Antipodal conical slot ultra-wideband antenna

Abstract

The invention discloses an antipodal conical slot ultra-wideband antenna. The antenna comprises an upper-layer metal floor, an upper-layer dielectric substrate, a radiation patch, a lower-layer dielectric substrate and a lower-layer metal floor which are sequentially stacked from top to bottom, wherein the radiation patch, the upper-layer metal floor and the lower-layer metal floor all comprise oval metal parts, and the oval metal part of the radiation patch and the oval metal part of the lower-layer metal floor are distributed in an axial symmetry mode in the length direction of the dielectric substrate; and the elliptical metal part of the radiation patch and the elliptical metal parts of the upper and lower metal floors are respectively provided with three open slots. The traditional antipodal conical slot antenna is improved by slotting and introducing the additional metal ground, and the design of the high-gain ultra-wideband antenna is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of microwaves and antennas, and in particular relates to an antipodal cone-shaped slot ultra-wideband antenna. Background Art

[0002] Traditional antipodal conical slot antennas usually broaden the antenna operating frequency (such as expanding to low frequencies) by opening slots, but they are usually complex in design and have insufficient bandwidth, which is insufficient to meet actual needs in the high-frequency band. In addition, traditional antipodal conical slot ultra-wideband antennas also have the problem of high cross-polarization. The reason is that the electric field between the radiating patch and the metal floor of the traditional antipodal conical slot antenna will produce a cross-polarization component. If the cross-polarization component is to be removed, a large design space will be required, which does not meet the current demand for antenna miniaturization. Summary of the invention

[0003] To solve the above technical problems, the present invention provides an antipodal conical slot ultra-wideband antenna, including a central elliptical radiation patch, a dielectric substrate symmetrically distributed on the upper and lower sides of the patch, and an elliptical metal floor, thereby realizing a high-gain ultra-wideband antenna design of 1~18GHz.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] A metatarsal conical slot ultra-wideband antenna, the antenna comprising an upper metal floor, an upper dielectric substrate, a radiation patch, a lower dielectric substrate, and a lower metal floor stacked in sequence from top to bottom; wherein:

[0006] The radiation patch and the upper and lower metal floors all include an elliptical metal portion, and the elliptical metal portion of the radiation patch and the elliptical metal portion of the lower metal floor are axially symmetrically distributed along a length direction parallel to the dielectric substrate;

[0007] The elliptical metal part of the radiation patch and the elliptical metal parts of the upper and lower metal floors are all provided with three opening grooves.

[0008] Furthermore, the projections of the elliptical metal part included in the upper metal floor and the elliptical metal part included in the lower metal floor along the stacking direction overlap.

[0009] Furthermore, the ellipticity of the elliptical metal part of the radiation patch is 1.3.

[0010] Furthermore, the radiation patch is fed by a microstrip line connected thereto.

[0011] Furthermore, the microstrip line is in the form of a feeding balun, which first transitions from a cone to a parallel microstrip line to achieve 50Ω impedance matching. , and The interpolation spline curve formed by the three points is connected to the elliptical metal part of the radiation patch.

[0012] Furthermore, the lengths of the three opening slots are , and , the length is set to ,in The corresponding wavelengths are 1.4, 1.6 and 12Ghz respectively. is the dielectric frequency of the upper and lower dielectric substrates, and the dielectric frequencies of the upper dielectric substrate and the lower dielectric substrate are the same.

[0013] The beneficial effects of the present invention are:

[0014] The present invention extends the main path of the current distribution of the radiation patch by introducing an open slot on the radiation patch to improve the low-frequency radiation gain; and provides a balanced radiation electric field through a symmetrically distributed metal floor to improve the high-frequency radiation gain and cross polarization. Through the above improvements, the present invention realizes the design of a high-gain ultra-wideband antenna of 1~18GHz. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The present invention is a schematic diagram of an antipodal conical slot ultra-wideband antenna structure, wherein (a) is a schematic diagram of the decomposition of the antenna dielectric substrate layer and the metal patch layer, (b) is a side view of the antenna, and (c) is a schematic diagram of the antenna metal patch design parameters;

[0016] Figure 2 This is a schematic diagram of the design of an antipodal conical slot ultra-wideband antenna of the present invention;

[0017] Figure 3 The current comparison diagram of whether the antenna is slotted or not, where (a) is the current distribution diagram of the antenna without slots, and (b) is the current distribution diagram of the antenna with slots;

[0018] Figure 4 The electric field vector analysis diagram of whether an additional metal ground is introduced into the antenna, wherein (a) is a schematic diagram of the antenna without the introduction of an additional metal ground, and (b) is a schematic diagram of the antenna with the introduction of an additional metal ground;

[0019] Figure 5 The figure is a comparison diagram of the simulated S parameters of the antenna of the present invention and the traditional antenna;

[0020] Figure 6 A comparison diagram of simulated gains between the antenna of the present invention and a conventional antenna;

[0021] Figure 7 A cross-polarization comparison diagram of the antenna of the present invention and a traditional antenna;

[0022] Figure 8 The figures are comparison diagrams of the directional patterns of the antenna of the present invention and the traditional antenna, wherein (a) is a comparison diagram of the directional pattern at 1.6 GHz, (b) is a comparison diagram of the directional pattern at 10 GHz, and (c) is a comparison diagram of the directional pattern at 18 GHz. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0024] The invention discloses an antipodal cone slot ultra-wideband antenna, the antenna structure is as follows Figure 1 As shown in (a)-(c), the antenna includes an upper metal floor, an upper dielectric substrate, a radiation patch, a lower dielectric substrate, and a lower metal floor stacked in sequence from top to bottom, wherein the upper and lower dielectric substrates are Rogers Rogers RT-duroid 5880 ( =2.33, =0.0012) dielectric substrate. The size of the dielectric substrate is determined by the lowest cutoff frequency of the antenna, expressed as:

[0025] ;

[0026] Where W and L represent the width and length of the dielectric substrate, respectively. is the lowest cutoff frequency of the antenna, and c represents the speed of light;

[0027] The radiation patch and the upper and lower metal floors all include an elliptical metal part, and the projections of the elliptical metal part of the upper metal floor and the elliptical metal part of the lower metal floor along the stacking direction overlap, and the elliptical metal part of the radiation patch is symmetrical with the elliptical metal part of the upper or lower metal floor along the length direction of the dielectric substrate.

[0028] The elliptical metal part of the radiation patch includes three slots, corresponding to 1.4GHz, 1.6GHz, and 12GHz, which must be opened to the edge to introduce additional current paths. Without loss of generality, the slot result shown in the figure is an example, and the slots do not have to be symmetrical or parallel. The design principle is to achieve three frequency points.

[0029] The lengths of the major axis and minor axis of the ellipse of the radiation patch are respectively and When the ellipticity is 1.3, the impedance matching bandwidth of the antenna reaches the maximum value. The radiation patch and the upper and lower metal floors are etched with open slots to introduce the current path of the corresponding frequency. The radiation patch is fed by the microstrip line connected to it. The microstrip line transitions from a cone to a parallel to achieve 50Ω impedance matching. The parallel microstrip line passes through , and The interpolation spline curve composed of three points is connected to the elliptical radiation patch, and the microstrip line runs from the bottom to The point is a conical connection. The lower part of the floor is a feed balun, which is mainly used for impedance matching. It belongs to the design of the traditional antipodal conical slot antenna. It is not the focus of this invention and will not be described here. The three interpolated points are used for parameter adjustment when the slot antenna is matched. The coordinates of the three points given are the results of parameter optimization.

[0030] The specific design parameters of the radiation patch and feeding structure are shown in Table 1.

[0031] Table 1 (Unit: mm)

[0032]

[0033] The design principle of the present invention is as follows Figure 2 As shown in the figure, in the study of the traditional antipodal conical slot antenna A, it was found that although the impedance matching of 1~18GHz was achieved, the radiation gain of the antenna at 1~2GHz was less than 2dBi. Therefore, the present invention introduces open slots on the radiation patch and the upper and lower metal floors to obtain the current path of the corresponding frequency, thereby achieving a gain improvement of 1~2GHz. Slot width is 2mm, and the lengths of the three slots are , and , which is set to ,in The corresponding wavelengths are 1.4, 1.6 and 12 GHz respectively. The current distribution of the first antenna A (no slot and no additional metal floor) and the second antenna B (slot and no additional metal floor) at 1.4 GHz is shown in the figure below. Figure 3 As shown in (a)-(b), it can be observed that a strong surface current is introduced at the second slot, corresponding to Figure 5 In the gain comparison, the second antenna B has a gain improvement of 1.9dBi at 1.4GHz compared to the first antenna A. The introduction of surface current and gain improvement were also observed at 1.6GHz and 12GHz, proving that the length is The open slot helps to improve the radiation gain of the antenna at the corresponding frequency.

[0034] The slot of the second antenna B achieves the gain improvement of the first antenna A in the low and medium frequencies, but the cross polarization of the second antenna B is higher at high frequencies. The causes of cross polarization are analyzed, such as Figure 4 As shown in (a), when the second antenna B radiates through the gap between the radiation patch and the lower metal floor, an inclined excitation electric field is generated between the elliptical patches on both sides of the dielectric substrate. When the radiation in the main polarization direction is realized, cross-polarization components are also generated. Due to the small thickness of the dielectric substrate, the cross-polarization component of the tilted electric field at low frequencies is small, but at high frequencies, the tilted electric field will not only produce large cross-polarization, but also cause serious beam tilt. Therefore, the third antenna C (slotted and with additional metal floor) generates an electric field vector parallel to the main polarization direction through the symmetrically placed upper and lower metal floors, such as Figure 4 As shown in (b), the electric field between the radiating patch and the upper and lower metal floors and The vertical components cancel each other out, and the horizontal components are all parallel to the main polarization direction, achieving cross-polarization suppression.

[0035] In summary, the present invention achieves low-frequency gain improvement and high-frequency cross-polarization suppression by introducing an open slot and an additional metal ground into the traditional antipodal conical slot antenna. The first, second, and third antennas A, B, and C are simulated using CST Microwave Studio to verify the above theory. The simulation S parameter results are shown in Figure 2. Figure 5 As shown in the figure, it can be seen that the three antennas have good impedance matching in the range of 1 to 18 GHz. The introduction of the open slot and the additional metal floor will not deteriorate the impedance matching of the antenna. The in-band gain comparison of the three antennas is shown in the figure. Figure 6 As shown, by introducing the open slot, the gain of the antenna at 1.6 GHz and 12 GHz is increased by 1.9 dBi and 1.4 dBi respectively. The introduction of the additional metal floor helps to improve the radiation pattern of the antenna at high frequencies, so the antenna also has a gain increase of 2.1 dBi at 18 GHz. Figure 7 The cross-polarization comparison diagram of the three antennas shows that the third antenna C has an obvious cross-polarization reduction, and the cross-polarization is reduced by about 10dB in the high frequency range of 10~18GHz. Figure 8 (a)-(c) show the radiation patterns of the first antenna A and the third antenna C at different frequencies. It can be seen that the third antenna C proposed in the present invention has higher gain and lower cross-polarization in the 1-18 GHz operating frequency band compared to the traditional antipodal conical slot first antenna A.

[0036] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An antipodal conical slot ultra-wideband antenna, characterized in that: The antenna comprises an upper metal floor, an upper dielectric substrate, a radiation patch, a lower dielectric substrate, and a lower metal floor which are stacked in sequence from top to bottom; wherein, The radiation patch and the upper and lower metal floors all include an elliptical metal portion, and the elliptical metal portion of the radiation patch and the elliptical metal portion of the lower metal floor are axially symmetrically distributed along a length direction parallel to the dielectric substrate; The elliptical metal part of the radiation patch and the elliptical metal parts of the upper and lower metal floors are all provided with three opening grooves.

2. The antipodal conical slot ultra-wideband antenna according to claim 1, characterized in that: The projections of the elliptical metal part included in the upper metal floor and the elliptical metal part included in the lower metal floor along the stacking direction overlap.

3. The antipodal conical slot ultra-wideband antenna according to claim 1, characterized in that: The ellipticity of the elliptical metal portion of the radiation patch is 1.

3.

4. The antipodal conical slot ultra-wideband antenna according to claim 1, characterized in that: The radiation patch is fed by a microstrip line connected thereto.

5. The antipodal conical slot ultra-wideband antenna according to claim 4, characterized in that: The microstrip line is in the form of a feeding balun, which first transitions from a cone to a parallel microstrip line to achieve 50Ω impedance matching. , and The interpolation spline curve formed by the three points is connected to the elliptical metal part of the radiation patch.

6. The antipodal conical slot ultra-wideband antenna according to claim 1, characterized in that: The lengths of the three opening slots are respectively , and , the length is set to ,in The corresponding wavelengths are 1.4, 1.6 and 12Ghz respectively. is the dielectric frequency of the upper and lower dielectric substrates, and the dielectric frequencies of the upper dielectric substrate and the lower dielectric substrate are the same.

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