Double-frequency decoupling patch antenna loaded with short-circuit stub

Abstract

The invention discloses a dual-frequency decoupling patch antenna loaded with a short-circuit stub. The dual-frequency decoupling patch antenna comprises a top metal layer, a dielectric substrate, a bottom metal layer and a coaxial probe feed structure, the top metal layer is provided with at least two rectangular metal patch units arranged along the same direction, each patch unit is provided with a double-frequency slot, short-circuit stubs consisting of metal strips and metalized through holes are symmetrically loaded on two sides, and the metalized through holes penetrate through the dielectric substrate and are electrically connected with the bottom metal layer. After the signal is injected, the patch unit excites the quasi TM10 mode radiation at the double frequency points, and the short-circuit stub line enables the feed port of the coupling patch to form a weak field area, thereby achieving the dual-band mutual coupling suppression and directional diagram decoupling. The antenna is simple in structure and low in profile, a linear array can be formed, coupling of adjacent and non-adjacent units is effectively reduced, and the radiation performance of the antenna is improved.

Description

A dual-frequency decoupling patch antenna with a loaded short-circuited stub. Technical Field

[0001] This invention relates to an antenna for a wireless communication system, and more particularly to a dual-band decoupled patch antenna. Background Technology

[0002] Compared to single-frequency antennas, dual-frequency antennas can significantly improve the channel capacity and spectrum utilization efficiency of communication systems. However, with the rapid development of wireless communication technology, the mutual coupling between antenna elements remains a key bottleneck restricting system performance. This mutual interference leads to a series of negative effects, including impedance matching degradation, radiation pattern distortion, and overall radiation performance deterioration. Currently, most common decoupling techniques are designed for single-frequency antennas. While they can suppress coupling between single-frequency antennas to some extent, they are difficult to apply directly to dual-frequency antennas because the latter requires effective decoupling in both operating frequency bands simultaneously. Therefore, exploring technical approaches to suppress mutual coupling between dual-frequency antenna array elements is of significant research importance.

[0003] In existing technologies, a decoupling scheme based on dual-band metasurfaces achieves high isolation, but it also introduces significant profile height and structural complexity, and fails to decouple the radiation pattern, making it difficult to apply to antenna arrays with simple structural requirements. To achieve both decoupling and pattern consistency across both frequency bands, an improved dual-band metasurface decoupling method maintains low coupling and pattern stability, but its structural complexity and profile dimensions still have room for further optimization.

[0004] Therefore, a novel dual-frequency decoupling design is needed to simplify the structure and reduce the profile while simultaneously decoupling the radiation pattern, thus providing a feasible technical path for dual-frequency decoupling antenna arrays in high-performance wireless communication systems. Summary of the Invention

[0005] Purpose of the invention: In view of the above-mentioned prior art, a dual-frequency decoupled patch antenna with loaded short-circuit stubs is proposed to simplify the structure and reduce the profile, while simultaneously decoupling the radiation pattern.

[0006] Technical Solution: A dual-band decoupled patch antenna with loaded short-circuit stubs, comprising a top metal layer, a dielectric substrate, a bottom metal layer, and a coaxial feed probe. The dielectric substrate is disposed between the top and bottom metal layers, and the coaxial feed probe penetrates the dielectric substrate to provide feeding. The top metal layer has at least two rectangular metal patch antenna elements arranged in the same direction. Each metal patch antenna element has a slot, which constitutes the dual-band structure of the antenna. Short-circuit stubs with identical structures are symmetrically loaded on the left and right sides of each metal patch antenna element. The short-circuit stubs consist of metal strips and metallized vias. The metallized vias penetrate the dielectric substrate and are electrically connected to the bottom metal layer. The short-circuit stubs constitute the decoupling structure of the antenna. The top metal patch antenna elements form a radiating structure. After the signal is injected through the coaxial feed probe, the metal patch antenna elements excite a quasi-TM at the dual-frequency point. 10 The short-circuit stub causes the feed port of the coupled patch antenna element to form a weak field region at the dual-frequency point, thereby achieving dual-band mutual coupling suppression and radiation pattern decoupling.

[0007] Furthermore, each of the metal patch antenna units has a slot on its upper and lower parts, and the slot is parallel to the upper and lower sides of the metal patch antenna unit and symmetrical about the horizontal center line of the patch.

[0008] Furthermore, the metal strip of the short-circuited stub is arranged parallel to the adjacent side of the metal patch antenna element, and the metallized vias are arranged along the long side of the metal strip.

[0009] Furthermore, each short-circuit stub is provided with two pairs of metallized through holes symmetrical about the horizontal centerline, namely two outer metallized through holes located at both ends of the metal strip, and two inner metallized through holes located opposite each other on the inner side.

[0010] Furthermore, there are two or four metal patch antenna elements, which form a 1×2 or 1×4 linear array respectively. All metal patch antenna elements have the same structure and size, and the short-circuit stub structure and size of each element are also the same.

[0011] Furthermore, the dual frequency points are 3.55GHz and 4.83GHz, and the dimensions of the rectangular metal patch antenna element are designed based on λ0, where λ0 is the free space wavelength corresponding to the center frequency of 3.55GHz. The length of the rectangular metal patch antenna element is 0.25λ0-0.30λ0, and the width is 0.2λ0-0.25λ0.

[0012] Furthermore, the length of the slot is 0.25λ0-0.3λ0, the width is 0.0006λ0-0.0055λ0, and the side-to-side spacing between the slot and the parallel sides adjacent to the metal patch antenna element is 0.009λ0-0.0095λ0.

[0013] Furthermore, the length of the metal strip is 0.20λ0-0.25λ0, the width is 0.010λ0-0.015λ0, and the side-to-side spacing between the parallel sides of the metal strip and the adjacent metal patch antenna element is 0.002λ0-0.0025λ0.

[0014] Furthermore, the center-to-center distance between the two outer metallized vias is 0.15λ0-0.2λ0, and the center-to-center distance between the two inner metallized vias is 0.05λ0-0.055λ0.

[0015] Furthermore, the side-to-side spacing of the two short-circuit stubs between two adjacent metal patch antenna elements is between 0.03λ0 and 0.035λ0.

[0016] Beneficial Effects: Most existing single-frequency antenna decoupling techniques are not directly applicable to dual-frequency antennas. Furthermore, existing dual-frequency decoupling antennas have high profiles and complex structures, and some antennas do not achieve pattern decoupling. This invention achieves simultaneous suppression of mutual coupling in both low-frequency and high-frequency bands and corrects the radiation pattern by symmetrically loading identical short-circuit stubs on both sides of each dual-frequency patch element. Each short-circuit stub consists of a metal strip and a metallized via. Compared to existing dual-frequency patch antenna decoupling techniques, this invention, by loading short-circuit stubs, is suitable for decoupling multi-element antennas, achieving a low profile, reduced structural complexity, and pattern decoupling. Attached Figure Description

[0017] Figure 1 is a cross-sectional view of the 1×2 dual-frequency decoupling patch antenna based on a loaded short-circuit stub; Figure 2 is a top-layer metal structure of the 1×2 dual-frequency decoupling patch antenna based on a loaded short-circuit stub; Figure 3 is a bottom-layer metal feed structure of the 1×2 dual-frequency decoupling patch antenna based on a loaded short-circuit stub; Figure 4 is a cross-sectional view of the 1×4 dual-frequency decoupling patch antenna based on a loaded short-circuit stub; Figure 5 is a top-layer metal structure of the 1×4 dual-frequency decoupling patch antenna based on a loaded short-circuit stub; Figure 6 is a bottom-layer metal feed structure of the 1×4 dual-frequency decoupling patch antenna based on a loaded short-circuit stub; Figure 7 is the S-parameter curve of the 1×2 array of the present invention; Figure 8 is the gain curve of the 1×2 array of the present invention; Figure 9 is the H-plane simulation radiation pattern of the 1×2 array of the present invention, where (a) corresponds to 3.55 At GHz, (b) corresponds to 4.83 GHz; Figure 10 is the S-parameter curve of the 1×4 array of the present invention; Figure 11 is the gain curve of the 1×4 array of the present invention; Figure 12 is the simulation radiation pattern of the 1×4 array of the present invention, where (a) is the H-plane simulation radiation pattern of port 1 at 3.55 GHz, (b) is the H-plane simulation radiation pattern of port 1 at 4.83 GHz, (c) is the H-plane simulation radiation pattern of port 2 at 3.55 GHz, and (d) is the H-plane simulation radiation pattern of port 2 at 4.83 GHz. Detailed Implementation

[0018] The present invention will be further explained below with reference to the accompanying drawings. Examples

[0019] A 1×2 dual-frequency decoupling patch antenna with a loaded short-circuit stub, as shown in Figures 1 to 3, consists of a top metal layer 1, a dielectric substrate 2, a bottom metal layer 3, and a coaxial feed probe 4. The overall structure is symmetrical about the vertical plane of the dielectric substrate 2.

[0020] The top metal layer 1 has two rectangular metal patches 11 arranged in a 1×2 configuration, which serve as radiators for the 1×2 patch unit. The length of the rectangular metal patch 11 is between 0.25λ0 and 0.30λ0, and the width is between 0.2λ0 and 0.25λ0, where λ0 is the free space wavelength corresponding to the center frequency of 3.55GHz.

[0021] The rectangular metal patch 11 has symmetrical horizontal slots 12 on its upper and lower parts, forming a dual-frequency structure. The length of the slot 12 is between 0.25λ0 and 0.3λ0, the width of the slot 12 is between 0.0055λ0 and 0.0006λ0, and the side-to-side spacing between the adjacent parallel sides of the slot 12 and the rectangular metal patch 11 is between 0.009λ0 and 0.0095λ0.

[0022] Each rectangular metal patch 11 has symmetrically arranged short-circuit stubs parallel to its sides on both sides. These short-circuit stubs serve as a decoupling structure, consisting of a metal strip 13 and four metal vias. The metal vias are spaced apart along the long side of the metal strip 13, connecting the metal strip 13 to the underlying metal layer 3. The length of the metal strip 13 is between 0.20λ0 and 0.25λ0, and its width is between 0.010λ0 and 0.015λ0. The side-to-side spacing between adjacent parallel sides of the metal strip 13 and the rectangular metal patch 11 is between 0.002λ0 and 0.0025λ0. On a single short-circuit stub, the four metal vias are symmetrically arranged about the horizontal centerline. The center-to-center spacing of the two outer metal vias 14 located at both ends is between 0.15λ0 and 0.2λ0, and the center-to-center spacing of the two inner metal vias 15 located opposite each other is between 0.1λ0 and 0.15λ0. The side-to-side spacing of the two short-circuit stubs between the two rectangular metal patches 11 arranged in a 1×2 configuration is between 0.03λ0 and 0.035λ0.

[0023] Two coaxial power probes 4 serve as the power feeding structure. Their inner conductors pass through the through-hole 31 on the bottom metal layer 3 and the dielectric substrate 2, and are connected to two rectangular metal patches 11 respectively. The connection point is located on the vertical center line of the patch unit.

[0024] When a signal is injected from the coaxial feed probe 4 on the left, the rectangular metal patch 11 located on the left side of the top layer is excited. The slot structure 12 on the patch ensures that the antenna can simultaneously excite the quasi-TM at two frequency points: 3.55 GHz and 4.83 GHz. 10 The pattern radiates outwards. The rectangular metal patch 11 on the right side of the top layer serves as a coupling patch unit. The short-circuit stub structure creates a weak field region at the two center frequencies of the feed port on the coupling patch. Since the energy in the weak field region is difficult to propagate to the feed port, the adjacent feed port cannot be effectively excited, thus achieving good port isolation characteristics.

[0025] Specifically, the metal strips 13, arranged parallel to the metal patches with a small spacing, can efficiently couple the electromagnetic energy propagating from the excitation unit, guiding the energy originally propagating to adjacent coupled units into the structure of the metal strip 13, achieving initial convergence of coupled energy. Four metallized vias are arranged along the long side of the metal strips, one end of which connects to the top metal strip 13, and the other end is electrically short-circuited to the bottom metal layer 3, forming a grounded electromagnetic energy absorption and dissipation structure. The overall dimensions of the short-circuit stub are designed for the electromagnetic resonance characteristics of 3.55GHz and 4.83GHz. At these two frequencies, the short-circuit structure will generate specific electromagnetic resonances, causing the electromagnetic field strength in the area surrounding the feed port of adjacent patch units to be significantly attenuated, forming a weak field region. The core characteristic of this region is extremely low electromagnetic energy density, and the weak field effect is effective at both frequencies simultaneously.

[0026] In this embodiment, the substrate material is Rogers RO4003C, with a dielectric constant of 3.55 and a loss angle of 0.0027. The rectangular metal patch 11 has a length of 0.30λ0 and a width of 0.21λ0, where λ0 is the free-space wavelength corresponding to the center frequency of 3.55 GHz. Within the rectangular metal patch 11, the groove 12 has a length of 0.28λ0, a width of 0.0059λ0, and a side-to-side distance of 0.0091λ0 between the edge of the groove 12 and the edge of the metal patch. In the short-circuit stub structure, the length of the metal strip 13 is 0.21λ0, the width is 0.012λ0, the center-to-center distance between the two outer metal through holes 14 is 0.2λ0, and the center-to-center distance between the two inner metal through holes 15 is 0.11λ0; the side-to-side distance between the parallel sides of the metal strip 13 and the rectangular metal patch 11 is 0.0024λ0, and the side-to-side distance between the two short-circuit stubs between the two rectangular metal patches 11 arranged in a 1×2 configuration is 0.031λ0.

[0027] The simulation results of the antenna matching, isolation, and gain response in this embodiment are shown in Figures 7 and 8. The impedance matching bandwidth of this embodiment is 0.3% at 3.55 GHz and 0.7% at 4.83 GHz. The maximum gain is 3.47 dBi at 3.55 GHz and 4.89 dBi at 4.83 GHz. The isolation is greater than 15.69 dB at 3.53 GHz and greater than 27.56 dB at 4.87 GHz.

[0028] Figure 9(a) shows the simulated H-plane radiation pattern of the 1×2 antenna array in this embodiment at 3.55 GHz, with a 3-dB beamwidth of 77.2° and a cross-polarization level of -22.5 dB within the 3-dB beamwidth; (b) shows the simulated H-plane radiation pattern at 4.83 GHz, with a 3-dB beamwidth of 93.4° and a cross-polarization level of -3.82 dB within the 3-dB beamwidth. Embodiment

[0029] The 1×2 dual-band decoupled patch antenna proposed in Example 1 is configured as a 1×4 array structure as shown in Figures 4 to 6. From left to right, the coaxial feed probes corresponding to the four patch elements are named Port 1, Port 2, Port 3, and Port 4, respectively. When any feed port is excited, with identical short-circuit stubs added to the left and right sides of each patch element in the multi-element array, the original quasi-TM frequency is still maintained at 3.55GHz and 4.83GHz. 10 In this mode, the mutual coupling between adjacent patch cells and non-adjacent patch cells is also significantly reduced.

[0030] As shown in Figures 10 and 11, in this embodiment, the 10-dB impedance matching bandwidth is 0.3% at 3.55 GHz and 0.7% at 4.83 GHz. The maximum gain of port 1 is 2.96 dBi at 3.55 GHz and 5.02 dBi at 4.83 GHz. The maximum gain of port 2 is 2.4 dBi at 3.55 GHz and 4.42 dBi at 4.83 GHz. The isolation between adjacent patch cells and non-patch adjacent cells is greater than 15.7 dB at 3.55 GHz and greater than 25.95 dB at 4.83 GHz.

[0031] Figure 12(a) shows the simulated H-plane radiation pattern of the patch element containing port 1 of the 1×4 antenna array at 3.55 GHz, with a 3-dB beamwidth of 88.2° and a cross-polarization level of -21 dB within the 3-dB beamwidth; (b) shows the simulated H-plane radiation pattern of the patch element containing port 1 at 4.83 GHz, with a 3-dB beamwidth of 93.7° and a cross-polarization level of -3 dB within the 3-dB beamwidth; (c) shows the simulated H-plane radiation pattern of the patch element containing port 2 of the 1×4 antenna array at 3.55 GHz, with a 3-dB beamwidth of 98.1° and a cross-polarization level of -22.6 dB within the 3-dB beamwidth. dB; (d) is the simulated H-plane radiation pattern of the patch element at port 2 of the 1×4 antenna array at 4.83 GHz. The 3-dB beamwidth in the H-plane is 105.6°, and the cross-polarization level within the 3-dB beamwidth in the H-plane is -1.85 dB.

[0032] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A dual-frequency decoupling patch antenna with a loaded short-circuited stub, characterized in that, The antenna comprises a top metal layer, a dielectric substrate, a bottom metal layer, and a coaxial feed probe. The dielectric substrate is disposed between the top and bottom metal layers, and the coaxial feed probe penetrates the dielectric substrate to provide power. The top metal layer has at least two rectangular metal patch antenna elements arranged in the same direction. Each metal patch antenna element has a slot, which constitutes a dual-band structure of the antenna. Each metal patch antenna element has a short-circuit stub with the same structure symmetrically loaded on its left and right sides. The short-circuit stub consists of a metal strip and a metallized via. The metallized via penetrates the dielectric substrate and is electrically connected to the bottom metal layer. The short-circuit stub constitutes a decoupling structure of the antenna. The top-layer metal patch antenna element forms the radiating structure. After the signal is injected through the coaxial feed probe, the metal patch antenna element excites the quasi-TM at dual frequencies. 10 The short-circuit stub causes the feed port of the coupled patch antenna element to form a weak field region at the dual-frequency point, thereby achieving dual-band mutual coupling suppression and radiation pattern decoupling.

2. The dual-frequency decoupling patch antenna with a loaded short-circuited stub as described in claim 1, characterized in that, Each of the metal patch antenna elements has a slot on its upper and lower parts, and the slot is parallel to the upper and lower sides of the metal patch antenna element and symmetrical about the horizontal center line of the patch.

3. The dual-frequency decoupling patch antenna with a loaded short-circuited stub as described in claim 1, characterized in that, The metal strip of the short-circuited stub is arranged parallel to the adjacent side of the metal patch antenna element, and the metallized vias are arranged along the long side of the metal strip.

4. The dual-frequency decoupling patch antenna with a loaded short-circuited stub as described in claim 3, characterized in that, Each short-circuit stub has two pairs of metallized vias symmetrical about the horizontal centerline: two outer metal vias located at both ends of the metal strip, and two inner metal vias located opposite each other on the inner side.

5. The dual-frequency decoupling patch antenna with a loaded short-circuited stub as described in claim 1, characterized in that, The metal patch antenna elements are either 2 or 4, forming a 1×2 or 1×4 linear array respectively. All metal patch antenna elements have the same structure and size, and the short-circuit stub structure and size corresponding to each element are also the same.

6. The dual-frequency decoupling patch antenna with a loaded short-circuited stub as described in claim 1, characterized in that, The dual frequency points are 3.55GHz and 4.83GHz. The dimensions of the rectangular metal patch antenna element are designed based on λ0, where λ0 is the free space wavelength corresponding to the center frequency of 3.55GHz. The length of the rectangular metal patch antenna element is 0.25λ0-0.30λ0, and the width is 0.2λ0-0.25λ0.

7. The dual-frequency decoupling patch antenna with a loaded short-circuited stub as described in claim 6, characterized in that, The length of the slot is 0.25λ0-0.3λ0, the width is 0.0006λ0-0.0055λ0, and the side-to-side spacing between the slot and the parallel sides adjacent to the metal patch antenna element is 0.009λ0-0.0095λ0.

8. The dual-frequency decoupling patch antenna with a loaded short-circuited stub as described in claim 6, characterized in that, The length of the metal strip is 0.20λ0-0.25λ0, the width is 0.010λ0-0.015λ0, and the side-to-side spacing between the parallel sides of the metal strip and the adjacent metal patch antenna element is 0.002λ0-0.0025λ0.

9. The dual-frequency decoupling patch antenna with a loaded short-circuited stub as described in claim 8, characterized in that, The center-to-center distance between the two outer metallized vias is 0.15λ0-0.2λ0, and the center-to-center distance between the two inner metallized vias is 0.05λ0-0.055λ0.

10. The dual-frequency decoupling patch antenna with a loaded short-circuited stub as described in claim 8, characterized in that, The side-to-side spacing of the two short-circuit stubs between two adjacent metal patch antenna elements is between 0.03λ0 and 0.035λ0.

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