Reconfigurable transmissive array antenna with low radar cross section

Abstract

The application discloses a reconfigurable transmissive array antenna with low radar cross section, which comprises an amplitude modulation layer, a phase modulation layer and a feed source, wherein the feed source is used for transmitting or receiving electromagnetic waves; the amplitude modulation layer is used for absorbing electromagnetic waves in free space to reduce the radar cross section of the antenna; the phase modulation layer is used for modulating the transmission phase of incident electromagnetic waves received by the feed source, and the working frequency band of the amplitude modulation layer is located on both sides of the working frequency band of the phase modulation layer. The application can have the functions of fast beam switching, beam shaping and electromagnetic stealth, etc.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a reconfigurable transmission array antenna with a low radar cross section. Background Technology

[0002] High-gain array antennas can significantly improve the signal-to-noise ratio, and therefore have wide applications in long-distance communications such as satellite communications, deep space networks, and radar systems. In recent decades, many array technologies have developed rapidly, such as phased array antennas, reflective array antennas, and transmission array antennas. However, high-gain array antennas often have a large aperture area, inevitably generating strong scattering fields, greatly increasing the probability of the combat system being detected by enemy radar. Therefore, designing array antennas with high-gain in-band radiation and low out-of-band scattering characteristics is a necessary and challenging task.

[0003] Currently, there are few reports on radar cross section (RCS) reduction techniques for transmission array antennas, because it is quite difficult to effectively reduce the out-of-band RCS while maintaining low insertion loss transmission and 360° phase modulation capability. Furthermore, achieving electrically controllable beam scanning capability while maintaining a low RCS transmission array antenna is even more challenging. In recent years, electrically reconfigurable transmission array antennas have been widely used due to their advantages such as low cost, high gain, and electrically controllable beams. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] To address this, the present invention provides a reconfigurable transmission array antenna with low radar cross-section, comprising a feed and an array composed of multiple amplitude and phase modulation units. The feed is used to transmit or receive electromagnetic waves, and the amplitude and phase modulation units are used to modulate the amplitude or phase of electromagnetic waves incident from different directions. The amplitude and phase modulation units, from top to bottom, include an amplitude modulation layer, an air layer, and a phase modulation layer. The amplitude modulation layer absorbs incident electromagnetic waves in free space to reduce the antenna's radar cross-section, and the phase modulation layer modulates the transmission phase of the electromagnetic waves incident from the feed. The operating frequency band of the amplitude modulation layer is located on both sides of the operating frequency band of the phase modulation layer. The amplitude modulation layer, from top to bottom, includes a metal strip with lumped resistors and a dielectric substrate. The lumped resistors are placed at the center of the elongated strip, thereby achieving beam focusing and scanning performance.

[0006] To achieve the above objectives, this invention proposes a reconfigurable transmission array antenna with low radar cross-section, comprising an amplitude modulation layer, a phase modulation layer, and a feed source, wherein...

[0007] The feed source is used to transmit or receive electromagnetic waves;

[0008] The amplitude modulation layer is used to absorb electromagnetic waves in free space to reduce the radar cross-section of the antenna.

[0009] The phase modulation layer is used to modulate the transmission phase of the incident electromagnetic wave received by the feed source, and the operating frequency band of the amplitude modulation layer is located on both sides of the operating frequency band of the phase modulation layer.

[0010] The reconfigurable transmission array antenna with low radar cross-section according to the present invention may also have the following additional technical features:

[0011] Furthermore, the reconfigurable transmission array antenna also includes an air layer.

[0012] Furthermore, the feed source includes one of a horn antenna, a microstrip antenna, and a microstrip antenna array;

[0013] The amplitude modulation layer includes a metal strip and a dielectric substrate on which lumped resistors are disposed;

[0014] The phase modulation layer includes a top elongated metal patch, an upper dielectric substrate, a metal layer with openings, a lower dielectric substrate, and a bottom elongated metal patch with digital control devices.

[0015] Furthermore, the metal strip of the amplitude modulation layer and the top elongated metal patch of the phase modulation layer are parallel to each other; the top elongated metal patch and the bottom elongated metal patch are perpendicular to each other and connected to each other through metal vias. The metal vias pass through the metal layer through openings. The connection position between the metal vias and the top elongated metal patch is off-center from the patch center, and the connection position between the metal vias and the bottom elongated metal patch is at the patch center. The digital control devices are symmetrically distributed on both sides of the bottom elongated metal patch.

[0016] Furthermore, the dielectric substrate has a relative permittivity of 3 and a substrate thickness of 0.015 wavelengths.

[0017] Furthermore, the length of the top-layer elongated metal patch is determined by the operating frequency band of the reconfigurable transmission array antenna.

[0018] Furthermore, the digital control device includes one of a PIN diode, a varactor diode, and a MEMS diode.

[0019] Furthermore, the digital control device is the PIN diode, and the operating state of the PIN diode includes conduction and cutoff. Two PIN diodes are loaded on each structural unit of the reconfigurable transmission array antenna, with the positive terminal of one PIN connected to the negative terminal of the other PIN.

[0020] When a positive voltage is applied to both layers of the bottom strip metal patch simultaneously, one PIN operates in the on state while the other is in the off state. When a negative voltage is applied, the states of the two PINs are interchanged.

[0021] Furthermore, the reconfigurable transmission array antenna comprises 16*16 structural units, and the operating frequency band is the C-band.

[0022] The reconfigurable transmission array antenna with low radar cross section of this invention uses digital control devices to adjust the transmission phase of each element and uses a horn feed to illuminate the entire surface from space. By adjusting the phase of each element on the surface through digital control, a high-gain focused dynamic scanning beam, agile beam, or multi-beam can be obtained. It has the advantages of low feed loss, large beam scanning angle, omnidirectional beam coverage, and strong array scalability.

[0023] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0024] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0025] Figure 1 This is a schematic diagram of the reconfigurable transmission array antenna structure with low radar cross section according to the present invention.

[0026] Figure 2 This is a schematic diagram of the reconfigurable transmission array antenna element with low radar cross section according to the present invention.

[0027] Figure 3 This is a schematic diagram of the simulation results of the single-station radar cross section of the present invention;

[0028] Figures 4(a) and 4(b) are schematic diagrams of the simulation results of beam scanning in the E-plane and H-plane of the present invention, respectively. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0031] The following description, with reference to the accompanying drawings, describes a reconfigurable transmission array antenna with low radar cross-section according to an embodiment of the present invention.

[0032] like Figure 1 As shown, the reconfigurable transmission array antenna with low radar cross section in this embodiment of the invention includes an amplitude modulation layer 1, an air layer 2, a phase modulation layer 3, and a feed 4. The amplitude modulation layer 1 is used to absorb electromagnetic waves incident in free space to reduce the radar cross section of the antenna, thereby achieving antenna stealth. The phase modulation layer 3 is used to modulate the transmission phase of the electromagnetic waves emitted by the feed 4, thereby achieving beam focusing and scanning performance. The operating frequency band of the amplitude modulation layer is located on both sides of the operating frequency band of the phase modulation layer. The feed 4 is used to transmit and receive electromagnetic waves.

[0033] It is understandable that a feed source can include a horn antenna, a microstrip antenna, and a microstrip antenna array;

[0034] In one embodiment of the present invention, the feed source 4 adopts a conventional parabolic antenna feed source, which can be a pyramidal horn, a circular horn, or a corrugated horn antenna, and its polarization is linear polarization; the feed source 4 adopts a positive feed form, and the feed source position is optimal for the antenna with the highest efficiency.

[0035] In one embodiment of the present invention, the amplitude modulation layer 1 includes a metal strip and a dielectric substrate on which lumped resistors are disposed;

[0036] In one embodiment of the present invention, the phase modulation layer 3 includes a top elongated metal patch, an upper dielectric substrate, a metal layer with openings, a lower dielectric substrate, and a bottom elongated metal patch with digital control devices.

[0037] Furthermore, Figure 2 This is a structural diagram of a reconfigurable transmission array antenna element with low radar cross section according to an embodiment of the present invention.

[0038] like Figure 2As shown in the diagram, the reconfigurable transmission array antenna element structure of this invention includes, from top to bottom: a bent metal strip 1-1, a lumped resistor 1-2 located at the center of the bent metal strip, a dielectric substrate 1-3, an air layer 2, a top elongated metal patch 3-1, an upper dielectric substrate 3-2, a metal layer 3-3 with openings, a lower dielectric substrate 3-4, and a bottom elongated metal patch 3-6 with two digital control devices 3-5; the top elongated metal patch 3-1 and the bottom elongated metal patch 3-6 are perpendicular to each other and are connected by a metal through-hole 3- 7 and 3-8 are interconnected. Metal vias 3-7 and 3-8 pass through the metal layer 3-3 through the opening. The connection position of metal via 3-7 and the top elongated metal patch 3-1 is off-center from the patch center. The connection position of metal via 3-8 and the bottom elongated metal patch 3-6 is located at the patch center. Two digital control devices 3-5 are symmetrically distributed on both sides of the bottom elongated metal patch 3-6. The direction of the metal segment where the lumped resistor 1-2 is located in the metal strip 1-1 of the amplitude modulation layer is parallel to the top elongated metal patch 3-1 of the phase modulation layer.

[0039] In one embodiment of the present invention, the metal strip 1-1 is appropriately bent to reduce the unit period and improve the angular stability of the structure; the dielectric plate 1-3 is Rogers RO3003 with a relative permittivity of 3, but it is not limited to a plate with this electromagnetic parameter, and can also be a dielectric plate with other electromagnetic parameters. The electrical dimension thickness of the dielectric plate 1-3 can be very thin or even without dielectric, but considering that the loaded metal strip and lumped resistor device need to be supported by a dielectric plate with a certain rigidity, the plate thickness is selected to be 0.015 wavelengths.

[0040] In one embodiment of the present invention, the length of the top elongated metal patch 3-1 is determined by the operating frequency of the antenna; the dielectric substrates 3-2 and 3-4 are both Rogers RO3003 with a relative permittivity of 3, but are not limited to substrates with this electromagnetic parameter, and can also be dielectric substrates with other electromagnetic parameters; the digital control devices 3-5 are all PIN diodes, whose operating states include: on and off. Two PIN diodes are loaded on each structural unit, with the positive terminal of one PIN connected to the negative terminal of the other PIN. When a positive voltage is applied to both the bottom elongated metal patch 3-6 and the bottom layer, one PIN operates in the on state and the other is in the off state. When a negative voltage is applied, the states of the two PINs are interchanged, so the equivalent circuit of the entire unit will change accordingly. Under two different bias voltages, the transmission phase of the unit changes by 180 degrees, so the unit has the function of discrete phase control. By adjusting the bias voltage of each radiating element on the antenna surface, fast beam switching, beamforming and other functions can be achieved.

[0041] In one embodiment of the invention, the antenna operates in the C-band and comprises 16×16 structural elements. Due to its scalability, this design can also be extended to other antenna aperture sizes and frequency bands.

[0042] Furthermore, Figure 3 Figures 4(a) and 4(b) show the simulation results of the single-station radar cross section (RCS) of an embodiment of the present invention, respectively. It can be seen that the embodiment of the present invention achieves a 37% reduction in 10dB-RCS near the low-frequency 4.5GHz and a 9.4% reduction in 10dB-RCS near the high-frequency 11GHz. Furthermore, the embodiment of the present invention achieves ±60° beam scanning performance and high-gain beam focusing in both the E-plane and H-plane at 7.5GHz.

[0043] The reconfigurable transmission array antenna with low radar cross section according to embodiments of the present invention obtains a high-gain focused dynamic scanning beam, agile beam, or multiple beams. It has advantages such as low feed loss, large beam scanning angle, omnidirectional beam coverage, and strong array scalability. By using a metal strip loaded with lumped resistance, the out-of-band radar cross section of the antenna can be effectively reduced, which greatly improves the antenna's stealth capability. It combines the characteristics of low radar cross section and electrically reconfigurable characteristics of transmission array antenna, and has the characteristics of low cost and simple structure, thus solving the technical blind spots in academia and industry.

[0044] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0045] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

Claims

1. A reconfigurable transmission array antenna with low radar cross-section, characterized in that, It includes an amplitude modulation layer, a phase modulation layer, and a feed source, among which, The feed source is used to transmit or receive electromagnetic waves; The amplitude modulation layer is used to absorb electromagnetic waves in free space to reduce the radar cross-section of the antenna. The phase modulation layer is used to modulate the transmission phase of the incident electromagnetic wave received by the feed source, and the operating frequency band of the amplitude modulation layer is located on both sides of the operating frequency band of the phase modulation layer. The reconfigurable transmission array antenna also includes an air layer; The feed source includes one of a horn antenna, a microstrip antenna, and a microstrip antenna array; The amplitude modulation layer includes a metal strip and a dielectric substrate on which lumped resistors are disposed; The phase modulation layer includes a top elongated metal patch, an upper dielectric substrate, a metal layer with openings, a lower dielectric substrate, and a bottom elongated metal patch with digital control devices. The metal strip of the amplitude modulation layer and the top elongated metal patch of the phase modulation layer are parallel to each other; the top elongated metal patch and the bottom elongated metal patch are perpendicular to each other and connected to each other through metal vias. The metal vias pass through the metal layers through openings. The connection position between the metal vias and the top elongated metal patch is off-center from the patch center, and the connection position between the metal vias and the bottom elongated metal patch is at the patch center. The digital control devices are symmetrically distributed on both sides of the bottom elongated metal patch.

2. The reconfigurable transmission array antenna according to claim 1, characterized in that, The dielectric substrate has a relative permittivity of 3 and a substrate thickness of 0.015 wavelengths.

3. The reconfigurable transmission array antenna according to claim 1, characterized in that, The length of the top-layer elongated metal patch is determined by the operating frequency band of the reconfigurable transmission array antenna.

4. The reconfigurable transmission array antenna according to claim 1, characterized in that, The digital control device includes one of a PIN diode, a varactor diode, and a MEMS diode.

5. The reconfigurable transmission array antenna according to claim 4, characterized in that, The digital control device is the PIN diode. The operating states of the PIN diode include on and off. Two PIN diodes are loaded on each structural unit of the reconfigurable transmission array antenna, with the positive terminal of one PIN connected to the negative terminal of the other PIN. When a positive voltage is applied to both layers of the bottom strip metal patch simultaneously, one PIN operates in the on state while the other is in the off state. When a negative voltage is applied, the states of the two PINs are interchanged.

6. The reconfigurable transmission array antenna according to claim 3, characterized in that, The reconfigurable transmission array antenna comprises 16*16 structural units, and the operating frequency band is the C-band.

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