Miniaturized Broadband Transmitting Antenna for Shipborne Ground Wave Radar and its Debugging Method

Abstract

A miniaturized broadband transmitting antenna for shipborne ground-wave radar and its debugging method are disclosed, comprising a hollow plastic cylinder, a metal radiating column, several quarter-wavelength metal wires corresponding to different frequencies, a variable inductor composed of a spiral metal wire, and an insulating and corrosion-resistant outer shell. The metal radiating column is wrapped around the hollow plastic cylinder; each quarter-wavelength metal wire is bent into a specific shape and wrapped around the metal radiating column; the bottom ends of the wires are connected together and then connected in series with a variable inductor composed of a spiral metal wire; the other end of the inductor is connected to the antenna feed port; the insulating and corrosion-resistant outer shell is the outermost layer of the antenna. The debugging method includes: bending the quarter-wavelength metal wires; successively adding quarter-wavelength metal wires; and using the variable inductor of the spiral metal wire to achieve impedance matching. The antenna and matching network in this invention can be integrated, solving the miniaturization problem of ultra-wideband transmitting antennas for shipborne ground-wave radar and simplifying impedance matching, making it easier to meet the requirements of engineering practicality.

Description

Technical Field

[0001] This invention relates to a miniaturized broadband transmitting antenna for shipborne ground wave radar and its debugging method, belonging to the field of miniaturization technology of high-frequency broadband transmitting antennas. Background Technology

[0002] Shipborne ground wave radar, as a new type of radar, can achieve long-range and beyond-line-of-sight detection of maritime targets, stealth targets, and ultra-low-altitude flying targets, as well as continuous real-time monitoring of the marine environment over a wide area. It also features a mobile and flexible platform and an adjustable observation area, and has broad application prospects in fields such as safeguarding maritime rights and interests and preventing and controlling marine disasters.

[0003] As a crucial component in the construction of shipborne ground-wave radar systems, the ultra-wideband and miniaturization of the transmitting antenna are key challenges in the development of such systems. However, traditional electric antennas, when transmitting vertically polarized shortwave signals propagating along the coastal (land) surface, not only need to be "high" in height to meet the requirement of being comparable to the wavelength, but also need to be erected as high as possible to optimize signal transmission from the coastal surface. Clearly, meeting these "dual height" requirements is difficult on a shipborne mobile platform, and the various masts and metal structures on the ship often run parallel to the electric antenna, interfering with signal transmission.

[0004] Currently, the most successful approach to miniaturizing (reducing antenna height) the transmitting antenna for shore-based ground wave radar, particularly for shipborne ground wave radar, is the loop shortwave transceiver antenna. However, its application in ground wave radar reception is not ideal, and the required transmit power cannot be too high. Top loading is another method to shorten antenna height, but this requires numerous guy wires, which is impractical on ships. In comparison, quarter-wavelength single-stage antennas are commonly used, but their operating bandwidth is narrow, and even at the lower end of shortwave frequencies (i.e., within the frequency coverage range of shipborne ground wave radar), a quarter-wavelength antenna still has a relatively high height. For example, a quarter-wavelength antenna corresponding to 3 MHz is 25 meters.

[0005] For shipboard ground-wave radar systems, the desired antenna height should be significantly lower than the radar's wavelength, and the frequency coverage bandwidth should meet broadband standards to better adapt to the maritime application environment. To date, no electric antenna structure can simultaneously meet the requirements of miniaturization and broadband for shipborne ground-wave radar transmitting antennas. Therefore, it is necessary to find new structural forms for electric antennas to overcome current technical challenges and promote the development and application of shipborne ground-wave radar. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing a miniaturized broadband transmitting antenna for shipborne ground wave radar and its debugging method.

[0007] A miniaturized broadband transmitting antenna for shipborne ground wave radar is characterized by comprising a hollow plastic cylinder, a metal radiating column, several quarter-wavelength metal wires corresponding to different frequencies, and an insulating and corrosion-resistant outer shell. The metal radiating column is wrapped around the hollow plastic cylinder, and the metal radiating column 2 enhances the signal radiation efficiency and also enhances the mutual coupling between the quarter-wavelength metal wires 6. Each quarter-wavelength metal wire is bent and wound around the metal radiating column. The bending significantly reduces the height of the antenna without changing the resonant characteristics of the wire at the corresponding quarter-wavelength frequency. The equivalent inductance of the wire should be minimized during bending. The bottom ends of the quarter-wavelength metal wires are connected to form a convergence point, which is then connected to the transmit signal output port of the broadband transmitting antenna feed line or the output port of the broadband transmitting antenna tuner. The insulating and corrosion-resistant outer shell is located on the outermost layer of the broadband transmitting antenna and serves to protect the antenna body.

[0008] In use, each 1 / 4 wavelength metal wire 6 corresponds to a different frequency. The bottom ends of the 1 / 4 wavelength metal wires are connected together to form a convergence point, and then a variable inductor composed of a spiral metal wire is connected in series. The other end of the variable inductor is connected to the transmit signal output port of the antenna feed line, realizing the integration of the matching network and the antenna, improving the maintainability and ease of use of the antenna.

[0009] When the quarter-wavelength metal wires are wrapped around the metal radiating pillar, they are wrapped in order from shortest to longest. The shorter the quarter-wavelength metal wire, the shorter the corresponding wavelength, and the longer the corresponding wavelength. Wrapping the short wires inside, based on the skin effect, makes the interaction between the short and long wires more compact, which can effectively expand the overall bandwidth of the antenna, and also facilitates assembly and maintenance.

[0010] The 1 / 4 wavelength metal conductor is a single-strand hard copper wire. Compared with multi-strand copper wire, the working bandwidth is further widened, the reliability is further improved, and it has enhanced corrosion resistance and damage resistance.

[0011] Each quarter-wavelength metal conductor is bent into an "S-shape" or "stepped shape." These two shapes have been proven in practice to have lower conductor inductance and a higher compression ratio between conductor length and antenna height.

[0012] The spiral metal wire includes multiple intermediate taps, each tap connected to one end of a switch, and the other ends of all switches connected to one end of the spiral metal wire. By switching the switches on and off, the optimal center frequency of the antenna can be changed, allowing for fine-tuning of the matching network and enhancing design flexibility.

[0013] The impedance matching and debugging method for the miniaturized broadband transmitting antenna of shipborne ground wave radar according to the present invention is characterized by including the following steps:

[0014] a) Set the bending pattern of the 1 / 4 wavelength metal wire and the frequency corresponding to the first 1 / 4 wavelength metal wire;

[0015] b) Add a 1 / 4 wavelength metal wire, making its frequency 30kHz higher than the corresponding frequency of the previous one;

[0016] c) By closing the switch, the inductance formed by the spiral metal wire is finely adjusted using a tap method to detect whether the impedance is matched;

[0017] d) If there is no match, add another 1 / 4 wavelength metal wire, so that its corresponding frequency is 30kHz higher than the frequency of the previous 1 / 4 wavelength metal wire, until impedance matching is achieved.

[0018] e) Wrap the metal radiating column and each 1 / 4 wavelength metal wire with an insulating and corrosion-resistant outer shell.

[0019] This invention involves bending several quarter-wavelength metal wires corresponding to different frequency points into specific shapes and arranging them in combination. These are then wrapped together on a metal radiating column to form a broadband transmitting antenna, achieving a reduction in antenna height and miniaturization. The antenna and matching network in this invention can be integrated, and the center frequency can be fine-tuned via a switch, making the antenna more readily suitable for practical engineering applications. The antenna tuning method of this invention satisfies both the transmitting antenna's operating bandwidth and impedance matching, and also extends the bandwidth. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of each component of the transmitting antenna of the present invention;

[0021] Figure 2 This is a schematic diagram of the 1 / 4 wavelength metal wire bending configuration of the present invention;

[0022] Figure 3 This is a schematic diagram of the spiral metal wire 5 inductor structure of the present invention.

[0023] Among them, 1. Hollow plastic cylinder, 2. Metal radiating column, 3. Insulating and corrosion-resistant shell, 4. Gap, 5. Spiral metal wire, 6. 1 / 4 wavelength metal wire, 7. Converging point, 8. Transmit signal output port, 9. On / off switch group, 10. Tap. Detailed Implementation

[0024] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0025] Figure 1This is a schematic diagram of the structure of the transmitting antenna of the present invention. It includes: a hollow plastic cylinder 1, a metal radiating column 2, several quarter-wavelength metal wires 6 for different frequencies, and an insulating and corrosion-resistant outer shell 3. The metal radiating column 2 wraps around the hollow plastic cylinder 1, enhancing signal radiation efficiency and also strengthening the coupling between the quarter-wavelength metal wires 6. Each quarter-wavelength metal wire 6 is bent, wrapped around the metal radiating column 2 rather than twisted, to reduce the antenna height without changing the resonant characteristics of the corresponding frequency point. The bending shape is chosen to minimize the equivalent inductance of the wire. The bottom ends of the quarter-wavelength wires 6 are connected together to form a convergence point 7, which is then connected in series with a variable inductor formed by a spiral metal wire 5. The other end of the variable inductor is connected to the transmit signal output port 8 at the antenna feed line. This design integrates the matching network and the antenna, improving the antenna's maintainability and ease of use. The insulating and corrosion-resistant outer shell is the outermost layer of the antenna, protecting the antenna body.

[0026] Alternatively, the bottom ends of each quarter-wavelength conductor 6 can be connected together and directly connected to the antenna feed output port 8 or the antenna tuner output port. When directly connected to the antenna feed output port 8, effective transmission is possible as long as the transmission signal frequency is selected at the antenna's inherent optimal frequency point. When connected to the antenna tuner output port, there is greater freedom in selecting the transmission signal frequency point, which is determined by the external antenna tuner and is not within the scope of this invention.

[0027] Figure 2 This is a configuration diagram of the 1 / 4 wavelength metal wire of the present invention. Figure 2 (a) Corresponds to the “S” shape. Figure 2 (b) is a "trapezoidal" shape. In fact, there are many other shapes for the bend. The key is to choose the shape that results in a smaller inductance of the quarter-wavelength metal wire 6, so as not to affect the inherent characteristics of the quarter-wavelength metal wire 6 as a monopole antenna. This can be determined by comparing different shapes in actual operation.

[0028] Figure 3 This is a schematic diagram of the inductor structure of the spiral metal wire 5 of the present invention. The diagram includes: a spiral metal wire 5, taps 10, and switches 9. The spiral metal wire 9 constitutes an inductor. Each tap 10 is connected to one end of its respective switch 9. The other ends of all switches 9 are connected together and then connected to one end of the spiral metal wire 5. Fine-tuning of the inductance is achieved by switching the switches 9 on and off, thus achieving optimal matching between the transmitted center point frequency signal and the antenna.

[0029] Experiments show that the following design parameters can be adopted: a hollow plastic cylinder 1 with a diameter of Ø200mm and a height of 4500mm is used; a metal radiating column 2 covers the hollow plastic cylinder, leaving a 2mm gap 4; a 1 / 4 wavelength metal wire 6 is added according to each 30KHz step frequency, covering a bandwidth of 4MHz-5MHz; a spiral metal wire 5 has five turns of inductance with a turn spacing of 60mm; four switches 9 are used to fine-tune the inductance; when installed on a shipboard platform, its transmitting antenna has a standing wave ratio of less than 1.5 in the 4MHz-5MHz bandwidth, and the center frequency can be adjusted by selecting the four switches.

[0030] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art. For example, in the above embodiments, the 1 / 4 wavelength metal wire 6 can be of other configurations, such as having a sparser metal wire at the bottom of the antenna and a denser one at the top, i.e., wrapping them with unequal spacing; the spiral metal wire inductor can also adopt other forms of inductor; the order in which the various 1 / 4 wavelength metal wires 6 are wrapped can be changed, etc.

Claims

1. A shipboard ground wave radar compact broadband transmit antenna, characterized by It comprises a hollow plastic cylinder (1), a metal radiation column (2), several 1 / 4 wavelength metal wires (6) for corresponding different frequencies, and an insulating anticorrosive shell (3); the metal radiation column (2) is wrapped on the hollow plastic cylinder (1), each 1 / 4 wavelength metal wire (6) is bent and wound on the metal radiation column (2); the bottom ends of the 1 / 4 wavelength metal wires (6) are connected to form a convergence point (7), which is connected to a transmitting signal output port (8) of a wideband transmitting antenna feeder end or a wideband transmitting antenna tuner output port; the insulating anticorrosive shell (3) is located at the outermost layer of the wideband transmitting antenna; In use, the 1 / 4 wavelength metal wires (6) corresponding to different frequencies are connected to form the convergence point (7), and then a variable inductor composed of a spiral metal wire (5) is connected in series to the convergence point (7); the other end of the variable inductor is connected to the transmitting signal output port of the antenna feeder end; When the 1 / 4 wavelength metal wires (6) are wrapped on the metal radiation column (2), they are wrapped on the metal radiation column (2) in the order from short to long; Each 1 / 4 wavelength metal wire (6) is bent into an "S" shape or a "ladder" shape; The spiral metal wire (5) comprises multiple taps (10), each tap (10) is connected to one end of a switch (9), and the other end of all the switches (9) is connected to one end of the spiral metal wire (5).

2. The ship-borne ground wave radar miniaturized wideband transmit antenna according to claim 1, characterized in that The 1 / 4 wavelength metal wire (6) is a single copper wire.

3. The shipboard ground-wave radar miniaturized wideband transmit antenna of claim 1, wherein A hollow plastic cylinder (1) with a diameter of 200 mm and a height of 4500 mm is used; the metal radiation column (2) covers the hollow plastic cylinder and leaves a 2 mm gap (4); one 1 / 4 wavelength metal wire (6) is added every 30 KHz of frequency step to cover a bandwidth of 4 MHz-5 MHz, the spiral metal wire (5) has five turns with a turn spacing of 60 mm; four switches (9) are used for fine adjustment of inductance selection.

4. The method for impedance matching and tuning of a shipborne ground wave radar compact broadband transmitting antenna according to claim 1, characterized in that It comprises the following steps: a) setting the bending pattern of the 1 / 4 wavelength metal wire (6) and the frequency corresponding to the first 1 / 4 wavelength metal wire (6); b) adding one 1 / 4 wavelength metal wire (6) to increase the frequency by 30 KHz compared to the frequency corresponding to the previous 1 / 4 wavelength metal wire (6); c) using the tap method to realize fine adjustment of the inductor composed of the spiral metal wire (5) by closing the switch (9), and detecting whether the impedance is matched; d) if not matched, continue to add one 1 / 4 wavelength metal wire (6) to increase the frequency corresponding to the 1 / 4 wavelength metal wire (6) by 30 KHz compared to the frequency corresponding to the previous 1 / 4 wavelength metal wire (6) until the impedance is matched; e) finally, the metal radiation column (2) and the 1 / 4 wavelength metal wires (6) corresponding to different frequencies are wrapped with the insulating anticorrosive shell (3).

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