CN113517553B

CN113517553B - Tightly-coupled ultra-wideband low-profile conformal phased array based on resistance ring loading

Info

Publication number: CN113517553B
Application number: CN202110786028.2A
Authority: CN
Inventors: 杨仕文; 鲍雨生; 杨锋; 黄明; 朱军; 乔文昇
Original assignee: University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China
Priority date: 2021-07-12
Filing date: 2021-07-12
Publication date: 2022-03-29
Anticipated expiration: 2041-07-12
Also published as: CN113517553A

Abstract

The invention discloses a tightly-coupled ultra-wideband low-profile conformal phased array based on resistance ring loading and a development method thereof. By providing a method for enhancing capacitive coupling, the traditional cross dipole is improved, a resistive frequency selection surface consisting of microstrip lines and lumped resistors is loaded between an antenna radiation patch and a floor, and the working bandwidth of the antenna is expanded. By applying the feed structure of the power divider and the double balun, better matching can be realized, and the section height of the antenna is reduced. The whole antenna array is subjected to conformal treatment, a light and thin medium substrate is used, a thick and heavy wide-angle impedance matching layer is omitted, the mass is lighter, and the metal floor is bent at a certain radian so as to be mounted on a working platform. The invention is in f_L‑8f_LThe scanning active standing wave of 45 degrees in the frequency band is less than 3, and the whole height of the antenna is less than 0.53 high-frequency wavelength.

Description

Tightly-coupled ultra-wideband low-profile conformal phased array based on resistance ring loading

Technical Field

The invention belongs to the technical field of antenna engineering, and particularly relates to a tightly-coupled ultra-wideband low-profile conformal phased array based on resistance ring loading and a development method thereof.

Background

Compared with the traditional mechanical scanning antenna, the phased array antenna has the advantages of easiness in beam forming, random beam direction change, easiness in multi-beam forming and the like. Ultra Wideband (UWB) phased arrays have attracted considerable attention in multi-functional applications, using multiple beams, polarizations and frequency bands to achieve different functions.

The conventional ultra-wideband antenna unit generally has a relatively large transverse or longitudinal dimension, and is difficult to realize a plurality of problems such as low profile, conformality, light and thin design and the like. Based on the disadvantages, a novel tightly coupled antenna has appeared in recent years, and unlike a traditional broadband phased array, the design idea of the tightly coupled antenna is to expand the bandwidth of the antenna by using coupling between units. The phased array antenna of the type can integrate multiple advantages of wide frequency band, small size, low profile, easy conformality and the like. Patent US6512487 proposes a low-profile ultra-wideband phased array based on the close coupling technique, but still stays in the field of planar antenna arrays, and does not propose an idea about the conformality of the close coupling array.

In 2018, the document "Broadband Antenna Aperture map of night coupled devices" proposes an ultra-wideband phased Array based on the close coupling technology. The antenna realizes the standing-wave ratio of less than 3 when the antenna scans to an angle of 60 degrees in the bandwidth of 1.2GHz-6GHz (5: 1). The design adopts the vertically placed dipole and the thick dielectric matching layer, so that the profile height and the mass of the antenna are increased, and the low frequency is not easy to expand.

In patent CN110085975A, the inventor proposes an airborne low-scattering ultra-wideband phased array based on the close coupling technology, which realizes a bandwidth of 0.5-2GHz (4: 1). The design adopts the magnetic dipole as a basic radiation unit, so that the conformal is facilitated, the dual polarization is difficult to realize, and the section of the antenna is high. In patent No. CN 112038753 a, the inventor adopts crossed electric dipoles to realize dual polarization, but the working bandwidth of the array antenna still needs to be further expanded, and it is difficult to meet the requirement of wider frequency band.

Aiming at the existing problems, the invention discloses a tightly-coupled ultra-wideband conformal phased array based on resistance ring loading, which aims to make a breakthrough in the aspects of bandwidth expansion, profile reduction, conformal design and the like.

Disclosure of Invention

The invention aims to solve the problems that the traditional tightly-coupled ultra-wideband antenna is insufficient in working bandwidth, high in section, not beneficial to conformality and the like, and provides a method for enhancing capacitive coupling, a resistive frequency selection structure is loaded, a feed structure of a power divider and a double balun is adopted, the section height of 0.53 high-frequency wavelengths and the bandwidth of fL-8fL are achieved, the working mode is double linear polarization, and 45-degree angle scanning can be achieved. The whole array is light in weight, easy to conform and convenient to install on a working platform.

In order to achieve the purpose, the invention adopts the following technical scheme:

the antenna array comprises a light, thin and flexible dielectric substrate (100), a cross-shaped dipole unit (101) printed on the dielectric substrate, a triangular parasitic patch (103) and a square parasitic patch (104) printed on the dipole and the next dielectric substrate, a resistive frequency selection surface (200) loaded between an antenna radiation unit and a metal floor, a modified Marchand balun (300) connecting a power divider and the dipole, a microstrip power divider (400) placed on the metal floor and a curved metal floor (500).

The dipole layer is made of a light and thin double-layer dielectric substrate, the upper surface of the first layer substrate is printed with an improved triangular cross dipole, and a parasitic patch with a similar shape is printed on the close connection dipole. And a coupling parasitic patch consisting of four small triangles and a square is printed on the second layer of substrate. The dipole is closely connected with the parasitic patch, and the gap between the metal patches and the upper and lower metal patches can generate enough capacitive coupling to offset the inductance generated by the low frequency due to ground short circuit, so that the bandwidth of the low frequency is expanded.

Further, the antenna unit comprises two polarizations which are arranged in a crossed mode, wherein each polarization is provided with two dipoles, each dipole is fed by a modified Marchand balun and is connected to a power divider arranged on the metal ground, and the power divider is fed by a 50-ohm coaxial connector. The dual balun feed approach may achieve an impedance transformation of the coaxial connector 50 ohms to the dipole layer.

Furthermore, the resistance ring loaded between the antenna radiation patch and the metal floor is composed of an annular microstrip line and a lumped resistor, the resistors are respectively arranged on four sides of the square annular microstrip line, and the symmetrical structure provides good polarization consistency. A through hole is formed in the middle of the resistance ring layer, and meanwhile holes are formed in the dipole substrate and the metal ground and fixed through nylon columns.

Furthermore, a series of through holes and mounting grooves are formed in the metal floor and are respectively used for mounting the balun, the connector, the power divider and the upper-layer medium substrate. The floor is curved, threaded holes are opened for mounting the angle aluminum and the joint, and the angle aluminum is used for fixing the balun and ensuring that the balun is vertical to the floor.

In summary, the antenna design has the following innovations: (1) the traditional dipole radiation patch structure is improved, the novel parasitic patch structure effectively increases the capacitive coupling, and the low-frequency bandwidth of the antenna is expanded. (2) A resistive frequency selection surface based on a resistance ring is loaded, and a symmetrical structure provides a consistent absorption characteristic for double linear polarization, so that the broadband matching of the antenna is improved. (3) By applying a feed feeding scheme of a power divider and double baluns, each polarization of each unit comprises two dipoles, and the baluns are effectively miniaturized and the section of the antenna is reduced under the condition that the caliber of the antenna and a rear end TR component are not increased. (4) The whole antenna array is subjected to conformal treatment, the array antenna is subjected to surface treatment according to the structure of the carrier platform, a light and thin flexible medium substrate is adopted, a traditional thick and heavy wide-angle impedance matching layer is omitted, and the whole antenna is lighter in mass and easy to conform.

Drawings

Fig. 1 is a schematic diagram of a tightly coupled ultra-wideband low-profile conformal phased array unit based on resistive ring loading. The antenna comprises a substrate, a radiating patch, a resistor ring, a Marchand balun, a micro-strip single-stage power divider, a cross-shaped dipole radiating patch, a parasitic coupling patch, a resistor ring, a Marchand balun, a micro-strip single-stage power divider and a bent floor, wherein 101 is a cross-shaped dipole radiating patch and a parasitic coupling patch, 300 is the resistor ring, 400 is the micro-strip single-stage power divider, and 500 is the bent floor.

Fig. 2 and 3 are schematic diagrams of the entire conformal array antenna at different angles, with the antenna array having 1 x 14 cells as described in fig. 1, exciting the middle 10 cells.

Fig. 4 is a coupled parasitic patch structure. The shape of 102 is the same as the dipole structure, the printed front side of the first layer of dielectric substrate is crossed with the dipole, 104 is a square metal patch, the printed back side of the second layer of dielectric substrate, 103 is a triangular metal patch, the printed back side of the first layer of dielectric substrate, and the gap between the parasitic patches and the upper and lower layers of patches can generate enough capacitive coupling, so that the low-frequency bandwidth is improved.

Fig. 5 shows a structure of a resistance ring, 201 is a microstrip line trace, 202 is a lumped resistor, and 203 is a lumped capacitor.

Fig. 6 shows a feed structure of a power divider and a double balun, 302 is a vertical connection point of the power divider and the balun, 303 is a vertical connection point of the balun and a dipole, 304 is a main body structure of a stripline balun, a square hole is formed in the ground of the balun so as to optimize impedance matching, and 401 is an isolation resistor of the power divider.

FIG. 7 is a test case of 0-45 degree scanning standing waves of a typical port of array antenna vertical polarization.

FIG. 8 is a test case of 0-45 degree scanning standing waves of a horizontally polarized typical port of an array antenna.

Fig. 9 is a test case where the array antenna scans the pattern at a low frequency fL.

Fig. 10 is a test case where the array antenna scans the pattern at the intermediate frequency of 4 fL.

Fig. 11 is a test case of the array antenna scanning the pattern at a high frequency of 8 fL.

Detailed description of the preferred embodiments

As shown in fig. 1, the tightly-coupled ultra-wideband low-profile conformal phased array based on resistance ring loading in this embodiment is composed of a cross dipole and a coupling parasitic patch 101 printed on a double-layer dielectric board, a resistance ring structure 200 with symmetric polarization, a Marchand balun 300 connecting a power divider and a dipole, a microstrip power divider 400 placed on a curved floor, and a metal floor 500 with a certain curvature.

The antenna dielectric substrates are all common dielectric substrates. The radiation patch layer 100 is a two-layer dielectric substrate laminated together. The feed balun is of a strip line structure and is formed by pressing double-layer dielectric plates together. The floor is made of carbon fiber materials, copper is coated on the two sides of the floor, the ground on the back of the microstrip power divider and the floor need to be welded together, and holes are formed in the dielectric substrate of the power divider and the floor for fixing. The floor is provided with a rectangular balun mounting groove and a threaded hole for fixing angle aluminum, the balun is mounted on the groove and is fixed on the back of the floor by the angle aluminum so as to ensure the verticality. And the vertical connection part of the balun and the power divider and the electric connection part of the balun and the dipole are ensured to be electrically connected through welding. The antenna layer, the resistance ring layer and the floor through hole are fixedly communicated through a nylon column.

The resistive ring structure shown in fig. 5 is composed of microstrip lines and lumped elements, the metal strips are printed on a single-layer common dielectric substrate, and the lumped elements are mounted on the microstrip lines by means of welding, and include 200 ohm resistance and 100pF capacitance.

The power divider and the balun dielectric substrate shown in fig. 6 both use a common dielectric substrate, the balun is in a strip line structure, the upper ground and the lower ground of the balun are connected through a metalized through hole, and the tail end of the balun is welded on a metal floor to ensure grounding. The power divider is welded on the floor, the coaxial connector can be switched from 50 ohms to 100 ohms in a one-to-two mode, and the impedance of the antenna layer is about 90 ohms, so that the balun stripline structure bears the impedance change from 100 ohms to 90 ohms, and the impedance matching is well realized under the condition that the length of the balun is not increased.

The overall cross-sectional height of the antenna is 0.53 high frequency wavelengths, including the thickness of the metal ground plate, and the distance between adjacent elements is 0.5 high frequency wavelengths.

Fig. 7 shows the active standing wave ratios of typical ports when the array antenna is vertically polarized and scans 0 °, 30 ° and 45 ° along the array direction, and it can be seen that the active standing wave ratio of the ports is less than 3 in the fL-8fL frequency band, which achieves good matching performance.

Fig. 8 shows the active standing wave ratios of typical ports when the array antenna is horizontally polarized and scans 0 °, 30 ° and 45 ° along the array direction, and it can be seen that the active standing wave ratio of the ports is less than 3 in the fL-8fL frequency band, which realizes good matching performance.

Fig. 9 is a comparison graph of main polarization and cross polarization gain when the array antenna scans 0 °, 30 ° and 45 ° along the array direction at the fL frequency point, and the directional diagram beam directivity is good, and the polarization isolation is all above 15 dB.

Fig. 10 is a comparison graph of main polarization and cross polarization gains when the array antenna scans 0 °, 30 ° and 45 ° along the array direction at the frequency point of 4fL, and directional diagram beams are good, and polarization isolation is above 20 dB.

Fig. 11 is a comparison graph of main polarization and cross polarization gains when the array antenna scans 0 °, 30 ° and 45 ° along the array direction at the frequency point of 8fL, and directional diagram beams are good, and polarization isolation is above 20 dB. The gain of the high frequency can reach 17dB when the scanning is not carried out.

The above-described embodiments merely represent specific embodiments of the present invention, which are described in detail and with particular reference thereto, it being understood that they have been presented by way of example only and are not to be taken as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.

Claims

1. The tightly-coupled ultra-wideband low-profile conformal phased array based on resistance ring loading is characterized by comprising a double-layer light and thin antenna dielectric substrate (100), a cross-shaped dipole unit (101) printed on the antenna dielectric substrate, a parasitic patch (102) printed on the same dielectric substrate as a dipole, a triangular parasitic patch (103) and a square parasitic patch (104) printed on the next dielectric substrate, a resistance ring layer (200) loaded between an antenna radiation unit and a metal floor, a Marchand balun (300) connected with a microstrip power divider (400) and the dipole, a microstrip power divider placed on the metal floor and a metal floor (500) with a certain curvature, wherein the cross-shaped dipole unit (101) and the parasitic patch (102) are placed in a cross mode and are both printed on the front face of the first dielectric substrate of the double-layer light and thin antenna dielectric substrate (100), a triangular parasitic patch (103) is printed on the back of a first layer of dielectric substrate of the double-layer light and thin antenna dielectric substrate (100), and a square parasitic patch (104) is printed on the back of a second layer of dielectric substrate of the double-layer light and thin antenna dielectric substrate (100); the resistance ring layer, the microstrip power divider and the Marchand balun are printed on a light and thin medium substrate, the resistance ring layer, the microstrip power divider medium substrate and the antenna medium substrate are placed in parallel, the Marchand balun and the antenna medium substrate are placed perpendicularly, and the overlapped part is kept fixed through a rectangular groove.

2. The tightly-coupled ultra-wideband low-profile conformal phased array based on resistive ring loading according to claim 1, characterized in that a combined parasitic patch of a triangular parasitic patch and a square parasitic patch is adopted to be tightly connected with a dipole antenna structure, so that coupling between antenna units is enhanced, and the working bandwidth of a low frequency band is effectively expanded.

3. The tightly-coupled ultra-wideband low-profile conformal phased array based on resistive ring loading according to claim 1, characterized in that a resistive frequency selective surface consisting of a microstrip line annular symmetric structure, lumped resistors and lumped capacitors is loaded between the antenna radiation patch and the metal floor, the annular symmetric structure providing good polarization consistency; the resistive frequency selection surface can effectively improve unit active standing waves, and compromise and balance of antenna radiation efficiency can be realized.

4. The tightly-coupled ultra-wideband low-profile conformal phased array loaded based on the resistor ring according to claim 1, is characterized in that each microstrip power divider is connected with 2 Marchand baluns, each Marchand balun is connected with 1 crossed dipole to form an antenna unit, impedance matching from characteristic impedance of a coaxial connector to a dipole layer can be well realized, the baluns have less impedance conversion functions, miniaturization of the baluns can be realized, and the overall profile height of the antenna is reduced.

5. The tightly-coupled ultra-wideband low-profile conformal phased array based on resistive ring loading according to claim 1, characterized in that the whole antenna array is subjected to conformal processing, the medium substrates are made of light, thin and flexible media, a traditional thick, heavy and wide-angle impedance matching layer is omitted, and the weight is lighter; the array antenna has a conformal carbon fiber floor, and the two sides of the floor are metallized with copper to ensure electrical performance.