A method for realizing one-way radiation of an antenna

Abstract

The present application relates to the technical field of wireless communication system, especially to a method for realizing one-way radiation of antenna, which gives different excitation phases to antenna one and antenna two which are adjacent and arranged at intervals to offset the backward radiation of the antenna. The present application offsets the backward radiation of the antenna through field offset principle, and gives different excitation phases to the antenna to offset the backward radiation of the antenna, thereby enhancing the forward radiation. The method for offsetting the backward radiation of the antenna does not need to increase additional structure, and the cross section is small. The radiation principle is simple to implement and easy to expand, and can be widely applied in communication system.

Description

Technical Field

[0001] This invention relates to the field of wireless communication system technology, specifically to a method for achieving unidirectional antenna radiation. Background Technology

[0002] Antennas are the primary devices in wireless communication systems that transmit or receive electromagnetic waves, and their radiation characteristics are an important feature for communication selection. A unidirectional radiating antenna is an antenna that transmits and receives electromagnetic waves very strongly in a specific direction, while transmitting and receiving electromagnetic waves in other directions is zero or extremely weak. When used for transmission, it can increase the effective utilization rate of radiated power and improve communication efficiency; when used for reception, it can increase anti-interference capability.

[0003] Common unidirectional radiating antennas include Yagi antennas, rhomboid antennas, and parabolic antennas, each with its own fixed design method. For antennas with significant back radiation, the back radiation can be reduced by increasing the antenna's forward gain. The most common method is to add a metal ground plane or metal cavity at a quarter wavelength position to reflect the back-radiated electromagnetic waves forward. Other methods include using metasurfaces and current chokes to reduce back radiation. Summary of the Invention

[0004] To address the problem of back radiation in existing technologies, this invention provides a method for achieving unidirectional radiation in antennas, which can improve the front-to-back ratio of the antenna, allowing two antennas at a certain distance to eliminate back radiation simply by changing the excitation phase, without the need for additional structures.

[0005] This invention is achieved through the following technical solution:

[0006] A method for achieving unidirectional radiation of an antenna involves applying different excitation phases to two adjacent and spaced-apart antennas (Antenna 1 and Antenna 2) to cancel out the antenna's back radiation.

[0007] Preferably, antenna one and antenna two are of the same type.

[0008] Preferably, the distance between antenna one and antenna two is 0 < d < λ / 2, where d is the distance between antenna one and antenna two, and λ is the wavelength of the antenna at its center frequency in free space.

[0009] Preferably, the excitation phase of antenna one is 0°.

[0010] Preferably, the excitation phase of antenna two is -180°-βd, where β is the propagation constant of antenna one and antenna two in their respective spaces, and d is the distance between antenna one and antenna two.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] This invention provides a method for achieving unidirectional antenna radiation. It utilizes the field cancellation principle to counteract the antenna's backward radiation. By applying different excitation phases to the antenna, the backward radiation can be canceled, thereby enhancing the forward radiation. The proposed method for eliminating antenna backward radiation requires no additional structure, has a small cross-section, and its radiation principle is simple to implement, easily expandable, and can be widely applied in communication systems. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the antenna excitation phase of the present invention.

[0014] Figure 2 This is a schematic diagram of the antenna phase of the present invention when the plane where the antenna is located is taken as the reference plane.

[0015] Figure 3 This is a schematic diagram of the antenna phase of the present invention when the plane containing antenna two is taken as the reference plane.

[0016] Figure 4 This is a 3D model diagram of a preferred embodiment of the present invention.

[0017] Figure 5 This is a top view of a preferred embodiment of the present invention.

[0018] Figure 6 This is a left view of a preferred embodiment of the present invention.

[0019] Figure 7 This is a top view of a dielectric substrate according to a preferred embodiment of the present invention.

[0020] Figure 8 This is a top view of a dielectric substrate according to a preferred embodiment of the present invention.

[0021] Figure 9 This is a schematic diagram of return loss curves for several embodiments of the present invention.

[0022] Figure 10 This is a schematic diagram of the overall efficiency curves for several embodiments of the present invention.

[0023] Figure 11 This is a schematic diagram of the before-and-after ratio curves for several embodiments of the present invention.

[0024] Figure 12 This is a schematic diagram of the E-plane direction at 2.45 GHz, representing a preferred embodiment of the present invention.

[0025] Figure 13 This is a schematic diagram of the H-plane direction at 2.45 GHz, representing a preferred embodiment of the present invention.

[0026] In the diagram: 1. Upper dipole left arm; 2. Upper dipole right arm; 3. Lower dipole left arm; 4. Lower dipole right arm; 5. Parallel stripline; 6. Dielectric substrate; 7. Feed port; 8. First rectangular patch; 9. Second rectangular patch; 10. Third rectangular patch; 11. Fourth rectangular patch. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0028] This invention discloses a method for achieving unidirectional radiation of an antenna, wherein different excitation phases are applied to adjacent and spaced antennas of the same type, antenna one and antenna two, to cancel out the back radiation of the antenna.

[0029] Wherein, the distance between antenna one and antenna two is 0 < d < λ / 2, and λ is the wavelength of the antenna at its center frequency in free space.

[0030] like Figure 1 As shown, the two antennas are named Antenna 1 and Antenna 2. For ease of analysis, the excitation amplitudes of the two antennas are assumed to be the same, although they can be different in practice. The excitation phase of Antenna 1 is 0°, and the excitation phase of Antenna 2 is -180°-βd, where β is the propagation constant of Antenna 1 and Antenna 2 in their respective spaces, and d is the distance between Antenna 1 and Antenna 2.

[0031] like Figure 2 As shown, when the plane where antenna one is located is taken as the reference plane, the analysis focuses on the forward radiation region of the antenna. With a fixed antenna excitation amplitude, the antenna's radiation field is determined by its total radiation phase, which is the sum of the antenna's excitation phase and propagation phase. Antenna one has an excitation phase of 0°, a propagation phase of 0°, and a total phase of 0°; antenna two has an excitation phase of -180°-βd, a propagation phase of -βd, and a total phase of -180°-2βd. Representing the total radiation phases of these two antennas in a Cartesian coordinate system, the solid arrows represent the total phases of the antennas, with the phase lead direction clockwise. For antenna one, its total radiation phase is always along the +x-axis; for antenna two, its total radiation phase depends on the antenna distance. The closer the dashed arrows representing the total radiation phases of antennas one and two are, the more pronounced the superposition of the radiation fields. However, as long as the dashed arrow representing the total radiation phase of antenna two deviates from the -x-axis, the two fields can achieve constructive interference.

[0032] like Figure 3As shown, when the plane containing antenna two is taken as the reference plane, the analysis focuses on the rearward radiation region of the antenna. The excitation phase of antenna one is 0°, the transmission phase is -βd, and the total phase is -βd; the excitation phase of antenna two is -180°-βd, the transmission phase is 0°, and the total phase is -180°-βd. Representing the total radiation phase of these two antennas in a Cartesian coordinate system reveals that the two fields are in opposite directions, forming destructive interference. The two fields cancel each other out, thus creating a null point at the rearward radiation location of the antenna, reducing its rearward radiation.

[0033] Taking antennas 1 and 2, both half-wavelength dipole antennas placed along the x-axis, as an example, this paper analyzes the impact of this method on the radiation pattern of an antenna composed of these two antennas. The radiation pattern function of the half-wavelength dipole antenna placed along the x-axis is given by...

[0034]

[0035] In the formula, This is the antenna E-plane radiation pattern function. Let θ be the antenna H-plane radiation pattern function, and θ be the angle between the line connecting a point on the antenna to the origin and the positive z-axis. Let be the angle between the projection line of a point on the antenna onto the xy plane and the positive x-axis.

[0036] Assuming dipole antenna 1 and dipole antenna 2 are placed in the XZ plane with coordinates (d / 2, 0) and (-d / 2, 0) respectively, the radiation fields of dipole 1 and dipole 2 are as follows:

[0037]

[0038]

[0039] In the formula, The radiation field of dipole 1. The radiation field of dipole 2. For along The unit vector of direction. Let θ be the unit vector along the θ direction, j be the imaginary unit, β be the propagation constant of the space where the combined antenna is located, and d be the distance between dipole antenna 1 and dipole antenna 2.

[0040] The total radiation field obtained by combining the two is:

[0041] +

[0042] This represents the total radiation field of the combined antenna.

[0043] The field of the combined antenna in the XZ plane (E plane) is as follows:

[0044]

[0045] This represents the field of the combined antenna in the XZ plane.

[0046] The forward and backward directivity of the combined antenna are as follows:

[0047]

[0048]

[0049] To determine the forward directivity of the combined antenna, This represents the rearward directivity of the combined antenna. It can be seen that the forward directivity of the antenna is not zero, while the rearward directivity is zero. This method achieves the elimination of rearward radiation from the antenna.

[0050] Reference Figure 4 , 5 6. Taking two intersecting dipole antennas as an example, the two antennas are connected by a parallel stripline in the middle. The antenna includes an upper dipole left arm 1, an upper dipole right arm 2, a lower dipole left arm 3, a lower dipole right arm 4, a parallel stripline 5, a dielectric substrate 6, a feed port 7, a first rectangular patch 8, a second rectangular patch 9, a third rectangular patch 10, and a fourth rectangular patch 10. The upper dipole left arm 1 and the upper dipole right arm 2 form the upper dipole, and the lower dipole left arm 3 and the lower dipole right arm 4 form the lower dipole. The upper and lower dipoles are connected by an air-filled parallel stripline 5.

[0051] The specific connection method is as follows: the upper dipole's left arm 1 is connected to the lower dipole's right arm 4, and the upper dipole's right arm 2 is connected to the lower dipole's left arm 3. This connection method ensures that the excitation phase of the upper dipole is 0° and the excitation phase of the lower dipole is -180°. The dipole's length and width are 57mm and 8mm, respectively. The parallel stripline 5 has a line spacing of 2mm, a width of 3mm, and a length equal to the antenna distance d. The thickness of both the dipole and the parallel stripline 5 is 0.5mm. An L-shaped metal block with a length of 5mm and a width of 3.5mm is etched on each arm of the upper dipole's left arm 1 and right arm 2 to achieve the aforementioned connection method.

[0052] Reference Figure 7 , 8A dielectric substrate 6, 0.5 mm thick, 4 mm long, and 2 mm wide, is inserted into the central blank space of the dipole to accommodate the feed port 7 and the matching network. The matching network is an L-shaped topology circuit. The dielectric substrate 6 is made of FR-4 material. A first rectangular patch 8 and a second rectangular patch 9 are located on the front side of the dielectric substrate 6, each 1 mm long and 0.5 mm wide, with a spacing of 0.35 mm between them. The two ends of capacitor C1 are connected to them. A third rectangular patch 10 and a fourth rectangular patch 11 are located on the back side of the dielectric substrate 6, each 1 mm long and 0.825 mm wide, with a spacing of 0.35 mm between them. The two ends of capacitor C2 are connected to them.

[0053] Specifically, taking antenna distances of 5mm, 10mm, and 20mm as examples, the antenna matching circuit will be described in detail. When the antenna distance is 5mm, capacitor C1 is 0.8pF and capacitor C2 is 2.5pF; when the antenna distance is 10mm, capacitor C1 is 0.8pF and capacitor C2 is 1.15pF; when the antenna distance is 20mm, capacitor C1 is 0.8pF and capacitor C2 is 0pF. The different matching networks are mainly used to achieve impedance matching at the antenna ports.

[0054] The performance of three preferred embodiments at different distances was tested using CST software. Figure 9 The diagram shows the return loss curves for several preferred embodiments. When the antenna spacing is 5mm, 10mm, and 20mm, the corresponding operating frequency bands of the antennas are 2.43-2.46GHz, 2.40-2.50GHz, and 2.32-2.56GHz, respectively, and their center frequencies are all around 2.45GHz.

[0055] Figure 10 This diagram illustrates the overall antenna efficiency of several preferred embodiments. When the antenna spacing is 5mm, 10mm, and 20mm, the average overall antenna efficiency is -2dB, -0.4dB, and -0.5dB, respectively.

[0056] Figure 11 The diagram shows the front-to-back ratio curves of several preferred embodiments, all of which have a front-to-back ratio greater than 7dB within the operating frequency band.

[0057] Figure 12 and Figure 13 This diagram shows the E-plane and H-plane radiation patterns of the antenna at 2.45 GHz when the antenna spacing is 10 mm. The radiation patterns for the other two cases are similar and will not be shown here. The forward gain of the antenna is 6.16 dBi, and the backward gain is -4.8 dBi.

[0058] This invention can have various variations, as long as the excitation phase satisfies the aforementioned principle, and the antenna form is not limited.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the technical solution of the present invention in any way. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can be modified and replaced in several simple ways, and these modifications and replacements are all within the scope of protection covered by the claims.

Claims

1. A method for achieving unidirectional radiation of an antenna, characterized in that, Different excitation phases are applied to adjacent and spaced antennas 1 and 2 to cancel out the back radiation of the antennas; Among them, the excitation phase of antenna one is 0°, the transmission phase is -βd, and the total phase is -βd; the excitation phase of antenna two is -180°-βd, the transmission phase is 0°, and the total phase is -180°-βd, where β is the propagation constant of antenna one and antenna two in their respective spaces, and d is the distance between antenna one and antenna two. The two antennas are connected by a parallel strip line in the middle; wherein, the antenna includes an upper dipole left arm (1), an upper dipole right arm (2), a lower dipole left arm (3), a lower dipole right arm (4), a parallel strip line (5), a dielectric substrate (6), a feed port (7), a first rectangular patch (8), a second rectangular patch (9), a third rectangular patch (10), and a fourth rectangular patch (11); wherein, the upper dipole left arm (1) and the upper dipole right arm (2) form an upper dipole as antenna one, and the lower dipole left arm (3) and the lower dipole right arm (4) form a lower dipole as antenna two, and the upper dipole and the lower dipole are connected by a parallel strip line (5) filled with air; The upper dipole left arm (1) and the lower dipole right arm (4) are connected, and the upper dipole right arm (2) and the lower dipole left arm (3) are connected; The dielectric substrate (6) is inserted into the center blank of the dipole to accommodate the feed port (7) and the matching network; wherein the matching network is an L-shaped topology circuit; the first rectangular patch (8) and the second rectangular patch (9) are located on the front side of the dielectric substrate (6), and the two ends of the capacitor C1 are connected to them; the third rectangular patch (10) and the fourth rectangular patch (11) are located on the back side of the dielectric substrate (6), and the two ends of the capacitor C2 are connected to them.

2. The method for achieving unidirectional antenna radiation according to claim 1, characterized in that, Antenna 1 and Antenna 2 are of the same type, and their polarization methods are not limited.

3. The method for achieving unidirectional antenna radiation according to claim 1, characterized in that, The distance between antenna one and antenna two is 0 < d < λ / 2, where d is the distance between antenna one and antenna two, and λ is the wavelength of the antenna at its center frequency in free space.

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