CN110718748A - A metamaterial unit for encoding metamaterial antennas - Google Patents

Abstract

The invention discloses a metamaterial unit for coding a metamaterial antenna, which includes a resonance unit, a back cavity and a transmission line structure; the resonance unit includes a resonance substrate, the middle of the resonance substrate is provided with a hollow slot that runs through and is provided with a sheet conductor inside. , a connection gap is formed between the sheet conductor and the resonant substrate, and two diodes are arranged in the connection gap; the back cavity includes a back cavity substrate, and a rectangular slot is formed in the middle of the back cavity substrate, and the four inner walls of the rectangular slot are respectively attached There is a metal film; the transmission line structure includes a waveguide substrate, and a waveguide slot is opened in the middle of the metal layer. The guided wave of the invention enters from the waveguide slot of the transmission line structure, realizes the indirect feeding of the resonance unit through the coupling effect of the back cavity, directly isolates the current path of the transmission line structure and the resonance unit, thereby suppressing the current flowing through the diode and reducing The ohmic loss when the diode is turned on is reduced, thereby improving the overall performance of the metamaterial unit used to encode the metamaterial antenna.

Description

A metamaterial unit for encoding metamaterial antennas

technical field

The invention belongs to the technical field of metamaterials, in particular to a metamaterial unit used for coding metamaterial antennas.

Background technique

Metamaterial technology is a cutting-edge interdisciplinary technology, and its technical fields include electromagnetics, microwaves, terahertz, photonics, advanced engineering design systems, communications, semiconductors and other fields. Compared with the phased array antenna of the phase-shift network, the metamaterial antenna using the metamaterial unit greatly reduces the system complexity, volume weight and cost, and has important application value. Since its radiation performance is directly determined by the radiation performance of the metamaterial unit, the study of metamaterial units with excellent performance is of great significance for better research on metamaterial antennas.

The structure of the metamaterial unit currently used to encode the metamaterial antenna is as follows: a rectangular CELC resonant unit with a PIN diode is directly constructed on the upper conductor surface of the transmission line structure, and the guided wave can be dynamically radiated through the CELC resonant unit to form a beam. However, since there is a strong current on the upper conductor surface of the transmission line, if the unit is built directly on the upper conductor surface, when the diode is turned on, a larger current flows directly through the parasitic resistance of the diode, which will cause a higher ohmic loss, resulting in an overall lower efficiency of the antenna.

American scientist Dr. Smith proposed an improved elliptical structure CELC resonant unit in 2016, which can reduce the ohmic loss to a certain extent. Compared with the traditional rectangular CELC resonant unit, the elliptical structure widens the metal circuit loop, so that the resistance of the metal part through which the current flows is significantly reduced. This design reduces the ohmic losses in the metal part, but does not address the ohmic losses when the diode is turned on.

Therefore, it is necessary to design a new metamaterial unit that further solves the ohmic loss problem caused by diode conduction on the basis of the above.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a novel metamaterial unit, which solves the problems of large loss and low efficiency of the traditional metamaterial unit used for coding metamaterial antennas.

In order to solve the above technical problems, the present invention is achieved through the following technical solutions: a metamaterial unit for coding a metamaterial antenna, including resonant units, a back cavity and a plate-like structure stacked in sequence from top to bottom transmission line structure, where,

The resonant unit includes a resonant substrate, the middle of the resonant substrate is provided with an escape groove that runs through the thickness direction, the air escape groove has a sheet conductor, and a connection gap is formed between the sheet conductor and the resonance substrate, so Two diodes are symmetrically arranged at both ends of the short axis of the hollow slot in the connection gap, and the positive and negative electrodes of the diodes are respectively electrically connected to the sheet conductor and the resonant substrate;

A back cavity, including a back cavity substrate, a rectangular groove running through the thickness direction is opened in the middle of the back cavity substrate, four inner walls of the rectangular groove are respectively attached with metal films, and the four metal films are enclosed to form a metal cavity , one end of the metal cavity close to the resonance unit abuts the resonance substrate, and one end away from the resonance unit abuts the transmission line structure;

The transmission line structure includes a waveguide substrate formed by fixedly bonding a dielectric layer and a metal layer, the metal layer abuts against the back cavity, and a waveguide slot is opened in the middle of the metal layer for passing the guide generated by the microwave source. Wave;

The geometric center of the hollow slot, the geometric center of the rectangular slot and the geometric center of the waveguide slot coincide.

Further, the sheet conductor includes a metal sheet, the metal sheet is an elliptical structure with a groove at each end of the long axis, and the distance between the short axis end point of the metal sheet and the short axis end point of the hollow groove d_gap is 0.15mm-0.47mm, and the distance d_cut between the point of the groove closest to the center of the metal sheet and the end point of the long axis of the void groove is 0.7mm-1mm.

Further, the metal layer is attached to one side of the dielectric layer close to the back cavity or both sides of the dielectric layer, and the geometric center of the metal layer coincides with the geometric center of the dielectric layer.

Further, the resonance unit, the back cavity and the transmission line structure are parallel to each other.

Further, the long-axis distance 2r ₂ of the hollow groove is 4 mm-5.6 mm, and the short-axis distance 2r ₁ is 3.2 mm-4.8 mm.

Further, the back cavity substrate is a plate with a uniform thickness made of RT6035HTC substrate material, and the dielectric layer is a uniform thickness made of any one or more materials of PCB, FR4 or Teflon. plate.

Further, the resonant substrate, the metal film and the metal layer are made of copper or silver.

Further, the resonance unit is a CELC resonance unit.

Further, the waveguide slot has a rectangular structure, the long side of which is parallel to the long axis of the hollow slot, and the short side is parallel to the short axis of the hollow slot.

The present invention also provides an equivalent circuit for encoding a metamaterial antenna feed structure, including a resistance, an inductance, and a metamaterial unit for encoding a metamaterial antenna as described above; the resistance, for encoding a metamaterial The metamaterial unit of the antenna and the inductor are connected in series in sequence. When the diode is disconnected, the equivalent circuit consists of a resistor, an inductor and a set of capacitors connected in series; when the diode is turned on, the equivalent circuit consists of a resistor and an inductor connected in series.

Compared with the prior art, the benefits of the present invention are:

The metamaterial unit used for coding the metamaterial antenna according to the present invention ensures the original resonance characteristics of the metamaterial unit, and at the same time, the guided traveling wave enters from the waveguide slot of the transmission line structure, and realizes the resonance through the coupling effect of the back cavity. The indirect feeding of the unit directly isolates the current path of the transmission line structure and the resonant unit, thereby suppressing the current flowing through the diode and reducing the ohmic loss when the diode is turned on. The total radiation efficiency of the metamaterial antenna is significantly improved, thereby improving the The metamaterial unit is used to encode the overall performance of the metamaterial antenna.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained according to the structures shown in these drawings without creative efforts.

Below in conjunction with accompanying drawing, the present invention is further described:

1 is an overall diagram of a metamaterial unit for coding a metamaterial antenna according to the present invention;

Fig. 2 is the composition structure exploded view of Fig. 1;

Fig. 3 is the structural representation of resonance unit;

Fig. 4 is the structural representation of back cavity;

FIG. 5 is a schematic structural diagram of a waveguide slot;

6 is a schematic structural diagram of an equivalent circuit for encoding a metamaterial antenna feed structure;

7 is a circuit diagram of an equivalent circuit for encoding a metamaterial antenna feed structure;

Figure 8 is a graph of various losses and radiated power results of a conventional feed structure in a closed state;

Fig. 9 is the result graph of various losses and radiation power of the feeding structure of the present invention in the closed state;

Fig. 10 is the simulation schematic diagram of the current flowing through the diode of the present invention;

1. Resonant unit; 2. Back cavity; 3. Transmission line structure; 4. Resistor; 5. Inductance; 11. Resonant substrate; 12. Avoidance slot; 13. Sheet conductor; 14. Connection gap; 15. Diode; 21 , back cavity substrate; 22, rectangular slot; 23, metal film; 31, waveguide substrate; 32, waveguide slot.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relationship between various components under a certain posture (as shown in the accompanying drawings). The relative positional relationship, the movement situation, etc., if the specific posture changes, the directional indication also changes accordingly.

In addition, descriptions such as "first", "second", etc. in the present invention are only for descriptive purposes, and should not be construed as indicating or implying their relative importance or implicitly indicating the number of indicated technical features. Thus, a feature delimited with "first", "second" may expressly or implicitly include at least one of that feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise expressly and specifically defined.

In the present invention, unless otherwise expressly specified and limited, the terms "connected", "fixed" and the like should be understood in a broad sense, for example, "fixed" may be a fixed connection, a detachable connection, or an integrated; It can be a mechanical connection, an electrical connection, a physical connection or a wireless communication connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction between the two elements. unless otherwise expressly qualified. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but must be based on the realization by those of ordinary skill in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered that the combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

Example 1

As shown in Fig. 1-Fig. 2 and Fig. 6, a metamaterial unit for coding a metamaterial antenna includes a resonant unit 1, a back cavity 2 and a transmission line structure 3 stacked in sequence from top to bottom. For the convenience of installation , the resonant unit 1, the back cavity 2 and the transmission line structure 3 are designed to be parallel to each other and have a plate-like structure, wherein:

The resonant unit 1 shown in FIG. 3 includes a resonant substrate 11 , a hollow groove 12 extending through the thickness direction is formed in the middle of the resonant substrate 11 , and a sheet conductor 13 is arranged in the hollow groove 12 . A connection slot 14 is formed between the conductor 13 and the resonant substrate 11 , and two diodes 15 are symmetrically arranged at both ends of the short axis of the hollow slot 12 in the connection slot 14 , and the positive and negative electrodes of the diodes 15 are respectively It is electrically connected to the sheet conductor 13 and the resonant substrate 11. In this embodiment, the hollow slot 12 is an elliptical slot; further, the resonance unit 1 is a CELC resonance unit; the CELC described in this embodiment The structural principle of the resonant unit refers to an improved CELC resonant unit with an elliptical structure proposed by American scientist Dr. Smith. Compared with the traditional rectangular CELC resonant unit, the elliptical structure widens the metal circuit loop, so that the resistance of the metal part through which the current flows is significantly reduced. Small;

The back cavity 2 as shown in FIG. 4 includes a back cavity substrate 21 , a rectangular groove 22 extending through the thickness direction is formed in the middle of the back cavity substrate 21 , and metal films 23 are respectively attached to the four inner walls of the rectangular groove 22 . The four metal films 23 are enclosed to form a metal cavity. The length of the metal cavity along the thickness direction of the back cavity substrate 21 is greater than the thickness of the back cavity substrate 21, and respectively protrudes to both sides for a certain distance, close to the back cavity substrate 21. One end of the resonant unit 1 abuts against the resonant substrate 11, and one end away from the resonant unit 1 abuts against the transmission line structure 3, thereby forming a space for coupling guided waves;

The transmission line structure 3 shown in FIG. 5 is the basic structure in the microwave circuit, and includes a waveguide substrate 31 formed by a dielectric layer and a metal layer that are fixedly bonded. The metal layer is attached to the dielectric layer and is close to the back cavity. 2. The metal layer is attached to one side or both sides of the dielectric layer, which can be connected by gluing or bolting. For the convenience of installation, the geometric center of the metal layer coincides with the geometric center of the dielectric layer, and the middle part of the metal layer A waveguide slot 32 is provided for passing the guided traveling wave generated by the microwave source, and the guided traveling wave propagates from the dielectric layer to the back cavity 2 and the resonance unit 1 through the waveguide slot, thereby completing the indirect feeding;

In order to ensure smooth feeding and structural integrity, the geometric center of the hollow slot 12 , the geometric center of the rectangular slot 22 and the geometric center of the waveguide slot 32 are coincident.

More specifically, the sheet conductor 13 includes a metal sheet, the metal sheet is an elliptical structure with two grooves at both ends of the long axis, and the short axis end point of the metal sheet is away from the short axis of the hollow groove 12 . The distance d_gap of the end point is 0.15mm-0.47mm, the distance d_cut from the point of the groove closest to the center of the metal sheet to the end point of the long axis of the hollow slot 12 is 0.7mm-1mm, and the distance d_cut of the hollow slot 12 is 0.7mm-1mm. The long axis distance 2r ₂ is 4mm-5.6mm, and the short axis distance 2r ₁ is 3.2mm-4.8mm.

Preferably, the back cavity substrate 21 is a plate with uniform thickness made of RT6035HTC substrate material, which has the characteristics of high thermal conductivity and low loss, and the dielectric layer is any one or more of PCB, FR4 or Teflon. A sheet of uniform thickness made by mixing various materials to maintain insulation between layers.

Preferably, the resonant substrate 11 , the metal film 23 and the metal layer are made of copper or silver, more preferably copper, which reduces the cost on the premise of ensuring high conductivity.

Preferably, the waveguide slot 32 has a rectangular structure. In this embodiment, the size of the waveguide slot 32 is 5.5mm*1.7mm, the long side of the waveguide slot 32 is parallel to the long axis of the avoidance slot 12, and the short side is parallel to the avoidance slot 12. The short axis of the hollow slot 12 is parallel, so that the polarization of the waveguide slot 32 and the resonance unit 1 are consistent, so as to achieve better feeding.

In order to further illustrate the performance and effect of this embodiment, the energy loss, radiated power and current flowing through the diode of the metamaterial antenna are simulated:

Figure 8 shows the results of various losses and radiated power of the traditional metamaterial unit when the resonance unit is turned off. It can be seen from the figure that with the increasing frequency, the dielectric loss, metal loss and radiation are all in low level, but the loss of the diode also increases accordingly;

Figure 9 shows the results of various losses and radiated power of the metamaterial unit in this embodiment when the resonance unit is turned off. It can be seen from the figure that as the frequency increases, the dielectric loss, metal loss , radiation and diodes are at low levels;

It can be seen that the metamaterial unit of this embodiment can obviously suppress the ohmic loss caused by the diode when the resonance unit is turned off.

Figure 10 shows the results of the simulation of the current flowing through the diode in the traditional metamaterial unit and the metamaterial unit of this embodiment when the resonant unit is turned on. It can be seen from the figure that when the diode is turned on, the traditional metamaterial unit is The current of the diode in the unit is about 0.16A, while the current of the diode in the metamaterial unit of this embodiment is about 0.01A. It can be seen that the metamaterial unit of this embodiment can reduce the ohmic impedance, so that the The current is extremely small, ensuring low ohmic losses and maintaining the high efficiency of the metamaterial antenna.

After simulation analysis, the minimum ohmic loss of this new metamaterial unit can be reduced to 1/25 of the traditional metamaterial unit. Since it does not change the shape of the metamaterial unit, it proposes a new type of feeding structure, which is also applicable to other metamaterial structures, so it has broad application prospects.

The specific use process of a metamaterial unit for coding a metamaterial antenna described in this embodiment is as follows: an intermediate layer, that is, a back cavity 2 is added between the CELC resonant unit of the improved elliptical structure and the transmission line structure 3, and the transmission line The metal layer on the structure 3 is separated from the resonant unit 1, thereby directly isolating the current path between the transmission line structure 3 and the waveguide slot 32, thereby suppressing the current flowing through the diode 15 and reducing the energy loss when the diode 15 is turned on .

By applying a DC bias voltage between the center of the CELC unit and the surrounding metal structures, the on-state and off-state control of the diode can be realized, thereby realizing the reconfigurable function of this embodiment.

Embodiment 2

As shown in Figure 6-7, an equivalent circuit for coding a metamaterial antenna feeding structure includes a resistor 4, an inductance 5 and the metamaterial unit for coding a metamaterial antenna as described in Embodiment 1; The resistance 4, the metamaterial unit used to encode the metamaterial antenna and the inductance 5 are connected in series in sequence, and when the diode 15 is disconnected, the equivalent circuit is composed of the resistance 4, the inductance 5 and a group of capacitors in series, and a group of capacitors is a chip. The shape conductor 13 , the connection slot 14 and the diode 15 are formed in parallel; when the diode 15 is turned on, the equivalent circuit consists of the resistor 4 and the inductor 5 in series.

The above descriptions are only the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Under the inventive concept of the present invention, the equivalent structural transformations made by the contents of the description and drawings of the present invention, or the direct/indirect application Other related technical fields are included in the scope of patent protection of the present invention.

Claims (10)

1. A metamaterial unit for encoding a metamaterial antenna, comprising: comprises a resonance unit (1), a back cavity (2) and a transmission line structure (3) which are sequentially superposed from top to bottom and are in a plate-shaped structure, wherein,

the resonant unit (1) comprises a resonant substrate (11), wherein a clearance groove (12) penetrating through the thickness direction is formed in the middle of the resonant substrate (11), a sheet conductor (13) is arranged in the clearance groove (12), a connecting gap (14) is formed between the sheet conductor (13) and the resonant substrate (11), and two diodes (15) are symmetrically arranged at two ends of a short shaft of the clearance groove (12) in the connecting gap (14);

the back cavity (2) comprises a back cavity substrate (21), a rectangular groove (22) penetrating through the thickness direction is formed in the middle of the back cavity substrate (21), metal films (23) are respectively attached to four inner walls of the rectangular groove (22), the four metal films (23) are enclosed to form a metal cavity, one end, close to the resonance unit (1), of the metal cavity abuts against the resonance substrate (11), and one end, far away from the resonance unit (1), of the metal cavity abuts against the transmission line structure (3);

the transmission line structure (3) comprises a waveguide substrate (31) formed by fixedly attaching a dielectric layer and a metal layer, wherein the metal layer is abutted against the back cavity (2), and a waveguide gap (32) is formed in the middle of the metal layer and used for passing through guided waves generated by a microwave source;

the geometric centers of the clearance grooves (12), the rectangular grooves (22) and the waveguide gaps (32) are coincident.

2. The metamaterial unit for encoding a metamaterial antenna as claimed in claim 1, wherein: the sheet conductor (13) comprises a metal sheet, the metal sheet is of an oval structure, two ends of a long axis of the metal sheet are respectively provided with a groove, the distance d _ gap between the end point of the short axis of the metal sheet and the end point of the short axis of the clearance groove (12) is 0.15mm-0.47mm, and the distance d _ cut between the point of the groove closest to the center of the metal sheet and the end point of the long axis of the clearance groove (12) is 0.7mm-1 mm.

3. The metamaterial unit for encoding a metamaterial antenna as claimed in claim 1, wherein: the metal layer is attached to one surface of the dielectric layer close to the back cavity (2) or two surfaces of the dielectric layer, and the geometric center of the metal layer is coincident with that of the dielectric layer.

4. The metamaterial unit for encoding a metamaterial antenna as claimed in claim 3, wherein: the resonance unit (1), the back cavity (2) and the transmission line structure (3) are parallel to each other.

5. The metamaterial unit for encoding a metamaterial antenna as claimed in claim 1, wherein: the clearance groove (12) is an elliptical groove with a long axle distanceFrom 2r₂4mm-5.6mm, short axis distance 2r₁Is 3.2mm-4.8 mm.

6. The metamaterial unit for encoding a metamaterial antenna as claimed in claim 3, wherein: back of body chamber base plate (21) is the even panel of thickness that adopts RT6035HTC base plate material preparation to form, the even panel of thickness that the dielectric layer is formed for adopting arbitrary one or more material mixture preparation of PCB, FR4 or teflon.

7. The metamaterial unit for encoding a metamaterial antenna as claimed in claim 3, wherein: the resonance substrate (11), the metal film (23) and the metal layer are made of copper or silver.

8. The metamaterial unit for encoding a metamaterial antenna as claimed in claim 1, wherein: the resonance unit (1) is a CELC resonance unit.

9. A metamaterial unit for encoding a metamaterial antenna as claimed in any one of claims 1 to 5, wherein: the waveguide slot (32) is of a rectangular structure, the long side of the waveguide slot is parallel to the long axis of the clearance groove (12), and the short side of the waveguide slot is parallel to the short axis of the clearance groove (12).

10. An equivalent circuit for a feed structure of an encoded metamaterial antenna, characterized by: the metamaterial unit for the encoding metamaterial antenna comprises a resistor (4), an inductor (5) and the metamaterial unit for the encoding metamaterial antenna as claimed in any one of claims 1 to 9, wherein the resistor (4), the metamaterial unit for the encoding metamaterial antenna and the inductor (5) are connected in series in sequence.

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