阅读说明：本技术 基于强耦合效应的锥台载二维共形低散射超宽带相控阵 (Frustum-mounted two-dimensional conformal low-scattering ultra-wideband phased array based on strong coupling effect ) 是由 杨仕文 张哲晨 屈世伟 陈益凯 胡俊 于 2020-12-17 设计创作，主要内容包括：本发明公开了一种基于强耦合效应的锥台载二维共形低散射超宽带相控阵天线,该它完全共形于锥台表面,偶极子辐射单元沿着圆周方向的间距随着锥台母线呈线性变化,呈现锥形变化的布阵方式,在6-18GHz的宽频带范围内实现了E面以及H面±45°扫描。通过加载长条金属贴片,有效改善了由共形环境引起的有源驻波恶化。此外,准周期性电磁超材料的加载在相控阵天线工作频的全频频范围内显著地降低相控阵天线自身的交叉极化RCS,共形相控阵的总体辐射效率保证在较高水平。最后,全裂口环的应用帮助实现了相控阵天线在具有超宽带宽角扫描特性的同时,保证了相控阵天线的散射特性。(The invention discloses a frustum-mounted two-dimensional conformal low-scattering ultra-wideband phased array antenna based on a strong coupling effect, which is completely conformal on the surface of a frustum, wherein the distance of dipole radiation units along the circumferential direction is linearly changed along with a frustum bus, and the array distribution mode of conical change is presented, so that scanning of +/-45 degrees of an E surface and an H surface is realized within a broadband range of 6-18 GHz. By loading the strip-shaped metal patch, the deterioration of the active standing wave caused by the conformal environment is effectively improved. In addition, the loading of the quasi-periodic electromagnetic metamaterial obviously reduces the cross polarization RCS of the phased array antenna in the full frequency range of the working frequency of the phased array antenna, and the overall radiation efficiency of the conformal phased array is ensured to be at a higher level. Finally, the application of the full split ring helps to realize that the phased array antenna has the ultra wide band wide angle scanning characteristic and simultaneously ensures the scattering characteristic of the phased array antenna.)

1. The frustum-mounted two-dimensional conformal low-scattering ultra-wideband phased array based on the strong coupling effect comprises an unbalanced feed structure (1) of an antenna; two metal shorting posts (2); a metal floor (3) having a certain thickness; a dielectric substrate (4) located above the metal floor for support; the dipole radiation unit (5) is printed on the upper surface of the supporting dielectric substrate and has a strong capacitive coupling structure, and the two metal short circuit columns are respectively arranged on the left arm and the right arm of the dipole radiation unit; a first wide-angle impedance matching layer (6) located above the supporting dielectric substrate; a resistive printing dielectric layer (7) positioned above the first wide-angle impedance matching layer; a second wide-angle impedance matching layer (8) positioned above the resistive printing medium layer; a quasi-periodic double-rectangular resistive patch (9) printed on the resistive printing medium layer, wherein the resistive patch and the dipole radiation unit are mutually orthogonal; a strip metal patch (10) printed over the second wide-angle impedance matching layer; a full split ring metal ring (11) printed above the second wide-angle impedance matching layer, wherein the full split ring is arranged along the arrangement direction of the dipole radiation units; the resistive patch (9), the wide-angle impedance matching layers (6) and (7), the full split ring metal ring (11) and the dielectric substrate (4) form a conformal electromagnetic metamaterial.

2. The strongly-coupling-effect-based frustum-mounted two-dimensional conformal low-scattering ultra-wideband phased array according to claim 1, characterized in that: the whole phased array antenna is completely conformal to the frustum carrier, the distance between the dipole radiation units along the circumferential direction is linearly changed along with the frustum bus, and the strip metal patch is loaded above the dipole radiation units, so that the deterioration of the phased array active standing wave caused by the frustum conformal environment can be effectively improved.

3. The strongly-coupling-effect-based frustum-mounted two-dimensional conformal low-scattering ultra-wideband phased array according to claim 1, characterized in that: the double-rectangular resistive patch is completely conformal on the surface of the carrier, the length of the double-rectangular resistive patch is linearly changed along with the position in the direction of the frustum bus, the double-rectangular resistive patch is a quasi-periodic structure, and the in-band scattering characteristic of the frustum-mounted conformal phased array can be effectively reduced.

4. The strongly-coupling-effect-based frustum-mounted two-dimensional conformal low-scattering ultra-wideband phased array of claim 1, further characterized in that: a full-split ring periodic structure is adopted above the dipole radiation unit, the structure improves the phase array scanning standing wave characteristic, and meanwhile, the structure keeps a transmission state for cross polarization incident waves, and the capacity of absorbing external electromagnetic waves of the loaded conformal electromagnetic metamaterial is guaranteed.

Technical Field

The invention belongs to the technical field of antenna engineering, and particularly relates to a two-dimensional conformal low-scattering ultra-wideband wide-angle scanning phased antenna array system, in particular to a phased antenna array which is based on a strong mutual coupling effect, loaded with electromagnetic metamaterials, conformal to a frustum carrier, good in scattering characteristic and capable of realizing ultra-wideband wide-angle scanning. The ultra-wideband wide-angle scanning platform is particularly suitable for the platform which requires good antenna stealth performance, integrates with the platform in a conformal way and can realize ultra-wideband wide-angle scanning.

Background

With the gradual development of the information-based war, especially the rapid progress of the radar detection technology, the stealth technology plays an increasingly important role in the modern electronic war. The Radar Cross Section (Radar Cross Section), abbreviated as RCS, is an important index for measuring the stealth performance of a detected target. The size of a radar scattering cross section directly determines the stealth performance of a detected target, and an antenna serving as one of strong scattering sources of a carrier platform has great influence on RCS (radar cross section). The antenna is an active target, and when the antenna is subjected to stealth processing, the antenna must be ensured to be capable of normally receiving and transmitting electromagnetic waves, so that the conventional stealth means cannot directly act on the antenna. The mutual coupling among units is not considered when array elements are designed in the traditional broadband phased array, so that the working bandwidth of the phased array is influenced to a greater extent after the array is formed. Furthermore, conventional phased array units having a wide frequency band characteristic generally have a large lateral or longitudinal dimension. If the transverse size is too large, the broadband wide-angle scanning characteristic of the phased array is influenced; too large a longitudinal dimension is not suitable for the realization of planar structures and is not conformable. And on some carriers, a phased array antenna is required to achieve conformal integration with the carrier.

The broadband phased array based on the strong mutual coupling effect is a new concept phased array antenna which is internationally proposed in recent years, and compared with the traditional phased array, the novel phased array antenna with the closely-arranged units is more suitable for being designed with the characteristics of miniaturization and broadband wide-angle scanning. In 2003, professor b.munk at state university in ohio first proposed this new type of Wideband Phased Array in U.S. patent No. 6512487, "Wideband Phased Array and related technology" (Wideband Phased Array Antenna and Associated Methods). The antenna is characterized in that the distance is shortened, the coupling is enhanced, the strong mutual coupling effect among the units is directly utilized to form continuous current, and the limitation of the mutual coupling effect on the bandwidth and the scanning angle of the antenna is overcome. The research in recent years shows that: the strong mutual coupling broadband phased array antenna has the characteristics of very good ultra wide band characteristic, wider grating lobe-free scanning angle than the traditional phased array antenna, low profile, plane structure as a whole, easy conformation with carriers such as aircrafts and the like, small influence on the whole pneumatic performance of the carriers and the like. However, the strong mutual coupling phased array still has the defects of high antenna profile, poor two-dimensional scanning effect and the like. At the same time, the team does not study or control the scattering properties of the antenna, and therefore the antenna itself does not have low RCS properties.

In order to further optimize the radiation performance of the strongly coupled antenna array and control the scattering performance of the strongly coupled antenna array, some improved forms of strongly coupled antenna arrays are proposed. The Chinese patent with application number of 201710509295.9 discloses a low-profile low-RCS ultra-wideband wide-angle scanning strong mutual coupling phased array antenna based on polarization conversion materials, wherein a metamaterial with a polarization rotation effect is placed above a floor of a strong coupling antenna array to reduce the RCS of the antenna, and the antenna has a certain effect. However, this structure is only suitable for RCS reduction outside the operating band of the antenna in order not to affect the radiation performance of the antenna.

Stefan vacuum published in the IEEE Transactions on extensions and Propagation journal in 2017 an article entitled "RCS Reduction with a Dual polarized selected-compensated Connected Array Antenna". The article provides a circuit model of a dual-polarization checkerboard-shaped self-complementary antenna, the reflection coefficient of an array unit is quickly optimized by using the circuit model, and finally, a phased array for realizing ultra wide band low scattering characteristics is designed. However, in the article, only the mode term scattering of the antenna is considered when the scattering of the antenna is optimized, and no specific analysis is made on the structure term scattering of the antenna. In addition, a designer does not design a proper feeding structure for the antenna, and only the radiation characteristic of the antenna under an ideal condition is considered. The engineering of this antenna remains a challenge.

Research on conformal phased arrays has focused primarily on narrow band or fixed beam arrays, of which microstrip patch antennas are representative. Research on ultra-wide band scanning conformal phased array is rarely reported, especially for strongly coupled phased array antennas that naturally have low profile characteristics.

In the chinese patent "a strong mutual coupling ultra wide band wide angle scanning dual polarization conformal phased array antenna" with application number 201710515792.X, a strong coupling phased array antenna conformal to a frustum is provided, but it essentially only realizes one-dimensional conformality, namely conformality on a cylinder, and does not research a two-dimensional conformal strong coupling phased array. In addition, the phased array antenna does not reduce the scattering characteristics

In a Chinese patent with application number of 201910388777.2, namely a wing-mounted low-scattering ultra-wideband conformal phased array based on a strong coupling effect, the antenna with the strongly coupled connecting elongated slot is conformal to the surface of a wing, and meanwhile, a resistive electromagnetic metamaterial is loaded to control the scattering characteristic of the phased array. However, the resistive electromagnetic metamaterial is only a simple periodic circular patch structure, and the effect of scattering reduction is limited. And half of the units in the array are dummy units and are in an unexcited state, so that the common radiation aperture is sacrificed.

Based on the application requirements, the invention provides a frustum-mounted two-dimensional conformal low-scattering ultra-wideband phased array antenna based on a strong coupling effect.

Disclosure of Invention

Under the background of the invention, the invention provides an ultra-wideband low-scattering strong-coupling two-dimensional conformal phased array antenna conformal to a frustum carrier platform on the basis of the theory of a strong-coupling planar antenna array. The broadband wide-angle scanning performance of E-plane and H-plane +/-45 DEG scanning standing wave ratio smaller than 3 is realized in the frequency band range of 6-18GHz, and the total section height of the antenna (including the wide-angle impedance matching layer) is only 0.308 high-frequency (18GHz) wavelength. And a resistive patch is loaded above the wide-angle impedance matching layer to form a resistive electromagnetic metamaterial, and the electromagnetic metamaterial can remarkably reduce RCS (radar cross section) of incident waves into cross-polarized electromagnetic waves in an antenna working frequency band under the condition that the radiation performance of the antenna is not influenced basically.

The technical scheme provided by the invention is as follows: a strong mutual coupling dipole printed on a conformal dielectric layer is used as a radiating element of the antenna. The dielectric layer of the dipole radiation unit and the metal ground are supported by the dielectric substrate, and the dielectric substrate is cut into long strips, so that the dielectric constant is reduced, and the modular installation of the phased array antenna is facilitated. The extending direction of the dipole sub-arrays cut into long strips is consistent with the direction of a bus of the frustum, and the distance between the sub-arrays is linearly changed along the direction of the bus, so that the array is completely conformal on the frustum. Due to the conformal environment, coupling between the phased array antenna elements is reduced, resulting in a deterioration of the active standing wave characteristics at low frequencies. In order to strengthen the coupling, long-strip metal patches are introduced among the units, so that the low-frequency standing wave is effectively improved. In addition, in order to reduce the RCS characteristics of a two-dimensional conformal phased array antenna, a resistive patch conformal to a frustum carrier is loaded over the phased array. In order to better realize RCS reduction of the frustum conformal phased array antenna, the resistive patch is specially designed for the frustum phased array antenna, a conventional periodic structure is broken through, the size of the resistive patch in the circumferential direction linearly changes along with a frustum bus, and the resistive patch is a quasi-periodic structure. The loading of the resistive quasi-periodic structure effectively reduces the RCS characteristics of the phased array antenna. Accordingly, the phased array antenna structure of the present invention comprises: an unbalanced feed structure (1) of the antenna; two metal shorting posts (2); a metal floor (3) having a certain thickness; a dielectric substrate (4) located above the metal floor for support; the dipole radiation unit (5) is printed on the upper surface of the supporting dielectric substrate and has a strong capacitive coupling structure, and the two metal short circuit columns are respectively arranged on the left arm and the right arm of the dipole radiation unit; a first wide-angle impedance matching layer (6) located above the supporting dielectric substrate; a resistive printing dielectric layer (7) positioned above the first wide-angle impedance matching layer; a second wide-angle impedance matching layer (8) positioned above the resistive printing medium layer; a quasi-periodic double-rectangular resistive patch (9) printed on the resistive printing medium layer, wherein the resistive patch and the dipole radiation unit are mutually orthogonal; a strip metal patch (10) printed over the second wide-angle impedance matching layer; a full split metal ring (11) printed above the second wide-angle impedance matching layer, wherein the full split ring is arranged along the arrangement direction of the dipole radiation units; the resistive patch (9), the wide-angle impedance matching layers (6) and (7), the full split ring (11) and the dielectric substrate (4) form a conformal electromagnetic metamaterial.

The innovation of the invention is that: the conformal integration of the strong coupling ultra-wideband phased array on the frustum carrier platform is realized. In order to compensate coupling weakening caused by a conformal platform, loading a strip metal patch on a phased array unit, and improving active standing waves of a phased array antenna; secondly, a quasi-periodic resistive patch is specially designed for the frustum conformal phased array antenna, the size of the patch is linearly changed along a frustum bus, and the scattering characteristic of the phased array antenna is effectively controlled; and thirdly, a full-split metal ring is loaded above the antenna, so that the wave-absorbing property of the electromagnetic metamaterial is ensured while the antenna scanning standing wave is improved.

In conclusion, the invention has the advantages that: a frustum-mounted two-dimensional conformal ultra-wideband low-profile ultra-wideband phased array based on a strong coupling effect is provided. The full conformal of the frustum carrier is realized, the modularized installation can be realized, and the processing and the assembly are convenient. The scanning standing-wave ratio of +/-45 degrees of the E surface and the H surface is less than 3 in a 6-18GHz frequency band, the overall section height of the antenna is only 0.308 high-frequency (18GHz) wavelength, RCS (radar cross section) in normal incidence can be remarkably reduced in the full frequency band range of the antenna operation, and meanwhile, the designed conformal phased array antenna is kept high.

Drawings

FIG. 1 is a top view of a frustum-mounted two-dimensional conformal low-scattering ultra-wideband phased array based on strong coupling effect. The antenna array shown in this figure is 9 x 10 size.

FIG. 2 is a side view of a frustum-mounted two-dimensional conformal low-scattering ultra-wideband phased array based on strong coupling effects. The antenna array shown in this figure is 9 x 10 size.

Fig. 3 is a structural diagram of one periodic unit in fig. 1, and the frustum-mounted two-dimensional conformal low-scattering ultra-wideband phased array based on the strong coupling effect in fig. 1 comprises a series of such structures. Each such periodic unit comprises the following parts: an unbalanced feed structure (1) of the antenna; two metal shorting posts (2); a metal floor (3) having a certain thickness; a dielectric substrate (4) located above the metal floor for support; the dipole radiation unit (5) is printed on the upper surface of the supporting dielectric substrate and has a strong capacitive coupling structure, and the two metal short circuit columns are respectively arranged on the left arm and the right arm of the dipole radiation unit; a first wide-angle impedance matching layer (6) located above the supporting dielectric substrate; a resistive printing dielectric layer (7) positioned above the first wide-angle impedance matching layer; a second wide-angle impedance matching layer (8) positioned above the resistive printing medium layer; a quasi-periodic double-rectangular resistive patch (9) printed on the resistive printing medium layer, wherein the resistive patch and the dipole radiation unit are mutually orthogonal; a strip metal patch (10) printed over the second wide-angle impedance matching layer; a full split ring metal ring (11) printed above the second wide-angle impedance matching layer, wherein the full split ring is arranged along the arrangement direction of the dipole radiation units; the resistive patch (9), the wide-angle impedance matching layers (6) and (7), the full split ring metal ring (11) and the dielectric substrate (4) form a conformal electromagnetic metamaterial.

FIG. 4 shows the standing wave ratios of the center unit in embodiment 1 during E-plane and H-plane scanning in the 6-18GHz band. As can be seen from the figure, the standing-wave ratio of the two-dimensional conformal low-scattering ultra-wideband phased array developed in example 1 is less than 3.0 when the E plane and the H plane are scanned at 0-45 degrees in a frequency band of 6-18 GHz.

Fig. 5 shows the main polarization and cross polarization of the antenna in the side-firing mode of embodiment 1. It can be seen from the figure that the main polarization gain is normal in the full frequency band of the antenna operation, and the cross polarization level is lower than-30 dB.

Fig. 6 shows a radiation pattern of the conformal phased array of embodiment 1 operating at 12GHz and broadside on the H-plane with a 45 ° scan angle. As can be seen from the figure, the array has stable beam pointing at the side-emitting and different scanning angles, and the radiation performance during scanning is good.

Fig. 7 is a radiation pattern of the conformal phased array of embodiment 1 operating at 12GHz with a broadside E-plane scan angle of 45 °. As can be seen from the figure, the array has stable beam pointing at the side-emitting and different scanning angles, and the radiation performance during scanning is good.

Fig. 8 shows the overall radiation efficiency of the antenna in the side-firing case of embodiment 1. As can be seen, the radiation efficiency is kept high in the whole frequency band in which the antenna operates.

Fig. 9 is a diagram of the results of single-station RCS when cross-polarized waves are incident perpendicularly, with a conformal resistive patch loaded over the antenna radiating patch, and without the above method, in accordance with embodiment 1. It can be seen that example 1 achieves an RCS reduction effect of at least 10dB or more over the entire frequency band at normal incidence of the cross-polarized wave.

Detailed description of the preferred embodiments

Example 1

Referring to fig. 1 to 3, embodiment 1 is a frustum-mounted two-dimensional conformal low-scattering ultra-wideband strongly-coupled phased array, an array is composed of 9 × 10 units in fig. 3, and the finite array is placed under an ideal absorption boundary condition for simulation. The antenna element structure of the present invention is described as follows: an unbalanced feed structure (1) of the antenna; two metal shorting posts (2); a metal floor (3) having a certain thickness; a dielectric substrate (4) located above the metal floor for support; the dipole radiation unit (5) is printed on the upper surface of the supporting dielectric substrate and has a strong capacitive coupling structure, and the two metal short circuit columns are respectively arranged on the left arm and the right arm of the dipole radiation unit; a first wide-angle impedance matching layer (6) located above the supporting dielectric substrate; a resistive printing dielectric layer (7) positioned above the first wide-angle impedance matching layer; a second wide-angle impedance matching layer (8) positioned above the resistive printing medium layer; a quasi-periodic double-rectangular resistive patch (9) printed on the resistive printing medium layer, wherein the resistive patch and the dipole radiation unit are mutually orthogonal; a strip metal patch (10) printed over the second wide-angle impedance matching layer; a full split ring metal ring (11) printed above the second wide-angle impedance matching layer, wherein the full split ring is arranged along the arrangement direction of the dipole radiation units; the resistive patch (9), the wide-angle impedance matching layers (6) and (7), the full split ring metal ring (11) and the dielectric substrate (4) form a conformal electromagnetic metamaterial.

FIG. 4 shows the standing wave ratio characteristics of the central unit of the limited large phased array of embodiment 1 during scanning. It can be seen that the wideband phased array of this example 1 has at least 3:1 impedance bandwidth, and realizes two-dimensional wide-angle scanning in the range of 6-18GHz, and the standing wave ratio of 0-45 ° for E-plane and H-plane scanning is less than 3.0.

Fig. 5 shows the main polarization and cross polarization gain plots as a function of frequency for the conformal large phased array of embodiment 1 at side-fire. The gain curve is normal, and the cross polarization level is below-30 dB.

Fig. 6 and fig. 7 show the scanning patterns of the conformal finite phased array of the embodiment 1 in 12.0GHz, H plane and E plane. It can be seen that its beam is accurately directed, and its directional diagram is good in form and has no distortion.

Fig. 8 shows the overall radiation efficiency of the conformal finite large phased array of embodiment 1 as a function of frequency at side-fire. The overall radiation efficiency of the phased array is kept at a high level, taking into account return loss and resistive material loss.

Fig. 9 shows a single-station RCS diagram of the conformal finite phased array of example 1 before and after loading the conformal resistive patch, and it can be seen that the loading of the electromagnetic metamaterial effectively reduces the in-band RCS of the antenna, and at least 10dB of RCS reduction is achieved in the range of 6-18 GHz.

While embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will, therefore, be apparent to persons skilled in the art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention without the use of inventive faculty. All of which are considered to be within the scope of the present invention.