A dual-band circularly polarized antenna for maritime communication

Abstract

This invention discloses a dual-band circularly polarized antenna for maritime communication, comprising: a first dielectric substrate, a radiating patch array, a second dielectric substrate, a slotted ground plane, and a transmission line; the radiating patch array is located on the upper surface of the first dielectric substrate, the slotted ground plane is located between the first and second dielectric substrates, and the transmission line is located on the lower surface of the second dielectric substrate; the radiating patch array consists of several truncated square patches disposed in the central region and parasitic patches disposed around the perimeter; a cross-shaped vertical slot is provided at the center of each truncated square patch; a star-shaped slot is formed on the slotted ground plane; the transmission line is an L-shaped planar transmission line composed of microstrip lines; the slotted ground plane and the transmission line constitute a feeding structure, which excites the circular polarization effect of the radiating patch array. This antenna has advantages such as structural stability, low profile, dual-band circular polarization, and wide bandwidth, and can be applied to fields such as maritime wireless communication and wireless positioning.

Description

Technical Field

[0001] This invention relates to the field of antenna design, and in particular to a dual-frequency circularly polarized antenna for use in maritime communications. Background Technology

[0002] In recent years, the rapid development of applications in marine exploration, marine environmental monitoring, marine disaster early warning, marine safety, marine fisheries, and marine transportation has led to a surge in demand for maritime wireless communication services. The rapid development of fifth-generation networks has brought numerous opportunities, driving new applications in areas such as the Internet of Things (IoT), and making it possible to interconnect everyday indoor devices during maritime voyages using various wireless technologies.

[0003] As terminal equipment in communication systems, antennas require designs that emphasize miniaturization, multi-bandwidth operation, ease of integration, and resistance to interference from extreme weather conditions at sea or other communication equipment. Microstrip antennas are commonly used in antenna design due to their advantages such as small size, light weight, and ease of integration with other objects. However, microstrip antennas also suffer from problems such as narrow bandwidth and low gain. Summary of the Invention

[0004] Purpose of the invention: To address the problems of microstrip antennas used in maritime communications having a single operating frequency band and large size, which cannot meet the needs of maritime wireless communication services, this invention discloses a dual-band circularly polarized antenna for maritime communications. It has advantages such as a very low profile, stable structure, and excellent radiation performance, and can achieve dual-band circular polarization.

[0005] Technical solution: A dual-band circularly polarized antenna for maritime communication, comprising: a first dielectric substrate, a radiating patch array, a second dielectric substrate, a slotted ground plane, and a transmission line; the radiating patch array is located on the upper surface of the first dielectric substrate, the slotted ground plane is located between the first dielectric substrate and the second dielectric substrate, and the transmission line is located on the lower surface of the second dielectric substrate.

[0006] The radiating patch array consists of several truncated square patches in the central region and parasitic patches around the perimeter; a cross-shaped vertical slit is provided at the center of each truncated square patch; a star-shaped slot is provided on the slotted ground plane; the transmission line is an L-shaped planar transmission line composed of microstrip lines; the slotted ground plane and the transmission line constitute a feeding structure, which excites the circular polarization effect of the radiating patch array.

[0007] Furthermore, the parasitic patches disposed around the perimeter include first parasitic patches disposed above and below the truncated square patch, and second parasitic patches disposed to the left and right of the truncated square patch. The lengths of the first and second parasitic patches are different, but both are less than the length of the truncated square patch.

[0008] Furthermore, both the first dielectric substrate and the second dielectric substrate are rectangular dielectric substrates.

[0009] Furthermore, the parasitic patch is a rectangular parasitic patch.

[0010] Furthermore, the thickness of the radiating patch array, the slotted ground plane, and the transmission line are all the same.

[0011] Furthermore, the star-shaped slot is obtained by etching two squares of different sizes in the center of the slotted ground plane. The two squares are etched in a staggered manner, so that the star-shaped slot has 8 right angles.

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

[0013] (1) The present invention adopts an L-shaped planar transmission line structure for feeding, which is easy to integrate into circuits or devices. The feeding structure of the present invention eliminates the need for winding, vias and corresponding parasitic source inductance, reduces radiation loss caused by surface waves, and increases antenna gain and bandwidth. Furthermore, the application of the L-shaped planar transmission line feeding structure of the present invention can effectively excite the circular polarization effect of the surface radiating patch. At the same time, combined with the cross-slot structure on the center patch of the array, the profile height of the antenna can be greatly reduced.

[0014] (2) The present invention uses the method of adding parasitic patches to design the antenna. The introduction of parasitic patches has obvious advantages in improving the directivity of the antenna, enhancing its circular polarization performance and expanding the antenna's working bandwidth.

[0015] (3) The present invention uses truncated square patch units to form an array. The truncated square patch and the cross-shaped gap in the middle change the direction of surface current flow, so that the current achieves a 90° equal amplitude phase difference and produces a circular polarization effect.

[0016] (4) The present invention performs star-shaped slotting on the ground plane between two dielectric substrates. By analyzing the surface current, the increase of star-shaped slots directly changes the current trajectory. The current flows along the edge and forms a 90° phase difference, which enhances the bandwidth of circular polarization and the impedance matching of the antenna.

[0017] (5) The antenna of the present invention has advantages such as stable structure, low profile, dual-frequency circular polarization and wide bandwidth, and can be applied to fields such as maritime wireless communication and wireless positioning. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of a dual-band circularly polarized antenna for maritime communication proposed in an embodiment, including a top view, an elevation view, a side view, and a star-shaped ground plane between the F4BM220 dielectric substrate and the FR-4 dielectric substrate;

[0019] Figure 2 The image shows the results of antenna simulation and testing return loss (S11), where the horizontal axis represents frequency (GHz) and the vertical axis represents return loss intensity (dB).

[0020] Figure 3 The diagram shows the axial ratio results of antenna simulation and testing.

[0021] Figure 4 E-plane radiation patterns of left-hand and right-hand circularly polarized antennas for antenna simulation and testing;

[0022] Figure 5 The left-hand circularly polarized and right-hand circularly polarized H-plane radiation patterns are used for antenna simulation and testing. Detailed Implementation

[0023] Circularly polarized antennas have attracted widespread attention in wireless communication systems due to their strong anti-interference capabilities and the arbitrariness of transmit and receive polarization. Circularly polarized electromagnetic waves, as a field of equal amplitude rotation, can be decomposed into two linearly polarized electromagnetic waves with the same amplitude but a 90° phase difference. If an antenna radiates a left-hand circularly polarized wave, it can only receive left-hand circularly polarized waves and cannot receive right-hand circularly polarized waves. When a circularly polarized electromagnetic wave encounters an obstacle, its polarization reverses, resulting in a reflection wave with a different direction of rotation than the incident wave. Therefore, using circularly polarized antennas can reduce interference in harsh environments and resist multipath reflections. Furthermore, circularly polarized waves transmitted by a circularly polarized antenna can be received by linearly polarized antennas of any direction, while a circularly polarized receiving antenna can accept incoming waves with linear polarization of any direction. Therefore, they are widely used in satellite communication and reconnaissance / jamming applications.

[0024] The technical solution of this embodiment will now be further described in conjunction with the accompanying drawings and examples.

[0025] like Figure 1 As shown, this embodiment discloses a dual-band circularly polarized antenna for maritime communication, such as... Figure 1 As shown, it includes: an F4BM220 dielectric substrate 1, a radiating patch array 2 located on the upper surface of the F4BM220 dielectric substrate 1, an FR-4 dielectric substrate 7, a slotted ground plane 8 located between the F4BM220 dielectric substrate and the FR-4 dielectric substrate 7, and an L-shaped planar transmission line 9 located at the bottom of the FR-4 dielectric substrate 7.

[0026] In this embodiment, the radiating patch array 2 consists of 2×2 truncated square patches 3, first rectangular parasitic patches 4 located at the top and bottom, and second rectangular parasitic patches 5 located on the left and right sides. A cross-shaped vertical slot 6 is provided at the center of each truncated square patch 3. The purpose of creating this cross-shaped vertical slot 6 is to change the current flow direction. Surface current analysis shows that the increase in the cross-shaped vertical slot directly changes the current trajectory, with the current flowing around the cross-shaped vertical slot from both the top and bottom. The cross-shaped vertical slot increases the number of effective modes, resulting in a broadband effect from multimode resonance. Under the combined effect of multiple modes, circular polarization is achieved between every two modes, optimizing the antenna's circular polarization effect.

[0027] In this embodiment, the lengths of the first rectangular parasitic patch 4 and the second rectangular parasitic patch 5 are both slightly smaller than the length of the truncated square patch, and the dimensions of the first rectangular parasitic patch 4 and the second rectangular parasitic patch 5 are different. The resonant frequency of the rectangular parasitic patch is higher than that of the truncated square patch. By adding a parasitic patch of appropriate size, the operating frequency band is shifted to the lower frequency range, widening the antenna bandwidth and generating a new circular polarization effect in the lower frequency range. In this embodiment, by adding rectangular parasitic patches around the truncated square patch 3, the introduction of the rectangular parasitic patches effectively induces higher-order mode resonance, thus expanding the antenna's operating bandwidth.

[0028] like Figure 1 As shown, the slotted ground plane 8 and the L-shaped planar transmission line 9 constitute a coplanar waveguide feeding structure. The slot of the slotted ground plane 8 has a star-shaped structure, which increases the current trajectory, helps the antenna to strengthen impedance matching, and optimizes the antenna's circular polarization effect. This star-shaped structure is obtained by etching two squares with dimensions of 32mm×32mm and 28mm×28mm respectively in the center of the slotted ground plane 8, and these two squares are etched in a staggered manner, so that the star-shaped slot has 8 right angles. The L-shaped planar transmission line 9 consists of a short microstrip line and two long microstrip lines, where the two long microstrip lines form an L-shape. Specifically, in this embodiment, the short microstrip line has dimensions of 8mm×1.5mm, and the long microstrip lines have dimensions of 30mm×6mm and 16mm×8mm respectively. The L-shaped planar transmission line 9 used in this embodiment is easy to integrate into circuits or devices. The coplanar waveguide feeding structure used in this embodiment is simple to manufacture and has a compact structure. It eliminates the need for winding, vias, and corresponding parasitic source inductance, reduces radiation loss caused by surface waves, and increases antenna gain. The application of this coplanar waveguide feeding structure can more effectively excite the circular polarization effect of the antenna radiating patch. At the same time, combined with the slot structure, it greatly reduces the antenna profile height.

[0029] In this embodiment, each truncated square patch 3 has a size of 10mm × 10mm and a truncated corner size of 3mm. The long side of the cross-shaped vertical slot 6 is 12mm × 1mm, and the short side is 4mm × 1mm. The first rectangular parasitic patch 4 has a size of 7mm × 5.5mm, and the second rectangular parasitic patch 5 has a size of 14mm × 4.75mm. In this embodiment, the F4BM220 dielectric substrate 1 has a relative permittivity of 2.2, a rectangular shape, a size of 53mm × 53mm, and a thickness of 3mm. The FR-4 dielectric substrate 7 has a relative permittivity of 4.4, a rectangular shape, a size of 53mm × 53mm, and a thickness of 0.813mm. The thickness of the radiating patch array 2, the slotted ground plane 8, and the L-shaped planar transmission line 9 proposed in this embodiment is 0.018mm.

[0030] Figure 2 The simulation and test results of the return loss (S11) of the dual-frequency circularly polarized antenna proposed in this embodiment are given. The simulation results show that the -10dB impedance bandwidth is 55.64% (2.23GHz-3.25GHz), and the test results show that the -10dB impedance bandwidth is 58.29% (3.48GHz-5.80GHz).

[0031] Figure 3 Simulation and test gain and axial ratio results of the dual-band circularly polarized antenna proposed in this embodiment are presented. At low frequencies, the maximum gain is 4.53 dBic; at high frequencies, the maximum gain is 5.89 dBic. The 3 dB axial ratio bandwidth is 18.9% (2.32–2.77 GHz) at low frequencies and 9.2% (4.65–5.20 GHz) at high frequencies.

[0032] Figure 4 The simulation and testing results of the single-layer dual-frequency circularly polarized metasurface antenna proposed in this embodiment are presented, showing the left-hand and right-hand circularly polarized E-plane and H-plane radiation patterns in the low-frequency range.

[0033] Figure 5 The simulation and testing results of the single-layer dual-frequency circularly polarized metasurface antenna proposed in this embodiment are presented, showing the left-hand and right-hand circularly polarized E-plane and H-plane radiation patterns in the high-frequency region.

[0034] Compared to conventional circularly polarized antennas, the dual-band circularly polarized antenna proposed in this embodiment innovatively features a cross-shaped vertical slit carved in the center of a truncated square patch. Rectangular parasitic patches are then added around the surface radiating patch. The introduction of these parasitic patches effectively induces higher-order mode resonance, expanding the antenna's operating bandwidth. Furthermore, star-shaped slots are implemented on the ground plane, increasing the current trajectory and helping to improve impedance matching while optimizing the antenna's circular polarization effect.

Claims

1. A dual-frequency circularly polarized antenna for maritime communication, characterized in that: include: First dielectric substrate, radiating patch array, second dielectric substrate, slotted ground plane and transmission line; The radiating patch array is located on the upper surface of the first dielectric substrate, the slotted ground plane is located between the first dielectric substrate and the second dielectric substrate, and the transmission line is located on the lower surface of the second dielectric substrate. The radiating patch array consists of several truncated square patches in the central region and parasitic patches around the perimeter; a cross-shaped vertical slit is provided at the center of each truncated square patch; a star-shaped slot is provided on the slotted ground plane; the transmission line is an L-shaped planar transmission line composed of microstrip lines; the slotted ground plane and the transmission line constitute a feeding structure, which excites the circular polarization effect of the radiating patch array.

2. The dual-frequency circularly polarized antenna for maritime communication according to claim 1, characterized in that: The parasitic patches arranged around the perimeter include first parasitic patches arranged above and below the truncated square patch, and second parasitic patches arranged to the left and right of the truncated square patch. The lengths of the first and second parasitic patches are different, but both are shorter than the length of the truncated square patch.

3. A dual-frequency circularly polarized antenna for maritime communication according to claim 1, characterized in that: Both the first dielectric substrate and the second dielectric substrate are rectangular dielectric substrates.

4. A dual-frequency circularly polarized antenna for maritime communication according to claim 1, characterized in that: The parasitic patch is a rectangular parasitic patch.

5. A dual-frequency circularly polarized antenna for maritime communication according to claim 1, characterized in that: The thickness of the radiating patch array, the slotted ground plane, and the transmission line are all the same.

6. A dual-frequency circularly polarized antenna for maritime communication according to claim 1, characterized in that: The star-shaped groove is obtained by etching two squares of different sizes in the center of the grooved ground plate. The two squares are etched in a staggered manner, so that the star-shaped groove has 8 right angles.

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