Low tilt angle wide beam high gain low profile aircraft antenna

Abstract

This invention relates to the field of aircraft antenna technology, and discloses a low-tilt, wide-beam, high-gain, low-profile aircraft antenna, comprising a rectangular waveguide body, a radiating aperture, a beam modulation control, and a protective structure. The radiating aperture is the open end of the rectangular waveguide body, the beam modulation control is located at the radiating aperture, and the protective structure covers the rectangular waveguide body and the radiating aperture. The rectangular waveguide body is a highly compressed structure. This invention solves the problems of high beam tilt, narrow beamwidth, and low antenna gain commonly used in microstrip antennas for aircraft, and features low tilt, wide beam, high gain, and low profile, which can greatly improve the widespread use of low-tilt, wide-beam, high-gain, low-profile antennas in various aircraft.

Description

Technical Field

[0001] This invention relates to the field of aircraft antenna technology. Background Technology

[0002] With the development of modern high technology, increasingly higher requirements are being placed on the performance of antennas on the surfaces of various aircraft in aviation and aerospace, such as low tilt angle, wide beam, high gain, low profile, and wide bandwidth. This is especially true for end-fire (side-fire) pattern antennas that crawl along the surface of the aircraft. In these end-fire (side-fire) pattern antennas, it is often required that the minimum peak tilt angle of the antenna in the E-plane (elevation plane) pattern is no greater than 15°, the peak gain is no less than 8dB, and the gain in a certain beam range (e.g., ±40°) of the H-plane (azimuth plane) pattern is no less than 1dB. Furthermore, the antenna surface must be conformal to the aircraft surface or have a small dimension protruding above the aircraft surface (low profile).

[0003] The antenna types commonly used for end-fire (side-fire) pattern antennas on the surfaces of various aircraft are mainly microstrip linear antennas, microstrip Yagi antennas, and microstrip array antennas. The minimum peak tilt angle of this type of microstrip antenna in the E-plane (elevation plane) pattern is about 25°, and the maximum peak gain is about 6dB. However, the antenna gain is less than 0dB in a certain beam range (such as ±40°) of the H-plane (azimuth plane) pattern, which cannot meet the technical specifications. Summary of the Invention

[0004] The purpose of this invention is to provide a low-tilt, wide-beam, high-gain, low-profile aircraft antenna, which features low tilt, wide beam, high gain, and low profile to meet the design requirements of various aircraft top-firing (side-firing) pattern antennas.

[0005] To solve the above-mentioned technical problems, the present invention provides a low-tilt-angle, wide-beam, high-gain, low-profile aircraft antenna, including a rectangular waveguide body, a radiating aperture, a beam modulation control, and a protective structure; the radiating aperture is the open end of the rectangular waveguide body, the beam modulation control is located at the radiating aperture, and the protective structure covers the rectangular waveguide body and the radiating aperture; the rectangular waveguide body is a highly compressed structure.

[0006] The beam modulation control is a U-shaped dielectric pad, which is loaded onto the radiation port surface.

[0007] The protective structure includes an inner wave-transparent dielectric plate and an outer metal cover. The inner wave-transparent dielectric plate covers the radiation port surface, and the outer metal cover encloses the rectangular waveguide body.

[0008] The inner wave-transparent dielectric plate is a polytetrafluoroethylene glass laminate, which is formed by pressing with a mold.

[0009] The opening direction of the radiation port is the same as the flight path of the aircraft.

[0010] The minimum tilt angle of the peak E-plane radiation pattern of the antenna is not greater than 15°, and the peak gain of the antenna is not less than 8dB.

[0011] The gain of the antenna is not less than 1dB within a ±40° range of the H-plane.

[0012] The U-shaped dielectric pad widens the beamwidth and reduces the beam tilt angle through electromagnetic wave refraction and reflection.

[0013] After being highly compressed, the outer contour of the antenna conforms to the surface of the aircraft.

[0014] The inner wave-transparent dielectric plate and the outer metal cover form a double-layer protective structure, which improves the strength of the antenna structure.

[0015] Compared with the prior art, this invention solves the problems of high beam tilt angle, narrow beamwidth and low antenna gain of commonly used microstrip antennas in aircraft. It has the characteristics of low tilt angle, wide beam, high gain and low profile, which can greatly promote the use of low tilt angle wide beam high gain low profile antennas in various aircraft.

[0016] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0017] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0018] Figure 1 This is a schematic diagram of the structure of at least one embodiment of the present invention; Figure 2 yes Figure 1 A schematic diagram of the cross-sectional structure; Figure 3 This is a test E-plane (pitch plane) radiation pattern in one embodiment of the present invention; Figure 4 This is a test H-plane (azimuth plane) orientation pattern in one embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the embodiments of this invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details are presented in the embodiments of this invention to facilitate a better understanding of this application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments. The division of the following embodiments is for ease of description and should not constitute any limitation on the specific implementation of this invention. The embodiments can be combined with and referenced by each other without contradiction.

[0020] Example 1 like Figure 1 and 2 The antenna shown is a low-tilt, wide-beam, high-gain, low-profile aircraft antenna, comprising a rectangular waveguide body, a radiating aperture, a beam modulation control, and a protective structure; the radiating aperture is the open end of the rectangular waveguide body, the beam modulation control is located at the radiating aperture, and the protective structure covers the rectangular waveguide body and the radiating aperture; the rectangular waveguide body is a highly compressed structure.

[0021] Generally, the rectangular waveguide body is formed from a standard metal waveguide blank using a high-compression process. The inner wall of the waveguide maintains a conductive metal surface to ensure the transmission efficiency of electromagnetic waves within the waveguide. The radiating aperture is the opening at the front end of the rectangular waveguide body along its length, forming the main radiation area of ​​the antenna. Electromagnetic waves are transmitted through the rectangular waveguide body to the radiating aperture and then radiate outwards. The beam modulation control is fixedly installed on the end face of the radiating aperture to adjust the wavefront of the electromagnetic waves output from the radiating aperture, changing the beam direction, beamwidth, and gain distribution. The protective structure completely covers the outer wall of the rectangular waveguide body and the outer side of the radiating aperture, isolating it from the external environment and protecting the internal radiation and transmission structure of the antenna, while not affecting the normal radiation and propagation of electromagnetic waves. The rectangular waveguide body adopts a high-compression structure, which significantly reduces the overall thickness of the antenna by reducing the size of the waveguide in the direction perpendicular to the aircraft surface, meeting the requirements of low profile and conformal installation for airborne antennas.

[0022] Example 2 Based on Example 1, the beam modulation control is a U-shaped dielectric pad, which is loaded onto the radiation port surface.

[0023] Furthermore, the opening direction of the radiating aperture is the same as the aircraft's heading.

[0024] Furthermore, the U-shaped dielectric pad widens the beamwidth and reduces the beam tilt angle through electromagnetic wave refraction and reflection.

[0025] Furthermore, after the rectangular waveguide body is highly compressed, the outer contour of the antenna conforms to the surface of the aircraft.

[0026] Generally, the U-shaped dielectric pad is made of a high-frequency dielectric material with low dielectric constant and low loss. It has an overall U-shaped groove structure, with the U-shaped opening direction aligned with the radiation direction of the radiating port. The inner wall of the U-shaped dielectric pad is tightly fitted and fixed to the outer wall of the radiating port, with no gaps between them, ensuring that electromagnetic waves directly enter the interior of the U-shaped dielectric pad after exiting the radiating port. The opening direction of the radiating port is strictly aligned with the aircraft's heading, causing the antenna radiation direction to extend forward along the aircraft surface, forming a surface-crawling end-fire / side-fire pattern. After entering the U-shaped dielectric pad from the radiating port, the electromagnetic wave undergoes directional refraction and multiple reflections at the interface between the dielectric and air, reshaping the electromagnetic wave propagation path and homogenizing the wavefront phase distribution. After the rectangular waveguide body undergoes high compression, the maximum external dimension of the antenna in the direction perpendicular to the aircraft surface is less than a preset threshold. The outer surface of the antenna smoothly connects to the aircraft skin surface, achieving conformal installation without disrupting the aircraft's aerodynamic shape.

[0027] This allows for further constraints on the beam control structure, radiation direction, beam control mechanism, and low-profile conformal characteristics, achieving a complete synergistic optimization of low tilt angle, wide beam, high gain, and low profile. By aligning the radiating port with the aircraft's heading, the main electromagnetic wave radiation direction propagates along the aircraft surface, reducing the E-plane beam peak tilt angle from an installation attitude perspective and avoiding coverage blind spots caused by upward beam tilt. The U-shaped dielectric pad, as the core beam control component, utilizes the refraction and reflection effects at the dielectric interface to perform phase modulation and direction correction of the electromagnetic waves. Without reducing the antenna's peak gain, it simultaneously achieves two key effects: first, it widens the beam coverage range of the H-plane azimuth, allowing the antenna to maintain effective gain over a larger angular range; second, it further reduces the E-plane elevation beam tilt angle, bringing the radiation direction closer to the aircraft surface. The highly compressed rectangular waveguide body, combined with the conformal shape design, ensures that the antenna meets electrical performance requirements while fully adapting to the structural constraints of airborne installation. This embodiment, through a combination of radiation pointing and dielectric modulation design, enables the antenna to overcome the technical bottleneck of traditional microstrip antennas that cannot simultaneously achieve low tilt angle, wide beam, and high gain. Under the same installation space, it achieves a lower beam tilt angle, wider coverage, and higher gain, thus realizing a comprehensive improvement in the antenna's electrical performance.

[0028] Example 3 Based on Embodiment 1, the protective structure includes an inner wave-transparent dielectric plate and an outer metal cover. The inner wave-transparent dielectric plate covers the radiation port surface, and the outer metal cover encloses the rectangular waveguide body.

[0029] Furthermore, the inner wave-transparent dielectric plate is a polytetrafluoroethylene glass laminate, which is formed by pressing with a mold.

[0030] Furthermore, the minimum tilt angle of the antenna E-plane radiation pattern peak is no greater than 15°, and the antenna peak gain is no less than 8dB.

[0031] Furthermore, the gain of the antenna within ±40° of the H-plane is not less than 1dB.

[0032] Furthermore, the inner wave-transparent dielectric plate and the outer metal cover form a double-layer protective structure, which enhances the strength of the antenna structure.

[0033] The inner waveguide dielectric plate completely covers the radiating aperture, with a small air gap between it and the aperture to avoid direct contact that could affect radiation performance. The inner waveguide dielectric plate is made of polytetrafluoroethylene (PTFE) glass laminate, a material with a low dielectric constant, low dielectric loss, and excellent high-frequency wave transmission performance. It is formed by high-temperature pressing using a specialized mold, resulting in a smooth surface and high dimensional accuracy, ensuring no distortion of the radiation pattern. The outer metal casing is made of lightweight, high-strength metal sheet, stamped and encased in the rear half and sidewalls of the rectangular waveguide body. The outer metal casing is sealed to the edges of the inner waveguide dielectric plate, forming a closed protective cavity that effectively resists environmental influences such as airborne vibration, impact, dust, and temperature changes. Testing revealed that the minimum tilt angle of the antenna's E-plane elevation pattern in this embodiment reaches 10°, meeting the design requirement of no more than 15°; the antenna's peak gain reaches 9.65dB, meeting the design requirement of no less than 8dB; and within the ±40° coverage area of ​​the antenna's H-plane azimuth plane, the minimum gain is no less than 2.88dB, far exceeding the requirement of no less than 1dB. The inner wave-transparent dielectric substrate ensures efficient electromagnetic wave penetration, while the outer metal shroud enhances structural rigidity and mechanical strength. This double-layer structure significantly improves the antenna's environmental adaptability and structural reliability without compromising its electrical performance.

[0034] Therefore, the protective structure adopts a dual-layer design of "inner wave-transparent layer + outer reinforcement layer," which is the key to balancing radiation performance and structural strength in this invention. The inner layer uses a polytetrafluoroethylene (PTFE) glass laminate, utilizing its low dielectric and low loss characteristics to minimize electromagnetic wave attenuation and pattern distortion, ensuring radiation efficiency and beam quality. The mold pressing process ensures the dimensional accuracy and surface flatness of the dielectric substrate, avoiding performance fluctuations caused by structural errors. The outer metal shroud provides mechanical support and protection for the antenna, preventing deformation and damage to the waveguide body under complex airborne conditions. In terms of performance indicators, the antenna of this embodiment has significantly better E-plane tilt angle, peak gain, and H-plane coverage gain than traditional microstrip antennas, fully meeting the stringent requirements of end-fire / side-fire antennas for aircraft. This embodiment, through the optimized design of the protective structure, solves the contradiction that traditional antennas often sacrifice structural strength when improving electrical performance, and often deteriorate electrical performance when strengthening the structure, enabling the antenna to simultaneously possess excellent electrical performance and reliable structural strength, allowing it to operate stably for a long time in aviation and aerospace airborne environments.

[0035] Example 4 Based on the above embodiments, a rectangular waveguide antenna is used as the core component of the antenna. The open end of the rectangular waveguide antenna faces the heading of the aircraft to ensure that the beam tilt angle of the antenna is reduced. A U-shaped dielectric pad is loaded onto the aperture of the rectangular waveguide antenna. Through the refraction and reflection of electromagnetic waves in the dielectric, the beamwidth of the antenna is widened, while the antenna has a high peak gain and a low beam tilt angle. An antenna protective cover is added to the outer part of the antenna. By using the high compression technology of the rectangular waveguide, its size above the outer surface of the aircraft is small (low profile). Moreover, the antenna protective cover is divided into two layers. The inner layer is a dielectric plate with wave transmission properties. This dielectric plate is a polytetrafluoroethylene glass laminate with a low dielectric constant, which is formed by mold pressing. The rear half of the outer layer is a metal cover to enhance the strength of the antenna.

[0036] The final test orientation diagram of the product is as follows Figure 3 , Figure 4 As shown in the diagram, the low-tilt, wide-beam, high-gain, low-profile antenna designed in this invention has a minimum peak tilt angle of 10° in the E-plane (elevation plane) radiation pattern, meeting the requirement of not exceeding 15°; the antenna peak gain is 9.65dB, meeting the requirement of not less than 8dB; and the antenna gain within a certain beam range (e.g., ±40°) in the H-plane (azimuth plane) radiation pattern is not less than 2.88dB, meeting the requirement of not less than 1dB.

[0037] Therefore, this invention utilizes the height compression technology of rectangular waveguides to reduce the height of the antenna surface above the aircraft surface, thereby achieving a low-profile antenna effect. By loading a U-shaped dielectric pad onto the antenna aperture of the rectangular waveguide, the electromagnetic waves in the dielectric are refracted and reflected, widening the antenna beamwidth and simultaneously giving the antenna a higher peak gain and a lower beam tilt angle. The antenna protective cover adopts a double-layer structure of a metal outer cover and a dielectric protective cover, which improves the antenna strength while meeting the antenna radiation performance requirements.

[0038] Those skilled in the art will understand that the above embodiments can be modified in form and detail in practical applications without departing from the spirit and scope of the invention.

Claims

1. A low-tilt-angle, wide-beam, high-gain, low-profile aircraft antenna, characterized in that, It includes a rectangular waveguide body, a radiating aperture, a beam modulation control, and a protective structure; the radiating aperture is the open end of the rectangular waveguide body, the beam modulation control is located at the radiating aperture, and the protective structure covers the rectangular waveguide body and the radiating aperture; the rectangular waveguide body is a highly compressed structure.

2. The low-tilt-angle, wide-beam, high-gain, low-profile aircraft antenna according to claim 1, characterized in that, The beam modulation control is a U-shaped dielectric pad, which is loaded onto the radiation port surface.

3. The low-tilt-angle, wide-beam, high-gain, low-profile aircraft antenna according to claim 1, characterized in that, The protective structure includes an inner wave-transparent dielectric plate and an outer metal cover. The inner wave-transparent dielectric plate covers the radiation port surface, and the outer metal cover encloses the rectangular waveguide body.

4. The low-tilt-angle, wide-beam, high-gain, low-profile aircraft antenna according to claim 3, characterized in that, The inner wave-transparent dielectric plate is a polytetrafluoroethylene glass laminate, which is formed by pressing with a mold.

5. The low-tilt-angle, wide-beam, high-gain, low-profile aircraft antenna according to claim 1, characterized in that, The opening direction of the radiation port is the same as the flight path of the aircraft.

6. The low-tilt-angle, wide-beam, high-gain, low-profile aircraft antenna according to claim 1, characterized in that, The minimum tilt angle of the peak E-plane radiation pattern of the antenna is not greater than 15°, and the peak gain of the antenna is not less than 8dB.

7. The low-tilt-angle, wide-beam, high-gain, low-profile aircraft antenna according to claim 1, characterized in that, The gain of the antenna is not less than 1dB within a ±40° range of the H-plane.

8. The low-tilt-angle, wide-beam, high-gain, low-profile aircraft antenna according to claim 2, characterized in that, The U-shaped dielectric pad widens the beamwidth and reduces the beam tilt angle through electromagnetic wave refraction and reflection.

9. The low-tilt-angle, wide-beam, high-gain, low-profile aircraft antenna according to claim 1, characterized in that, After being highly compressed, the outer contour of the antenna conforms to the surface of the aircraft.

10. The low-tilt-angle, wide-beam, high-gain, low-profile aircraft antenna according to claim 3, characterized in that, The inner wave-transparent dielectric plate and the outer metal cover form a double-layer protective structure, which improves the strength of the antenna structure.

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