Broadband magnetoelectric dipole antenna with second harmonic suppression

Abstract

The present invention discloses a broadband magnetoelectric dipole antenna with second harmonic suppression. The antenna comprises: an antenna feed structure comprising a bottom dielectric substrate, a rod-shaped stripline, and an H-shaped slot. The bottom dielectric substrate is provided with an upper floor and a lower floor, respectively, on both surfaces thereof. The H-shaped slot is etched into the upper floor, and the rod-shaped stripline is disposed within the bottom dielectric substrate. An antenna radiator structure comprises a top dielectric substrate, a main patch disposed on the top surface of the top dielectric substrate, and the main patch is connected to the upper floor via a grounded metal post. An antenna filter structure comprises an open resonant ring, a grounded metal branch, and a feeder branch. The open resonant ring is printed on the top surface of the top dielectric substrate. The grounded metal branch is located within the top dielectric substrate and connected to the upper floor. The feeder branch is printed on the top surface of the bottom dielectric substrate and connected to the rod-shaped stripline. This antenna can achieve second harmonic suppression without increasing the antenna volume and without affecting in-band matching.

Description

Technical Field

[0001] The present invention relates to the field of wireless communications, and in particular to a broadband magnetoelectric dipole antenna with second harmonic suppression. Background Art

[0002] With the development of wireless communication technology, the range of frequency bands used is expanding. At the same time, antenna operation often excites second harmonics, causing energy leakage and interference with RF devices. To overcome this problem, in the context of the development trend towards miniaturized, low-power, and multifunctional wireless communication systems, a solution is to use magnetoelectric dipole antennas with a filter-loaded structure. Magnetoelectric dipole antennas can produce wide bandwidth and directional radiation, meeting the multi-band requirements of RF devices. Antennas with filter-loaded structures can introduce radiation nulls without additional circuitry, effectively suppressing the antenna's second harmonics and achieving miniaturization and low loss in RF devices. The key specifications of magnetoelectric dipole antennas with filter-loaded structures include bandwidth, gain suppression, and efficiency. The antenna unit is generally required to have a wide operating bandwidth, high gain suppression within the stopband, and low radiation efficiency.

[0003] In order to improve the filtering performance of magnetoelectric dipole antenna units, many advanced technical solutions have emerged in recent years.

[0004] Among existing solutions, Z. Wei, Z. Zhou, Z. Tang, J. Y. Yin, J. Ren, and Y. Yin, "Broadband Filtering Magnetoelectronic Dipole Antenna With Quasi-Elliptic Gain Response," IEEE Trans. Antennas. Propag., vol. 68, no. 4, pp. 3225-3230, April 2020, proposes a broadband magnetoelectric dipole antenna unit with filtering performance. This unit is excited by a forked microstrip line through slot coupling. Low-frequency and high-frequency nulls are introduced by loading feed branches and U-shaped ground branches, achieving good filtering performance. The antenna has a 10dB impedance bandwidth of 53.5%, and out-of-band rejection of both high and low frequencies reaches 17.9dB.

[0005] A broadband magnetoelectric dipole filtering antenna is proposed in the literature RX Hou, J. Ren, Y. T. Liu, Y. M. Cai, J. X. Liu, and Y. Yin, "Broadband Magnetoelectric Dipole Filtering Antenna for 5G Applications," IEEE Antennas Wireless Propag. Lett., pp. 1-5, October 2022. This antenna introduces two radiation nulls at high frequencies through T-shaped branches and a ground wall, and utilizes the low-frequency radiation null created by the magnetoelectric dipole itself to achieve excellent filtering performance. The antenna operates in the 3.2-5.3 GHz range, achieving out-of-band rejection of 16.6 dB at low frequencies and 26 dB at high frequencies.

[0006] The suppression effect of the antenna in the prior art is designed to be near the working frequency band to achieve effective suppression of the near frequency, without considering the suppression of the second harmonic by the antenna. Summary of the Invention

[0007] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, an object of the present invention is to provide a broadband magnetoelectric dipole antenna with second harmonic suppression.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A broadband magnetoelectric dipole antenna with second harmonic suppression, comprising:

[0010] The antenna feeding structure includes a bottom dielectric substrate, a stripline, and an H-shaped slot. An upper floor and a lower floor are respectively provided on two surfaces of the bottom dielectric substrate. The H-shaped slot is etched on the upper floor. The stripline is provided in the bottom dielectric substrate.

[0011] The antenna radiator structure includes a top dielectric substrate, a main patch is provided on the upper surface of the top dielectric substrate, and the main patch is connected to the upper floor through a grounding metal column;

[0012] The antenna filtering structure includes an open resonant ring, a grounded metal branch and a feeder branch. The open resonant ring is printed on the upper surface of the top dielectric substrate. The grounded metal branch is located inside the top dielectric substrate and connected to the upper floor. The feeder branch is printed on the upper surface of the bottom dielectric substrate and connected to the strip line.

[0013] Furthermore, the strip line is a rod-shaped strip line, the width of the rod-shaped strip line gradually widens, and the shape is rod-shaped.

[0014] Furthermore, the main patch is composed of metal patches arranged in an array and symmetrical about the center of the top dielectric substrate.

[0015] Furthermore, one corner of the metal patch is a rectangular cut corner.

[0016] Furthermore, it also includes a metal strip and an isolation wall, the metal strip and the isolation wall surround the rod-shaped strip line, and the isolation wall is arranged on the periphery of the metal strip.

[0017] Furthermore, there are two grounding metal branches, each of which includes at least one grounding metal column and one grounding patch. The two grounding metal branches are symmetrically arranged up and down and are located above the H-shaped gap.

[0018] Furthermore, the open resonant ring is H-shaped, symmetrical about the center of the top dielectric substrate, and located between the main patches.

[0019] Furthermore, the grounding metal branch is symmetrical about the center point of the top dielectric substrate and is located below the open resonant ring.

[0020] Furthermore, the H-shaped gap is arranged on the diagonal line of the upper floor.

[0021] Furthermore, the main patch is connected to the upper floor through a grounding metal column, and there are three grounding metal columns arranged in a triangle.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0023] (1) The present invention focuses on suppressing the second harmonic rather than suppressing frequencies close to the operating frequency band, and does not affect the antenna's in-band matching. When two antennas operating in adjacent frequency bands are placed together, they often cause energy interference, affecting signal transmission.

[0024] To reduce near-band interference and improve antenna selectivity, existing technologies implement near-band suppression by adding appropriate filtering structures. However, the second harmonic excited during antenna operation can cause energy leakage and severe interference to other RF devices. Therefore, second harmonic suppression is crucial. The present invention introduces radiation nulls fn3 and fn4 at the second harmonic, in addition to the original two radiation nulls fn1 and fn2, by adding grounded metal branches, feeder branches, and an H-shaped split resonant ring. This effectively suppresses the second harmonic and reduces interference from the antenna's second harmonic.

[0025] (2) In the prior art, the loaded filtering structure affects the in-band matching of the antenna, thus requiring optimization of the antenna. However, the loaded filtering structure of the present invention is relatively small in size relative to the radiating antenna because it operates at the second harmonic. At the same time, the loading of the filtering structure does not change the structure of the radiating antenna, so it can achieve second harmonic suppression without increasing the volume of the antenna and without affecting the in-band matching. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the present invention;

[0027] Figure 2 yes Figure 1 Side view of;

[0028] Figure 3 yes Figure 1 A top view of

[0029] Figure 4(a), Figure 4(b) and Figure 4(c) are Figure 1 Dimensional diagram;

[0030] FIG5( a ) is a schematic structural diagram of a magnetoelectric dipole antenna (antenna 1) without a filter structure in Comparative Example 1;

[0031] FIG5( b ) is a schematic structural diagram of a magnetoelectric dipole antenna (antenna II) loaded with grounded metal branches in Comparative Example 2;

[0032] FIG5( c ) is a magnetoelectric dipole antenna loaded with grounded metal branches and feeder branches in Comparative Example 3;

[0033] FIG6( a ) shows the S parameters of the antenna at the second harmonic of Comparative Examples 1, 2, 3 and this embodiment;

[0034] FIG6( b ) is a schematic diagram of the gain of the antenna at the second harmonic in Comparative Examples 1, 2, 3 and this embodiment;

[0035] Figure 7 are the S parameters and gain of the broadband magnetoelectric dipole antenna with second harmonic suppression of the present invention;

[0036] Figure 8 1 is a schematic diagram of the efficiency of the broadband magnetoelectric dipole antenna with second harmonic suppression according to the present invention;

[0037] FIG9( a ) is a directional diagram of a broadband magnetoelectric dipole antenna with second harmonic suppression at 6 GHz according to the present invention;

[0038] FIG9( b ) is a directional diagram of the broadband magnetoelectric dipole antenna with second harmonic suppression at 8 GHz according to the present invention;

[0039] FIG9( c ) is a directional diagram of the broadband magnetoelectric dipole antenna with second harmonic suppression at 10 GHz according to the present invention. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

[0041] Example 1

[0042] like Figure 1 、 Figure 2 and Figure 3 As shown, a broadband magnetoelectric dipole antenna with second harmonic suppression is composed of three parts.

[0043] The first part is the antenna feed structure, which includes a rod-shaped stripline 8, an H-shaped slot 7, and a bottom dielectric substrate 13. The upper and lower surfaces of the bottom dielectric substrate 13 are respectively provided with an upper floor 6 and a lower floor 12.

[0044] The H-shaped gap 7 is set on the upper floor. Specifically: the H-shaped gap is set on the diagonal line of the upper floor. The H-shaped gap is set horizontally, and its two ends are two long strips of the same size. The two long strips are connected by a rectangle, and the length and width of the rectangle are smaller than the long strips at both ends.

[0045] In order to avoid energy leakage of the strip line and cavity resonance on the dielectric substrate and ensure that the energy can be effectively radiated, the antenna feeding structure also includes a metal strip 10 and an isolation wall 11. The metal strip 10 and the isolation wall 11 surround the rod-shaped strip line 8. The shape of the metal vias on the metal strip 10 can be square, hexagonal or circular, etc., and the isolation wall is located on the periphery of the metal strip.

[0046] Furthermore, the rod-shaped strip line has a gradually increasing width and a rod-shaped shape.

[0047] The second part is the antenna radiator structure, which includes a top dielectric substrate 5. A main patch 1 is set on the upper surface of the top dielectric substrate 5. The main patch 1 is connected to the upper floor through a grounding metal column 2. The main patch 1 is printed on the upper surface of the top dielectric substrate.

[0048] In this embodiment, the main patch 1 is composed of 2×2 metal patches, which are symmetrical in the upper and lower parts. The metal patch is specifically a rectangular patch, and a small rectangle is cut out from one corner of the rectangular patch to form a rectangular corner cut. The main patch can also be a square metal patch or other shapes.

[0049] Three grounding metal posts 2 are set on each metal patch to connect the main patch 1 and the upper floor 6. The three grounding metal posts 2 are arranged in a triangular structure near the corners of the center. The shape of the grounding metal posts 2 can be square, hexagonal, or circular.

[0050] The third part is the antenna filter structure, which includes an H-shaped split resonant ring 3, a grounded metal branch 4, and a feeder branch 9. The H-shaped split resonant ring, along with the main patch 1, is printed on the top surface of the top dielectric substrate and located between the four metal patches, symmetrically about the center point of the top dielectric substrate. There are two grounded metal branches, each including at least one grounded metal column and one ground patch. The two grounded metal branches are symmetrically arranged above and below the H-shaped gap. Specifically, they are located above the center point of the H-shaped gap.

[0051] The H-shaped open resonant ring is placed horizontally, and openings are provided at both ends.

[0052] The shape of the grounding patch is square, hexagonal or circular, and the shape of the grounding metal column can be square, hexagonal or circular.

[0053] The metal posts of the feeder branch 9 connect the patch and the rod-shaped stripline 8 on the feeder branch 9. The patch and H-shaped slot 7 of the feeder branch are printed together on the top surface of the bottom dielectric substrate 13, with the patch located in the center of the H-shaped slot. The patch and metal posts of the feeder branch can be square, hexagonal, or circular in shape, for example.

[0054] In this embodiment, the grounding metal branch includes a rectangular grounding patch and three grounding metal columns.

[0055] The broadband magnetoelectric dipole antenna with second harmonic suppression proposed in this invention is fabricated using LTCC. The dielectric substrate is FerroA6M with a dielectric constant of 5.5. The metal thickness on the dielectric substrate is 0.008mm. The overall dimensions of the antenna unit are 17mm × 17mm × 4.89mm, and the antenna has a symmetrical structure.

[0056] In the antenna feed structure, the widths of the rod-shaped stripline, w8 and w9, are 0.011λ and 0.039λ, respectively; the widths of the H-shaped slot, l6 and l7, are 0.022λ and 0.034λ, respectively; the lengths, w6 and w7, are 0.022λ and 0.14λ, respectively; the diameter r2 of the metal column in the metal strip is 0.011λ, and the distance d2 between the metal columns is 0.034λ. λ is the free space wavelength corresponding to the center frequency.

[0057] In the antenna radiator structure, the length l1 and width w1 of the main patch are 0.115λ and 0.157λ respectively, the lengths l2 and w2 of the cut rectangular corners are 0.048λ and 0.045λ respectively, the diameter r2 of the grounded metal post on the main patch is 0.011λ, and the distance d1 between the metal posts is 0.034λ. Where λ is the free space wavelength corresponding to the center frequency

[0058] In the antenna filter structure, the lengths l3, w3, and l4 of the split resonant ring are 0.028λ, 0.034λ, and 0.011λ, respectively, and the width w4 of the split resonant ring is 0.003λ. The length l5 and width w5 of the grounding patch of the grounding metal branch are 0.025λ and 0.028λ, respectively, and the distance d3 between the grounding metal posts of the grounding metal branch is 0.056λ. The side length l8 of the feeder branch is 0.011λ. Where λ is the free space wavelength corresponding to the center frequency.

[0059] The dimensions of the dielectric substrate are: the bottom dielectric substrate and the top dielectric substrate are both made of FerroA6M, with a dielectric constant of 5.5 and thicknesses of 0.032λ and 0.105λ respectively. Where λ is the free space wavelength corresponding to the center frequency

[0060] The broadband magnetoelectric dipole antenna with second harmonic suppression has an overall dimension a of 0.476λ. Wherein, λ is the free space wavelength corresponding to the center frequency.

[0061] In this embodiment, the broadband magnetoelectric dipole antenna with second harmonic suppression has the following specific dimensions:

[0062] As shown in Figures 4(a), 4(b), and 4(c), in the antenna feeding structure, the widths w8 and w9 of the rod-shaped strip lines are 0.4 mm and 1.4 mm, respectively; the widths l6 and l7 of the H-shaped slots are 0.8 mm and 1.2 mm, respectively, and the lengths w6 and w7 are 0.8 mm and 5 mm, respectively; the diameter r2 of the metal pillars in the metal strip is 0.4 mm, and the distance d2 between the metal pillars is 1.2 mm;

[0063] In the antenna radiator structure, the length l1 and width w1 of the main patch are 4.11 mm and 5.6 mm respectively, the lengths l2 and w2 of the cut rectangular corners are 1.71 mm and 1.6 mm respectively, the diameter r2 of the grounding metal column on the main patch is 0.4 mm, and the distance d1 between the metal columns is 1.2 mm.

[0064] In the antenna filter structure, the lengths l3, w3, and l4 of the split resonant ring are 1 mm, 1.2 mm, and 0.4 mm, respectively, and the width w4 of the split resonant ring is 0.1 mm. The length l5 and width w5 of the grounding patch of the grounding metal branch are 0.9 mm and 1 mm, respectively, and the distance d3 between the grounding metal posts of the grounding metal branch is 2 mm. The side length l8 of the feeder branch is 0.4 mm.

[0065] The specific dimensions of the dielectric substrate are as follows: the bottom dielectric substrate and the top dielectric substrate are both made of FerroA6M, with a dielectric constant of 5.5 and thicknesses of 1.128 mm and 3.76 mm respectively.

[0066] The broadband magnetoelectric dipole antenna with second harmonic suppression has an overall dimension a of 17 mm.

[0067] Figure 7 The S parameters and gain of the antenna of the present invention vary with frequency. The S parameters of the antenna unit of the present invention satisfy the reflection coefficient S11<-10dB in the in-band range (6-10.8GHz) and the reflection coefficient S11<-0.5dB in the second harmonic range (17-21GHz). Considering the loss, there is no energy input at the second harmonic; the average in-band gain is 5.5dBi, the out-of-band gain is <-11.6dB, and the out-of-band suppression reaches 17dB. Figure 8 Figure 9(a), (b), and (c) show the normalized gain patterns at 6 GHz, 8 GHz, and 10 GHz. The difference between the main polarization and the cross-polarization is >30 dB, indicating good cross-polarization suppression. The gain patterns are symmetrical in both the phi = 0° and phi = 90° planes.

[0068] The magnetoelectric dipole antenna with second harmonic suppression of the present invention can work in a satellite communication system.

[0069] The antenna structure adopting the above structure has the following effects:

[0070] 1) Broadband matching technology: A signal is input from one end of a rod-shaped stripline and coupled to the magnetoelectric dipole antenna through an H-shaped gap. By adjusting the tapered width of the rod-shaped stripline, the shape of the coupling gap, and the shape of the patch on the magnetoelectric dipole, a wide 10dB impedance bandwidth can be achieved. Furthermore, the addition of metal strips and isolation walls prevents energy leakage from the stripline and cavity resonance on the dielectric substrate, ensuring effective energy radiation.

[0071] 2) Filtering Structure: Magnetoelectric dipole antennas have a wide bandwidth and produce directional radiation, but they also excite second harmonics. By adding a grounded metal post, feeder branch, and H-shaped split resonant ring, two additional radiation nulls can be introduced in addition to the original two radiation nulls of the magnetoelectric dipole antenna, effectively suppressing the second harmonic range. The metal posts and patches of the grounded metal branches can be circular, square, or have one, two, or three or more posts. The metal posts and patches of the feeder branch can also be circular, square, or other shapes.

[0072] The working principle and effect of the antenna unit of this structure are explained through three comparative examples. Figure 5(a)-Figure 5(c) As shown in Figures 6(a) and 6(b).

[0073] Comparative Example 1 is a magnetoelectric dipole antenna (antenna 1) without a loaded filtering structure. As shown in Figure 5(a), the signal is input from the head end of the rod-shaped stripline 8, and the energy is coupled to the main patch 1 and the grounded metal column 2 through the H-shaped gap 7 etched on the upper floor 6. The grounded metal column 2 excites a magnetic dipole; the grounded metal column 2 and the main patch 1 excite an electric dipole, and both radiate simultaneously, forming a magnetoelectric dipole antenna, which produces directional radiation. A wider impedance matching is achieved by changing the shape of the main patch 1, the width and length of the H-shaped gap 7, and the width and length of the rod-shaped stripline 8. Since the magnetoelectric dipole antenna will excite the second harmonic when it is working, causing energy leakage and interfering with other RF devices working in the second harmonic frequency band, the second harmonic is suppressed by loading a filtering structure.

[0074] Comparative Example 2 is a magnetoelectric dipole antenna (antenna II) loaded with a grounded metal branch 4. As shown in Figures 5(b) and 6, the magnetoelectric dipole antenna without a filter structure already has two radiation nulls fn1 and fn2. The radiation null fn1 is generated by the H-shaped gap 7, and the radiation null fn2 is generated by the stripline (8). However, a resonance point is generated in the suppression frequency band, and it has a large gain, but the degree of suppression of the second harmonic is poor. By loading the grounded metal branch 4, a radiation null fn3 is introduced in the suppression frequency band, and the degree of suppression in the 17-19 GHz band is improved, but the gain in the 19-21 GHz band is still high.

[0075] Comparative Example 3 is a magnetoelectric dipole antenna (Antenna III) loaded with grounded metal branches 4 and feeder branches 9. Because the radiation null fn2 is higher than 21 GHz, the suppression level in the 17-19 GHz range is insufficient. Therefore, the radiation null fn2 can be shifted to lower frequencies by increasing the length of the rod-shaped stripline, thereby enhancing the suppression level in the 17-19 GHz range. However, increasing the length of the rod-shaped stripline affects the in-band matching. Therefore, by loading the feeder branch 9, the equivalent electrical length of the stripline can be changed, shifting the radiation null fn2 to lower frequencies. This improves the suppression level in the 19-21 GHz band without affecting the in-band matching. However, the overall suppression level in the 17-21 GHz range is still poor.

[0076] The broadband magnetoelectric dipole antenna with second harmonic suppression (Antenna IV) proposed in this invention builds upon Antenna III by adding an H-shaped split resonant ring 3 and introducing a radiation null fn4, improving the suppression level across the entire suppression band to 17 dB. This effectively suppresses the second harmonic without the use of additional filters.

[0077] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A broadband magnetoelectric dipole antenna with second harmonic suppression, characterized in that: include: The antenna feeding structure includes a bottom dielectric substrate, a stripline, and an H-shaped slot. An upper floor and a lower floor are respectively provided on two surfaces of the bottom dielectric substrate. The H-shaped slot is etched on the upper floor. The stripline is provided in the bottom dielectric substrate. The antenna radiator structure includes a top dielectric substrate, a main patch is provided on the upper surface of the top dielectric substrate, and the main patch is connected to the upper floor through a grounding metal column; The antenna filtering structure includes an open resonant ring, a grounded metal branch, and a feeder branch. The open resonant ring is printed on the upper surface of the top dielectric substrate. The grounded metal branch is located inside the top dielectric substrate and connected to the upper floor. The feeder branch is printed on the upper surface of the bottom dielectric substrate and connected to the stripline. There are two grounding metal branches, each of which includes at least one grounding metal column and one grounding patch. The two grounding metal branches are symmetrically arranged above and below and are located above the H-shaped gap; The split resonant ring is H-shaped, symmetrical about the center of the top dielectric substrate, and located between the main patches; The grounding metal branches are symmetrical about the center point of the top dielectric substrate and are located below the open resonant ring.

2. The broadband magnetoelectric dipole antenna with second harmonic suppression according to claim 1, characterized in that: The strip line is a rod-shaped strip line, the width of the rod-shaped strip line gradually widens, and the shape is rod-shaped.

3. The broadband magnetoelectric dipole antenna with second harmonic suppression according to claim 1, characterized in that: The main patch is composed of metal patches arranged in an array and is symmetrical about the center of the top dielectric substrate.

4. The broadband magnetoelectric dipole antenna with second harmonic suppression according to claim 3, characterized in that: One corner of the metal patch is a rectangular cut corner.

5. The broadband magnetoelectric dipole antenna with second harmonic suppression according to any one of claims 1 to 4, characterized in that: The invention also includes a metal strip and an isolation wall, wherein the metal strip and the isolation wall surround the rod-shaped strip line, and the isolation wall is arranged on the periphery of the metal strip.

6. The broadband magnetoelectric dipole antenna with second harmonic suppression according to claim 1, characterized in that: The H-shaped gaps are arranged on the diagonal lines of the upper floor.

7. The broadband magnetoelectric dipole antenna with second harmonic suppression according to claim 1, characterized in that: The main patch is connected to the upper floor through a grounding metal column. There are three grounding metal columns arranged in a triangle.

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