A dual-frequency dipole airborne antenna for flight check

Abstract

This application discloses a dual-frequency dipole airborne antenna for flight calibration, belonging to the field of airborne navigation. It includes a dielectric substrate, radiating arms symmetrically fixedly mounted on the dielectric substrate, a coplanar waveguide fixedly mounted on the dielectric substrate near the two sets of radiating arms, and a coaxial mount fixedly mounted on the side of the coplanar waveguide away from the radiating arms. A feeding gap is provided between the two radiating arms. This dual-frequency dipole airborne antenna device achieves dual-band compatibility, miniaturization, and easy integration through the coordinated cooperation of slotted design, serpentine bending structure, and coplanar waveguide feeding design. It can simultaneously adapt to glide slope, heading, and Vortex airborne calibration signal reception, eliminating the need for multiple calibration antennas, effectively simplifying the airborne system integration layout, reducing antenna size, avoiding dielectric substrate drilling, and adapting to the limited airborne installation space.

Description

Technical Field

[0001] This application relates to the field of airborne navigation technology, specifically a dual-frequency dipole airborne antenna for flight calibration. Background Technology

[0002] The Instrument Landing System (ILS), a critical navigation facility for precise aircraft approach and landing guidance, consists of a localizer (frequency range 108.10–111.95 MHz) and a glide slope beacon (frequency range 329.15–335 MHz). By transmitting modulated dual-frequency signals, they create overlapping localizers and glide slopes along the approach path, providing pilots with accurate horizontal and vertical guidance and ensuring safe landings in complex weather conditions such as low visibility. Additionally, the Very High Frequency (VHF) omnidirectional beacon (VOR), operating in the 108–117.95 MHz band, provides aircraft with magnetic azimuth information relative to ground stations and is often used in conjunction with a distance measuring instrument (DME) for positioning. To ensure navigation signal accuracy, periodic flight calibration using UAV-borne receiving equipment is necessary. Currently, airborne calibration antennas typically need to cover both VHF and UHF bands, often employing multi-antenna combinations, leading to complex system integration and potentially impacting the UAV's aerodynamic performance and flight stability.

[0003] To address the aforementioned problems, Chinese Patent Publication No. CN115377631B discloses an airborne navigation antenna. This antenna includes a glide slope radiating element, a directional radiating element, a ground wire, and a high-impedance stripline. Each radiating element has an element composed of striplines and is connected to a matching stripline. The glide slope radiating element and the directional radiating element are connected via the high-impedance stripline. The directional radiating element is connected to the ground wire via an inductor. The antenna feeds signals through the glide slope radiating element. This airborne navigation antenna has the advantages of a compact structure and no matching losses due to the absence of matching circuits. However, this antenna has a high VSWR and low gain in the directional band, affecting the signal-to-noise ratio. Furthermore, the beam directivity of the directional and glide slope bands is inconsistent, placing high demands on the attitude of the UAV.

[0004] Therefore, this application provides a dual-frequency dipole airborne antenna for flight calibration to solve the above problems. Summary of the Invention

[0005] This application provides a dual-frequency dipole airborne antenna for flight calibration, aiming to solve the problems of existing airborne flight calibration antennas mentioned in the background art, such as large VSWR in the heading band, low gain, poor signal-to-noise ratio, inconsistent beam directivity in the heading and glide slope bands, and high requirements on the attitude of the calibration UAV.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] A dual - frequency dipole airborne antenna for flight calibration, comprising a dielectric substrate, radiation arms symmetrically and fixedly mounted on the dielectric substrate, a coplanar waveguide fixedly mounted on the dielectric substrate near the two groups of radiation arms, and a coaxial socket fixedly mounted on the side of the coplanar waveguide away from the radiation arms. There is a feeding gap between the two radiation arms. The radiation arm includes a main radiation patch structure fixedly mounted on the dielectric substrate, a serpentine bending mechanism fixedly mounted on the dielectric substrate near the main radiation patch structure, and an end loading fixedly mounted on the dielectric substrate near the serpentine bending mechanism. The main radiation patch is rectangular, with a triangular cut - off angle on one side close to the symmetry line, and the center point at the end of the main radiation patch is connected to one side of the serpentine bending mechanism. The main radiation patch structure includes a main radiation patch fixedly mounted on the dielectric substrate and a rectangular groove opened on the mutually - remote sides of the two main radiation patches. The coplanar waveguide includes a coplanar waveguide ground fixedly mounted on one side of the dielectric substrate, a tapered signal line fixedly arranged on one side of the coplanar waveguide ground, and a defective coplanar waveguide ground fixedly arranged on the side of the tapered signal line away from the coplanar waveguide ground.

[0008] As a further scheme of the present invention: The serpentine bending mechanism is composed of a plurality of "Z" - shaped bending segments connected in series.

[0009] As a further scheme of the present invention: The inner core of the coaxial socket is fixedly welded to the feeding end of the tapered signal line, and the grounding pins of the coaxial socket are respectively fixedly welded to the defective coplanar waveguide ground and the coplanar waveguide ground.

[0010] As a further scheme of the present invention: The defective coplanar waveguide ground is rectangular, one side of the tapered signal line away from the radiation arm is rectangular, the other side of the tapered signal line is trapezoidally tapered and connected to the radiation arm, the shape of the coplanar waveguide ground is rectangular, and the length of the coplanar waveguide ground is the same as the length of the defective coplanar waveguide ground.

[0011] As a further scheme of the present invention: The dielectric substrate is an FR4 epoxy glass cloth substrate, and the radiation arms and the coplanar waveguide are both copper - printed circuit layers.

[0012] As a further scheme of the present invention: The dielectric substrate is installed between the lower antenna cover and the upper antenna cover, and the lower antenna cover and the upper antenna cover are connected by bolts.

[0013] As a further scheme of the present invention: Both the lower antenna cover and the upper antenna cover are made of fiberglass.

[0014] Compared with the prior art, the beneficial effects of the present invention are: <......<......This dual-band dipole airborne antenna device achieves dual-band compatibility, miniaturization, and easy integration through the coordinated use of slotted design, serpentine bending structure, and coplanar waveguide feeding design. It can simultaneously adapt to glide slope, heading, and Vortex airborne calibration signal reception without the need for multiple calibration antennas, effectively simplifying the airborne system integration layout. At the same time, it reduces antenna size, avoids drilling holes in the dielectric substrate, and is suitable for narrow airborne installation spaces.

[0016] This dual-band dipole airborne antenna device achieves stable antenna performance, convenient processing, and controllable cost through size optimization, end-capacitor design, and the application of FR4 dielectric and PCB printing technology. It not only enables the antenna to have excellent gain and return loss characteristics in the target frequency band, improves the receiving signal-to-noise ratio and operating range, and facilitates subsequent tuning, but also enables lightweight antenna production, reduces processing and manufacturing costs, and adapts to the complex operating conditions of UAVs during flight calibration. Attached Figure Description

[0017] Figure 1 A schematic diagram of the structure of a dual-frequency dipole airborne antenna used for flight calibration;

[0018] Figure 2 A schematic diagram of the dielectric substrate in a dual-frequency dipole airborne antenna used for flight verification;

[0019] Figure 3 A schematic diagram of the coplanar waveguide structure of a dual-frequency dipole airborne antenna used for flight calibration;

[0020] Figure 4 Impedance matching S11 diagram of a dual-frequency dipole airborne antenna used for flight calibration;

[0021] Figure 5 Voltage standing wave ratio (VSWR) diagram of a dual-frequency dipole airborne antenna used for flight calibration;

[0022] Figure 6 A horizontal gain pattern of a dual-frequency dipole airborne antenna used for flight calibration.

[0023] In the picture:

[0024] 1. Dielectric substrate;

[0025] 2. Radiation arm; 21. Main radiation patch structure; 211. Main radiation patch; 212. Rectangular groove; 22. Serpentine bending mechanism; 23. End loading;

[0026] 3. Coplanar waveguide; 31. Defective coplanar waveguide ground; 32. Tapered signal line; 33. Coplanar waveguide ground;

[0027] 4. Coaxial mount; 5. Lower radome; 6. Upper radome. Detailed Implementation

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0029] As Figure 1 、 Figure 2 and Figure 3 shown, an embodiment of the present invention provides a dual-frequency dipole airborne antenna for flight calibration, including a dielectric substrate 1, radiation arms 2 symmetrically and fixedly installed on the dielectric substrate 1, a coplanar waveguide 3 fixedly installed on the dielectric substrate 1 near the two groups of radiation arms 2, and a coaxial socket 4 fixedly installed on the side of the coplanar waveguide 3 away from the radiation arms 2. There is a feeding gap between the two radiation arms 2. The radiation arm 2 includes a main radiation patch structure 21 fixedly installed on the dielectric substrate 1, a serpentine bending mechanism 22 fixedly installed on the dielectric substrate 1 near the main radiation patch structure 21, and a terminal loading 23 fixedly installed on the dielectric substrate 1 near the serpentine bending mechanism 22. The main radiation patch 211 is rectangular, there is a triangular cut corner on one side of the main radiation patch 211 close to the symmetry line, and the center point at the end of the main radiation patch 211 is connected to one side of the serpentine bending mechanism 22. The main radiation patch structure 21 includes a main radiation patch 211 fixedly installed on the dielectric substrate 1 and a rectangular slot 212 opened on the side where the two main radiation patches 211 are away from each other. The coplanar waveguide 3 includes a coplanar waveguide ground 33 fixedly installed on one side of the dielectric substrate 1, a tapered signal line 32 fixedly arranged on one side of the coplanar waveguide ground 33, and a defective coplanar waveguide ground 31 fixedly arranged on the side of the tapered signal line 32 away from the coplanar waveguide ground 33.

[0030] It should be added that: setting a triangular cut corner on the main radiation patch 211 can improve the impedance matching performance of the antenna in the high-frequency band; the rectangular slot 212 opened on the main radiation patch structure 21 can change the surface current distribution of the antenna, introduce an additional resonance path, enable a single antenna to cover the glide, localizer, and VOR working frequency bands simultaneously, and achieve dual-frequency multiplexing; the overall radiation arm 2 is connected to the serpentine bending mechanism 22 and the terminal loading 23 to form a complete current radiation path, and the overall adopts a planar printed structure layout, with a compact structure, suitable for the narrow installation space on the aircraft.

[0031] As Figure 1 and Figure 2 shown, optionally, the serpentine bending mechanism 22 is composed of a plurality of "J"-shaped bending segments connected in series.

[0032] It should be noted that: the serpentine bending mechanism 22 adopts a series arrangement of multiple "Z" - shaped bending segments. Under the condition of limited planar size of the dielectric substrate 1, it effectively extends the electrical path of the radiation current, equivalently reduces the occupied size of the working wavelength, and realizes antenna miniaturization; by optimizing the number of bending segments, the bending spacing, and the line width, while reducing the external dimension of the antenna, it also takes into account the antenna radiation efficiency and the working bandwidth, avoiding the defects of attenuation of radiation gain and narrowing of the working bandwidth caused by too - dense bending.

[0033] As Figure 2 and Figure 3 shown, optionally, one end of the tapered signal line 32 is electrically connected to the radiation arm 2, and one end of the coplanar waveguide ground 33 is electrically connected to the radiation arm 2; the inner core of the coaxial socket 4 is fixedly welded to the input end of the tapered signal line 32, and the grounding pins of the coaxial socket 4 are respectively fixedly welded to the defective coplanar waveguide ground 31 and the coplanar waveguide ground 33.

[0034] It should be noted that: this electrical connection and welding structure can realize the conversion of the unbalanced RF signal of the coaxial socket 4 to the balanced feeding structure of the dipole radiation arm 2, achieving symmetric balanced feeding; the overall surface - welding method is adopted, without drilling holes and threading for feeding on the dielectric substrate 1, simplifying the PCB processing technology, reducing the feeding loss, and improving the stability of antenna signal reception and the signal - to - noise ratio.

[0035] As Figure 2 and Figure 3 shown, optionally, the defective coplanar waveguide ground 31 is rectangular, one side of the tapered signal line 32 away from the radiation arm 2 is rectangular, the other side of the tapered signal line 32 is trapezoidally tapered and connected to the radiation arm 2, the shape of the coplanar waveguide ground 33 is rectangular, and the length of the coplanar waveguide ground 33 is the same as the length of the defective coplanar waveguide ground 31.

[0036] It should be noted that: the trapezoidal taper structure of the tapered signal line 32 can achieve broadband progressive impedance matching, effectively reducing the return loss of the feeding port; at the same time, the overall size is adapted to the pin mounting pitch of the coaxial socket 4.

[0037] As Figure 1 shown, optionally, the dielectric substrate 1 is an FR4 epoxy glass cloth substrate, and both the radiation arm 2 and the coplanar waveguide 3 are copper - printed circuit layers.

[0038] As Figure 1 shown, optionally, the dielectric substrate 1 is installed between the lower antenna cover 5 and the upper antenna cover 6, and the lower antenna cover 5 and the upper antenna cover 6 are connected by bolts.

[0039] It should be noted that the upper and lower radomes are used to cover and embed the antenna, which can provide physical protection and isolation for the internal antenna circuitry; the bolted connection method ensures a secure assembly and convenient disassembly and assembly, facilitating the later debugging, inspection and maintenance of the antenna.

[0040] like Figure 1 As shown, optionally, both the lower radome 5 and the upper radome 6 are made of fiberglass.

[0041] Figure 4 The S11 diagram shows the impedance matching of a dual-frequency dipole airborne antenna for flight verification in one embodiment of the present invention. The antenna return loss is better than 6dB in the Volt and heading bands and better than 16dB in the glide slope band.

[0042] Figure 5 The image shows a voltage standing wave ratio (VSWR) diagram of a dual-frequency dipole airborne antenna used for flight verification in one embodiment of the present invention. The VSWR is 3:1 in the Volt and heading bands and 1.4:1 in the glide slope band.

[0043] Figure 6 This is a horizontal gain pattern of a dual-frequency dipole airborne antenna for flight verification in one embodiment of the present invention. The far-field patterns of the antenna in the high and low frequency bands have the same directivity, with a 3dB beamwidth of 40° at 113MHz and a 3dB beamwidth of 30° at 332MHz.

[0044] In this embodiment, the external radio frequency signal is input through the coaxial base 4. The inner core of the coaxial base 4 guides the signal into the gradient signal line 32. The grounding pin is reliably connected to the defective coplanar waveguide ground 31 and the coplanar waveguide ground 33. The coplanar waveguide 3 completes the conversion of the unbalanced port signal into the balanced feed signal of the dipole antenna, which is symmetrically fed into the two radiating arms 2, exciting the radiating arms 2 to form an electromagnetic radiation field, and realizing the stable reception of the glide slope, heading, and Volt band wireless signals for flight verification.

[0045] The radiating arm 2 consists of a main radiating patch structure 21, a serpentine bending mechanism 22, and an end loading device 23 connected sequentially to form a continuous current path. The main radiating patch 211 and the serpentine bending traces form a low-frequency resonant circuit, covering the heading and Volt frequency bands. The rectangular slot 212 on the side of the main radiating patch 211 disturbs the surface current distribution, exciting additional high-frequency resonant modes, covering the glide slope frequency band. This single-plane structure achieves dual-frequency and three-band compatibility, replacing the traditional multi-antenna combination layout. The triangular chamfer on the main radiating patch 211 optimizes the high-frequency impedance characteristics, improving return loss and VSWR.

[0046] The serpentine bending mechanism 22 extends the electrical current path through multiple "Z" - shaped multi - segment bends, achieving miniaturized antenna design without increasing the substrate occupation area; the end loading 23 forms a capacitive loading structure, which can change the current distribution at the end of the radiation arm and the magnitude of capacitive reactance by fine - tuning its own geometric dimensions, and can perform post - tuning on the antenna resonance frequency point and standing - wave parameters, canceling out the performance deviation caused by PCB processing tolerances and improving the consistency of mass - produced products.

[0047] The coplanar waveguide 3 adopts a tapered signal - line trapezoidal transition structure to achieve smooth wide - band impedance matching and reduce feed - back loss.

[0048] Antenna size table

[0049] symbol describe Value (mm) L3 Antenna total length 876 W1 Antenna total width 115 d1 End loading length 25 d2 Snake-shaped bend line width 5 d3 serpentine bend spacing 9 L1 Main radiating patch length 250 L2 Rectangular groove length 100 W2 Rectangular slot width 18 g1 Chamfer width 9 a1 Coplanar waveguide length 40 a2 Gradient signal line width 2 g2 Gradient signal line and coplanar waveguide ground gap 1 Dielectric board thickness 1.6

[0050] As described above, it is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application, according to the technical solution and its concept of the present application, making equivalent replacements or changes, should be covered within the protection scope of the present application.

Claims

1. A dual - frequency dipole airborne antenna for flight calibration, comprising a dielectric substrate (1), radiation arms (2) symmetrically and fixedly mounted on the dielectric substrate (1), a coplanar waveguide (3) fixedly mounted on the dielectric substrate (1) near the two groups of radiation arms (2), and a coaxial socket (4) fixedly mounted on the side of the coplanar waveguide (3) away from the radiation arms (2). There is a feeding gap between the two radiation arms (2); Its features are: The radiation arm (2) includes a main radiation patch structure (21) fixedly mounted on the dielectric substrate (1), a serpentine bending mechanism (22) fixedly mounted on the dielectric substrate (1) near the main radiation patch structure (21), and a tip loading (23) fixedly mounted on the dielectric substrate (1) near the serpentine bending mechanism (22). The main radiation patch (211) is rectangular, there is a triangular cut - off on one side of the main radiation patch (211) near the symmetry line, and the center point at the end of the main radiation patch (211) is connected to one side of the serpentine bending mechanism (22); The main radiation patch structure (21) includes a main radiation patch (211) fixedly mounted on the dielectric substrate (1) and rectangular slots (212) opened on the sides of the two main radiation patches (211) away from each other; The coplanar waveguide (3) includes a coplanar waveguide ground (33) fixedly mounted on one side of the dielectric substrate (1), a tapered signal line (32) fixedly arranged on one side of the coplanar waveguide ground (33), and a defective coplanar waveguide ground (31) fixedly arranged on the side of the tapered signal line (32) away from the coplanar waveguide ground (33).

2. The dual-frequency dipole airborne antenna for flight calibration according to claim 1, characterized in that: The serpentine bending mechanism (22) is composed of a plurality of "Z" - shaped bending segments connected in series.

3. The dual-frequency dipole airborne antenna for flight calibration according to claim 1, characterized in that: One end of the tapered signal line (32) and the coplanar waveguide ground (33) is electrically connected to the radiation arm (2). The inner core of the coaxial socket (4) is fixedly welded to the input end of the tapered signal line (32), and the grounding pins of the coaxial socket (4) are respectively fixedly welded tothe defective coplanar waveguide ground (31) and the coplanar waveguide ground (33).

4. The dual-frequency dipole airborne antenna for flight calibration according to claim 1, characterized in that: The defective coplanar waveguide ground (31) is rectangular, one side of the tapered signal line (32) away from the radiation arm (2) is rectangular, the other side of the tapered signal line (32) is trapezoidally tapered and connected to the radiation arm (2). The coplanar waveguide ground (33) is rectangular in shape, and the length of the coplanar waveguide ground (33) is the same as the length of the defective coplanar waveguide ground (31).

5. The dual-frequency dipole airborne antenna for flight calibration according to claim 1, characterized in that: The dielectric substrate (1) is an FR4 epoxy glass cloth substrate, and the radiation arms (2) and the coplanar waveguide (3) are both copper - printed circuit layers.

6. The dual-frequency dipole airborne antenna for flight calibration according to claim 1, characterized in that: The dielectric substrate (1) is installed between the lower radome (5) and the upper radome (6), and the lower radome (5) and the upper radome (6) are connected by bolts.

7. The dual-frequency dipole airborne antenna for flight calibration according to claim 6, characterized in that: Both the lower radome (5) and the upper radome (6) are made of fiberglass.

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