the coplanar coupling line 103 is connected to one end of the parallel metal strip 104, and the other end of the parallel metal strip 104 is flush with the edge of the dielectric substrate 201. The rectangular metal ground 301 is located on the lower surface of the dielectric substrate, and the upper and lower sides of the rectangular metal ground 301 are flush with the upper and lower ends of the parallel metal strip 104. Among them, the coplanar coupling line 103 mainly plays the role of impedance matching. The parallel metal strip 104, the dielectric substrate 201 and the rectangular metal ground 301 constitute a coupled microstrip line.

[0016] In the present invention, the differential signal excites the short dipole after passing through the coupled microstrip line and the coplanar coupled line, and is coupled to the long dipole. Under the action of the short dipole, the long dipole and the rectangular metal ground, a flat top end radiation is formed. In this process, the short dipole presents a half-wave current distribution mode along its length direction, and the long dipole presents a three-half-wave current distribution mode with periodic inversion along its length direction. The ratio of the current intensity of the two modes is controlled by the gap between the two, forming a half-wave mode and a three-half-wave mode with controllable amplitude ratio and end-to-end spacing. When the gap between the two modes is about one-tenth of the wavelength, the two modes are E The overlap of the far-field area produces a flat-top radiation effect. If the gap is small, the coupling is strong, and three-beam radiation is presented. If the gap is large, the coupling is weak, and a pointed single-beam radiation is presented. Therefore, it is necessary to maintain a suitable gap to maintain flat-top radiation. The rectangular metal ground acts as a reflector to reduce back radiation. Therefore, under the action of the short dipole, the long dipole and the rectangular metal ground, flat-top top radiation can be achieved, and due to the superposition of modes, the flat-top radiation gain fluctuation is low. At the same time, the superposition of the half-wave mode and the three half-wave modes avoids the use of higher-order modes, so the overall size of the antenna is small and the structure is simple.

[0017] Compared with the best existing technology, the present invention can realize flat-top radiation and can take into account low flat-top radiation gain fluctuation, small size, simple structure and low loss.

[0018] The substrate used in this embodiment is Rogers RO4003C, and the horizontal antenna size only needs to be 1.352λ0. The gap between the long dipole 101 and the short dipole 102 is 11mm, the length of the long dipole 101 is 142mm, the length of the short dipole 102 is 43.24mm, and the length of the coplanar coupling line 103 is 12mm. The simulated matching response is as follows: Figure 2 As shown, it can be seen that the 10-dB impedance matching bandwidth covers 2.74-2.91 GHz, that is, the relative bandwidth is 6.0%. Figure 3 is the central frequency (2.82 GHz) of the embodiment of the present invention. E The simulated radiation pattern is realized by flat-top radiation within the range of ±30°, and the gain within this range is between 2.86 dBi±0.05 dB, with small gain fluctuation.

[0019] 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 flat-top radiating quasi-Yagi antenna based on dipole mode superposition, characterized in that: The overall structure is bilaterally symmetrical, comprising: a dielectric substrate (201), a long dipole (101), a short dipole (102), a coplanar coupling line (103), and parallel metal strips (104) located on the upper surface of the dielectric substrate (201), and a rectangular metal ground (301) located on the lower surface of the dielectric substrate (201); the long dipole (101) is located in front of the short dipole (102), and the two are parallel to each other; the short dipole (102), the coplanar coupling line (103), and the parallel metal strips (104) are connected in sequence; and the parallel metal strips (104), the dielectric substrate (201), and the rectangular metal ground (301) form a coupled microstrip line.

2. The flat-top radiating quasi-Yagi antenna according to claim 1, characterized in that: The gap between the long dipole (101) and the short dipole (102) is between 0.08λ0 and 0.12λ0, the length of the long dipole (101) is between 1.33λ0 and 1.37λ0, the length of the short dipole (102) is between 0.38λ0 and 0.42λ0, and λ0 is the air wavelength corresponding to the center frequency.

3. The flat-top radiating quasi-Yagi antenna according to claim 2, characterized in that: The length of the coplanar coupling line (103) is between 0.10λ0 and 0.14λ0.

4. The flat-top radiating quasi-Yagi antenna according to any one of claims 1 to 3, characterized in that: The upper and lower sides of the rectangular metal ground (301) are flush with the upper and lower ends of the parallel metal strips (104).

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