Dual-frequency dual-circularly polarized antenna based on transmission line dispersion

Abstract

The invention provides a dual-frequency dual-circularly polarized antenna based on transmission line dispersion. The dual-frequency dual-circularly polarized antenna comprises an upper substrate, a lower substrate, a feed network for generating feed signals with a phase difference of + / -90 degrees, a feed column and a group of antennas, the group of antennas are respectively arranged on the upper radiating surface and the lower radiating surface of the upper-layer substrate; the feed network is arranged on the lower surface of the lower-layer substrate, and a grounding layer is arranged on the upper surface of the lower-layer substrate; one end of the feed column is connected with the feed network, and the other end of the feed column is connected with the antenna of the upper radiating surface to feed the antenna; the feed network comprises a transmission line TL1 and a transmission line TL2 which can generate a phase difference of + / -90 degrees in different frequency bands, and the transmission line TL1 and the transmission line TL2 are arranged in a spiral shape and are different in length. The antenna is simple in structure and flexible in structural design, and can meet various frequency ratio requirements, so that the practicability of the antenna is improved. In addition, according to the structure, the overall size of the antenna is greatly reduced, and it is guaranteed that the antenna achieves good electrical characteristics in the working frequency band.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic communications, and more particularly to a dual-frequency dual-circular polarization antenna based on transmission line dispersion. Background Art

[0002] In modern wireless communication systems, dual-band, dual-circularly polarized antennas have become core components for scenarios such as satellite navigation and mobile satellite services. They achieve full-duplex operation and increase channel capacity through frequency band isolation and polarization orthogonality. Depending on system architecture, dual-band, dual-circularly polarized antenna designs are primarily categorized as dual-port independently fed and single-port multiplexed, with significant differences in their implementation paths and technical characteristics.

[0003] Typically, there are two approaches to achieving dual circular polarization excitation. One approach involves exciting the radiator's inherent operating modes in two different frequency bands, eliminating the need for a complex feed network. This design offers the advantage of compactness, but is limited by the coupling effects of the resonant modes, resulting in a narrow bandwidth and limited flexibility in frequency ratio adjustment.

[0004] Another approach utilizes a single feed network to excite different radiator modes in two different frequency bands. This approach is particularly suitable for scenarios with large frequency ratios, but the significantly increased complexity of the feed network requires extremely high fabrication precision. Furthermore, antennas employing feed networks have a narrow bandwidth, limiting design flexibility to accommodate varying frequency ratios and failing to meet the frequency flexibility requirements of modern communications equipment. Furthermore, existing dual-band, dual-circularly polarized antennas employing feed networks are complex, require a large footprint, and are complex to manufacture. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings and deficiencies of the prior art by providing a dual-band, dual-circularly polarized antenna based on transmission line dispersion. This dual-band, dual-circularly polarized antenna features a simple structure and flexible design, meeting various frequency ratio requirements and thus improving its practicality. Furthermore, its miniaturized structure significantly reduces the antenna's overall size while ensuring excellent electrical characteristics across its operating frequency band.

[0006] To achieve the above-mentioned object, the present invention is implemented by the following technical solution: a dual-frequency dual-circularly polarized antenna based on transmission line dispersion, characterized by comprising an upper substrate, a lower substrate, a feeding network for generating a feeding signal with a ±90° phase difference, a feeding post for transmitting left-handed and right-handed circularly polarized signals, and a group of antennas for receiving the left-handed and right-handed circularly polarized signals transmitted from the feeding network;

[0007] The group of antennas are respectively arranged on the upper radiating surface and the lower radiating surface of the upper substrate; the feeding network is arranged on the lower surface of the lower substrate, and the upper surface of the lower substrate is provided with a ground layer; one end of the feeding post is connected to the feeding network, and the other end is connected to the antenna on the upper radiating surface to feed the antenna; the feeding network includes two transmission lines TL1 and TL2 that can generate a phase difference of ±90° in different frequency bands. The two transmission lines TL1 and TL2 are arranged in a spiral shape and have different lengths.

[0008] In a group of antennas, each antenna comprises a circular patch and two groups of slots; the two groups of slots are symmetrically opened on the circular patch.

[0009] The feeding network also includes an input port, a power splitter and two output ports; the input port is arranged at the center of the lower surface of the lower substrate, and the power splitter is connected to the input port; one end of the two transmission lines TL1 and TL2 is respectively connected to the power splitter, and the other end is respectively connected to the two output ports.

[0010] An isolation resistor is provided at the connection between the power divider and the two transmission lines TL1 and TL2 to ensure signal isolation.

[0011] The power splitter is a one-to-two Wilkinson power splitter.

[0012] The length difference between the two transmission lines TL1 and TL2 is calculated and designed based on the conditions that the two resonant frequencies f1 and f2 produce a phase difference of ±90°, so as to realize left-hand circular polarization feeding and right-hand circular polarization feeding.

[0013] Realizing left-hand circular polarization feeding and right-hand circular polarization feeding means that the phase difference of right-hand circular polarization feeding is -90° or 2nπ of -90°, and the phase difference of left-hand circular polarization feeding is 90° or 2mπ of 90°; wherein n and m are both natural numbers.

[0014] The following computational design steps were used:

[0015] The first step is to determine the two required resonant frequencies f1 and f2 and their corresponding circular polarization modes;

[0016] The second step is to select the materials of the lower and upper substrates according to the selected frequency band, determine the thickness h of the lower substrate and the width w of the transmission lines TL1 and TL2, and then set the phase constant β;

[0017] In the third step, the integers n, m and the length difference Δd between the transmission lines TL1 and TL2 are calculated using the following formula based on the circularly polarized modes of the resonant frequencies f1 and f2:

[0018]

[0019] Among them, εe is the effective dielectric constant of the substrate material, c is the speed of light in free space;

[0020] In the fourth step, when the iteration cannot be performed, return to the second step, use new materials for the lower and upper substrates, and repeat the process until the formula is satisfied.

[0021] In the third step, the lengths of the two transmission lines TL1 and TL2 are designed according to the length difference Δd between the transmission lines TL1 and TL2 , and the spiral shapes and arrangements of the two transmission lines TL1 and TL2 on the lower surface of the lower substrate are designed.

[0022] The length of the power divider is designed by the resonant frequency f1; the power divider has an axisymmetric structure, and the transmission line length of the power divider is equal to 1 / 4 wavelength of the resonant frequency f1.

[0023] The advantages of the dual-frequency dual circularly polarized antenna based on transmission line dispersion of the present invention are as follows: the dual-frequency dual circularly polarized antenna is designed with a dual-frequency dual circularly polarized feeding network. This feeding network has two feed lines of different lengths (transmission lines TL1 and TL2). It is based on the dispersion characteristics of the feeding network and can generate a phase difference of ±90° in two different frequency bands. The feeding network is cascaded with the antenna, and each antenna includes two pairs of slots. The feeding network is arranged in a spiral shape to achieve miniaturization and improve impedance matching. At the same time, the dual-frequency dual circularly polarized antenna of the present invention can meet various frequency ratio requirements. The length difference between the two transmission lines TL1 and TL2 is calculated according to various frequency ratios, so that the structure of the feeding network can be flexibly designed, making the antenna design more flexible.

[0024] This dual-band, dual-circularly polarized antenna achieves right-hand circular polarization at the low-band frequency of 2.2 GHz and left-hand circular polarization at the high-band frequency of 2.88 GHz. The antenna's overall dimensions are 0.36λ0 × 0.36λ0 × 0.03λ0, where λ0 = 136 mm, representing the wavelength of a 2.2 GHz radio wave in free space. The antenna boasts a simple design, easy assembly, and low cost. Different operating frequencies can be designed to accommodate both left-hand and right-hand polarization, depending on the operating frequency band. These advantages fully meet the application requirements of dual-band, dual-circular polarization in satellite communications.

[0025] 1) Miniaturization: The present invention greatly reduces the size of the antenna by arranging the feed network in a spiral shape. This not only significantly reduces the overall volume of the antenna, but also ensures that the antenna achieves good electrical characteristics in the operating frequency band;

[0026] 2) The corresponding structure can be designed according to the frequency ratio to achieve left and right circular polarization: The dual-frequency dual circular polarization antenna of the present invention can meet various frequency ratio requirements. The length difference between the two transmission lines TL1 and TL2 is calculated according to various frequency ratios, so as to flexibly design the structure of the feeding network, realize the flexible design of the feeding structure with adjustable left and right circular polarization, and improve the practicality of the antenna.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] 1. The dual-frequency dual circularly polarized antenna based on transmission line dispersion of the present invention has a simple structure and flexible structural design, which can meet various frequency ratio requirements, thereby improving the practicality of the antenna.

[0029] 2. The miniaturized structure of the dual-frequency dual circularly polarized antenna of the present invention not only greatly reduces the overall volume of the antenna, but also ensures that the antenna achieves good electrical characteristics in the operating frequency band. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the structure of the dual-frequency dual circularly polarized antenna based on transmission line dispersion of the present invention;

[0031] Figure 2 Schematic diagram of the lower substrate of the dual-frequency dual circularly polarized antenna based on transmission line dispersion of the present invention;

[0032] Figure 3 1. It is a top view of the dual-frequency dual circularly polarized antenna based on transmission line dispersion of the present invention;

[0033] Figures 4(a)-4(b) and Figures 5(a)-5(b) Respectively represent the simulated normalized radiation patterns of the miniaturized dual-frequency dual circularly polarized antenna proposed in the present invention at 2.2 GHz (right-hand circular polarization) and 2.88 GHz (left-hand circular polarization);

[0034] Among them, 1 is the upper substrate, 2 is the lower substrate, 3 is the circular patch 1, 4 is the circular patch 2, 5 is the feeding network, 6 is the feeding column, 7 is the input port, 8 is the output port, 9 is the Wilkinson power divider, 10 is the slot 1, 11 is the slot 2, and 12 is the isolation resistor. DETAILED DESCRIPTION

[0035] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0036] Example

[0037] like Figures 1 to 5(b)As shown, the dual-frequency dual circularly polarized antenna based on transmission line dispersion of the present invention includes an upper substrate 1, a lower substrate 2, a feeding network 5 for generating a feeding signal with a phase difference of ±90°, a feeding post 6 for transmitting left-handed circularly polarized signals, and a group of antennas for receiving left-handed circularly polarized signals transmitted from the feeding network, wherein a group of antennas are respectively arranged on the upper radiating surface and the lower radiating surface of the upper substrate 1, and the feeding network is arranged on the lower surface of the lower substrate 2, and a ground layer is provided on the upper surface of the lower substrate 2. One end of the feeding post 6 of the present invention is connected to the feeding network 5, and the other end is connected to the antenna on the upper radiating surface to realize feeding of the antenna. The feeding network 5 includes two transmission lines TL1 and TL2 that can generate a phase difference of ±90° in different frequency bands. The two transmission lines TL1 and TL2 are arranged in a spiral shape and have different lengths.

[0038] Specifically, one antenna group includes antenna 1 and antenna 2. Antenna 1 includes circular patch 1 3 and two sets of slots 10, which are symmetrically arranged on circular patch 1 3. Antenna 2 includes circular patch 2 4 and two sets of slots 2 11, which are symmetrically arranged on circular patch 2 4. One end of feed post 6 is connected to feed network 5, and the other end is connected to circular patch 1 3.

[0039] The feed network 5 of the present invention also includes an input port 7, a one-to-two Wilkinson power splitter 9, and two output ports 8. The input port 7 is located at the center of the lower surface of the lower substrate 2, and the Wilkinson power splitter 9 is connected to the input port 7. One end of two transmission lines TL1 and TL2 are connected to the Wilkinson power splitter 9, and the other end is connected to the two output ports 8. Isolation resistors 12 are provided at the connection between the Wilkinson power splitter 9 and the two transmission lines TL1 and TL2 to ensure signal isolation.

[0040] In addition, the length difference between the two transmission lines TL1 and TL2 is calculated and designed to achieve left-hand circularly polarized feeding and right-hand circularly polarized feeding by using the conditions that the two resonant frequencies f1 and f2 respectively produce a phase difference of ±90°, which means that the phase difference of right-hand circularly polarized feeding is -90° or 2nπ of -90°, while the phase difference of left-hand circularly polarized feeding is 90° or 2mπ of 90°; where n and m are both natural numbers.

[0041] The following calculation and design steps are used:

[0042] The first step is to determine the two required resonant frequencies f1 and f2 and their corresponding circular polarization modes;

[0043] The second step is to select the materials of the lower and upper substrates according to the selected frequency band, determine the thickness h of the lower substrate and the width w of the transmission lines TL1 and TL2, and then set the phase constant β;

[0044] In the third step, the integers n, m and the length difference Δd between the transmission lines TL1 and TL2 are calculated using the following formula based on the circularly polarized modes of the resonant frequencies f1 and f2:

[0045]

[0046] Among them, ε e is the effective dielectric constant of the substrate material, c is the speed of light in free space;

[0047] In the fourth step, when the iteration cannot be performed, return to the second step, use new materials for the lower and upper substrates, and repeat the process until the formula is satisfied.

[0048] In the third step, the lengths of the two transmission lines TL1 and TL2 are designed according to the length difference Δd between the transmission lines TL1 and TL2 , and the spiral shapes and arrangements of the two transmission lines TL1 and TL2 on the lower surface of the lower substrate 2 are designed.

[0049] The length of the Wilkinson power divider 9 is designed according to the resonant frequency f1; the Wilkinson power divider 9 is an axisymmetric structure, and the transmission line length of the Wilkinson power divider 9 is equal to 1 / 4 wavelength of the resonant frequency f1.

[0050] For example, in this embodiment, the antenna is designed with two resonant frequencies f1 and f2 of 2.2 GHz and 2.88 GHz, respectively, and the corresponding circular polarization modes are LHCP and RHCP, respectively. Through the above design steps, the length difference Δd between the transmission lines TL1 and TL2 is calculated to be 138.8 mm, resulting in a -90° phase difference at 2.2 GHz, which can produce right-hand circular polarization; and a +90° phase difference at 2.88 GHz, which can produce left-hand circular polarization. At the same time, the lengths of the two transmission lines TL1 and TL2 are designed based on the length difference Δd between the transmission lines TL1 and TL2 as shown in the following table, and the spiral shape and arrangement of the two transmission lines TL1 and TL2 on the lower surface of the lower substrate 2 are designed, as shown in the following table. Figure 2 The transmission line length TL3 of the Wilkinson power divider 9 is equal to 1 / 4 wavelength of the resonant frequency f1.

[0051]

[0052] Dual-band dual circular polarization antenna size parameters

[0053] The dual-frequency dual circularly polarized antenna of the present invention simulates the normalized radiation pattern at 2.2 GHz (right-hand circular polarization) and 2.88 GHz (left-hand circular polarization) as follows: Figures 4(a)-4(b) and Figures 5(a)-5(b) shown.

[0054] After the feed network 5 is designed in this embodiment, the dimensions of other components are designed as shown in the following table:

[0055]

[0056] Dual-band dual circular polarization antenna size parameters

[0057] Wherein, x1 is the slot length of antenna 1 3 in the x-axis direction, y1 is the slot length of antenna 1 3 in the y-axis direction, x2 is the slot length of antenna 2 4 in the x-axis direction, y2 is the slot length of antenna 2 4 in the y-axis direction, w1 is the slot width of antenna 1 3 and antenna 2 4 in the x-axis direction, w2 is the slot width of antenna 1 3 and antenna 2 4 in the y-axis direction, R1 is the radius of antenna 2 4, R2 is the radius of antenna 1 3 and upper substrate 1, R3 is the radius of lower substrate 2, and (a, a) is the coordinate point of feeding column 6.

[0058] The advantages of the dual-frequency dual circularly polarized antenna based on transmission line dispersion of the present invention are as follows: the dual-frequency dual circularly polarized antenna is designed with a dual-frequency dual circularly polarized feeding network. This feeding network 5 has two feed lines of different lengths (transmission lines TL1 and TL2), which is based on the dispersion characteristics of the feeding network and can generate a phase difference of ±90° in two different frequency bands. The feeding network 5 is cascaded with antenna 1 3 and antenna 2 4, and antenna 1 3 and antenna 2 4 each include two pairs of slots. By arranging the feeding network 5 in a spiral shape, miniaturization is achieved and impedance matching is improved. At the same time, the dual-frequency dual circularly polarized antenna of the present invention can meet various frequency ratio requirements, and the length difference between the two transmission lines TL1 and TL2 is calculated according to various frequency ratios, so that the structure of the feeding network 5 can be flexibly designed, making the design of the antenna more flexible.

[0059] This dual-band, dual-circularly polarized antenna achieves right-hand circular polarization at the low-band frequency of 2.2 GHz and left-hand circular polarization at the high-band frequency of 2.88 GHz. The antenna's overall dimensions are 0.36λ0 × 0.36λ0 × 0.03λ0, where λ0 = 136 mm, representing the wavelength of a 2.2 GHz radio wave in free space. The antenna boasts a simple design, easy assembly, and low cost. Different operating frequencies can be designed to accommodate both left-hand and right-hand polarization, depending on the operating frequency band. These advantages fully meet the application requirements of dual-band, dual-circular polarization in satellite communications.

[0060] 1) Miniaturization: The present invention greatly reduces the size of the antenna by arranging the feed network 5 in a spiral shape. This not only significantly reduces the overall volume of the antenna, but also ensures that the antenna achieves good electrical characteristics in the operating frequency band;

[0061] 2) The corresponding structure can be designed according to the frequency ratio to achieve left and right circular polarization: The dual-frequency dual circular polarization antenna of the present invention can meet various frequency ratio requirements. The length difference between the two transmission lines TL1 and TL2 is calculated according to various frequency ratios, so as to flexibly design the structure of the feeding network 5, realize the flexible design of the feeding structure with adjustable left and right circular polarization, and improve the practicality of the antenna.

[0062] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above 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 dual-band dual-circularly polarized antenna based on transmission line dispersion, characterized by: It includes an upper substrate, a lower substrate, a feeding network for generating a feeding signal with a phase difference of ±90°, a feeding post for transmitting left-handed circularly polarized signals, and a group of antennas for receiving left-handed circularly polarized signals transmitted from the feeding network; The group of antennas are respectively arranged on the upper radiating surface and the lower radiating surface of the upper substrate; the feeding network is arranged on the lower surface of the lower substrate, and the upper surface of the lower substrate is provided with a ground layer; one end of the feeding post is connected to the feeding network, and the other end is connected to the antenna on the upper radiating surface to feed the antenna; the feeding network includes two transmission lines TL1 and TL2 that can generate a phase difference of ±90° in different frequency bands. The two transmission lines TL1 and TL2 are arranged in a spiral shape and have different lengths.

2. The dual-frequency dual circularly polarized antenna based on transmission line dispersion according to claim 1, characterized in that: In a group of antennas, each antenna comprises a circular patch and two groups of slots; the two groups of slots are symmetrically opened on the circular patch.

3. The dual-frequency dual circularly polarized antenna based on transmission line dispersion according to claim 1, characterized in that: The feeding network also includes an input port, a power splitter and two output ports; the input port is arranged at the center of the lower surface of the lower substrate, and the power splitter is connected to the input port; one end of the two transmission lines TL1 and TL2 is respectively connected to the power splitter, and the other end is respectively connected to the two output ports.

4. The dual-frequency dual circularly polarized antenna based on transmission line dispersion according to claim 3, characterized in that: An isolation resistor is provided at the connection between the power divider and the two transmission lines TL1 and TL2 to ensure signal isolation.

5. The dual-frequency dual circularly polarized antenna based on transmission line dispersion according to claim 3, characterized in that: The power splitter is a one-to-two Wilkinson power splitter.

6. The dual-frequency dual circularly polarized antenna based on transmission line dispersion according to claim 3, characterized in that: The length difference between the two transmission lines TL1 and TL2 is calculated and designed based on the conditions that the two resonant frequencies f1 and f2 produce a phase difference of ±90°, so as to realize left-hand circular polarization feeding and right-hand circular polarization feeding.

7. The dual-frequency dual circularly polarized antenna based on transmission line dispersion according to claim 6, characterized in that: Realizing left-hand circular polarization feeding and right-hand circular polarization feeding means that the phase difference of right-hand circular polarization feeding is -90° or 2nπ of -90°, and the phase difference of left-hand circular polarization feeding is 90° or 2mπ of 90°; wherein n and m are both natural numbers.

8. The dual-frequency dual circularly polarized antenna based on transmission line dispersion according to claim 7, characterized in that: The following computational design steps were used: The first step is to determine the two required resonant frequencies f1 and f2 and their corresponding circular polarization modes; The second step is to select the materials of the lower and upper substrates according to the selected frequency band, determine the thickness h of the lower substrate and the width w of the transmission lines TL1 and TL2, and then set the phase constant β; In the third step, the integers n, m and the length difference Δd between the transmission lines TL1 and TL2 are calculated using the following formula based on the circularly polarized modes of the resonant frequencies f1 and f2: Among them, ε e is the effective dielectric constant of the substrate material, c is the speed of light in free space; In the fourth step, when the iteration cannot be performed, return to the second step, use new materials for the lower and upper substrates, and repeat the process until the formula is satisfied.

9. The dual-frequency dual circularly polarized antenna based on transmission line dispersion according to claim 8, characterized in that: In the third step, the lengths of the two transmission lines TL1 and TL2 are designed according to the length difference Δd between the transmission lines TL1 and TL2 , and the spiral shapes and arrangements of the two transmission lines TL1 and TL2 on the lower surface of the lower substrate are designed.

10. The dual-frequency dual circularly polarized antenna based on transmission line dispersion according to claim 8, characterized in that: The length of the power divider is designed by the resonant frequency f1; the power divider has an axisymmetric structure, and the transmission line length of the power divider is equal to 1 / 4 wavelength of the resonant frequency f1.

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