A protective cassegrain antenna with field-induced transmission subreflector

Abstract

The application belongs to the technical field of antennas and relates to a protective Cassegrain antenna with a field-induced transmission sub-reflector, which comprises a support, a feed source, a main reflector and a protective array. The protective array comprises a plurality of protective units, each of which comprises a dielectric layer and a radiation layer. The radiation layer comprises four first radiation patches and four second radiation patches. The first radiation patches are triangular in structure and are rotationally symmetrical about the center of the dielectric layer. The second radiation patches are strip-shaped in structure, one corresponding end of each of which is arranged at the center of the dielectric layer, and the other corresponding end of each of which is arranged at a corner of the dielectric layer to form a cross-shaped structure, and the symmetry axis of the strip-shaped structure coincides with the diagonal of the dielectric layer. The first radiation patches and the second radiation patches are arranged at intervals, and a diode is arranged on each of the second radiation patches to achieve electromagnetic protection by changing the states of different diodes. The protective array is used as a sub-reflector to form the Cassegrain antenna. The application can achieve electromagnetic protection of the Cassegrain antenna.

Description

Technical Field

[0001] The present application relates to the field of antenna technology, and in particular to a protective Cassegrain antenna with a field-induced transmission sub-reflector. Background Art

[0002] Electromagnetic pulse weapons are a highly efficient electronic warfare technology that can attack electronic equipment such as radars, communication systems, and navigation equipment by releasing powerful electromagnetic pulses. The principle is to use electromagnetic pulse interference to destroy target electronic equipment and make it lose its combat capability.

[0003] With the development of powerful electromagnetic weapons, this new form of warfare is gradually entering actual combat, posing a significant threat to the viability and operational effectiveness of electronic information systems such as communications and radar systems. Due to the high sensitivity of electronic information equipment in communications and radar systems, strong electromagnetic pulses can easily cause interference, damage, or even burn through the equipment. To ensure the normal operation of sensitive systems under attack from powerful electromagnetic weapons, appropriate protective measures are necessary.

[0004] Extensive research has been conducted both domestically and internationally on the mechanisms of strong electromagnetic pulse coupling in devices. However, much of this research focuses on backdoors. While electromagnetic protection technology for these devices is already mature, frontdoor protection primarily relies on additional components like limiters and frequency-selective surfaces to achieve effective protection. Furthermore, current frontdoor protection technology suffers from large field protection structures, difficulty in achieving common designs, and high costs.

[0005] However, with the development of technology, Cassegrain antennas have been widely used in communication and radar system equipment. They are core components of communication systems and radar systems, with broadband characteristics and simple structure. However, they are also the main way to protect radar communication systems from strong electromagnetic attacks. How to achieve electromagnetic protection for Cassegrain antennas is of great significance and challenging. Summary of the Invention

[0006] Based on this, it is necessary to provide a protective Cassegrain antenna with a field-transmitting sub-reflector to address the above technical problems, which can achieve strong electromagnetic protection for the Cassegrain antenna.

[0007] A protective Cassegrain antenna with a field-transmission sub-reflector, comprising: a bracket, a feed source, a main reflector, and a protective array;

[0008] The protection array includes a plurality of protection units distributed in an array, and the protection unit includes: a dielectric layer and a radiation layer arranged on top of the dielectric layer;

[0009] The dielectric layer is a flat plate structure;

[0010] The radiation layer includes: four first radiation patches and four second radiation patches; the first radiation patch is a triangular structure, and the four first radiation patches are rotationally symmetrically distributed about the center of the dielectric layer; the second radiation patch is an axisymmetric strip structure, one corresponding end of the strip structure is arranged at the center of the dielectric layer, and the other corresponding ends are respectively arranged at the four corners of the dielectric layer, so that the four second radiation patches form a "cross" structure, and the symmetry axis of the strip structure in the length direction coincides with a diagonal line of the dielectric layer; the first radiation patch and the second radiation patch are arranged at intervals, and a diode is provided on the second radiation patch to achieve electromagnetic protection by changing the working state of the diode on different protection units;

[0011] The protection array has a field-induced transmission characteristic. The protection array serves as a secondary reflector, and the secondary reflector, the bracket, the feed source, and the main reflector together form a Cassegrain antenna.

[0012] In one embodiment, the first radiation patch is an isosceles right triangle structure, and the hypotenuse of the isosceles right triangle structure is collinear with the side of the dielectric layer.

[0013] In one embodiment, a square groove is provided on the right-angled side of the isosceles right-angled triangle structure.

[0014] In one embodiment, two diodes are provided on each second radiation patch.

[0015] In one embodiment, the two diodes on each second radiation patch are in opposite directions, and the four diodes near the center of the dielectric layer are in the same direction.

[0016] In one embodiment, the diode far from the center of the dielectric layer is arranged on the symmetry axis of two adjacent grooves.

[0017] In one embodiment, the width of the second radiation patch is changed to achieve frequency shift.

[0018] In one embodiment, a width of the second radiation patch is smaller than a side length of the groove.

[0019] In one embodiment, the dielectric layer is a square structure, and the radiation layer is a centrosymmetric structure.

[0020] In one embodiment, the bracket is arranged on the antenna platform, the main reflecting surface is arranged on the bracket, the feed source is arranged at the center of the main reflecting surface, and the secondary reflecting surface is arranged on the main reflecting surface and is spaced apart and parallel to the plane where the opening of the main reflecting surface is located.

[0021] The above-mentioned protective Cassegrain antenna with a field-induced transmission sub-reflector is an energy-selective Cassegrain antenna, which uses a protection array as a sub-reflector, and the protection units in the protection array are field-induced transmission energy-selective units (also a high-pass energy-selective unit, which reflects weak electromagnetic waves at low electromagnetic energy and transmits strong electromagnetic waves at strong electromagnetic energy). When facing normal electromagnetic waves (i.e., weak electromagnetic waves) or strong electromagnetic waves, the diodes can be adaptively cut off or turned on to adaptively change the reflection or transmission state of the protection units, thereby achieving normal operation and strong electromagnetic protection. At the same time, the protection array of the present application is a square planar structure, with a square plane sub-reflector replacing the circular arc sub-reflector, and a protection array composed of field-induced transmission energy-selective units replacing the pure metal sub-reflector, which has strong electromagnetic protection capabilities, reduces the difficulty of conformality, and can still maintain good gain and radiation patterns. In other words, under the same focal ratio, the present application enables the antenna to have strong electromagnetic protection capabilities, can be adjusted according to changes in electric field strength, and does not affect the performance of the antenna during normal operation, thereby reducing the cost of electromagnetic protection. Furthermore, the protection units of this application are distributed in an axially, centrally, and rotationally symmetrical manner, enabling the antenna to protect against strong electromagnetic wave attacks from any angle. This application can be applied to Cassegrain antennas in radar communication systems, providing a reliable solution to addressing the ever-increasing electromagnetic interference and security needs, and possesses strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of a protection unit of a protective Cassegrain antenna with a field-transmission sub-reflector according to one embodiment;

[0023] Figure 2 FIG1 is a schematic diagram of a protective Cassegrain antenna with a field-transmission sub-reflector in one embodiment;

[0024] Figure 3 is a diagram of the transmission coefficient and reflection coefficient of the protection unit in the conductive state in one embodiment;

[0025] Figure 4 is a diagram of the transmission coefficient and reflection coefficient of the protection unit in the cut-off state in one embodiment;

[0026] Figure 5 FIG1 is a front view of a Cassegrain antenna without a sub-reflector in one embodiment;

[0027] Figure 6 FIG1 is a front view of a Cassegrain antenna based on a square metal plate sub-reflector according to an embodiment;

[0028] Figure 7 A front view of a Cassegrain antenna based on a protective array sub-reflector in one embodiment;

[0029] Figure 8 A side view of a Cassegrain antenna based on a guard array sub-reflector according to one embodiment;

[0030] Figure 9 A one-dimensional Cartesian coordinate gain comparison diagram of a Cassegrain antenna in one embodiment;

[0031] Figure 10 FIG. 1 is a one-dimensional polar coordinate gain comparison diagram of a Cassegrain antenna in one embodiment.

[0032] Reference numerals:

[0033] dielectric layer 1;

[0034] Radiation layer 2, first radiation patch 21, second radiation patch 22, diode 23, groove 24;

[0035] Normal electromagnetic wave A, strong electromagnetic wave B, protection unit C. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in this application without creative work are within the scope of protection of this application.

[0037] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0038] In addition, the terms "first," "second," and so on, used in this application are for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, "multiple groups" means at least two groups, such as two groups, three groups, and so on, unless otherwise specifically defined.

[0039] In this application, unless otherwise specified or limited, the terms "connect," "fix," etc. should be understood in a broad sense. For example, "fix" can mean a fixed connection, a detachable connection, or an integral connection; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean internal communication between two elements or an interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0040] In addition, the technical solutions between the various embodiments of the present application can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0041] The present application provides a protective Cassegrain antenna with a field-induced transmission sub-reflector, such as Figure 1 As shown, in one embodiment, it includes: a bracket, a feed source, a main reflecting surface and a protection array.

[0042] The protection array exhibits field-induced transmission characteristics, with the protection array serving as a secondary reflector. The secondary reflector, along with the bracket, feed, and primary reflector, forms a Cassegrain antenna. Specifically, the bracket is mounted on an antenna platform (the platform on which the antenna is to be mounted), the primary reflector is mounted on the bracket, the feed is located at the center of the primary reflector and illuminates the secondary reflector, and the secondary reflector is mounted on the primary reflector and spaced parallel to the plane where the opening of the primary reflector is located. It should be noted that a horn waveguide can be used as the feed. The bracket, feed, primary reflector, and their interconnection methods are all prior art and will not be further described here.

[0043] The protection array includes: multiple protection units, and the multiple protection units are distributed in an array. The specific number of protection units is set according to the focal diameter ratio.

[0044] The protection unit includes: a dielectric layer and a radiation layer, the dielectric layer is made of non-metallic material, and the radiation layer is made of metallic material.

[0045] The dielectric layer is a flat plate structure. Preferably, the dielectric layer is a square flat plate structure, so that the plurality of protection units form a square protection array.

[0046] The radiation layer is arranged on the top of the dielectric layer and has a central symmetrical structure, including: a first radiation patch, a second radiation patch and a diode; the first radiation patch and the second radiation patch are arranged at intervals, and the distance between any first radiation patch and the adjacent second radiation patch is equal.

[0047] There are four first radiation patches, all of which are triangular structures, and the four first radiation patches are rotationally symmetrically distributed about the center of the dielectric layer, so that the protection unit can reach the resonance point when the diode is cut off and turned on.

[0048] Preferably, the first radiation patch is an isosceles right triangle structure, and the hypotenuse of the isosceles right triangle structure is collinear with the side of the dielectric layer to enhance the resonance effect and thereby improve the antenna performance.

[0049] Further preferably, square grooves are provided on the right-angled sides of the isosceles right triangle structure to enhance the stability of the antenna dual polarization, wherein the dual polarization refers to linear polarization and circular polarization.

[0050] There are four second radiation patches, all of which are strip structures. One corresponding end of the strip structure is located at the center of the dielectric layer, and the other corresponding ends are located at the four corners of the dielectric layer, so that the four second radiation patches form a "cross" structure as a whole; the second radiation patch is an axisymmetric structure, and the symmetry axis of the strip structure in the length direction coincides with a diagonal line of the dielectric layer, that is, the symmetry axis of the two oppositely arranged strip structures along the length direction coincides with a diagonal line of the dielectric layer, and the symmetry axis of the other two oppositely arranged strip structures along the length direction coincides with the other diagonal line of the dielectric layer.

[0051] Preferably, the width of the second radiation patch is changed to achieve frequency shift.

[0052] Further preferably, the width of the second radiation patch is smaller than the side length of the groove, so that the capacitance formed by the coupling between the second radiation patch and the first radiation patch is smaller, and the capacitance can meet the requirement of the unit to achieve resonance.

[0053] There are eight diodes, divided into four equal groups. The two diodes in each group are arranged on a second radiation patch to adaptively change the resonance mode when different electromagnetic waves are incident, and to ensure that resonance can be achieved when the diodes are cut off or turned on at the same frequency point; the directions of the two diodes on each second radiation patch are opposite, and the directions of the four diodes near the center of the dielectric layer are the same, that is, the directions of the two diodes in each group are opposite, and the directions of the diodes on the same corresponding end of the second radiation patch are the same.

[0054] Preferably, the diode can be a PIN diode, which has different capacitance and resistance under different electromagnetic wave intensities. When exposed to normal electromagnetic waves, the diode is in the cut-off state, showing capacitance, which is equivalent to a capacitor. The "cross" structure formed by the second radiation patch is equivalent to a small inductor. When exposed to strong electromagnetic waves, the diode is in the on state, showing resistance, which is equivalent to a resistor. The "cross" structure formed by the second radiation patch is equivalent to a large inductor, and has simple parameters and low price.

[0055] Further preferably, the diode far away from the center of the dielectric layer is arranged on the symmetry axis of two adjacent grooves. On the same second radiation patch, the distance between the two diodes is equal to the distance between the diode close to the center of the dielectric layer and the center of the dielectric layer, and the distance between the two diodes is equal to three times the length of the diode, so as to achieve strong electromagnetic protection through transmission while improving the gain of the antenna.

[0056] like Figure 2 As shown, in this application, by adaptively changing the working state of the diodes on different protection units, field-induced transmission is generated, and the protection array can switch between the reflection state and the transmission state, thereby realizing the adaptive strong electromagnetic protection of the Cassegrain antenna. Specifically: when normal electromagnetic waves are irradiated, the diodes are in the cut-off state, equivalent to a capacitor, and the protection array is in the reflection state. The normal electromagnetic waves reaching the protection array from the feed source are almost all reflected to the main reflection surface, and then radiated from the main reflection surface to the larger space outside. The antenna can operate normally, efficiently transmit and receive signals, and achieve high gain of the antenna; when strong electromagnetic waves are irradiated, the diodes are in the conduction state, equivalent to a resistor, and the protection array is in the transmission state. The strong electromagnetic waves attacking from the outside are converged from the main reflection surface to the protection array, and most of them are then transmitted through the protection array into the air, thereby realizing strong electromagnetic protection. In addition, the "cross" structure formed by the second radiating patch is equivalent to an inductor, and the coupling between the second radiating patch and the first radiating patch forms a capacitor. The capacitor and the inductor are connected in parallel to form a bandpass characteristic in the x-band.

[0057] The above-mentioned protective type Cassegrain antenna with a field-induced transmission sub-reflector is an energy selection Cassegrain antenna, which uses a protective array as a sub-reflector, and the protective units in the protective array are field-induced transmission energy selection units (which are also high-pass energy selection units, and when the electromagnetic energy is low, the electromagnetic wave is reflected, and when the electromagnetic energy is high, the electromagnetic wave is transmitted), which can adaptively change the reflection or transmission state of the protective unit by the self-adaptive cutoff or conduction of the diode when facing normal electromagnetic wave (i.e. weak electromagnetic wave) or strong electromagnetic wave, thereby realizing normal operation and strong electromagnetic protection. At the same time, the protective array of the present application is a square planar structure, which replaces the circular arc sub-reflector with a square planar sub-reflector, and replaces the pure metal sub-reflector with a protective array composed of field-induced transmission energy selection units, thereby having strong electromagnetic protection capability, reducing the difficulty of conformal, and still maintaining good gain and pattern, that is, the present application enables the antenna to have strong electromagnetic protection capability under the same focal ratio, can adjust according to the change of electric field intensity, and does not affect the performance of the antenna in normal operation, thereby reducing the cost of electromagnetic protection. In addition, the protective units of the present application are simultaneously distributed in axial symmetry, central symmetry and rotational symmetry, so that the antenna can realize protection against strong electromagnetic wave attack at any angle. The present application can be applied to the Cassegrain antenna of the radar communication system equipment, and provides a reliable solution for coping with the increasing electromagnetic interference and safety requirements, and has strong practicability.

[0058] In a specific embodiment, the protective array includes 8*8 protective units, and the overall size is 80mm*80mm. The dielectric layer is a square planar structure made of a non-metallic material with a relative dielectric constant of 2.2, and has a side length of 10mm and a thickness of 1.5mm. The first radiating patch is an isosceles right triangle structure with a hypotenuse side length of 7.45mm, and a square recess is arranged on the right angle side with a side length of 0.6mm. The width of the second radiating patch is 0.4mm. There are eight diodes, which are arranged on four second radiating patches. The length of each diode is 0.5mm (that is, eight 0.5mm gaps are arranged on the second radiating patch to arrange eight diodes). On the same second radiating patch, the distances of the two diodes from the center of the dielectric layer are 1.5mm and 3mm respectively, and the diode away from the center of the dielectric layer is arranged on the symmetry axis of the two adjacent recesses.

[0059] This embodiment mainly focuses on the X-band, and the working frequency band and working bandwidth are: 9.300GHz±100.00MHz.

[0060] The transmission coefficient and reflection coefficient of the protective unit are simulated in CST by using the floquet periodic simulation method, and the results are shown in Figure 3 、 Figure 4 and Table 1.

[0061] Table 1: Transmission coefficient and reflection coefficient of the protection unit (9.3GHz)

[0062]

[0063] Depend on Figure 3 、 Figure 4 As can be seen from Table 1, in the 9.3 GHz state, the protection unit has a high reflection coefficient and a low transmission coefficient in the 9.3 GHz state. When the diode is cut off, that is, the diode is resistive, the protection unit reflects the electromagnetic waves incident on the protection unit. When the diode is turned on, that is, the diode is capacitive, the protection unit has a high transmission coefficient and a low reflection coefficient, and transmits the electromagnetic waves incident on the protection unit.

[0064] CST simulation is used to compare the gain of the Cassegrain antenna in four cases, specifically: the Cassegrain antenna without a sub-reflector (such as Figure 5 As shown), Cassegrain antenna with square metal sub-reflector (as shown Figure 6 As shown), the Cassegrain antenna of the protective array sub-reflector under normal working conditions (such as Figure 7 and Figure 8 As shown), Cassegrain antenna for protecting the sub-reflector of the array under strong electromagnetic attack (as shown Figure 7 and Figure 8 As shown), the size of the protective array sub-reflector is the same as the size of the square metal sub-reflector, and the result is as follows Figure 9 、 Figure 10 And shown in Table 2.

[0065] Table 2: Gain of Cassegrain antenna

[0066]

[0067] Depend on Figure 9 、 Figure 10 As can be seen from Table 2, the gain of the Cassegrain antenna without a sub-reflector is 15.3 dB, the gain of the Cassegrain antenna with a square metal sub-reflector is 27.9 dB, the gain of the Cassegrain antenna with a protected array sub-reflector is 27.4 dB under normal working conditions, and the gain of the Cassegrain antenna with a protected array sub-reflector under strong electromagnetic attack is 16.5 dB.

[0068] From the above comparison, it can be seen that when the diode is cut off, that is, when normal electromagnetic waves are incident, the protective Cassegrain antenna of the present application works normally, and when the diode is turned on, that is, when strong electromagnetic waves are incident, the gain of the protective Cassegrain antenna of the present application is 16.5dB, while the gain of the Cassegrain antenna without a sub-reflector is 15.3dB. That is to say, when a strong electromagnetic attack occurs, the protective array sub-reflector of the present application will offset the gain of the sub-reflector, reduce the antenna gain to the feed level, and achieve strong electromagnetic protection.

[0069] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0070] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A protective Cassegrain antenna with a field-transmission sub-reflector, characterized in that: include: Bracket, feed, main reflector and protection array; The protection array includes a plurality of protection units distributed in an array, and the protection unit includes: a dielectric layer and a radiation layer arranged on top of the dielectric layer; The dielectric layer is a flat plate structure; The radiation layer includes: four first radiation patches and four second radiation patches; the first radiation patches are triangular structures, and the four first radiation patches are rotationally symmetrically distributed about the center of the dielectric layer; the second radiation patches are axially symmetrical strip structures, one corresponding end of the strip structure is arranged at the center of the dielectric layer, and the other corresponding ends are respectively arranged at the four corners of the dielectric layer, so that the four second radiation patches form a "cross" structure, and the symmetry axis of the strip structure in the length direction coincides with a diagonal line of the dielectric layer; the first radiation patch and the second radiation patch are arranged at intervals, and a diode is provided on the second radiation patch to achieve electromagnetic protection by changing the working state of the diode on different protection units; The protection array has a field-induced transmission characteristic. The protection array serves as a secondary reflector, and the secondary reflector, the bracket, the feed source, and the main reflector together form a Cassegrain antenna.

2. The protective Cassegrain antenna with a field transmission sub-reflector according to claim 1, characterized in that: The first radiation patch is an isosceles right triangle structure, and the hypotenuse of the isosceles right triangle structure is collinear with the side of the dielectric layer.

3. The protective Cassegrain antenna with a field transmission sub-reflector according to claim 2, characterized in that: A square groove is provided on the right-angled side of the isosceles right-angled triangle structure.

4. The protective Cassegrain antenna with a field transmission sub-reflector according to claim 3, characterized in that: Two diodes are provided on each second radiation patch.

5. The protective Cassegrain antenna with a field transmission sub-reflector according to claim 4, characterized in that: The directions of the two diodes on each second radiation patch are opposite, and the directions of the four diodes near the center of the dielectric layer are the same.

6. The protective Cassegrain antenna with a field transmission sub-reflector according to claim 4 or 5, characterized in that: The diode far away from the center of the dielectric layer is arranged on the symmetry axis of two adjacent grooves.

7. The protective Cassegrain antenna with a field transmission sub-reflector according to any one of claims 1 to 5, characterized in that: The width of the second radiation patch is changed to achieve frequency shift.

8. The protective Cassegrain antenna with a field transmission sub-reflector according to any one of claims 3 to 5, characterized in that: The width of the second radiation patch is smaller than the side length of the groove.

9. The protective Cassegrain antenna with a field transmission sub-reflector according to any one of claims 1 to 5, characterized in that: The dielectric layer has a square structure, and the radiation layer has a centrosymmetric structure.

10. The protective Cassegrain antenna with a field transmission sub-reflector according to any one of claims 1 to 5, characterized in that: The bracket is arranged on the antenna platform, the main reflecting surface is arranged on the bracket, the feed source is arranged at the center of the main reflecting surface, and the secondary reflecting surface is arranged on the main reflecting surface and is spaced and parallel to the plane where the opening of the main reflecting surface is located.

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