CN115799818A

CN115799818A - Broadband circularly polarized endfire antenna

Info

Publication number: CN115799818A
Application number: CN202111059778.6A
Authority: CN
Inventors: 赵力为; 郭永新
Original assignee: Chongqing New National University Research Institute; National University of Singapore
Current assignee: Chongqing New National University Research Institute; National University of Singapore
Priority date: 2021-09-10
Filing date: 2021-09-10
Publication date: 2023-03-14

Abstract

Broadband circularly polarized endfire antenna. The broadband circularly polarized endfire antenna comprises a first dielectric layer, a second dielectric layer and a substrate integrated waveguide structure. The first dielectric layer comprises a first dielectric substrate and a first metal coating layer arranged on the first dielectric substrate. The second dielectric layer comprises a second dielectric substrate and a second metal coating layer arranged on the second dielectric substrate. The substrate integrated waveguide structure defines a radiation axis and is arranged between the first dielectric layer and the second dielectric layer along a thickness axis direction perpendicular to the radiation axis, and the substrate integrated waveguide structure comprises a waveguide substrate, and a first waveguide metal cladding layer and a second waveguide metal cladding layer which are arranged on the opposite surfaces of the waveguide substrate and respectively provided with a first opening and a second opening.

Description

Broadband circularly polarized endfire antenna

Technical Field

The invention relates to an antenna, in particular to a broadband circularly polarized end-fire antenna.

Background

As a communication technology which has attracted the most attention in recent years, a fifth generation wireless communication system has a significant innovation in a wireless communication module including an antenna. Under the condition of limited bandwidth of a frequency band, a fifth generation wireless communication system ensures sufficient data transmission rate through a plurality of channels, and simultaneously, the adopted higher frequency band has the problems that electromagnetic wave attenuation is fast and barriers are easy to shield. Such as luneberg lens antennas, have great potential in terms of multi-beam, high gain, operating bandwidth, support of circular polarization, and the like. The luneberg lens antenna is usually composed of a luneberg lens and a feed antenna, and the key of the feed antenna as the design of the luneberg lens antenna will determine the overall performance of the luneberg lens antenna in terms of the operating bandwidth and far-field radiation. The feed of the existing Luneberg lens mostly adopts a rectangular open waveguide antenna, a microstrip antenna and a substrate integrated waveguide antenna. The rectangular open waveguide antenna has wide impedance bandwidth, stable radiation performance and capability of realizing broadband circular polarization, but has the problems of larger volume, difficult installation and the like; the working bandwidth of the microstrip antenna is relatively narrow, so that the overall performance of the luneberg lens antenna is limited; the substrate integrated waveguide antenna has the advantages of wide band, low profile and the like, but is difficult to simultaneously consider the aspects of wide working bandwidth, end-fire circular polarization, high front-to-back ratio, stable gain and the like. Therefore, there is a need for a broadband circularly polarized endfire antenna which can be used as a feed in a spherical dielectric luneberg lens and is radiation stable.

Disclosure of Invention

The invention provides a broadband circularly polarized endfire antenna for a Luneberg lens, comprising: the first dielectric layer comprises a first dielectric substrate and a first metal coating, and the first metal coating is arranged on the first dielectric substrate; the second dielectric layer comprises a second dielectric substrate and a second metal coating, and the second metal coating is arranged on the second dielectric substrate; and a substrate integrated waveguide structure defining a radiation axis, the substrate integrated waveguide structure being disposed along a thickness axis between the first dielectric layer and the second dielectric layer, the thickness axis being perpendicular to the radiation axis, the substrate integrated waveguide structure comprising a waveguide substrate and a first waveguide metal cladding and a second waveguide metal cladding disposed on opposite sides of the waveguide substrate, the first waveguide metal cladding being provided with a first opening that is open along the radiation axis, the second waveguide metal cladding being provided with a second opening that is open along the radiation axis, the first metal cladding, the second metal cladding, the first waveguide metal cladding and the second waveguide metal cladding being disposed at intervals along the thickness axis, the first dielectric layer being provided with at least one first metalized via that penetrates through the first dielectric layer, the at least one first metalized via extending from the first metal cladding to the first opening, the second dielectric layer being provided with at least one second metalized via that penetrates through the second dielectric layer, the at least one second metalized via extending from the second metal cladding to the second opening.

The broadband circularly polarized endfire antenna may further comprise: the waveguide substrate is provided with a first array of metallized vias extending from the first waveguide metal cladding to the second waveguide metal cladding forming an electrical connection between the first waveguide metal cladding and the second waveguide metal cladding.

The broadband circularly polarized endfire antenna may further comprise: the first array of metallized vias includes two rows of metallized vias.

The broadband circularly polarized endfire antenna may further comprise: the first array of metallized vias includes two rows of metallized vias arranged in parallel.

The broadband circularly polarized end fire antenna may further include a first metal strip and a second metal strip disposed on the first dielectric substrate and the second dielectric substrate, respectively, wherein the first dielectric layer is formed with a second metalized via array extending from the first metal strip to the first waveguide metal cladding, and the second dielectric layer is formed with a third metalized via array extending from the second metal strip to the second waveguide metal cladding, the second and third metalized via arrays forming an electrical connection between the first metal strip and the second metal strip.

The broadband circularly polarized endfire antenna may further comprise: the first waveguide metal cladding and the second waveguide metal cladding are rotationally symmetric with respect to a radiation axis.

The broadband circularly polarized endfire antenna may further comprise: the first metal cap layer and the second metal cap layer are arranged as a spiral metal cap layer.

The broadband circularly polarized endfire antenna may further comprise: the first waveguide metal cladding layer and the second waveguide metal cladding layer cover a portion of each respective surface of the waveguide substrate.

The broadband circularly polarized endfire antenna may further comprise: the first waveguide metal cladding layer and the second waveguide metal cladding layer extend to the outside of the first dielectric layer and the second dielectric layer.

The broadband circularly polarized endfire antenna may further comprise: the first opening and the second opening are arranged as trapezoidal openings.

To further illustrate aspects of the present invention, detailed descriptions of specific examples are provided below in conjunction with the accompanying drawings.

Brief description of the drawings

Fig. 1 is a schematic diagram of a wideband circularly polarized endfire antenna according to an embodiment of the present invention.

Fig. 2 is an exploded view of the broadband circularly polarized endfire antenna of fig. 1.

Fig. 3 is an exploded cross-sectional view of the broadband circularly polarized endfire antenna of fig. 1.

Fig. 4A to 4C are schematic diagrams illustrating a radiation mechanism of the broadband circularly polarized end fire antenna shown in fig. 1.

Fig. 5 is a graph of the mode value of the reflection coefficient of the input port of the broadband circularly polarized end-fire antenna shown in fig. 1 versus frequency.

Fig. 6 is a graph of gain and axial ratio versus frequency for the wideband circularly polarized endfire antenna of fig. 1.

Fig. 7A to 7C are radiation patterns of the broadband circularly polarized end fire antenna shown in fig. 1 at 28GHz, 33GHz and 38GHz, respectively.

Fig. 8 is a schematic diagram of the broadband circularly polarized endfire antenna of fig. 1 used for a luneberg lens feed.

Fig. 9 is a graph of the mode value versus frequency of the input-end reflection coefficient for luneberg lens applications for the broadband circularly polarized end-fire antenna of fig. 1.

Fig. 10 is a graph of the relationship between gain and axial ratio frequency for lobb lens applications for the broadband circularly polarized endfire antenna of fig. 1.

Fig. 11A, 11B, and 11C are radiation patterns of 28GHz, 33GHz, and 38GHz, respectively, for the application of the broadband circularly polarized endfire antenna of fig. 1 to a luneberg lens.

Detailed Description

According to one embodiment, as shown in fig. 1 to 3, the broadband circularly polarized endfire antenna 100 of the present invention comprises a first dielectric layer 110, a second dielectric layer 120, and a substrate integrated waveguide structure 130.

The first dielectric layer 110 includes a first dielectric substrate 116 and a first metal cap layer 112, and the first metal cap layer 112 is disposed on the first dielectric substrate 116, for example, on one surface of the first dielectric substrate 116. The second dielectric layer 120 includes a second dielectric substrate 126 and a second metal cladding layer 122, and the second metal cladding layer 122 is disposed on the second dielectric substrate 126, for example, on one surface of the second dielectric substrate 126. The first dielectric substrate 116 and the second dielectric substrate 126 can be made of a glass microfiber reinforced polytetrafluoroethylene composite, such as a Rogers 5880 substrate. Alternatively, the first dielectric substrate 116 and the second dielectric substrate 126 may be made of a ceramic-filled polytetrafluoroethylene composite. As an example, the first dielectric layer substrate 116 and the second dielectric layer substrate 126 may have a length of 8 mm, a thickness of 1.575 mm, a width of 7.5 mm, and a relative dielectric constant of 2.2. A first metal strap 114 may also be disposed on the first dielectric substrate 116 and a second metal strap 124 may also be disposed on the second dielectric substrate 126. As one example, the first metal strip 114 and the second metal strip 124 may be arranged as rectangular metal strips, which may be 7.2 millimeters in length and 1 millimeter in width.

The substrate integrated waveguide structure 130 defines a radiation axis 140 and a thickness axis 150, the radiation axis 140 being parallel to a major plane of the substrate integrated waveguide structure 130, the thickness axis 150 being perpendicular to the radiation axis 140 and extending in a thickness direction of the substrate integrated waveguide structure 130. Substrate integrated waveguide structure 130 is disposed between first dielectric layer 110 and second dielectric layer 120 along thickness axis 150. The substrate integrated waveguide structure 130 includes a waveguide substrate 136 and a first waveguide metal cladding layer 132 and a second waveguide metal cladding layer 134 disposed on opposite surfaces of the waveguide substrate 136. As an example, the first waveguide metal cladding 132 is disposed on a first surface 1360 of the waveguide substrate 136, the second waveguide metal cladding 134 is disposed on a second surface 1362 of the waveguide substrate 136, and the second surface 1362 of the waveguide substrate 136 is disposed opposite the first surface 1360. The first waveguide metal cladding 132 is provided with a first opening 1322 that is open along the radiation axis 140, and the second waveguide metal cladding 134 is provided with a second opening 1324 that is open along the radiation axis 140. The first opening 1322 and the second opening 1324 may be configured as trapezoidal openings, and the

trapezoidal openings

1322 and 1324 are opened along the opening direction 142. The upper, lower, and height of the

trapezoidal openings

1322, 1324 may be 0.4 mm, 2.9 mm, and 1.7 mm, respectively. Alternatively, the first opening 1322 and the second opening 1324 may be provided as openings having other shapes and open along the opening direction 142. The first and second waveguide metal cladding layers 132 and 134 cover a portion of the first and second surfaces 1360 and 1362 of the waveguide substrate 136, respectively, i.e., do not completely cover the first and second surfaces 1360 and 1362. Waveguide substrate 136, first waveguide metal cladding 132, and second waveguide metal cladding 134 extend outside of first dielectric layer 110 and second dielectric layer 120.

First metal cladding 112, second metal cladding 122, first waveguide metal cladding 132, and second waveguide metal cladding 134 are spaced apart from one another along thickness axis 150. First dielectric layer 110 is provided with at least one first metalized via 1122 extending through first dielectric layer 110, at least one first metalized via 1122 extending from first metal cap 112 to first opening 1322. Second dielectric layer 120 is provided with at least one second metalized via 1222 extending through second dielectric layer 120, at least one second metalized via 1222 extending from second metal cap 122 to second opening 1324. The first waveguide metal cladding 132 and the second waveguide metal cladding 134 are rotationally symmetric with respect to the radiation axis 140. As an example, first metalized via 1122 and second metalized via 1222 may have a radius of 0.2 mm and a hole pitch of 0.65 mm.

The first dielectric substrate 116 may be formed with a second metallized via array 1142, the second metallized via array 1142 extending from the first metal strip 114 to the first waveguide metal cladding 132. The second dielectric substrate 126 may be formed with a third array of metalized vias 1242, the third array of metalized vias 1242 extending from the second metal strip 124 to the second metal waveguide cladding 134. Second and

third arrays

1142, 1242 of metalized vias form electrical connections between first and

second metal strips

114, 124.

The first metal cladding 112, the second metal cladding 122, the first waveguide metal cladding 132, and the second waveguide metal cladding 134 may be metallic copper cladding and may be formed on or disposed on the respective first dielectric substrate 116, the second dielectric substrate 126, and the waveguide substrate 136 by any suitable means, such as pre-lamination, plating, adhesion, and the like. The first metal cap layer 112 and the second metal cap layer 122 may be disposed as a spiral metal cap layer. The helical edge may be in accordance with the expression

Curve (c) of (d). The thickness of first metal cladding 112, second metal cladding 122, first waveguide metal cladding 132, and second waveguide metal cladding 134 may be 18 microns or 35 microns. The surface roughness of first metal cladding 112, second metal cladding 122, first waveguide metal cladding 132, and second waveguide metal cladding 134 may be set to match the actual circuit to the design performance.

The substrate integrated waveguide structure 130 may be configured as a substrate integrated waveguide structure operating in the TE10 mode of the master mode. The waveguide substrate 136 may be provided with a first array of metalized vias 1320, the first array of metalized vias 1320 extending from the first waveguide metal cladding 132 to the second waveguide metal cladding 134 forming an electrical connection between the first waveguide metal cladding 132 and the second waveguide metal cladding 134. The first metalized via array 1320 may comprise two rows of metalized vias, and each of the metalized vias may have a radius set to 0.25 mm and a hole pitch set to 0.65 mm. As an example, the first metalized via array 1320 comprises two rows of metalized vias arranged in parallel, the two rows of metalized vias having a center-to-center spacing of 5.3 mm. The substrate integrated waveguide structure 130 further includes two metallized vias 1302 disposed at ends of the substrate integrated waveguide structure 130, respectively, adjacent to the first metallized via array 1320. As an example, metalized via 1302 may have a length of 0.52 mm and a width of 0.25 mm.

Fig. 4A to 4C are schematic diagrams illustrating the radiation mechanism of the broadband circularly polarized endfire antenna shown in fig. 1, showing the distribution and phase relationship of the main radiation current and the direction and phase relationship of the far-field electric field generated by the main radiation current. The far-field radiation of the antenna can be regarded as being generated by two electromagnetic dipoles with equal size, orthogonal to each other and 90 degrees phase difference, each electromagnetic dipole being composed of a pair of electric dipole and magnetic dipole with equal size, orthogonal to each other and in-phase.

As one example, the

trapezoidal openings

1322, 1324 define a front end in the opening direction 142 of the radiation axis 140, and define a rear end in a direction opposite to the opening direction of the

trapezoidal openings

1322, 1324 in the radiation axis 140. The electric field defines the E-plane and the magnetic field defines the H-plane. The front-to-back ratio may be defined as the ratio of the power flux density in the maximum radiation direction of the antenna main lobe (i.e., the opening direction 142 of the

trapezoidal openings

1322, 1324 along the radiation axis 140) to the maximum power flux density near the opposite direction (the direction opposite to direction 142), where the opposite direction vicinity may include any direction within an angular magnitude of ± 20 °.

When the radiation current source of the antenna satisfies the distribution and phase relationship shown in fig. 4A, the antenna will generate a front-end radiation electric field shown in fig. 4B and a back-end radiation electric field shown in fig. 4C, i.e., the electric field generated by each electromagnetic dipole is superimposed at the front end and cancelled at the back end, and the fields generated by the two electromagnetic dipoles together realize circular polarization at the front end, wherein the dotted line in the figure represents a phase lag of 90 degrees. And finally, the antenna simultaneously realizes end-fire circular polarization, almost coincident directional diagrams of an E surface and an H surface and higher front-to-back ratio.

As shown in fig. 3, in the antenna, the radiation axis 140 defines an x-axis, the thickness axis 150 defines a z-axis, and a y-axis perpendicular to the radiation axis 140 and the thickness axis 150 is defined. The horizontal magnetic dipole is realized by the substrate integrated waveguide operating in the terminal opening of the TE10 mode of the main mode, and the horizontal electric dipole is realized by the

trapezoidal openings

1322, 1324 of the substrate integrated waveguide. The edges of the first and second

waveguide metal cladding

132, 134 that are uncut at the ends of the

trapezoidal openings

1322, 1324 generate large horizontal currents, and the

trapezoidal openings

1322, 1324 reduce the effect on the surface currents of the substrate integrated waveguide. The distribution of the TE10 mode field propagating along the z-axis can be expressed as calculated equation (1), and the relationship of the surface current to the magnetic field can be expressed as calculated equation (2):

J _s ＝e _n ×H _t (2)

it can be obtained that when the electric field at the radiation aperture of the substrate integrated waveguide structure 130 is the largest, the edge of the first and second waveguide metal cladding layers 132, 134 of the substrate integrated waveguide structure generates a larger horizontal current to reach its minimum value, i.e. the horizontal electric dipole leads the horizontal magnetic dipole by 90 degrees.

The vertical electric dipole is realized by first and

second metalized vias

1122 and 1222 centered in first and second

dielectric layers

110 and 120, and directly excited by the radiated electric field generated by the open-ended substrate integrated waveguide. The vertical electric dipoles are in phase with the horizontal magnetic dipoles due to the close placement of the first and

second metalized vias

1122, 1222 to the radiating aperture. The first and

second metalized vias

1122, 1222 are positioned above the

respective trapezoidal openings

1322, 1324 of the substrate integrated waveguide and do not contact the first waveguide metal cladding 132 or the second waveguide metal cladding 134 of the substrate integrated waveguide structure. Since any shape of the same amplitude and phase of the loop current can be equivalent to a magnetic dipole perpendicular to the plane enclosed by the loop current, the far field radiation of the vertical magnetic dipole is approximately equivalent to the radiation field generated by the surface current of the first metal cladding 112 or the second metal cladding 122 at the center of the first dielectric layer and the second dielectric layer. According to the expression (3) that the electrical ringlet is equivalent to a magnetic dipole:

I _m l＝jSωμI ₀ (3)

a circular current of equal amplitude and in phase is obtained that lags the equivalent electric dipole by 90 degrees, so that the vertical magnetic dipole realized by first metal cap 112 or second metal cap 122 also leads the vertical electric dipole realized by first and

second metalized vias

1122, 1222 centered in first dielectric layer 110 and second dielectric layer 120 by 90 degrees.

Fig. 5 is a graph of the mode value of the reflection coefficient of the input port of the broadband circularly polarized end-fire antenna shown in fig. 1 versus frequency. The reflection coefficient may be defined as the ratio of reflected energy to incident energy. The incident energy may be equal to the sum of the radiated energy, various energy losses in the antenna, i.e., reflected energy. As can be seen from fig. 5, the-10 dB impedance bandwidth of the antenna is greater than 25GHz to 40GHz (46.2%).

Fig. 6 is a graph of gain and axial ratio versus frequency for the wideband circularly polarized endfire antenna of fig. 1. Antenna gain may be defined as the ratio of the power density of the signal produced by the antenna at the same point in space as the ideal radiating element. Antenna gain may define the ability of an antenna to transmit and receive signals in one direction. As shown in FIG. 6, the 3dB axial ratio bandwidth of the antenna completely covers the Ka wave band, and the variation range of the gain in the working bandwidth is 6.84 dBi-7.88 dBi. Wherein the frequency of the Ka band may be in the range of 26.5GHz to 40 GHz.

Fig. 7A to 7C are radiation patterns of the broadband circularly polarized end fire antenna shown in fig. 1 at frequencies of 28GHz, 33GHz, and 38GHz, respectively. As shown in fig. 7A-7C, the antenna has coincident E-plane and H-plane patterns, and a high front-to-back ratio, especially at a frequency of 33GHz, of up to 17.3dB.

Therefore, in summary, the broadband circularly polarized endfire antenna has the advantages of small size, wide operating bandwidth, endfire circularly polarization, high front-to-back ratio, and overlapped E-plane and H-plane directional patterns, and achieves the advantages in the application scenario of "lunbo lens feeding".

Fig. 8 is a schematic diagram of a system 200 for a luneberg lens for the broadband circularly polarized endfire antenna of fig. 1. As one example, the luneberg lens 210 may be provided as an ideal ten-layer spherical dielectric luneberg lens having a diameter of 48 millimeters, and the antenna 100 may be disposed at the focal point of the luneberg lens. The antenna may be provided as a feed antenna to the luneberg lens. Fig. 9 is a graph of the mode value of the input end reflection coefficient for a luneberg lens application versus frequency for the broadband circularly polarized end-fire antenna of fig. 1. Fig. 10 is a graph of the relationship between gain and axial ratio frequency for the use of a luneberg lens for the broadband circularly polarized endfire antenna of fig. 1. Fig. 11A to 11C show the radiation patterns of 28GHz, 33GHz, and 38GHz of the broadband circularly polarized endfire antenna of fig. 1 for luneberg lens applications.

As used herein, the singular forms "a", "an" and "the" may be interpreted to include the plural forms "one or more" unless expressly stated otherwise.

The foregoing disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limiting. Many modifications and variations will be apparent to practitioners skilled in this art. The example embodiments were chosen and described in order to explain the principles and practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.

Thus, although the illustrative example embodiments have been described herein with reference to the accompanying drawings, it is to be understood that the description is not limiting and that various other changes and modifications may be effected therein by one skilled in the art without departing from the scope of the disclosure.

Claims

1. A broadband circularly polarized endfire antenna, said antenna comprising:

the first dielectric layer comprises a first dielectric substrate and a first metal coating, and the first metal coating is arranged on the first dielectric substrate;

the second dielectric layer comprises a second dielectric substrate and a second metal coating, and the second metal coating is arranged on the second dielectric substrate; and

a substrate integrated waveguide structure defining a radiation axis, the substrate integrated waveguide structure disposed along a thickness axis between the first dielectric layer and the second dielectric layer, the thickness axis perpendicular to the radiation axis, the substrate integrated waveguide structure including a waveguide substrate and a first waveguide metal cladding and a second waveguide metal cladding disposed on opposite sides of the waveguide substrate, the first waveguide metal cladding being provided with a first opening that is open along the radiation axis, the second waveguide metal cladding being provided with a second opening that is open along the radiation axis, the first metal cladding, the second metal cladding, the first waveguide metal cladding and the second waveguide metal cladding being disposed at intervals from one another along the thickness axis, the first dielectric layer being provided with at least one first metalized via that penetrates through the first dielectric layer, the at least one first metalized via extending from the first metal cladding to the first opening, the second dielectric layer being provided with at least one second metalized via that penetrates through the second dielectric layer, the at least one second metalized via extending from the second metalized cladding to the second opening.

2. The broadband circularly polarized endfire antenna of claim 1, wherein said waveguide substrate is provided with a first array of metallized vias extending from said first waveguide metal cladding to said second waveguide metal cladding forming an electrical connection between the first waveguide metal cladding and the second waveguide metal cladding.

3. The wideband circularly polarized endfire antenna of claim 2, wherein said first array of metallized vias comprises two rows of metallized vias.

4. A wideband circularly polarized endfire antenna according to claim 3, wherein the two rows of metallized vias are arranged parallel to each other.

5. The wideband circularly polarized endfire antenna of claim 2, further comprising first and second metal strips disposed on said first and second dielectric substrates, respectively, wherein said first dielectric layer is formed with a second array of metallized vias extending from said first metal strip to said first metal waveguide cladding layer, and said second dielectric layer is formed with a third array of metallized vias extending from said second metal strip to said second metal waveguide cladding layer, said second and third arrays of metallized vias forming an electrical connection between said first and second metal strips.

6. The broadband circularly polarized endfire antenna of claim 1, wherein the first waveguide metal cladding layer and the second waveguide metal cladding layer are rotationally symmetric with respect to the radiation axis.

7. The wideband circularly polarized endfire antenna of claim 1, wherein said first metal cladding and said second metal cladding are arranged as a spiral metal cladding.

8. The broadband circularly polarized endfire antenna of claim 1, wherein said first waveguide metal cladding layer and said second waveguide metal cladding layer cover a portion of each respective surface of said waveguide substrate.

9. The broadband circularly polarized endfire antenna of claim 1, wherein the first waveguide metal cladding layer and the second waveguide metal cladding layer extend outside the first dielectric layer and the second dielectric layer.

10. The broadband circularly polarized endfire antenna of claim 1, wherein the first and second openings are arranged as trapezoidal shaped openings.