阅读说明：本技术 两比特超材料周期性时序调制方法、超材料及相控阵天线 (Two-bit metamaterial periodic time sequence modulation method, metamaterial and phased array antenna ) 是由 白旭东 曹岸杰 孔凡伟 宋云卓 徐晟阳 孙运涛 吕艳亭 孙朦朦 于 2019-06-14 设计创作，主要内容包括：本发明涉及两比特超材料周期性时序调制方法、超材料及相控阵天线,对每个两比特数字编码超材料单元进行周期性时序调制,通过控制一个调制周期内各单元通道上允许通过的射频信号的时间比例,实现对该两比特数字编码超材料单元的幅度加权；通过控制一个调制周期各单元通道上通过的射频信号的起始时刻,实现对该两比特数字编码超材料单元的相位加权。两比特数字编码超材料单元包括压控变容二极管,对压控变容二极管施加不同的偏置电压,两比特数字编码超材料单元对入射波呈现出不同的相位响应。该两比特数字编码超材料可作为一种低成本相控阵天线,具有电子波束扫描、电磁隐身以及方向图综合能力,本发明尤其适用于需要低复杂度、结构简洁、低成本的具有波束扫描和跟踪能力的雷达、通信、导航以及电子战系统。(The invention relates to a periodic time sequence modulation method of a two-bit metamaterial, a metamaterial and a phased array antenna, wherein each two-bit digital coding metamaterial unit is subjected to periodic time sequence modulation, and amplitude weighting of the two-bit digital coding metamaterial unit is realized by controlling the time proportion of a radio frequency signal allowed to pass through each unit channel in a modulation period; the phase weighting of the two-bit digital coding metamaterial unit is realized by controlling the starting time of the radio frequency signal passing through each unit channel in one modulation period. The two-bit digital coding metamaterial unit comprises a voltage-controlled variable capacitance diode, different bias voltages are applied to the voltage-controlled variable capacitance diode, and the two-bit digital coding metamaterial unit presents different phase responses to incident waves. The two-bit digital coding metamaterial can be used as a low-cost phased array antenna, has the comprehensive capabilities of electronic beam scanning, electromagnetic stealth and directional patterns, and is particularly suitable for radar, communication, navigation and electronic warfare systems which need low complexity, simple structure and low cost and have beam scanning and tracking capabilities.)

1. The periodic time sequence modulation method of the two-bit digital coding metamaterial is characterized in that each two-bit digital coding metamaterial unit is subjected to periodic time sequence modulation, and amplitude weighting of the two-bit digital coding metamaterial units is realized by controlling the time proportion of radio frequency signals allowed to pass through each two-bit digital coding metamaterial unit in a modulation period; the phase weighting of the two-bit digital coding metamaterial units is realized by controlling the starting time of the radio frequency signal passing through each two-bit digital coding metamaterial unit in one modulation period.

2. The two-bit digitally encoded metamaterial periodic time series modulation method of claim 1, wherein under given constraints of beam pointing and sidelobe levels, normalized amplitude weights and phase weights to be applied to each two-bit digitally encoded metamaterial unit are obtained by a beam pattern synthesis method, and the amplitude weight to be applied to the ith two-bit digitally encoded metamaterial unit is set as a_iThe phase weight to be applied is phi_i；

In a modulation period T_pAllowing the radio frequency signal to pass for a time A_iT_p；

Will be a modulation period T_pTime A allowing radio frequency signal to pass through_iT_pEqually dividing into four parts to respectively generate phase states of 0 degree, 90 degrees, 180 degrees and 270 degrees, namely setting the phase state of 0 degree as the initial phase state, and then in one modulation period T_pThe modulation time delay of the initial phase state of the ith two-bit digital coding metamaterial unit is

3. The method of periodic time-series modulation of a two-bit digitally encoded metamaterial as claimed in claim 1, wherein the dominant energy of the electromagnetic waves reflected or transmitted by the two-bit digitally encoded metamaterial unit is shifted to the first harmonic component.

4. The two-bit digital coding metamaterial is an array structure formed by a plurality of two-bit digital coding metamaterial units, and is characterized in that the two-bit digital coding metamaterial units comprise voltage-controlled variable capacitance diodes, different bias voltages are applied to the voltage-controlled variable capacitance diodes, and the two-bit digital coding metamaterial units can present different phase responses to incident waves; the two-bit digital coding metamaterial adopts the two-bit digital coding metamaterial periodic time sequence modulation method as claimed in any one of claims 1 to 3.

5. The two-bit digitally encoded metamaterial according to claim 4, wherein the two-bit digitally encoded metamaterial unit exhibits four phase responses to an incident wave: 0 degree, 90 degrees, 180 degrees and 270 degrees, which correspond to the four coding states of digital "00", digital "01", digital "10" and digital "11", respectively.

6. The phased array antenna of the two-bit digital coding metamaterial is characterized in that the antenna array is the two-bit digital coding metamaterial, and the two-bit digital coding metamaterial periodic time sequence modulation method according to any one of claims 1 to 3 is adopted to realize beam scanning and multi-beam radiation.

7. The two-bit digitally encoded metamaterial phased array antenna of claim 6, wherein the two-bit digitally encoded metamaterial is an array structure arranged by a plurality of two-bit digitally encoded metamaterial units, the two-bit digitally encoded metamaterial units include voltage-controlled varactors, different bias voltages are applied to the voltage-controlled varactors, and the two-bit digitally encoded metamaterial units exhibit different phase responses to incident waves.

8. The two-bit digitally encoded metamaterial phased array antenna of claim 7, wherein the two-bit digitally encoded metamaterial unit exhibits four phase responses to incident waves: 0 degree, 90 degrees, 180 degrees and 270 degrees, which correspond to the four coding states of digital "00", digital "01", digital "10" and digital "11", respectively.

Technical Field

The invention relates to the technical field of antenna engineering, in particular to a periodic time sequence modulation method of a two-bit metamaterial, the metamaterial and a phased array antenna.

Background

The electromagnetic metamaterial is a periodic or aperiodic sub-wavelength structure array, and by designing an artificial scatterer (superatomic) structure and an arrangement mode of the artificial scatterer structure, the electromagnetic metamaterial can generate corresponding response to an external electromagnetic field, and can obtain extraordinary physical properties which are not possessed by natural materials, so that the electromagnetic metamaterial has a series of novel electromagnetic regulation and control capabilities and has great application prospects in systems such as radar antennas and the like.

In the existing literature, the research on the electrically controllable metamaterial and the metamaterial surface is to realize the functions of electronic beam scanning, multi-beam radiation and the like by controlling the spatial coding distribution of units on the metamaterial, and most of the commonly used units are one bit, so that the problems of low phase quantization precision, low scanning gain, high side lobe level value, poor scanning precision and the like are generated, and the research is greatly limited in practical application.

Disclosure of Invention

The invention aims to provide a two-bit metamaterial periodic time sequence modulation method, a metamaterial and a phased array antenna, wherein space domain coding and periodic time sequence modulation are combined, and the performance of the antenna is improved.

In order to achieve the above object, the present invention provides a two-bit digital coding metamaterial periodic time sequence modulation method, which performs periodic time sequence modulation on each two-bit digital coding metamaterial unit, and realizes amplitude weighting of the two-bit digital coding metamaterial unit by controlling a time ratio of a radio frequency signal allowed to pass through each two-bit digital coding metamaterial unit in a modulation period; the phase weighting of the two-bit digital coding metamaterial units is realized by controlling the starting time of the radio frequency signal passing through each two-bit digital coding metamaterial unit in one modulation period.

According to the two-bit digital coding metamaterial periodic time sequence modulation method, under the constraint conditions of given beam direction and side lobe level, the normalized amplitude weight and the phase weight which are applied to each two-bit digital coding metamaterial unit are obtained through a beam pattern synthesis method, and the amplitude weight which is applied to the ith two-bit digital coding metamaterial unit is set to be A_iThe phase weight to be applied is phi_i(ii) a In a modulation period T_pAllowing the radio frequency signal to pass for a time A_iT_p(ii) a Will be a modulation period T_pTime A allowing radio frequency signal to pass through_iT_pEqually dividing into four parts to respectively generate phase states of 0 degree, 90 degrees, 180 degrees and 270 degrees, namely setting the phase state of 0 degree as the initial phase state, and then in one modulation period T_pThe modulation time delay of the initial phase state of the ith two-bit digital coding metamaterial unit is

According to the two-bit digital coding metamaterial periodic time sequence modulation method, the main energy of the electromagnetic wave reflected or transmitted by the two-bit digital coding metamaterial unit is moved to the first harmonic component.

The two-bit digital coding metamaterial has an array structure formed by arranging a plurality of two-bit digital coding metamaterial units, wherein each two-bit digital coding metamaterial unit comprises a voltage-controlled varactor diode, different bias voltages are applied to the voltage-controlled varactor diodes, and the two-bit digital coding metamaterial units show different phase responses to incident waves; the two-bit digital coding metamaterial adopts the two-bit digital coding metamaterial periodic time sequence modulation method.

The two-bit digital coding metamaterial has the advantages that the two-bit digital coding metamaterial unit has four phase responses to incident waves: 0 degree, 90 degrees, 180 degrees and 270 degrees, which correspond to the four coding states of digital "00", digital "01", digital "10" and digital "11", respectively.

The invention further provides a two-bit digital coding metamaterial phased-array antenna, wherein the antenna array is a two-bit digital coding metamaterial, and the two-bit digital coding metamaterial periodic time sequence modulation method is adopted to realize beam scanning and multi-beam radiation.

The two-bit digital coding metamaterial phased-array antenna is characterized in that the two-bit digital coding metamaterial is an array structure formed by arranging a plurality of two-bit digital coding metamaterial units, each two-bit digital coding metamaterial unit comprises a voltage-controlled variable capacitance diode, different bias voltages are applied to the voltage-controlled variable capacitance diodes, and the two-bit digital coding metamaterial units show different phase responses to incident waves.

The two-bit digital coding metamaterial phased-array antenna has the advantages that the two-bit digital coding metamaterial unit presents four phase responses to incident waves: 0 degree, 90 degrees, 180 degrees and 270 degrees, which correspond to the four coding states of digital "00", digital "01", digital "10" and digital "11", respectively.

Compared with the prior art, the invention has the beneficial technical effects that:

1) according to the invention, spatial coding modulation and periodic time sequence modulation of units are combined, so that the energy of a radio frequency signal can be shifted to a first harmonic component, the simultaneous weighting of phase and amplitude is realized, and the problems of low scanning gain, high side lobe level value, poor scanning precision and the like of the traditional tuned metamaterial are effectively solved;

2) compared with a traditional two-bit metamaterial unit adopting a double PIN diode, the two-bit digital coding metamaterial unit greatly simplifies the unit structure and effectively reduces the number of bias control lines by introducing the voltage-controlled variable capacitance diode;

3) the two-bit digital coding metamaterial can be manufactured by adopting a conventional PCB process, is easy to process and convenient for mass production, and has the advantages of small thickness, low cost, high integration level and the like;

4) the invention provides a novel multifunctional phased array antenna system with simple structure, low loss, electronic beam scanning, electromagnetic stealth and directional diagram comprehensive capability, and is particularly suitable for radar, communication, navigation and electronic warfare systems with beam scanning and tracking capability and low complexity and cost.

Drawings

The periodic time sequence modulation method of the two-bit metamaterial, the metamaterial and the phased array antenna are provided by the following embodiments and the attached drawings.

FIG. 1 is a schematic diagram of a two-bit digitally encoded metamaterial according to a preferred embodiment of the present invention.

FIG. 2 is a schematic diagram of a two-bit digitally encoded metamaterial unit in accordance with a preferred embodiment of the present invention.

FIG. 3 is a drawing of a structure dimension label of a two-bit digitally encoded metamaterial unit in accordance with a preferred embodiment of the present invention.

FIG. 4 is an amplitude-frequency characteristic curve of scattering parameters of a two-bit digitally encoded metamaterial unit in accordance with a preferred embodiment of the present invention when representing four digital states "00", "01", "10", and "11".

FIG. 5 is a phase-frequency characteristic curve of scattering parameters of a two-bit digitally encoded metamaterial unit in accordance with a preferred embodiment of the present invention for representing four digital states "00", "01", "10", and "11".

FIG. 6 is a diagram of an 8 × 8 two-bit digitally encoded metamaterial according to a preferred embodiment of the present invention.

FIG. 7 shows a cell α according to a preferred embodiment of the present invention_mnThe relative relationship between the phase modulation timing of the reference unit and the phase modulation timing of the reference unit is shown.

FIG. 8 is a normalized frequency spectrum of a RF signal after periodic phase modulation according to a preferred embodiment of the present invention.

FIG. 9 is a diagram of the beam pattern of a two-bit digitally encoded metamaterial in accordance with a preferred embodiment of the present invention.

Detailed Description

The two-bit metamaterial periodic timing modulation method, the metamaterial and the phased array antenna of the present invention will be described in further detail with reference to fig. 1 to 9.

FIG. 1 is a schematic diagram of a two-bit digitally encoded metamaterial according to a preferred embodiment of the present invention; FIG. 2 is a schematic diagram of a two-bit digitally encoded metamaterial unit in accordance with a preferred embodiment of the present invention; FIG. 3 is a drawing showing the structure dimension of a two-bit digitally encoded metamaterial unit in accordance with a preferred embodiment of the present invention.

Referring to fig. 1 to 3, the two-bit digitally encoded metamaterial of the present embodiment includes two-bit digitally encoded metamaterial units and a signal processing board 2, and a plurality of the two-bit digitally encoded metamaterial units are arranged in an array structure. The two-bit digital coding metamaterial unit comprises a first dielectric substrate 11, a metal floor 12, a second dielectric substrate 13, a reflection patch 14, a voltage-controlled variable-capacitance diode 15 and a bias control line 16; the first dielectric substrate 11, the metal floor 12 and the second dielectric substrate 13 are sequentially stacked to form a sandwich structure; the reflective patch 14 is attached to the first dielectric substrate 11; the bias control line 16 is arranged between the surfaces of the first dielectric substrate 11 and the second dielectric substrate 13; one end of the voltage-controlled variable capacitance diode 15 is grounded, and the other end of the voltage-controlled variable capacitance diode is connected with the reflection patch 14; one end of the bias control line 16 is connected to a voltage zero point at the center of the reflective patch 14, and the other end is connected to the signal processing board 2; one end of the bias control line 16 connected with the reflective patch is designed with a fan-shaped branch 17 with an open terminal so as to reduce the influence on high-frequency signals.

The digital coding metamaterial unit of the embodiment is characterized in that a voltage-controlled varactor 15 is integrated in the structure of the unit, and the digital coding metamaterial unit presents four phase responses to incident waves by applying different bias voltages to the voltage-controlled varactor 15: 0 degree, 90 degrees, 180 degrees and 270 degrees, which correspond to four encoding states of digital "00", digital "01", digital "10" and digital "11", respectively, that is, the digital encoding metamaterial unit of the present embodiment is a two-bit digital encoding metamaterial unit.

For each two-bit digital coding metamaterial unit, the signal processing board 2 controls the bias voltage applied to the voltage-controlled variable capacitance diode 15 in the two-bit digital coding metamaterial unit through a two-bit digital instruction, so that the two-bit digital coding metamaterial unit presents corresponding different phase responses to incident waves.

The invention creatively adds the periodic time sequence modulation to each two-bit digital coding metamaterial unit on the basis of the traditional digital coding metamaterial spatial coding modulation. Both spatial domain coded modulation and periodic time-series modulation of each two-bit digitally coded metamaterial unit are realized by using the signal processing board 2.

For a two-bit digitally encoded metamaterial unit, the periodic timing modulation comprises:

the amplitude weighting of the two-bit digital coding metamaterial units is realized by controlling the time proportion of the allowed radio frequency signals on each two-bit digital coding metamaterial unit in a modulation period;

the phase weighting of the two-bit digital coding metamaterial units is realized by controlling the starting time of the radio frequency signal passing through each two-bit digital coding metamaterial unit in one modulation period.

For the two-bit digital coding metamaterial, the following periodic time sequence modulation method is adopted to realize beam scanning:

under the constraint conditions of given beam direction and side lobe level, the normalization which is applied to each two-bit digital coding metamaterial unit is obtained by a beam pattern synthesis methodAn amplitude weight and a phase weight; let the amplitude weight value to be applied to the ith two-bit digital coding metamaterial unit be A_iThe phase weight to be applied is phi_i；

In a modulation period T_pIn the method, a control voltage (namely a bias voltage) is applied to a voltage-controlled variable capacitance diode 15 in the ith two-bit digital coding metamaterial unit by using a signal processing board 2, and the time for allowing a radio frequency signal to pass is A_iT_p；

Will be a modulation period T_pTime A allowing radio frequency signal to pass through_iT_pEqually dividing into four parts to respectively generate phase states of 0 degree, 90 degrees, 180 degrees and 270 degrees, namely setting the phase state of 0 degree as the initial phase state, and then in one modulation period T_pThe modulation time delay of the initial phase state of the ith two-bit digital coding metamaterial unit is

It should be noted that the periodic time sequence modulation method of the present invention is not limited to be applied to the two-bit digitally encoded metamaterial unit of the present embodiment, and is also applicable to the two-bit metamaterial unit using the conventional double PIN diode.

In this embodiment, different bias voltages are applied to the vcvaractor 15, and the vcvaractor 15 exhibits four different capacitance values C ═ 60fF,23fF,17.5fF, and 10fF, which correspond to four reflection phase responses of the two-bit digitally encoded metamaterial unit: 0 degree, 90 degrees, 180 degrees and 270 degrees, thereby forming four coding states of digital "00", digital "01", digital "10" and digital "11".

FIG. 4 shows the amplitude-frequency characteristic curve of the scattering parameter of the two-bit digitally encoded metamaterial unit of the present embodiment when representing four digital states "00", "01", "10", and "11"; the two-bit digital coding metamaterial unit keeps good transmission characteristics in four digital states, and unit loss at a central frequency point of 33GHz is less than 2 dB. Fig. 5 shows a phase-frequency characteristic curve of the two-bit digitally encoded metamaterial unit of the present embodiment when representing four digital states, and a reflection phase difference of the two-bit digitally encoded metamaterial unit in the four digital states at a center frequency of 33GHz is maintained at 90 °.

The two-bit digital coding metamaterial with 8 × 8 rectangular distribution as shown in fig. 6 has α units_mn(m, n ═ 1, 2.., 8.) it is assumed that the feed antenna is fed to unit α_mnA distance of l_mnIf the transmitting wave beam formed by the two-bit digital coding metamaterial is required to point (30 degrees and 60 degrees), the phase weight on each unit can be obtained as phi by adopting an equiphase plane directional diagram synthesis method_mn. In order to obtain the highest array gain, equal-amplitude weighting is adopted, namely the normalized amplitude weight on each two-bit digital coding metamaterial unit is 1.

Element α taking into account the phase difference between the feed antenna and the two-bit digitally encoded metamaterial_mnPhase to be generated

The following relationship should be satisfied:

where λ is the wavelength of the transmitted signal, which can be determined from the above formula

Comprises the following steps:

FIG. 7 is a schematic diagram showing the phase-shifted states loaded on each two-bit digitally encoded metamaterial unit, where the phase shifts of 0, 90, 180, and 270 are generated by the signal processing board controlling the bias voltages of the voltage-controlled varactors in the two-bit digitally encoded metamaterial unit. The first row in FIG. 7 shows the phase shift state at phase 0, knowing that the phase shift state on the two-bit digitally encoded metamaterial unit switches between 0, 90, 180 and 270 degrees, and the period is repeatedIs T_pCorrespondingly, element α_mnThe phase weights of

Then the load is at element α_mn。

α_mnThe amount of time shift of the modulation time above with respect to the modulation time with the phase 0 is:

assume that the carrier frequency of the transmitted signal is 1GHz and the modulation period is 1 us. The normalized frequency spectrum of the signal generated after modulation under the periodic time-series modulation is shown in fig. 8, and it can be seen from fig. 8 that after the single-frequency signal (1GHz) is subjected to the periodic time-series modulation, the main energy thereof has moved to the first harmonic component (1.001 GHz).

After the periodic time-series modulation is completed on each unit of the two-bit digital coding metamaterial, the beam pattern of the first harmonic component (at 1.001GHz) is shown in fig. 9, and it can be seen that the side lobe level value is reduced by more than 25dB compared with the maximum gain.

According to the foregoing amplitude and phase control method, this embodiment further provides a phased array antenna, which uses the two-bit digitally encoded metamaterial as an antenna array, and implements beam scanning and multi-beam radiation by combining spatial coding modulation and periodic time sequence modulation.

In this embodiment, a two-bit digital coding metamaterial and a two-bit digital coding metamaterial periodic time sequence modulation method of the invention are introduced by taking a reflective two-bit digital coding metamaterial as an example, but the innovative idea is also applicable to a transmissive two-bit digital coding metamaterial.

The phased array antenna of the present invention is particularly useful in radar, communication, navigation, and electronic warfare systems requiring low complexity, low cost, beam scanning and tracking capabilities.