Ultra-wideband miniaturized vertical polarization end-fire antenna

Abstract

The application discloses a kind of ultra-wideband miniaturized vertical polarization end-fire antennas, belong to wireless communication technology and radar technology field.The antenna includes columnar metal carrier, half-module Vivaldi antenna and PCB top plate;Half-module Vivaldi antenna is uniformly arranged on the outside of metal carrier, and PCB top plate is arranged above half-module Vivaldi antenna, and they are vertically arranged and electrically connected;Arc-round combined slot is arranged on the radiation patch of half-module Vivaldi antenna, first rectangular slot is arranged on the PCB top plate, and they are communicated and synergistic, form slot radiation mode working in low frequency band;Two rows of periodic U-shaped slots are further arranged on the PCB top plate, compensate the impedance mismatch caused by ground current change, break the horizontal polarization current path at the same time, improve the cross polarization performance of antenna.The application adopts half-module low profile Vivaldi structure, reduces the space occupied by antenna;Through slot radiation mode, working cut-off frequency is effectively reduced, and low frequency bandwidth is expanded;Periodic slotting structure improves cross polarization characteristics and realizes good conformal.The application has the characteristics of ultra-wideband and miniaturization, and is suitable for wireless communication and radar system.

Description

Technical Field

[0001] This invention belongs to the fields of wireless communication technology and radar technology, and specifically relates to an ultra-wideband miniaturized vertically polarized end-fire antenna. Background Technology

[0002] The rapid development of aircraft technology in recent years has created a demand for small, stable, and reliable direction-finding radar systems, posing significant challenges to antenna performance. An ideal direction-finding antenna must not only be miniaturized to accommodate increasingly compact terminal equipment installations but also possess low-profile conformal capabilities to match the aerodynamic shape of the aircraft. Vertically polarized end-fire antennas can cover the airspace along the aircraft's flight path, providing guidance. Meanwhile, to meet the demands of transmitting massive amounts of signals, ultra-wideband technology, with its advantages of low power consumption, resistance to multipath interference, and high data transmission rates over short distances, is a crucial indicator supporting direction-finding radar systems.

[0003] Existing ultra-wideband vertically polarized end-fire antennas struggle to simultaneously achieve both low profile and small footprint. Reducing the profile causes the real part of the input impedance of the end-fire vertically polarized antenna to approach zero at low frequencies, significantly decreasing the bandwidth. Increasing the antenna's lateral dimensions can expand the bandwidth, but this also leads to a larger footprint. Therefore, overcoming the mutual constraint between antenna bandwidth and antenna size is a pressing research challenge. This invention addresses the challenges of integrating ultra-wideband, miniaturized, vertically polarized, and end-fire antenna technologies.

[0004] The 2023 paper "Deng Dongliang. Research on 10-octave ultra-wideband low-profile antenna and tightly coupled array [D]. Nanjing: Nanjing University of Science and Technology, 2023" proposes and analyzes a half-mode Vivaldi antenna loaded with a pure metal top plate. This antenna achieves a relative bandwidth of 185.5% and occupies a space of 0.014 λ. low 3 (λ) low (The lowest operating frequency wavelength); the article points out that the larger the metal top plate, the better the in-band matching of the antenna, but this cannot achieve a small footprint.

[0005] The design challenge of this type of antenna lies in the fact that a smaller antenna size leads to deterioration in low-frequency impedance, resulting in a reduction in antenna bandwidth. Existing designs can achieve bandwidths of over 4 octaves on their own, and can also achieve smaller antenna sizes on their own. However, they cannot simultaneously meet the requirements of ultra-wideband applications (over 4 octaves) and smaller antenna sizes. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention proposes an ultra-wideband miniaturized vertically polarized end-fire antenna. The main radiator of this antenna employs a half-mode Vivaldi antenna structure, and the antenna bandwidth is extended and cross-polarization is optimized by loading a PCB top plate, making it suitable for applications such as aircraft direction-finding systems.

[0007] The technical solution adopted in this invention is as follows:

[0008] An ultrawideband miniaturized vertically polarized end-fire antenna includes a metal carrier, a half-mode Vivaldi antenna, and a PCB top plate;

[0009] The metal carrier is a cylinder or a regular polygonal cylinder; the outer surface of the metal carrier is provided with a first elongated groove arranged at equal intervals for inserting and fixing a half-mode Vivaldi antenna.

[0010] The half-mode Vivaldi antenna, used for end-firing vertically polarized waves, includes an antenna substrate, a radiating patch disposed on the front side of the antenna substrate, and a microstrip feed line disposed on the back side.

[0011] The bottom end of the antenna substrate is inserted into the first elongated groove, and the top end is inserted into the second elongated groove;

[0012] The top side of the radiating patch is a straight edge that coincides with the top side of the antenna substrate, and the bottom side is configured with an exponentially tapered groove. The starting end of the exponentially tapered groove is connected to a semi-circular groove. A metal carrier is used as a mirror ground plane to form a half-mode Vivaldi antenna. The radiating patch is provided with an arc-circular combination groove. The opening end of the arc-circular opening groove is located on the straight edge of the radiating patch. The left side from the opening end downwards is a smooth curve that bends to the right, the right side is a straight line, and the end is configured as a circular groove.

[0013] The microstrip feed line is used to power the half-mode Vivaldi antenna;

[0014] The PCB top plate is located above the half-mode Vivaldi antenna, and the two are arranged vertically and electrically connected; the PCB top plate includes a top dielectric substrate and a metal layer covering the back of the top dielectric substrate;

[0015] A second elongated groove is provided on the lower side of the top dielectric substrate along the centerline for inserting and fixing a half-mode Vivaldi antenna;

[0016] The metal layer has a first rectangular groove etched in the middle, corresponding to the arc-shaped opening groove. The two work together to form a groove radiation mode that operates in the low frequency band, thus expanding the low frequency bandwidth.

[0017] Preferably, the radiating patch is further provided with a plurality of parallel rectangular slots; the rectangular slots are of the same size, are equally spaced, and the opening ends are located on the straight side of the radiating patch.

[0018] Preferably, the microstrip feed line has a consistent linewidth, its starting end is a straight segment connected to the SMA coaxial feed line, and its ending end gradually becomes an arc curve and is connected to the metal carrier to achieve balanced antenna feeding.

[0019] Preferably, when the metal carrier is a regular polygonal prism, the left side of the metal layer is provided with two rows of periodic U-shaped grooves; the two rows of periodic U-shaped grooves are mirror symmetrical about the center line of the PCB top plate and have opposite opening directions.

[0020] Preferably, the metal layer is further provided with a gradient rectangular slot array; the gradient rectangular slot array includes several parallel and equally spaced second rectangular slots, the width of the second rectangular slots is the same, the length increases uniformly from right to left, and at least one rectangular slot is located to the left of the first rectangular slot; by setting a gradient rectangular slot array with varying length gradient, the current distribution on the PCB top plate surface is controlled to achieve impedance matching optimization in the ultra-wideband.

[0021] Preferably, the length of the second rectangular slot located to the left of the first rectangular slot is less than that of the longest second rectangular slot and greater than that of the shortest second rectangular slot; by adjusting the length of the second rectangular slot at the end, the antenna impedance matching can be further optimized.

[0022] This invention uses a metal carrier as the mirror ground plane for the Vivaldi antenna, utilizing the principle of electromagnetic mirroring to achieve a low profile with half the height of the Vivaldi antenna. Addressing the issue that the miniaturized Vivaldi antenna itself has a high cutoff frequency, failing to meet low-frequency coverage requirements, this invention etches a combination of arc and circular slots on the radiating patch, connecting it to a first rectangular slot on the PCB top plate. This combined slotting technique of the half-mode Vivaldi antenna and the PCB top plate creates a resonant cavity, forming a resonant mode operating in the low-frequency band, effectively extending the antenna's low-frequency bandwidth.

[0023] Furthermore, when a regular polygonal prism is used as the carrier of the Vivaldi antenna, the ground current distribution on the carrier surface differs from that on the planar ground, leading to a deterioration in the antenna's in-band matching performance. This invention compensates for the impedance mismatch caused by the change in ground current by setting two rows of U-shaped slots on the top plate of the PCB. At the same time, this structure breaks the horizontal polarization current path, thereby improving the antenna's cross-polarization performance.

[0024] In summary, the beneficial effects of the present invention are as follows:

[0025] 1. This invention designs an ultra-wideband miniaturized vertically polarized end-fire antenna. The radiator of this antenna adopts a half-mode low-profile Vivaldi antenna, which achieves a smaller footprint compared to traditional structures.

[0026] 2. This invention designs and utilizes the slot radiation mode formed by the main radiator and the PCB top plate, which effectively reduces the antenna cutoff frequency and achieves a larger bandwidth.

[0027] 3. The periodic slotted structure etched on the top plate of the PCB in this invention can effectively improve the cross-polarization performance of the antenna and achieve a good conformal effect. Attached Figure Description

[0028] Figure 1 This is a perspective view of the ultra-wideband miniaturized vertically polarized end-fire antenna array provided in an embodiment of the present invention.

[0029] Figure 2 This is a perspective view of the half-mode Vivaldi antenna provided in an embodiment of the present invention.

[0030] Figure 3 This is a perspective view of the PCB top plate provided in an embodiment of the present invention.

[0031] Figure 4 This is a perspective view of the antenna unit provided in an embodiment of the present invention.

[0032] Figure 5 These are the S-parameters of the ultra-wideband miniaturized vertically polarized end-fire antenna provided in this embodiment of the invention.

[0033] Figure 6 These are the E-plane and H-plane radiation patterns of the ultra-wideband miniaturized vertically polarized horizontal omnidirectional radiating antenna provided in this embodiment of the invention at 2 GHz, 5 GHz, and 8 GHz.

[0034] Explanation of reference numerals in the attached drawings: 1. Half-mode Vivaldi antenna; 11. Antenna substrate; 12. Arc-circular combination slot; 13. Open rectangular slot; 14. Semi-circular slot; 15. Microstrip feed line; 2. PCB top plate; 21. Top dielectric substrate; 22. Metal layer; 23. First rectangular slot; 24. U-shaped slot; 25. Second rectangular slot; 3. Metal carrier. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0036] This embodiment provides an ultra-wideband miniaturized vertically polarized end-fire antenna operating in the 2–8 GHz frequency band, the structure of which is as follows: Figure 1As shown, it includes a metal carrier, a half-mode Vivaldi antenna, and a PCB top plate.

[0037] The metal carrier is a regular octagonal prism with a height of 87.0 mm; the outer surface of the regular octagonal prism is 45.5 mm wide, and a first elongated groove is provided at the center of each outer surface for inserting and fixing a half-mode Vivaldi antenna.

[0038] The half-mode Vivaldi antenna, such as Figure 2 As shown, for end-firing vertically polarized waves, it includes an antenna substrate, a radiating patch disposed on the front side of the antenna substrate, and a microstrip feed line disposed on the back side.

[0039] The antenna substrate is a rectangular substrate with a length of 75.0 mm and a width of 11.0 mm. Its bottom end is inserted into a first elongated groove in the metal carrier, and its top end is inserted into a second elongated groove in the PCB top plate.

[0040] The top side of the radiating patch is a straight edge that coincides with the top side of the antenna substrate. The bottom side is configured with an exponentially tapered groove. The starting end of the exponentially tapered groove connects to a semi-circular groove with a radius of 6.0 mm. A metal carrier serves as a mirror ground plane, thereby forming a half-mode Vivaldi antenna. The radiating patch also has an arc-circular combination groove and four open rectangular grooves. The opening end of the arc-circular opening groove is located on the straight edge of the radiating patch. The left side from the opening end downwards is a smooth curve curving to the right, and the right side is a straight line, with a circular groove at the end. The length × width of the open rectangular groove is 5.0 mm × 1.0 mm, the spacing is 3.0 mm, and its opening end is located on the straight edge of the radiating patch, which is used to further optimize impedance matching.

[0041] The microstrip feed line has a linewidth of 2.5 mm. Its starting end is a straight segment connected to the SMA coaxial feed line, and its ending end gradually becomes an arc curve and is welded to the metal carrier to achieve balanced antenna feeding.

[0042] like Figures 3-4 As shown, the PCB top plate is located above the half-mode Vivaldi antenna, and the two are arranged vertically and electrically connected; the PCB top plate includes a top dielectric substrate and a metal layer covering the bottom surface of the top dielectric substrate.

[0043] The top dielectric substrate has a length × width of 75.0 mm × 25.8 mm, and a second elongated groove is provided on its lower side along the center line for inserting and fixing a half-mode Vivaldi antenna.

[0044] The metal layer has a first rectangular groove etched in the middle, corresponding to the arc-shaped opening groove, with a length × width of 25.0 mm × 5.0 mm; the two work together to form a groove radiation mode that operates in the low frequency band, thus expanding the low frequency bandwidth.

[0045] The left side of the metal layer is provided with two rows of periodic U-shaped grooves. Each row of U-shaped grooves has 5 grooves, a period of 4.4 mm, a groove line width of 1.2 mm, and a longest side of 10.8 mm. The two rows of periodic U-shaped grooves are mirror symmetrical about the center line of the PCB top plate and have opposite opening directions.

[0046] The metal layer is also provided with a gradient rectangular slot array; the gradient rectangular slot array includes 15 parallel and equally spaced second rectangular slots, the 11th, 12th and 13th second rectangular slots from right to left at least partially overlap with the first rectangular slots; the width of the second rectangular slots is 1.0 mm, the spacing is 3.0 mm, the length of the rightmost second rectangular slot is 9.0 mm, the length increases from right to left in a gradient of 1.0 mm, and the length of the two leftmost second rectangular slots is shortened to 13.0 mm; by setting a gradient rectangular slot array with varying length gradients and optimizing the length of the leftmost slot, the current distribution on the PCB top plate surface is controlled, and impedance matching optimization in the ultra-wideband is achieved.

[0047] Figure 5 The simulation results of the S-parameters of the antenna in this embodiment are presented. As can be seen from the figure, the antenna exhibits an impedance bandwidth of 4th harmonics with |S11| ≤ -9dB within the 2–8 GHz range.

[0048] Figure 6 The E-plane and H-plane radiation patterns of the antenna in this embodiment at 2 GHz, 5 GHz, and 8 GHz are shown. As can be seen from the figures, the antenna has a stable end-fire pattern in the E and H planes, and the end-fire cross-polarization ratio is greater than 10 dBi in the frequency range of 2–8 GHz.

Claims

1. An ultra-wideband miniaturized vertically polarized end-fire antenna, characterized in that, Includes metal carrier, half-mode Vivaldi antenna, and PCB top plate; The metal carrier is a cylinder or a regular polygonal cylinder; the outer surface of the metal carrier is provided with a first elongated groove arranged at equal intervals for inserting and fixing a half-mode Vivaldi antenna. The half-mode Vivaldi antenna, used for end-firing vertically polarized waves, includes an antenna substrate, a radiating patch disposed on the front side of the antenna substrate, and a microstrip feed line disposed on the back side. The bottom end of the antenna substrate is inserted into the first elongated groove, and the top end is inserted into the second elongated groove; The top side of the radiating patch is a straight edge that coincides with the top side of the antenna substrate, and the bottom side is configured with an exponentially tapered groove. The starting end of the exponentially tapered groove is connected to a semi-circular groove. A metal carrier is used as a mirror ground plane to form a half-mode Vivaldi antenna. The radiating patch is provided with an arc-circular combination groove. The opening end of the arc-circular opening groove is located on the straight edge of the radiating patch. The left side from the opening end downwards is a smooth curve that bends to the right, the right side is a straight line, and the end is configured as a circular groove. The microstrip feed line is used to power the half-mode Vivaldi antenna; The PCB top plate is located above the half-mode Vivaldi antenna, and the two are arranged vertically and electrically connected; the PCB top plate includes a top dielectric substrate and a metal layer covering the back of the top dielectric substrate; A second elongated groove is provided on the lower side of the top dielectric substrate along the centerline for inserting and fixing a half-mode Vivaldi antenna; The metal layer has a first rectangular groove etched in the middle, corresponding to the arc-shaped opening groove. The two work together to form a groove radiation mode that operates in the low frequency band, thus expanding the low frequency bandwidth.

2. The ultra-wideband miniaturized vertically polarized end-fire antenna as described in claim 1, characterized in that, The radiating patch is also provided with a number of parallel rectangular slots; the rectangular slots are of the same size, are equally spaced, and the opening ends are located on the straight side of the radiating patch.

3. The ultra-wideband miniaturized vertically polarized end-fire antenna as described in claim 2, characterized in that, The microstrip feed line has a consistent linewidth. Its starting end is a straight segment connected to the SMA coaxial feed line, and its ending end gradually becomes an arc curve and is connected to the metal carrier to achieve balanced antenna feeding.

4. An ultra-wideband miniaturized vertically polarized end-fire antenna as described in any one of claims 1-3, characterized in that, When the metal carrier is a regular polygonal prism, two rows of periodic U-shaped grooves are provided on the left side of the metal layer; the two rows of periodic U-shaped grooves are mirror symmetrical about the center line of the PCB top plate and have opposite opening directions.

5. The ultra-wideband miniaturized vertically polarized end-fire antenna as described in claim 4, characterized in that, The metal layer is also provided with a gradient rectangular groove array; the gradient rectangular groove array includes several parallel and equally spaced second rectangular grooves, the width of the second rectangular grooves is the same, the length increases uniformly from right to left, and at least one rectangular groove is located to the left of the first rectangular groove.

6. The ultra-wideband miniaturized vertically polarized end-fire antenna as described in claim 5, characterized in that, The length of the second rectangular groove located to the left of the first rectangular groove is less than that of the longest second rectangular groove and greater than that of the shortest second rectangular groove.

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