CN113206389B - Adjustable semiconductor device based on adjustable reflecting material loading - Google Patents

Abstract

The invention relates to an adjustable semiconductor device based on adjustable reflection material loading, and belongs to the technical field of semiconductors. The reflected wave is modulated into a desired signal by loading the modulated signal. The hardware structure of the multi-unit adjustable reflection array is similar to that of an adjustable reflection material, and periodic array units are adopted; instead of using uniform signal modulation for all elements of the reflective material, each reflective element in a multi-element reflective array can be controlled using a phased device or switch so that it has similar beam shaping capabilities as a conventional phased array.

Description

Adjustable semiconductor device based on adjustable reflecting material loading

Technical Field

The invention belongs to the technical field of semiconductors, and relates to a loading adjustable semiconductor device based on an adjustable reflecting material.

Background

The wind power plant can generate strong Doppler clutter and electromagnetic shadows, and interfere the operation of a radar system, so that false alarms or missing alarms of an airplane and severe weather are caused. On the one hand, the wind turbine of the wind power plant is a strong scatterer for the secondary signal of the navigation management radar, and Doppler clutter and electromagnetic shadows generated by the strong scatterer can threaten the safe flight of an airplane; on the other hand, clutter and electromagnetism in a wind farm can also affect a meteorological observation radar, so that false alarm is caused.

In view of the above, there are a great number of evaluations and methods for solving the above problems at home and abroad, but it is not possible to fundamentally distinguish the desired target from the wind farm interference. The novel solution is provided for the electromagnetic scattering problem of the wind power plant, aims to fundamentally solve the problem of radar interference of the wind power plant, is favorable for reducing Doppler clutter generated by the wind power plant, and greatly improves the influence of the wind power plant on the aspects of navigation management radar and weather radar.

The method mainly comprises two methods of wind turbine design and radar setting signal processing.

On the basis of not affecting the power generation performance of the wind farm, wind turbines have three improvements. A first improvement is to reduce the radar cross-sectional area (RCS) of the wind turbine by modifying the physical structure of the wind turbine; the second improvement measure is to reduce the influence of the wind farm on the radar system by changing the layout of the wind farm so that the layout is positioned outside the radar sight line; a third improvement is to facilitate the detection of aircraft targets between wind turbines located within the wind farm by increasing the distance between wind turbines in the wind farm so that the wind turbines are located at different distance units.

Obviously, the three methods are carried out on the basis of not affecting the power generation performance of the wind power plant, otherwise, the method is unfavorable for effectively utilizing wind energy, and a large amount of wind energy is lost. Meanwhile, the layout of the wind power plant is changed or the distance between wind turbines is increased according to the situation of the terrain around the wind power plant.

In addition to this, there is a way to reduce wind turbine RCS by using wave-absorbing paint, and thus reduce wind turbine noise. Stealth technology is to add a wave-absorbing coating to the wind turbine surface to reduce the reflection of radar electromagnetic waves on the wind turbine surface. In view of aerodynamic related factors, the blade shape is relatively complex, and most of the blade shape is made of composite materials such as glass fiber, and the blade surface or the blade interior is made of metal so as to prevent lightning strike. In general, a blade 40 meters in length can reduce 15-20 dB of RCS by the wave absorbing material. The effect of the wave-absorbing material is different for different blade structures.

Therefore, the effect of the wave-absorbing material is not stable and versatile. This practice adds virtually to the weight and cost of the wind turbine.

In general, clutter suppression techniques associated with wind turbine designs require changes in their design structure, wind turbine layout in wind farms, etc., which can reduce wind energy utilization to some extent, depend on the geographic environment, and increase costs.

The interference suppression technology related to radar equipment mainly comprises detection post clutter suppression technologies such as parallel high-low beam configuration, blind radar addition, adaptive beam scanning and the like. For wind farm clutter suppression technology before and during detection, related technologies such as three-coordinate radar, data processing technology and radar signal processing are adopted.

For parallel high and low beam configurations, the technique distinguishes between wind turbines and targets of different heights. The radar is configured with "dual beams" for detecting long-range low-altitude targets as well as short-range high-altitude targets, and performs beam switching at a predetermined distance. A large number of low beams in a short time are generally considered wind farm echoes, while high beams are aircraft echoes. However, when the wind farm is far away, the low-altitude target detection capability drops sharply and the wind turbine RSC is large, the effect is limited.

For the addition of blind-supplement radars, the method adopts a multi-radar data fusion technology, and the data of other radars in a wind power field area are used for replacing the data of the original radars in the wind power field area so as to fill the radar blind area caused by the wind power field. The blind patch radar is required to be relatively simple in design and low in cost, and special design schemes or measures are required to be adopted to improve the target detection probability of the local area of the blind patch radar.

For radar adaptive scanning, wind turbine clutter energy received by a radar can be limited by changing a radar scanning mode of an area where the wind turbine is located, so that clutter signals can be reduced in a data processing process. However, this approach reduces the detection distance of the radar to some extent. In addition, a method for suppressing wind power plant clutter by using a phased array radar can also be adopted. But the data processing is somewhat computationally intensive.

For the use of three-dimensional radar, the united kingdom has been used to combat east coast wind farm interference, taking as an example the TRS-77 surveillance radar system of some company in the united states. TPS-77 radar system has three-dimensional resolution, which is known to better distinguish wind farm debris from flying objects, but its popularity is limited by the high price of 2000 thousands of dollars each.

Disclosure of Invention

Accordingly, it is an object of the present invention to provide a tunable semiconductor device based on tunable reflective material loading.

In order to achieve the above purpose, the present invention provides the following technical solutions:

the planar tunable reflective material consists of a single layer of frequency selective surface (Frequency Selective Surface, FSS) and a back plate (Perfect Electrical Conductor, PEC); the FSS impedance is adjustable, so that characteristic impedance transformation of the whole reflecting material is realized, and absorption of incoming wave signals is realized; unlike tunable reflective materials, the FSS is replaced by a set of reflective arrays, the array elements being individually controllable. If the modulation signal is loaded, beam forming can be realized, and the direction of the reflected wave can be controlled.

A simple model of a single reflection unit is first analyzed. A single element of the array may be considered to have an upper layer of reflective elements combined with a lower layer of reflective elements. The reflecting unit is controlled by a switching signal: either upper reflection or lower reflection may be achieved at any one time. The array factor may be written as such,

E(e，t)＝Eu(θ，t)+El(θ，t)

where E (θ, t) represents the pattern of the entire reflective element at time t, including the lower element reflection and the upper element reflection. Eu (θ, t) represents the set of all upper layer unit reflections, and El (θ, t) represents the set of all lower layer unit reflections. Eu (Eu) _i (θ) represents the pattern of the ith upper layer element, el _i (θ) represents the pattern of the i-th lower layer unit. exp (ja) _i ) And exp (jb) _i ) Respectively represent the phase factors of the upper and lower layer units due to the unit positions,

a _i ＝β*p _i *sin(θ)

b _i ＝β*(p _i *sin(θ)+d+d*cos(θ))

wherein the method comprises the steps of

Is the propagation constant, d is the spacing between two layers, p _i Is the pitch (typically half a wavelength) of the array elements. />

At any one time, only one of the upper layer and lower layer units is reflecting; in other words, a state in which neither or both are totally reflected is impossible. Then its switching timing canExpressed as a periodic function, where T ₀ Is a full cycle time.

Since the switching sequence is a periodic variation, any periodic function can be written in the form of its set of sinusoidal functions, depending on the fourier series. Then for Iu _i (t) and Il _i The coefficients of the mth order fourier series of (t) can be expressed as follows.

Further can be derived as follows. At this time, the fourier coefficient thereof takes the form of an exponential function, which can be regarded as a weighted weight composed of an absolute value and a phase value.

Using the above formula, the reflection pattern of the entire reflection array can be represented by a Fourier series. The array pattern of the mth order harmonics can be expressed as:

assuming Eu _i (θ)＝El _i (θ)＝1，

Whereas the pattern at the fundamental frequency is only related to the length of the switching time,

the invention has the beneficial effects that: based on the principle of a controllable reflective array, a new target fractal unit echo regulation scheme is provided by referring to the mechanism of the VanATa reflective array, namely a variable-capacitance tube impedance controllable network is loaded between split scattering bodies, and rapid modulation is realized on the echo phase and amplitude of the split scattering bodies, so that the scattering bodies RCS are subjected to severe change, the nonlinear modulation function, namely the spread spectrum effect of echo power, is realized, and the purpose of stealth is achieved.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and other advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the specification.

Drawings

For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in the following preferred detail with reference to the accompanying drawings, in which:

FIG. 1 is a diagram of a conventional tunable reflective material in comparison to a reflective array;

FIG. 2 is a simple model of a single reflection unit;

FIG. 3 is a schematic diagram of a switch control signal;

FIG. 4 is a pattern of an 8-cell reflective array at periodic timing, FIG. 4 (a) is a time series; fig. 4 (b) is a pattern;

FIG. 5 is an improved timing and reflection pattern, and FIG. 5 (a) is an improved time series; FIG. 5 (b) is a modified pattern;

FIG. 6 is a pattern of periodic half-on and half-off of the cell, and FIG. 6 (a) is a time sequence under half-on and half-off; FIG. 6 (b) is a pattern diagram under half-on and half-off;

FIG. 7 is a schematic diagram of a reflective array of an adjustable half-wave vibrator;

FIG. 8 is a pattern of an 8x2 reflective array at an ideal and modified incremental timing, FIG. 8 (a) being an ideal and modified incremental timing; FIG. 8 (b) is a diagram of a sum 8x2 reflective array;

FIG. 9 is a diagram of an 8x2 reflective array at a half-on half-off increment timing, FIG. 9 (a) is a half-on half-off increment timing; FIG. 2 is a diagram of an 8x2 reflective array at half-on and half-off incremental timing;

FIG. 10 is a model diagram of a four cell array loaded and unloaded impedance controllable network;

FIG. 11 is a graph of the reflected spectrum distribution after an ideal square wave modulation;

FIG. 12 is a schematic diagram of the present invention.

Detailed Description

Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention. It should be noted that the illustrations provided in the following embodiments merely illustrate the basic idea of the present invention by way of illustration, and the following embodiments and features in the embodiments may be combined with each other without conflict.

Wherein the drawings are for illustrative purposes only and are shown in schematic, non-physical, and not intended to limit the invention; for the purpose of better illustrating embodiments of the invention, certain elements of the drawings may be omitted, enlarged or reduced and do not represent the size of the actual product; it will be appreciated by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The same or similar reference numbers in the drawings of embodiments of the invention correspond to the same or similar components; in the description of the present invention, it should be understood that, if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc., that indicate an azimuth or a positional relationship based on the azimuth or the positional relationship shown in the drawings, it is only for convenience of describing the present invention and simplifying the description, but not for indicating or suggesting that the referred device or element must have a specific azimuth, be constructed and operated in a specific azimuth, so that the terms describing the positional relationship in the drawings are merely for exemplary illustration and should not be construed as limiting the present invention, and that the specific meaning of the above terms may be understood by those of ordinary skill in the art according to the specific circumstances.

Assume that an 8-cell double-layer reflection array is provided, and the incoming wave direction is the normal direction. The array unit can flexibly switch between upper reflection and lower reflection. The spacing between the two plates is long as the free space with a thickness of a quarter wavelength.

FIG. 1 is a diagram of a conventional tunable reflective material in comparison to a reflective array; FIG. 2 is a simple model of a single reflection unit; fig. 3 is a schematic diagram of a switch control signal. In fig. 3, 1 represents reflection, and 0 represents no reflection.

Patterns under different time sequences are tried, and the change rule of the reflected signal under different time sequences is tried to be grasped. FIGS. 4, 5, and 6 show the reflection patterns of the dual-layer reflection array at the standard increment sequence, the optimized increment sequence, and the half-on half-off increment sequence, respectively. The pattern uses normalization processing and the reference value is the power at the maximum direction of the radiation power of the whole array when all 8 units are fully on. As can be seen from the figure, the harmonics generated by the periodic switching units reflect the incident wave in all directions, and in order to make the reflected wave zero in the incoming wave direction, the time series needs to be set as shown in fig. 6 (a). FIG. 4 is a pattern of an 8-cell reflective array at periodic timing, FIG. 4 (a) is a time series; fig. 4 (b) is a pattern; FIG. 5 is an improved timing and reflection pattern, and FIG. 5 (a) is an improved time series; FIG. 5 (b) is a modified pattern; FIG. 6 is a pattern of periodic half-on and half-off of the cell, and FIG. 6 (a) is a time sequence under half-on and half-off; fig. 6 (b) is a pattern in the half-on and half-off state.

The relationship between the switching time and the magnitude of each harmonic power was analyzed as shown in fig. 6. The results show that at a switching time of 0.5, the sum of the reflected power variances at the different harmonics of the entire reflective array is minimal, where the power subdivisions are the most averaged.

FIG. 7 is a schematic diagram of a reflective array of an adjustable half-wave vibrator; FIG. 8 is a pattern of an 8x2 reflective array at an ideal and modified incremental timing, FIG. 8 (a) being an ideal and modified incremental timing; FIG. 8 (b) is a diagram of a sum 8x2 reflective array; FIG. 9 is a diagram of an 8x2 reflective array at a half-on half-off increment timing, FIG. 9 (a) is a half-on half-off increment timing; and (b) is a pattern of an 8x2 reflective array at half-on and half-off incremental timing.

For further verification, semi-physical simulation verification is adopted, and a reflective array based on an adjustable half-wave vibrator is designed by using CST.

In the aspect of array design, each unit can work well at 1.1GHz-1.6GHz. Due to the size constraints of the simulation model, a 2x8 cell array arrangement is employed. In CST, the excitation signal is plane wave in the-Z direction; a reflected power pattern Monitor (Monitor) is provided at 1.2GHz to read the reflected pattern of each cell (one cell "on" and the other cell "off"), by

Recording. Wherein the medium is free space and the layer thickness is 7.5cm.

In terms of simulation, the improved formula is adopted, because

The phase difference generated by the array arrangement is included, so that the array phase factor is omitted,

using formulas and CST simulation results

The pattern of the 2x8 cell array at multiple harmonics was calculated. Fig. 8 and 9 show the patterns of an 8x2 reflective array and a half-on half-off (fig. 9) under ideal and modified incremental timing, respectively. The results of which conform to the results given by the mathematical model. But as can be seen in the pattern of fig. 9, its fundamental frequency (Fundamental Frequency) is higher than the mathematical model; this is because a true double layer reflective surface does not fully achieve the desired "on" (total upper reflection) and "off" (total lower reflection).

The invention also carries out modeling simulation on a 2×2 four-unit rectangular patch array, and the model is shown in fig. 10. The dielectric substrate has the following dimensions: 100mm by 0.5mm. The plate material is FR4 (epsilon) _r =4.4). The rectangular patch size is: 25mm by 0.1mm, the spacing is 15mm, and the material is copper. Fig. 10 includes an unconnected model, a model with wires between patches, and a model with a controllable impedance network loaded between patches. After the impedance controllable network is connected between the two scatterers, the impedance characteristic of the network can be changed by adjusting the control voltage, which is equivalent to the virtual change of the length of the connecting wire. C (C) ₁ And C ₂ Is a blocking capacitor L ₁ And L ₂ R is a radio frequency choke ₁ 、R ₂ 、R ₃ 、R ₄ And R is ₅ Form a shunt voltage dividing circuit D ₁ As a varactor, taking Toshiba varactor 1SV291 as an example, when the reverse bias voltage increases from 0V to 30V, the junction capacitance decreases from 8.0pF to 0.6pF.

The Fourier change is adopted to analyze the performance of a reflected echo of an incident signal after passing through the two-phase modulation plate with the diamond structure on the frequency spectrum, so as to know the frequency spectrum shifting effect. For an ideal square wave signal, if the input signal is a sine wave signal (single frequency), the reflected signal can be expressed as:

when ω=2pi·1ghz and t=10ns, the spectrum of the reflected signal can be obtained by the fast fourier transform as shown in fig. 11.

From the spectrogram of the reflected wave, it can be seen that the spectrum of the incident wave is modulated onto a series of harmonic components, the spectrum of the incident frequency point is greatly compressed, and the even harmonic component is 0, as can be seen from the frequency domain expression of the signal described below

Wherein f _c Is the frequency of the incident wave, f _s Is the frequency of the modulated square wave signal, f _s =10mhz. The modulation board shows ideal wave-absorbing (transferring) performance at a specific frequency point, and then the average reflection coefficient of the modulation board for time is 0; for two-phase modulation, it should be satisfied that

ρ ₁ τ ₁ +ρ ₂ (T-τ ₁ )＝0

Further evolution

At a frequency of 1.5GHz ρ ₁ And ρ ₂ 0.28-0.73j and-0.25 +0.82j, respectively, with the amplitudes and phases shown in the table below.

F＝1.5GHz	Absolute value of ρ	Phase of ρ
			2Ohm (on)	0.782	-69
5000Ohm (Guanzhong)	0.857	107

Duty cycle is adjusted so that

The reflection coefficient of the frequency point can be made 0. The frequency of the incident wave is assumed to be 1.5GHz, the period of the modulated wave is 10ns, the corresponding modulation frequency is 0.1GHz, and the reflected wave spectrum at this time is shown in FIG. 11. It can be seen from the figure that the incident wave power is shifted from 1.5GHz to a plurality of harmonics, the first order harmonic frequency and the incident wave frequency being different by a factor of 2 from the frequency of the modulated signal. FIG. 12 is a schematic diagram of the present invention.

Finally, it is noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the present invention, which is intended to be covered by the claims of the present invention.

Claims (1)

1. An adjustable semiconductor device loaded based on an adjustable reflective material, characterized in that: the semiconductor device is composed of a three-layer structure;

the first layer of the semiconductor device is a harmonic oscillator array loaded with PIN diodes, and all resonance units are connected through diodes;

the second layer of the semiconductor device is a spacer layer with the thickness of d=50mm, and the relative dielectric constant is 1.08;

the third layer of the semiconductor device is a copper plate with the same size as the resonant array;

the diodes are connected in series and in parallel and are uniformly controlled by the modulation signal;

the semiconductor device is loaded by adopting an adjustable reflection material;

the resonance units of the first layer of the semiconductor device adopt a diamond-shaped cross groove structure, the lengths of diagonal lines of the diamond are respectively a=71.2 mm, b=76 mm, the groove widths g=1.2 mm, and the intervals between adjacent resonance units are m=1.2 mm;

PIN diodes are arranged at four corners of the diamond and used for adjusting the characteristic impedance of the semiconductor device;

the reflecting array comprises an upper PIN diode resonant reflecting array and a lower copper plate unit reflecting array, and the reflecting array is arranged on an FR-4 printed circuit board with a relative dielectric constant of 4.4 and a thickness of 1 mm;

the semiconductor device realizes the adjustability of the working frequency point and the frequency band, loads a modulation signal, and modulates the reflected wave into a desired signal;

loading a modulation signal on the semiconductor device to realize beam forming and control the direction of reflected waves;

the reflection pattern of the adjustable frequency selective surface loaded with the modulated signal is expressed as:

wherein m represents the adjacent resonant cell spacing; τ _ioff Indicating the on time of the switch; τ _ion Indicating the time at which the switch is off; e, e ^-jπm Representing adjacent resonant cell phases; θ represents an incident wave angle;

the pattern on the fundamental frequency is expressed as:

array factor writing:

E(θ,t)＝Eu(θ，t)+El(θ，t)

wherein E (θ, t) represents the pattern of the entire reflective element at time t, including lower element reflection and upper element reflection; eu (θ, t) represents the set of all upper layer unit reflections, and El (θ, t) represents the set of all lower layer unit reflections; eu (Eu) _i (θ) represents the pattern of the ith upper layer element, el _i (θ) represents the pattern of the ith lower layer element, τ _ioff -τ _ion Indicating the switching time length; exp (ja) _i ) And exp (jb) _i ) Respectively represent the phase factors of the upper and lower layer units due to the unit positions,

a _i ＝β*p _i *sin(θ)

b _i ＝β*(p _i *sin(θ)+d+d*cos(θ))

wherein the method comprises the steps of

Is the propagation constant, d is the spacing between two layers, p _i Is the spacing of the array units, which is half wavelength;

if the signal input to the semiconductor device is a sine wave signal, for an ideal square wave signal, the reflected signal is expressed as:

the frequency domain expression of the reflected signal is:

wherein f _c Is the frequency of the incident wave, f _s Is the frequency of the modulated square wave signal.

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