CN112751184A

CN112751184A - Phased array antenna with high radiation efficiency and low scattering characteristic

Info

Publication number: CN112751184A
Application number: CN202011591029.3A
Authority: CN
Inventors: 李鹏发; 屈世伟; 李小秋; 周志鹏; 孙红兵
Original assignee: University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China
Priority date: 2020-12-29
Filing date: 2020-12-29
Publication date: 2021-05-04
Anticipated expiration: 2040-12-29
Also published as: CN112751184B

Abstract

The invention discloses a patch phased array antenna with high radiation efficiency and low scattering characteristic, and belongs to the technical field of antenna engineering and the technical field of radar stealth. The invention adopts the laminated patch to increase the bandwidth of the antenna; the isolation between the circuit and the antenna is increased through the feed patches and the matching circuits on different layers and the grounding plate arranged between the feed patches and the matching circuits, so that the feed patches and the matching circuits can be independently designed; and (3) solving an optimal load impedance curve for realizing zero backscattering in the band from a phased array antenna scattering mechanism, and finally performing fitting design of a corresponding matching circuit to remarkably reduce the single-station RCS in the antenna band. In the unit selection and design, an antenna unit with lower structural item scattering is selected, or appropriate structural item scattering reduction is carried out, so that the broadband reduction of the single-station RCS can be realized on the premise that standing waves are not deteriorated and the radiation efficiency is not reduced.

Description

Phased array antenna with high radiation efficiency and low scattering characteristic

Technical Field

The invention belongs to the technical field of antenna engineering and radar stealth, and relates to a phased array antenna with high radiation efficiency and low back scattering.

Background

Aircraft stealth is an important subject of modern electronic warfare, and a phased array antenna in an airborne radar generates strong scattering and becomes the biggest obstacle for further improving the aircraft stealth performance, so that the RCS (radar scattering cross section) reduction of the phased array antenna is of great importance. The current mainstream antenna RCS reduction methods include the following methods:

first, a loading material or metamaterial. For example, in the document "Development of a Low Radar Cross Section Antenna With Band-Notched Absorber", a Radar wave-absorbing metamaterial is proposed, which absorbs scattering energy through a material, and this method usually accompanies the loss of Antenna gain and efficiency, especially when used for in-Band RCS reduction, because the absorptive material can absorb the radiation energy in a radiation state at the same time of absorbing the scattering energy in a receiving state; as another example, in the document "A Low-Profile waveguide and Tight Coupled polarized Array With Reduced Polarization Conversion Material", a symmetric Polarization Conversion material is laid on the ground to make the scattered waves from the ground cancel each other in the incoming wave direction. The laying of metamaterials requires a certain space and is not suitable for all antenna structures, especially for tightly arranged phased array antennas.

Second, antenna structure shaping. For example, in the document "Design of Vivaldi Antenna With wide Antenna Cross Section Reduction", the in-band RCS of Vivaldi Antenna is reduced by digging out a metal structure on the Vivaldi Antenna arm, which has little influence on the radiation characteristics, but the Vivaldi Antenna itself can realize unidirectional radiation without ground, most phased array antennas have a complete metal floor, and the method has a limited effect on processing the scattering from the ground.

Third, the antenna standing wave is optimized. For example, in the document "An Ultra-Wideband polarized Array Co-Designed With Low Scattering Characteristics", a wide-angle matching layer is loaded to optimize the standing wave and reduce the Scattering field of the phased Array antenna pattern item. However, the scattered field of the antenna is theoretically the vector sum of the scattered fields of the mode item and the structural item, and the reduction of the total scattered field cannot be guaranteed by reducing the standing wave of the antenna alone, so that the method is only suitable for the antenna with low structural item scattering.

The first method and the second method aim at reducing the scattering of structural items of the antenna, and the third method aims at reducing the scattering of mode items of the antenna, and are relatively one-sided and limited in application scene. In the literature, "fine Antenna Arrays and FSS", a method for realizing in-band single-station RCS reduction by adjusting Antenna reflected waves and mode item scattered fields generated thereby by changing Antenna loads, so that the mode item and structure item scattered fields are cancelled in the incoming wave direction, however, on one hand, all loads that can be used in engineering are real impedances (usually 50 Ω) that are not frequency-varying, and the optimal load impedances required for different frequency points are different, so that the method is only suitable for single-frequency point or narrow-band RCS reduction, and on the other hand, the method often means worsening of standing waves and low gain and low system efficiency caused thereby.

Aiming at the problems, the invention provides a method for reducing the in-band RCS (radar cross section) by loading a broadband matching network on the premise of not deteriorating antenna standing waves and reducing the antenna radiation efficiency, and particularly designs a phased array antenna with high radiation efficiency and low back scattering.

Disclosure of Invention

The invention provides an X-waveband 1 multiplied by 32E surface linear array on the basis of the background technology, a PCB processing technology is adopted, a broadband matching network is loaded through a circuit layer, the reflection coefficient of the antenna is kept below-10 dB in the band, and meanwhile, compared with a phased array antenna which directly adopts 50 omega load feed, the RCS has the advantage that the in-band normal single-station RCS is generally reduced by more than 7 dB.

The technical scheme adopted by the invention is as follows: a patch phased array antenna having high radiation efficiency and low scattering characteristics, the antenna comprising, stacked in order from bottom to top: the antenna comprises a metal floor, a matching circuit layer, a coupling feed layer and a radiation patch layer;

the radiation patch layer includes: the antenna comprises a first radiation patch, a first PCB (printed circuit board), a second radiation patch and a second PCB; the first radiation patch is arranged on the upper surface of the first PCB; the second radiation patch is arranged on the upper surface of the second PCB, and the first PCB is overlapped on the second PCB;

the coupling feed layer includes: the power feed patch, the third PCB, the first grounding plate and the fourth PCB are arranged on the PCB; the third PCB is arranged on the fourth PCB; the feed patch is a rectangular microstrip line and is arranged on the upper surface of the third PCB; the first ground plate is printed on the upper surface of the fourth PCB, an I-shaped coupling groove is formed in the center of the fourth PCB, the I-shaped coupling groove is of a structure which is symmetrical up and down, left and right, and the axis of the middle structure of the I-shaped coupling groove is perpendicular to the axis of the first radiation patch in the radiation patch layer;

the matching circuit layer includes: the second grounding plate, the fifth PCB, the sixth PCB and the matching circuit; the fifth PCB is arranged on the sixth PCB; the second ground plate is printed on the upper surface of the fifth PCB, and the matching circuit is arranged on the upper surface of the sixth PCB; the matching circuit comprises an impedance matcher, an open-circuit branch and a short-circuit branch which are realized by strip lines with different lengths and widths, and the impedance matcher, the open-circuit branch and the short-circuit branch are respectively equivalent to a distributed resistor, a capacitor and an inductor; the starting end of the matching circuit is connected with a feed patch in the coupling feed layer through a metalized through hole, the tail end of the matching circuit is connected with an SMA joint inner core through the metalized through hole, and the SMA joint inner core is electrically isolated from the metal floor when penetrating through a through hole on the metal floor; and the tail end of a short circuit branch in the matching circuit is connected with the second grounding plate through a first short circuit pin and is connected with the metal floor through a second short circuit pin.

The invention adopts the laminated patch to increase the bandwidth of the antenna; the isolation between the circuit and the antenna is increased through the feed patches and the matching circuits on different layers and the grounding plate arranged between the feed patches and the matching circuits, so that the feed patches and the matching circuits can be independently designed; and (3) solving an optimal load impedance curve for realizing zero backscattering in the band from a phased array antenna scattering mechanism, and finally performing fitting design of a corresponding matching circuit to remarkably reduce the single-station RCS in the antenna band. In the unit selection and design, an antenna unit with lower structural item scattering is selected, or appropriate structural item scattering reduction is carried out, so that the broadband reduction of the single-station RCS can be realized on the premise that standing waves are not deteriorated and the radiation efficiency is not reduced.

Drawings

Fig. 1 is a schematic view of a multilayer structure of an antenna unit in embodiment 1 of the present invention.

Fig. 2 shows an optimal load impedance curve, a fitted RLC circuit output impedance curve, and an impedance curve implemented by a true matching circuit in embodiment 1 of the present invention.

Fig. 3 shows standing waves of an antenna element and a reference antenna element (terminated by a 50 Ω ideal load) in embodiment 1 of the present invention.

Fig. 4 shows a normal single station RCS of an ideal metal plate of the same size, with an antenna element and a reference antenna element in embodiment 1 of the present invention.

Fig. 5 shows a normal direction single station RCS of a 1 × 32E planar phased array antenna, a reference antenna array (all elements are terminated with 50 Ω ideal load) and an ideal metal plate of the same size in embodiment 2 of the present invention.

Detailed Description

Example 1: low-scattering E-plane phased array antenna unit

The structure of the antenna unit in this embodiment is shown in fig. 1, and the unit size is 16 × 16mm²(x, y direction respectively), operating frequency 8 ~ 10GHz, antenna from the top down divide into four layers, do in proper order: the antenna comprises a radiation patch layer, a coupling feed layer, a matching circuit layer and a metal floor; the antenna total has six layers of PCB boards, and its material all is Rogers 5880, and dielectric constant 2.2, first ~ sixth PCB board (1 ~ 6) thickness do in proper order: 1.5mm, 0.5mm, 1.5 mm; the thickness of the metal floor is 13 mm.

The radiation patch layer includes: first radiation patch 11, first PCB board 1, second radiation patch 21, second PCB board 2. The first radiation patch 11 is a rectangular patch and is arranged in the center of the upper surface of the first PCB board 1; the second radiation patch 21 is a rectangular patch and is disposed at the center of the upper surface of the second PCB 2. The antenna operating bandwidth can be improved by the laminated patch.

The coupling feed layer includes: a feed patch 31, a first microstrip line-to-stripline metalized via hole 32, a third PCB 3, a first ground plate 41, a second microstrip line-to-stripline metalized via hole 42, an i-shaped coupling slot 43, and a fourth PCB 4; the feed patch 31 is arranged on the upper surface of the third PCB 3, and the first microstrip line-to-stripline metalized via 32 passes through the third PCB 3; the second microstrip to stripline metalized via 42 passes through the fourth PCB 4; the upper layer grounding plate 41 is arranged on the upper surface of the fourth PCB 4, and the center of the upper layer grounding plate is provided with an I-shaped coupling groove 43; the

metalized vias

32 and 42 and the lower metalized via 52 are located at the same horizontal position and are used as probes for the microstrip line to strip line. The antenna realizes electromagnetic coupling feeding through the feeding patch 31 and the I-shaped coupling slot on the grounding plate 41.

The matching circuit layer includes: a second ground plate 51, a third microstrip line-to-stripline metalized via 52, a first shorting pin 54, a fifth PCB 5, a stripline matching patch 61, a second shorting pin 64, a stripline-to-coaxial line metalized via 65, and a sixth PCB 6; the second ground plate 51 is arranged on the upper surface of the fifth PCB 5, and the third microstrip line-to-stripline metalized via 52 passes through the fifth PCB 5; the matching patch 61 is arranged on the upper surface of the sixth PCB 6, and the strip line-to-coaxial line metalized via hole 65 penetrates through the sixth PCB 6; the shorting

pins

54 and 64 are respectively metalized through holes penetrating through the

PCB boards

5 and 6 and are positioned in the same horizontal direction to form short circuit branches; the matching circuit is composed of distributed resistance, capacitance and inductance elements and is realized by strip line matching branches, open-circuit branches and short-circuit branches respectively. The second ground plate 51 serves as an upper microstrip line and a lower stripline, and simultaneously separates the coupling feed layer from the matching circuit layer, so that good isolation between the antenna and the circuit can be realized, and the purpose of separately designing the antenna and the matching circuit can be achieved.

A through hole 75 is arranged in the metal floor 7, the metal floor and the metalized via hole 65 are positioned in the same horizontal direction, and the SMA joint inner core penetrates through the through hole 75 and the metalized via hole 65 to feed electricity to the antenna.

And calculating the optimal load impedance of the antenna through the simulation results of the radiation field, the input impedance and the structural item scattering field of the antenna, so as to realize zero backscattering in the normal direction. The optimal load impedance curve in band is shown in fig. 2, and impedance fitting is performed using parallel RLC circuits. The parameters of the parallel RLC circuit after least square fitting are R40.5 omega, L0.31 nH and C1 pF, the distributed equivalent capacitance and inductance are realized by adopting short branches of open-circuit and short-circuit strip lines in the design of a matching circuit, the equivalent resistance is realized by adopting a quarter-wavelength impedance converter, and no power consumption resistance element is used, so that the radiation efficiency is not reduced. Fig. 2 also shows the impedance curve of the ideal circuit and the impedance curve of the distributed parameter circuit finally realized in the simulation, which are almost consistent, and the impedance curve of the optimal load is close to the impedance curve in the band, which shows that the matching circuit in the embodiment can realize the expected effect.

As shown in fig. 3, the standing wave of the phased array antenna unit in this embodiment and fed by directly adopting a 50 Ω ideal port is seen to be deteriorated after the designed matching circuit is loaded, but the standing wave can work well with the band inner under-10 dB; as shown in fig. 4, the single-station RCS of the antenna unit in the normal direction is a single-station RCS, which is shown in fig. 4, and it can be seen that most of the frequency band in the band of the single-station RCS of the antenna unit in this embodiment is reduced by more than 7dB compared with the antenna unit fed by using a 50 Ω ideal port, and is lower by more than 15dB than the typical value of ground scattering in the same size; the antenna element thus achieves significant in-band normal single station RCS reduction while maintaining good standing wave and radiation efficiency. Example 2: low-scattering 1X 32E-plane phased array antenna

In this embodiment, the antenna units in embodiment 1 are used to form an E-plane 1 × 32 linear array, and 32 antenna units are horizontally arranged on the E-plane (xoz) of the antenna.

The single-station RCS in the normal direction of the phased array antenna is shown in fig. 5, and it can be seen that the phased array antenna in this embodiment achieves the same reduction effect as the antenna unit in embodiment 1: the single station RCS has most frequency bands reduced by more than 7dB compared with the antenna unit adopting 50 omega ideal port feed, and is lower than the typical value of ground scattering of the same size by more than 15 dB.

In summary, the present invention provides a method for reducing the single station RCS in a phased array antenna band, and the antenna unit and the array designed based on the method do not significantly deteriorate the antenna standing wave, and do not introduce extra radiation loss, and can significantly reduce the antenna RCS on the premise of maintaining good radiation characteristics. The present disclosure describes in detail an embodiment of a phased array antenna unit and an E-plane 1 x 32 linear array, and selects a parallel RLC circuit as a matching circuit, and performs impedance fitting using the least squares method, but the above description should not be construed as limiting the present invention.

Claims

1. A patch phased array antenna having high radiation efficiency and low scattering characteristics, the antenna comprising, stacked in order from bottom to top: the antenna comprises a metal floor, a matching circuit layer, a coupling feed layer and a radiation patch layer;