A filter dipole antenna based on multi-path coupling

Abstract

This invention discloses a filtered dipole antenna based on multipath coupling, comprising a dielectric substrate and an input port. The upper and lower surfaces of the dielectric substrate are provided with first and second copper cladding layers. Two symmetrical radiating elements are arranged on the first copper cladding layer. The input port is located at the center of symmetry between the two radiating elements. Each radiating element consists of a long strip half-wavelength dipole radiator, a horizontally folded full-wavelength dipole radiator, and the upper half of a vertically folded full-wavelength dipole radiator. The lower half of the vertically folded full-wavelength dipole radiator is arranged on the second copper cladding layer. The upper half of the vertically folded full-wavelength dipole radiator is connected to the lower half of the vertically folded full-wavelength dipole radiator via a metal pillar. The antenna of this invention has a simple and reliable structure, small size, and high integration. It exhibits highly selective gain filtering, with an operating bandwidth of 1.85 GHz–2.7 GHz and a relative bandwidth of 37.36%. The gain is flat and stable within the passband, and it has distinct radiation nulls at the out-of-band edges of 1.73 GHz and 2.8 GHz.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a filtered dipole antenna based on multipath coupling. Background Technology

[0002] Dipole antennas are widely used in wireless communication systems due to their stable radiation, simple structure, and ease of fabrication. However, traditional dipole antennas suffer from narrow bandwidth, low selectivity, and poor out-of-band suppression, making it difficult to cover multiple frequency bands in communication systems. In previous designs, researchers and engineers focused on extending the antenna bandwidth by utilizing multi-mode compression and multi-radiator coupling to mitigate the narrow bandwidth limitation. However, while the bandwidth was extended, the low out-of-band selectivity and poor suppression made them susceptible to interference from out-of-band signals. To achieve high selectivity and out-of-band suppression, researchers and engineers proposed filtered dipole antennas. In these designs, a filter is loaded at the front end of the dipole antenna. While this achieves gain filtering, direct loading of the filter introduces significant insertion loss. Introducing multipath coupling within the multi-radiator system can achieve both broadband bandwidth and avoid the additional insertion loss of the loaded filter, resulting in excellent filtering characteristics. Therefore, we will improve the design of the filtered dipole antenna based on multipath coupling within the multi-radiator system.

[0003] An investigation and understanding of existing technologies was conducted, specifically as follows:

[0004] In 2016, G.-H. Sun et al. proposed a filtered dipole antenna designed using a cascaded low-pass filter and a dipole antenna. By cascading a multi-order low-pass filter at the front end of the dipole antenna, the filtering effect of the dipole antenna was achieved. At the same time, parasitic elements were loaded above the dipole, and the relative bandwidth reached 27.5%. However, its radiation efficiency was low and its size was large.

[0005] In 2022, C. Chen proposed a filtered dipole antenna with multiple parasitic metal strips. By loading one parasitic metal strip and one parasitic folded metal strip above the U-shaped radiating arm, respectively, filtering effect and high selectivity are achieved through the electrical and magnetic coupling between the two parasitic elements and the radiating arm. However, due to the large number of parasitic elements, the coupling gap between the elements is difficult to adjust independently.

[0006] In summary, existing work includes considerable research on dipole antennas with filtering effects. However, filter-based collaborative design often leads to efficiency degradation, and structures based on loaded parasitic elements are difficult to control flexibly. Therefore, this paper proposes to improve the design of dipole antennas based on multi-path coupling of multiple radiators, achieving broadband performance and high selectivity. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings and disadvantages of the prior art and propose a multipath-coupled filtered dipole antenna. This antenna can operate stably in the range of 1.85 GHz to 2.7 GHz, with a reflection coefficient of less than -10 dB in the frequency range of 1.85 GHz to 2.7 GHz. It has flat gain and stable radiation in the passband, with an average gain of about 2 dBi in the passband. It also has obvious radiation nulls at 1.73 GHz and 2.8 GHz, and has high selectivity.

[0008] To achieve the above objectives, the technical solution provided by this invention is as follows: a filtered dipole antenna based on multipath coupling, comprising a dielectric substrate and an input port. The upper surface of the dielectric substrate is provided with a first copper-clad layer, and its lower surface is provided with a second copper-clad layer. Two symmetrically arranged radiating elements are provided on the first copper-clad layer. The input port is located at the center of symmetry of the two radiating elements. Each radiating element consists of a long strip half-wavelength dipole radiator, a horizontally folded full-wavelength dipole radiator, and the upper half of a vertically folded full-wavelength dipole radiator. The horizontally folded full-wavelength dipole radiator surrounds the outer side of the long strip half-wavelength dipole radiator. A vacancy is formed in the wavelength dipole radiator, and the upper half of the vertically folded full-wavelength dipole radiator is located in the vacancy. The upper half of the long strip half-wavelength dipole radiator, the horizontally folded full-wavelength dipole radiator, and the vertically folded full-wavelength dipole radiator are all excited by the input port, and they couple energy with each other through gaps to realize multiple coupling paths from the port to the radiation space. The lower half of the vertically folded full-wavelength dipole radiator is provided on the second copper cladding layer. The upper half of the vertically folded full-wavelength dipole radiator of each radiation unit is connected to the lower half of the vertically folded full-wavelength dipole radiator through a metal pillar penetrating the dielectric substrate.

[0009] Furthermore, the two radiating units are connected as a whole by horizontally folded full-wavelength dipole radiators.

[0010] Furthermore, there are two metal pillars located at both ends of the lower half of the vertically folded full-wavelength dipole radiator.

[0011] Furthermore, the dielectric substrate has a thickness of 0.8 mm, a length of 55 mm, a width of 14 mm, a dielectric constant of 4.38, and a loss tangent of 0.005.

[0012] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0013] 1. The antenna of the present invention has a highly selective gain filtering effect.

[0014] 2. The antenna of this invention has an operating bandwidth of 1.85GHz-2.7GHz, and its relative bandwidth reaches 37.36%.

[0015] 3. The antenna of the present invention has a flat and stable gain within the passband, and has obvious radiation nulls at the out-of-band edges of 1.73 GHz and 2.8 GHz.

[0016] 4. The antenna of this invention has a simple and reliable structure, small size, high integration, and good application prospects. Attached Figure Description

[0017] Figure 1 This is a perspective view of the antenna in this embodiment.

[0018] Figure 2 This is a cross-sectional view of the antenna in this embodiment.

[0019] Figure 3 This is a structural diagram of the upper surface of the dielectric substrate of the antenna in this embodiment.

[0020] Figure 4 This is a structural diagram of the lower surface of the dielectric substrate of the antenna in this embodiment.

[0021] Figure 5 The diagram shows the simulation results of the S-parameters of the antenna in this embodiment.

[0022] Figure 6 This is a simulation result of the antenna gain curve in this embodiment.

[0023] Figure 7 This is a simulated radiation pattern of the antenna in this embodiment at a frequency of 2.25 GHz. Detailed Implementation

[0024] The present invention will be further described below with reference to specific embodiments.

[0025] See Figures 1 to 4As shown, this embodiment discloses a filtered dipole antenna based on multipath coupling, including a dielectric substrate 1 and an input port 9. The upper surface of the dielectric substrate 1 is provided with a first copper-clad layer 2, and its lower surface is provided with a second copper-clad layer 3. Two symmetrical radiating elements are provided on the first copper-clad layer 2. The input port 9 is located at the center of symmetry of the two radiating elements. Each radiating element consists of a strip-shaped half-wavelength dipole radiator 4, a horizontally folded full-wavelength dipole radiator 5, and an upper half 6 of a vertically folded full-wavelength dipole radiator. The horizontally folded full-wavelength dipole radiator 5 surrounds the outside of the strip-shaped half-wavelength dipole radiator 4, and the strip-shaped half-wavelength dipole radiator 4 forms vacancies. The upper half 6 of the vertically folded full-wavelength dipole radiator is located at... At this vacancy, the long strip half-wavelength dipole radiator 4, the horizontally folded full-wavelength dipole radiator 5, and the upper half 6 of the vertically folded full-wavelength dipole radiator are all excited by the input port 9, and they couple energy with each other through gaps to achieve multiple coupling paths from the port to the radiation space; the horizontally folded full-wavelength dipole radiators 5 of the two radiation units are connected as a whole; the second copper clad layer 3 is provided with the lower half 7 of the vertically folded full-wavelength dipole radiator, and the upper half 6 of the vertically folded full-wavelength dipole radiator of each radiation unit is connected to the lower half 7 of the vertically folded full-wavelength dipole radiator through a metal pillar 8 penetrating the dielectric substrate 1. The two metal pillars 8 are located at both ends of the lower half 7 of the vertically folded full-wavelength dipole radiator.

[0026] Specifically, dielectric substrate 1 has a dielectric constant of 0.8 mm, a length of 55 mm, a width of 14 mm, a dielectric constant of 4.38, and a loss tangent of 0.005.

[0027] See Figure 5 The figure shows the simulation results of the S-parameters of the antenna described in this embodiment. The simulation results show that the frequency range with a reflection coefficient less than -10dB is 1.85GHz-2.7GHz, and the relative bandwidth exceeds 37%.

[0028] See Figure 6 The figure shows the simulation results of the antenna in this embodiment. The simulation results show that the gain is flat and stable in the frequency range of 1.85 GHz to 2.7 GHz, with an average gain of approximately 1.8 dBi. It also exhibits two radiation nulls at 1.73 GHz and 2.8 GHz, significantly improving selectivity.

[0029] See Figure 7The image shows the simulated radiation pattern of the antenna described in this embodiment at a center frequency of 2.25 GHz. The simulation results show that the antenna of this invention can radiate omnidirectionally at the center frequency, with a cross-polarization level of -25 dB in the E-plane and -50 dB in the H-plane, exhibiting a low cross-polarization level.

[0030] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Therefore, any changes made in accordance with the shape and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A filtered dipole antenna based on multipath coupling, comprising a dielectric substrate (1) and an input port (9), wherein the upper surface of the dielectric substrate (1) is provided with a first copper layer (2) and the lower surface is provided with a second copper layer (3), characterized in that: Two symmetrical radiating units are provided on the first copper cladding layer (2). The input port (9) is located at the center of symmetry of the two radiating units. The radiating unit consists of a strip half-wavelength dipole radiator (4), a horizontally folded full-wavelength dipole radiator (5), and the upper half (6) of a vertically folded full-wavelength dipole radiator. The horizontally folded full-wavelength dipole radiator (5) surrounds the outside of the strip half-wavelength dipole radiator (4). The strip half-wavelength dipole radiator (4) forms a vacancy, and the upper half (6) of the vertically folded full-wavelength dipole radiator is located at the vacancy. The long strip half-wavelength dipole radiator (4), the horizontally folded full-wavelength dipole radiator (5), and the upper half (6) of the vertically folded full-wavelength dipole radiator are all excited by the input port (9), and they couple energy with each other through gaps to realize multiple coupling paths from the port to the radiation space; the second copper cladding layer (3) is provided with the lower half (7) of the vertically folded full-wavelength dipole radiator, and the upper half (6) of the vertically folded full-wavelength dipole radiator of each radiation unit is connected to the lower half (7) of the vertically folded full-wavelength dipole radiator through the metal pillar (8) penetrating the dielectric plate (1).

2. The filtered dipole antenna based on multipath coupling according to claim 1, characterized in that: The two horizontally folded full-wavelength dipole radiators (5) of the two radiating units are connected as a whole.

3. The filtered dipole antenna based on multipath coupling according to claim 1, characterized in that: There are two metal pillars (8), located at both ends of the lower half (7) of the vertically folded full-wavelength dipole radiator.

4. A filtered dipole antenna based on multipath coupling according to claim 1, characterized in that: The dielectric substrate (1) has a thickness of 0.8 mm, a length of 55 mm, a width of 14 mm, a dielectric constant of 4.38, and a loss tangent of 0.005.

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