CN108539435A - Scanning Phased Array Antenna with Broadband based on slot antenna and frequency-selective surfaces - Google Patents

Abstract

The invention discloses a kind of Scanning Phased Array Antenna with Broadband based on slot antenna and frequency-selective surfaces belongs to Radar Technology, wireless communication technique neck.The antenna includes lowest level metal floor, fit closely the perpendicular row medium substrate for being printed with strip line balun for two layers, upper surface is printed with the middle level dielectric-slab of metal patch, upper layer frequency-selective surfaces structure and coaxial fitting.The present invention realizes the effect coupled strongly between antenna array unit using slot antenna unit and interdigital structure, the impedance matching of frequency-selective surfaces structural improvement antenna element made of the rectangular metal patch combination by medium substrate and periodic arrangement, the active voltage standing-wave ratio for effectively reducing antenna makes antenna while having the ability of broadband character and wide-angle scanning.

Description

Wide bandwidth angular scanning phased array antenna based on slotted antenna and frequency selective surface

technical field

The invention belongs to the technical fields of radar technology and wireless communication, and in particular relates to a wide-band, wide-angle scanning phased array antenna based on a slotted antenna and a frequency selective surface, which is suitable for microwave, millimeter wave and other radar and communication systems.

Background technique

Over the past few decades, broadband, wide-angle scanning phased array antennas have received widespread attention in the military and commercial fields, and are often used in systems such as broadband radar, satellite communications, and radio astronomy. The demand for multifunctional (surveillance, identification, and target tracking) systems on military airborne platforms has also promoted the development of broadband, wide-angle phased array antennas. For a traditional phased array antenna, as the scanning angle increases, the input impedance of the antenna array unit will change drastically, causing port mismatch, resulting in a sharp deterioration of the antenna's VSWR. Therefore, the traditional phased array antenna unit can no longer meet the requirements, and it is urgent to design a new type of antenna unit and a new phased array antenna design idea.

In the past ten years, relevant scholars in the field of international antennas have proposed a new idea of using strong coupling antenna elements to realize broadband phased array antennas. The theoretical basis of this idea can be traced back to the continuous current surface theory proposed by Wheeler in 1965. In US Patent No. US6512487, the radiation arms of adjacent dipole units are connected through an interdigitated capacitor structure, and the capacitive reactance added by the interdigitated structure effectively offsets the inductive reactance loading of the ground. Due to the compact arrangement of the antenna array elements and the strong coupling with each other, the current distribution on the dipole unit is almost constant, which effectively expands the bandwidth and verifies the continuous current surface theory. However, in the state of strong mutual coupling, the strong mutual coupling effect of the antenna makes the state change greatly when scanning at a large angle compared with that when scanning sideways, causing large fluctuations in its own active impedance, and it is difficult for the antenna to scan at a large angle. Therefore, in order to achieve a larger scanning angle, other measures are required.

To sum up, it is difficult for traditional phased array antennas to have the capability of wide-band and wide-angle scanning at the same time, and it is also difficult to scan large angles using strongly coupled dipole antenna arrays. The present invention proposes at these key problems just.

Contents of the invention

The object of the present invention is to solve the above problems and provide a wide-bandwidth angular scanning phased array antenna with a tightly coupled slotted antenna unit and a frequency-selective surface structure to improve the antenna impedance matching effect.

In order to achieve the above object, the present invention adopts the following technical solution: a wide-band, wide-angle scanning phased array antenna based on a slotted antenna and a frequency selective surface, including a metal floor on the bottom layer, two layers closely bonded and printed with a strip line bar Lun's vertical dielectric substrate, the middle dielectric board with metal patches printed on the upper surface, the upper frequency selective surface structure, and the coaxial joint; the inner core of the coaxial joint passes through the opening on the lower metal floor and the strip line The inner conductors of the balun are connected, and the metal patches on the front and rear surfaces of the stripline balun are connected to the metal patches on the middle dielectric board for power feeding.

The shape of the grooved part of the metal patch on the middle dielectric plate is the same as that of a bow tie dipole, and an interdigitated structure is arranged on one side of the larger metal patch;

The upper frequency selective surface structure includes five layers of upper dielectric substrates that are bonded together, and rectangular metal patches of the same size are periodically arranged on the upper surface of each layer of upper dielectric substrates.

The beneficial effects of the present invention are: adopting the slotted antenna unit and the interdigitated structure to realize the effect of strong coupling between the antenna array units, and adopting the frequency selective surface structure composed of a dielectric substrate and periodically arranged rectangular metal patches to improve The impedance matching of the antenna unit can effectively reduce the active voltage standing wave ratio of the antenna, so that the antenna has broadband characteristics and the ability to scan at a large angle.

Description of drawings

FIG. 1 is a schematic structural diagram of a 3×16 wide-band, wide-angle scanning phased array antenna based on a slotted antenna and a frequency selective surface described in Embodiment 1.

FIG. 2 is a schematic diagram of the basic antenna unit of the broadband, wide-angle scanning phased array antenna based on the slotted antenna and the frequency selective surface described in Embodiment 1. FIG.

Fig. 3 is a schematic diagram of the frequency selective surface and the middle dielectric plate described in Example 1 (the structure needs to be clearer).

FIG. 4 is a simulation result of the active voltage standing wave ratio of the E plane of the basic antenna unit described in Embodiment 1. FIG.

FIG. 5 is a simulation result of the H-plane active voltage standing wave ratio of the basic antenna unit described in Embodiment 1. FIG.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the implementation manners and accompanying drawings.

Example 1

The wide-band, wide-angle scanning phased array antenna based on the slotted antenna and the frequency selective surface of this embodiment adopts a 3×16 planar array form, as shown in FIG. 1 . The structure of the basic antenna unit is shown in FIG. 2 . The metal floor 100 at the bottom layer plays a role of fixing and supporting, and at the same time, it can reflect the backward radiation energy of the antenna and enhance the directivity of the antenna. The vertical dielectric substrate 102 and the vertical dielectric substrate 103 are closely attached together, and the front and rear surfaces are respectively printed with metal patches 113 of the same shape, and the common surface is printed with metal patches 112, which are combined to form a stripline balun, and realize 50 Ohm to 100 ohm impedance conversion. The inner core of the coaxial connector 111 passes through the metal floor 100 and is connected to the metal patch 112 for power feeding, and the metallized via hole 114 provided on the stripline balun is used to prevent energy leakage. The upper surface of the middle dielectric substrate 103 is printed with a metal patch 109. The slotted part of the metal patch 109 has the same shape as the bow-tie dipole. According to the principle of Babinet's complementarity, the radiation pattern of the slotted antenna and its complementary antenna direction Same diagram, with the polarization rotated by 90°. When the antenna array is working, its working principle of obtaining broadband characteristics is the same as that of the complementary tightly coupled dipole array, which increases the bandwidth of the antenna through the strong coupling between the array elements. There is an interdigitated structure on the chip to further enhance the mutual coupling between antenna elements, which can effectively reduce the active voltage standing wave ratio of the antenna when it works in the low frequency band. By adjusting the gap size and length of the interdigitated structure, the capacitance can be controlled The strength of the coupling can offset the inductive reactance introduced by the metal floor 100 .

The upper frequency selective surface structure includes 5 layers of upper dielectric substrates that are laminated together. The upper surface of each upper dielectric substrate is periodically arranged with rectangular metal patches 110 of the same shape, which are used to improve the impedance matching effect of the antenna and effectively reduce the antenna unit. The active voltage standing wave ratio further increases the scanning angle of the antenna.

Fig. 4 and Fig. 5 respectively show the simulation results of the active voltage standing wave ratio of the E plane and the H plane of the basic antenna unit in this embodiment varying with frequency at different scan angles. It can be seen from Figure 4 that within the ±80° scanning range of the E plane, the impedance bandwidth of the active VSWR less than 3 reaches 5.54:1, and within the ±75° scanning range, the active VSWR is less than 2.5 The impedance bandwidth reaches 5.44:1. It can be seen from Figure 5 that within the ±45° scanning range of the H surface, the impedance bandwidth of the active voltage standing wave ratio less than 3 reaches 5.12:1, realizing the broadband and wide-angle scanning of the phased array antenna.

Example 2

Specifically, a planar array of any size can be formed by extending each basic antenna unit in a two-dimensional direction. Other structures are the same as those described in detail in Example 1.

The foregoing descriptions of the present invention and its embodiments are provided to those skilled in the art of the invention and are to be considered illustrative rather than restrictive. Engineers and technicians can implement specific operations based on the ideas in the claims of the invention, and can make various changes in form and details without departing from the spirit and scope of the present invention defined by the appended claims. Variety. All of the above should be considered as the scope of the present invention.

Claims (2)

1. A wide bandwidth angular scanning phased array antenna based on a slotted antenna and a frequency selective surface, characterized in that: it includes a bottom metal floor, two layers of vertical dielectric substrates that are closely attached and printed with stripline baluns, A middle dielectric board with metal patches printed on the upper surface, an upper frequency selective surface structure, and a coaxial connector; The inner core of the coaxial joint is connected to the inner conductor of the stripline balun through the opening on the lower metal floor, and the metal patch on the front and rear surfaces of the stripline balun is connected to the metal patch on the middle dielectric board for power feeding ; The shape of the grooved portion of the metal patch on the middle dielectric plate is the same as that of a bow-tie dipole, and an interdigitated structure is provided on one side of the larger metal patch. 2. A kind of wide bandwidth angular scanning phased array antenna based on slotted antenna and frequency selective surface as claimed in claim 1, characterized in that: the upper layer frequency selective surface structure comprises 5 layers of upper layer dielectric substrates , rectangular metal patches of the same size are periodically arranged on the upper surface of each upper dielectric substrate.