CN104733868A - Low-profile circuit analog absorber based on dipole array - Google Patents

Abstract

The invention discloses a new type of low profile circuit simulated absorber, adopting a method that can effectively reduce the thickness of the simulated absorber based on a dipole array circuit - the inductive ground plane method, not only can effectively reduce the thickness of the absorber, but also can broaden the original The operating bandwidth of the structure. Based on the classic transmission line theory, the method introduces a short-circuit patch array between the center-loaded dipole array circuit and the ground plane to realize the conversion of the ordinary ground plane to the inductive ground plane, thereby effectively reducing the thickness of the circuit analog absorber; in addition , the coupling effect between the inductive ground plane and the reactive component of the surface circuit can also be used to broaden the operating bandwidth of the absorber. This technology is mainly realized by short-circuit patch arrays. It has a simple structure, adopts ordinary PCB board technology, is easy to process, and its cost and weight are relatively small, so it can be widely used in the design of circuit analog absorbers.

Description

Low Profile Circuit Simulating Absorber Based on Dipole Array

technical field

The invention relates to an electromagnetic wave absorbing circuit for electromagnetic compatibility and radar absorbing materials, in particular to a dipole-based low profile circuit analog absorber.

Background technique

The research on the safety of electronic equipment in the electromagnetic environment originated from the research on the prevention of electromagnetic information leakage of military equipment, which is called TEMPEST technology (electromagnetic information leakage protection technology). With the wide application and rapid replacement of civilian electronic information products, the electromagnetic environment safety of electronic equipment has also received attention. Different from TEMPEST technology, civil electronic information products mainly consider not only their own information leakage, but whether the external electromagnetic field will affect the normal operation of their own equipment, and whether the electromagnetic waves emitted by themselves will affect the normal operation of other electronic information products. Work. In addition, with the continuous improvement of modern reconnaissance and detection technology, higher requirements are placed on the performance of radar absorbing materials.

The use of electromagnetic wave absorbers is an effective means to shield electromagnetic waves from interfering with other equipment and from being interfered by other equipment. According to their different mechanisms of action, the research on absorbers is mainly divided into two categories: one is the research on new materials, such as the design of composite materials such as absorbers and wave-absorbing materials, and the application of metamaterials. The application of metamaterials is usually Absorbers with a very low profile can be realized, but their bandwidth is very narrow; the other is the design based on circuit theory, such as metal mesh, Salisbury screen, Jaumann absorber and complex impedance circuit simulation absorber. At present, the research on circuit analog absorbers focuses on the research on resistive materials, and the absorption of incident electromagnetic waves can be achieved by designing resistive films with different shapes and different impedance values. For this type of absorber, if it is desired to obtain ideal absorption performance in a wider bandwidth, the main means to be adopted is to increase the number of layers of the absorber layer, but this will not only increase the production cost, but also make the absorber Increased size and weight.

Therefore, the implementation method in the prior art is relatively complicated, and it is difficult to realize a microwave absorber with both wide operating bandwidth and low profile characteristics at the same time.

Contents of the invention

The technical problem solved by the present invention is to provide a low-profile circuit analog absorber based on dipoles, which can not only effectively reduce the thickness of the original circuit analog absorber based on a quarter wavelength, but also effectively widen the absorber. Working bandwidth.

The technical solution to realize the object of the present invention is: a low-profile circuit analog absorber based on a dipole array, including a number of absorber units, the absorber units are two-dimensionally arranged periodically in the form of a square grid to form an array, each Each absorber unit includes a dipole, a thin film chip resistor, an upper dielectric substrate, a square metal patch, a lower dielectric substrate, a metal plate, a first metallized through hole, and a second metallized through hole;

A metal plate is arranged on the bottom of the lower dielectric substrate, a square metal patch is arranged in the middle of the upper surface of the lower dielectric substrate, and a first metallized through hole and a second metallized through hole are opened on the lower dielectric substrate. On both sides of the type metal patch, the upper dielectric substrate is arranged above the lower dielectric substrate, the dipole is arranged in the middle of the upper surface of the upper dielectric substrate, and the thin film chip resistor is arranged in the middle of the dipole. The extension direction of the dipole is consistent with the two The lines connecting the centers of the metallized through holes are parallel to each other.

The dielectric constants ε _r of the upper dielectric substrate and the lower dielectric substrate are both 2.2 to 10.2; the total thickness of the double-layer dielectric substrate is Wherein λ ₀ is the wavelength in free space, and the thickness of the lower dielectric substrate is 0.5 mm to 1 mm.

The dielectric materials of the upper dielectric substrate and the lower dielectric substrate are the same.

The side length of the square metal patch is Where N is [0.75,0.80], λ ₀ is the wavelength in free space, ε _r is the dielectric constant, and the diameters of the two metallized via holes are both 0.5 mm.

The width of a dipole is one-thirtieth of its length, which is

The resistance value of the thin film chip resistor is greater than the input impedance value of the dipole.

The width between two adjacent absorber units is λ ₀ is the wavelength in free space, and ε _r is the dielectric constant.

Compared with the prior art, the present invention has the following remarkable advantages: 1) The low-profile circuit analog absorber based on the dipole structure proposed by the present invention has a thickness of only one-seventh of the guided wave wavelength, which is different from that of ordinary single-layer circuits. Compared with the structure of the simulated absorber, the thickness is reduced by nearly 45%; at the same time, the bandwidth is nearly 110% wider than the ordinary dipole array absorber based on the common ground plane; 2) the dipole-based structure proposed by the present invention The low-profile circuit simulates the absorber. Although it adopts a double-layer circuit structure, it can be fixed with ordinary plastic screws without changing its working characteristics. With the use of thin film chip resistors, the structure is simple and easy to process, and The cost and weight are relatively small, so it can be mass-produced; in addition, it can also be combined with other technologies, such as MEMS switch technology, to design radar system components with functions of receiving, emitting and absorbing.

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Description of drawings

FIG. 1 is a schematic diagram of a dipole and an upper dielectric substrate of the present invention.

Fig. 2 is a schematic diagram of a square metal patch, a metallized through hole and a lower dielectric substrate of the present invention.

Fig. 3 is a schematic diagram of a square metal patch, a metallized through hole and a metal plate of the present invention.

Figure 4 is a top view of a dipole-based low-profile circuit analog absorber structure.

Detailed ways

With reference to Fig. 1, Fig. 2, Fig. 3 and Fig. 4, a low-profile circuit analog absorber of the present invention includes several absorber units, and the absorber units are two-dimensionally arranged periodically in the form of a square grid to form an array, each Each absorber unit includes dipole 1, thin film chip resistor 2, upper dielectric substrate 3, square metal patch 4, lower dielectric substrate 5, metal plate 6, first metallized through hole 7, second metallized through hole 8;

A metal plate 6 is arranged at the bottom of the lower dielectric substrate 5, a square metal patch 4 is arranged in the middle of the upper surface of the lower dielectric substrate 5, and a first metallized through hole 7 and a second metallized through hole 8 are opened on the lower dielectric substrate 5. Two metallized through holes are located on both sides of the square metal patch 4, an upper dielectric substrate 3 is arranged above the lower dielectric substrate 5, a dipole 1 is arranged in the middle of the upper surface of the upper dielectric substrate 3, and a middle part of the dipole 1 is arranged In the thin film chip resistor 2, the extension direction of the dipole 1 is parallel to the line connecting the centers of the two metallized through holes.

The dielectric constants ε _r of the upper dielectric substrate 3 and the lower dielectric substrate 5 are both 2.2 to 10.2; the total thickness of the double-layer dielectric substrate is Wherein λ ₀ is the wavelength in free space, and the thickness of the lower dielectric substrate 5 is 0.5mm˜1mm.

The dielectric materials of the upper dielectric substrate 3 and the lower dielectric substrate 5 are the same.

The side length of the square metal patch 4 is Where N is [0.75,0.80], λ ₀ is the wavelength in free space, ε _r is the dielectric constant, and the diameters of the two metallized through holes are both 0.5 mm.

The width of dipole 1 is one-thirtieth of its length, which is

The resistance value of the thin film chip resistor 2 is greater than the input impedance value of the dipole 1 .

The width between two adjacent absorber units is λ ₀ is the wavelength in free space, and ε _r is the dielectric constant.

The details and working conditions of the specific device of the present invention will be described in detail below.

The width of the dipole 1 is 0.8mm, and the length is 10.8mm; the middle of the dipole 1 is loaded with a thin film chip resistor 2, the package type is 0603, and the resistance value is 110Ω; the above structure is used as a periodic unit for two-dimensional arrangement And printed on the upper dielectric substrate 3, wherein the size of the periodic unit is 11.8mm*11.8mm, the dielectric constant of the upper dielectric substrate 3 is 2.65, and the thickness is 3mm; the side length of the square metal patch 4 is 8mm, which is relatively The distance between two adjacent square metal patches 4 is 11.8mm, forming a two-dimensional periodic array and printed on the lower dielectric substrate 5, wherein the dielectric constant of the lower dielectric substrate 5 is 2.65, and the thickness is 0.5mm; The first metallized through-hole 7 and the second metallized through-hole 8 are respectively opened downward on the top 5, and the two metallized through-holes are located on both sides of the square metal patch 4, and the connection line between the centers of the two through-holes and the dipole The extension direction of sub-1 is the same, and the diameters of the two metallized through-holes are both 0.5 mm.

This example contains 18*18 periodic units, the overall cross-sectional size is 212.4mm*212.4mm, the total thickness is 3.5mm, and the total weight is 363 grams. According to the numerical calculation and actual test, when the electromagnetic wave is vertically incident on the sample, the frequency range of 90% absorption rate is 8.05GHz-13.65GHz, and the relative bandwidth is 52%.

The preparation process of the dipole-based low-profile circuit analog absorber of the present invention is described in detail below:

(1) First, determine the center frequency of the circuit simulated absorber and the parameters of the two-layer dielectric substrate, mainly the dielectric constant. (2) According to the central operating frequency and the dielectric constant of the dielectric substrate, determine the equivalent operating wavelength and determine the length of the dipole antenna, which is usually half of the equivalent wavelength.

(3) According to the requirements of the main mode of the periodic structure on the unit size, determine the width of the unit, usually 1.05 times the equivalent half wavelength, and the chip resistance value loaded in the center is the coupling between the radiation resistance of the dipole antenna and the surrounding units sum of resistances. (4) The period of the metal patch array constituting the inductive ground plane is the same as that obtained in step (3), and the side length of the metal patch is equal to 75%-80% of the equivalent half-wavelength; according to the specific processing accuracy, determine The diameter of the metallized through hole is generally 0.5mm; the thickness of the dielectric substrate is 0.5mm, and its bottom surface is all metallized.

(5) The thickness of the simulated absorber based on the low-profile dipole is one-seventh of the equivalent wavelength, so the thickness of the upper circuit is Where λ ₀ is the wavelength in free space and ε _r is the dielectric constant.

It can be seen from the above that the present invention is designed to meet the requirement of low profile of the electromagnetic wave absorber, and considering the problem that the bandwidth of the simulated absorber based on the dipole array circuit is too narrow, the inductive ground plane technology is adopted. The thickness of the low-profile circuit analog absorber based on dipoles is only about one-seventh of the equivalent working wavelength, and the thickness is reduced by nearly 45% compared with the original quarter-wavelength electric absorber; and the working bandwidth can reach 52%. It is nearly 110% wider than the working bandwidth (about 21%) of the common circuit analog absorber based on dipoles.

Claims (7)

1. A low-profile circuit analog absorber, characterized in that it comprises a number of absorber units, the above-mentioned absorber units are arranged two-dimensionally periodically in a square grid form to form an array, and each absorber unit includes a dipole[ 1], thin film chip resistors [2], upper dielectric substrate [3], square metal patch [4], lower dielectric substrate [5], metal plate [6], first metallized through hole [7], second metallized via [8]; A metal plate [6] is arranged at the bottom of the lower dielectric substrate [5], a square metal patch [4] is arranged in the middle of the upper surface of the lower dielectric substrate [5], and a first metallized through hole is opened on the lower dielectric substrate [5]. 7], the second metallized through hole [8], the two metallized through holes are located on both sides of the square metal patch [4], the upper dielectric substrate [3] is set above the lower dielectric substrate [5], the upper layer The middle part of the upper surface of the dielectric substrate [3] is provided with a dipole [1], and the middle part of the dipole [1] is provided with a thin film chip resistor [2]. The lines connecting the centers of the circles are parallel. 2. The low-profile circuit analog absorber according to claim 1, characterized in that, the dielectric constants _εr of the upper dielectric substrate [3] and the lower dielectric substrate [5] are both 2.2 to 10.2; The total thickness is Where λ ₀ is the wavelength in free space, and the thickness of the lower dielectric substrate [5] is 0.5mm-1mm. 3. The low-profile circuit simulation absorber according to claim 2, characterized in that the dielectric materials of the upper dielectric substrate [3] and the lower dielectric substrate [5] are the same. 4. The low-profile circuit simulation absorber according to claim 1 or 2, wherein the side length of the square metal patch [4] is Where N is [0.75,0.80], λ ₀ is the wavelength in free space, ε _r is the dielectric constant, and the diameters of the two metallized through holes are both 0.5 mm. 5. The low-profile circuit simulation absorber according to claim 1 or 2, wherein the width of the dipole [1] is one-thirtieth of its length, which is 6. The low-profile circuit simulation absorber according to claim 1 or 2, characterized in that the resistance value of the thin film chip resistor [2] is greater than the input impedance value of the dipole [1]. 7. The low-profile circuit simulation absorber according to claim 1 or 2, wherein the width between two adjacent absorber units is λ ₀ is the wavelength in free space, and ε _r is the dielectric constant.