A waveguide structure electromagnetic surface wave beam scanning array

Abstract

The application discloses a waveguide structure electromagnetic surface wave beam scanning array, which comprises a multilayer electromagnetic surface structure and a waveguide structure. The electromagnetic surface structure comprises a plurality of array-arranged electromagnetic surface units. The multilayer electromagnetic surface structure layers are separated by a dielectric layer. Adjacent electromagnetic surface units are isolated by the waveguide structure. The application can be used for portable satellite communication and has the characteristics of low profile, high conformal, low cost, low power consumption, easy processing and easy implementation.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of microwave technology, and particularly relates to a waveguide structure electromagnetic surface wave beam scanning array. BACKGROUND

[0002] Since the last century, wireless communication technology has developed rapidly, and antennas have been widely used in radar, broadcasting, electronic countermeasures, navigation and other fields. The amount of information and the complexity of information handled by modern communication are increasing, and it is required that the signal loss in the transmission process be as small as possible. Considering the needs of modern communication, single-function antennas have been gradually eliminated, and higher requirements have been put forward for the performance of antennas, such as wideband, beam scanning, polarization reconfigurable, etc.

[0003] However, because the size and weight of the traditional dielectric lens are large, and when the gradient dielectric constant lens is implemented, the layered dielectric causes impedance discontinuity, which easily causes large loss, and also brings processing difficulties and other problems. In order to overcome the above shortcomings, the electromagnetic surface array is used to realize the gradient phase delay, and the advantages of small size and light weight of the electromagnetic surface can realize the electromagnetic lens in the millimeter wave frequency band, achieve high gain and low sidelobe, and realize light weight and miniaturization at the same time.

[0004] Electromagnetic surface beam scanning technology is a frontier research direction derived from metamaterial technology in recent years, and it is of great significance for the design of new electrically scanned antennas. It has the advantages of low cost, low power consumption, low profile and flexible controllability, and has important application prospects in electromagnetic field radiation, stealth and other fields. The electromagnetic surface is loaded with PIN diodes, MEMS switches or varactor diodes and other active devices in the sub-wavelength artificial layered periodic structure material (metamaterial) unit to change the working state of the unit, and the modulation state of the electromagnetic surface antenna is controlled in real time by using the FPGA circuit system, so as to realize the dynamic controllability of the spatial electromagnetic wave. The introduction of electromagnetic surface can increase the bandwidth of beam scanning by design, and the processing difficulty is greatly reduced, and the process requirement is reduced.

[0005] Designing beam scanning by using passive phase gradient electromagnetic surface is an important research direction, but the traditional passive electromagnetic surface beam scanning design still has obvious shortcomings: after being prepared, its function and electromagnetic properties cannot be adjusted, and the working mode control is still not flexible enough.

[0006] However, in practical applications, it is necessary to dynamically switch between two or more scanning angles, that is, a dynamically adjustable artificial electromagnetic metamaterial. There are usually three methods to achieve dynamic adjustment: 1. Change the (physical) structure, which can use mechanical operation methods such as stretching and rotating; 2. Change the electrical response, which essentially changes the material properties, and can use variable property dielectric materials such as ferrite, semiconductor materials or phase change materials; 3. Use active devices such as PIN tubes, varactor diodes, etc. By adjusting the bias voltage of the active device to change the capacitance or resistance value in the equivalent circuit model of the unit structure, the dynamic adjustment of the electromagnetic properties of the unit is realized. The scheme for realizing a reconfigurable beam scanning electromagnetic surface uses an electrical adjustment method, which has the advantages of simple operation, fast switching speed, flexible control, etc.

[0007] The electromagnetic surface using the electrical adjustment method has the following modes: loading PIN tubes, varactor diodes, etc.: In the linear-circular polarization converter designed by the electromagnetic surface loaded with PIN tubes in "Polarization-Reconfigurable Circularly Polarized Planar Antenna Using Switchable Polarizer", the on / off state of different PIN tubes is switched to change the working state of different electromagnetic surface units, and the left / right circular polarization of the transmitted wave is switched. However, the PIN tube in conduction will produce direct current power consumption, which is suitable for structures with low frequency, and the control state is discrete, which cannot meet the continuous scanning phase requirement. In "FSS-Inspired Transmitarray for Two-Dimensional Antenna Beamsteering", varactor diodes are loaded on the electromagnetic surface, and different two-dimensional electronic scanning beams are obtained by setting different voltage values, but this combination method will cause mutual coupling between the electromagnetic surface units, resulting in high side lobes. SUMMARY

[0008] The present application aims at the deficiencies of the prior art and proposes a waveguide structure electromagnetic surface beam scanning array. By changing the bias voltage of the varactor diode, the size of the varactor diode capacitance can be adjusted to obtain different progressive phase differences of the transmitted wave, thereby realizing effective electronic scanning beams. At the same time, the electromagnetic surface units are placed in the waveguide structure, which maximally reduces the mutual coupling and transverse radiation between the electromagnetic surface units. The present application can be used in high-performance portable satellite communication, low-slow-small target detection and other occasions, and has the characteristics of low profile, high conformal, wide frequency band, flexible control, low cost, low power consumption, easy processing and easy implementation.

[0009] The application aims to realize the technical scheme of a waveguide structure electromagnetic surface wave beam scanning array, which comprises a multilayer electromagnetic surface structure and a waveguide structure, the electromagnetic surface structure comprises a plurality of arrayed electromagnetic surface units, the multilayer electromagnetic surface structure is separated by a dielectric layer, and adjacent electromagnetic surface units are isolated by the waveguide structure.

[0010] Further, two implementation manners of the electromagnetic surface structure are provided.

[0011] In the first manner, each layer of the electromagnetic surface structure comprises a dielectric substrate and a periodically arranged metal pattern printed on the front and back surfaces of the dielectric substrate.

[0012] The metal pattern printed on the front surface of the dielectric substrate comprises an inner solid metal patch, an outer square metal ring and a vertical bias line, a varactor diode is symmetrically loaded between the inner solid metal patch and the outer square metal ring, the vertical bias line is connected with the outer square metal ring and used for changing the electromagnetic characteristics of the transmitted wave.

[0013] The metal pattern printed on the back surface of the dielectric substrate is a horizontally biased line.

[0014] The vertical bias line and the horizontal bias line are used for providing a bias voltage for the varactor diode, the capacitance of the varactor diode is adjusted by changing the bias voltage of the varactor diode, so that the transmitted waves with different progressive phase differences are obtained, and effective electronic scanning beams are realized.

[0015] In the second manner, each layer of the electromagnetic surface structure comprises a plurality of dielectric substrates, a periodically arranged metal pattern is arranged between adjacent dielectric substrates, the metal patterns on the outer sides of the two outermost dielectric substrates are periodically arranged and symmetrically loaded with varactor diodes, at least one intermediate layer metal pattern provides a bias voltage for the varactor diode, and the other intermediate layer metal patterns expand the working bandwidth of the electromagnetic surface structure.

[0016] Further, the dielectric constant of the dielectric layer between the multilayer electromagnetic surface structure layers is higher than the dielectric constant of the dielectric substrate of the electromagnetic surface structure, so that the high and low dielectric constant materials are alternately distributed, the parasitic resonant cavity mode existing in the electromagnetic surface structure is eliminated, and the profile height of the electromagnetic surface is greatly reduced.

[0017] Further, the varactor diode is loaded in the horizontal direction or the vertical direction, and the loading direction is the same as the polarization direction of the incident wave. Alternatively, the varactor diode is loaded in the horizontal direction and the vertical direction at the same time, the varactor diode in the vertical direction is used for regulating the incident electromagnetic wave with the vertical linear polarization, the varactor diode in the horizontal direction is used for regulating the incident electromagnetic wave with the horizontal linear polarization, and the orthogonal direction polarized electromagnetic wave is controlled by loading the varactor diodes in the orthogonal directions at the same time.

[0018] Further, the waveguide structure adopts a closed structure, the electromagnetic surface unit is placed inside the waveguide structure, one end of the waveguide structure is fed with electromagnetic waves, and the other end radiates electromagnetic waves to the free space, the electric field intensity on the waveguide wall is zero, thereby realizing isolation of the electromagnetic surface unit and minimizing the mutual coupling and transverse radiation between the electromagnetic surface units.

[0019] Further, the waveguide structure is a ridge waveguide structure or a dielectric-filled waveguide structure, and the ridge waveguide structure includes a single-ridge waveguide structure, a double-ridge waveguide structure, and a quadrature ridge waveguide structure.

[0020] Further, the waveguide structure is realized by directly processing a metal into a waveguide cavity or by using a metalized via instead of a metal waveguide wall.

[0021] Further, by designing the size of the waveguide structure, single-mode transmission of electromagnetic waves in the target frequency band is ensured, and grating lobes in the scanning beam are avoided, specifically: the cavity length and width of the waveguide structure are A and B respectively, wherein A < λ0 / 2 and B < λ0 / 2, to avoid grating lobes in the scanning beam, wherein λ0 is the minimum free space wavelength of the transmitted or received electromagnetic waves; in the waveguide structure, the electromagnetic wave mode propagating is TE mn , m and n represent mode numbers, the main mode cutoff frequency where v is the phase velocity, by adjusting the cavity length A and width B, so that the target frequency f satisfies f c <f<f h , f h is the high-order mode cutoff frequency, to ensure single-mode transmission of electromagnetic waves in the target frequency band.

[0022] Further, the dielectric substrate can be increased to three layers, a metal pattern is printed outside the two outermost dielectric substrates to load a varactor diode, a horizontal bias line is printed on the middle layer, and a cross metal pattern is printed on one layer to expand the operating bandwidth.

[0023] Compared with the prior art, the present application has the following advantages:

[0024] 1. The novel waveguide structure electromagnetic surface beam scanning array has wideband characteristics due to the adoption of a multi-layer structure.

[0025] 2. The novel waveguide structure electromagnetic surface beam scanning array does not require direct current power consumption due to the adoption of a varactor diode, and can be used for high-performance millimeter wave antenna arrays.

[0026] 3. The novel waveguide structure electromagnetic surface beam scanning array can minimize the mutual coupling and transverse radiation between the electromagnetic surface units due to the adoption of a waveguide structure. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1Front view schematic diagram of waveguide structure electromagnetic surface wave beam scanning array of embodiment of the present application;

[0028] Figure 2 Back view schematic diagram of waveguide structure electromagnetic surface wave beam scanning array of embodiment of the present application;

[0029] Figure 3 Side view schematic diagram of waveguide structure electromagnetic surface wave beam scanning array of embodiment of the present application;

[0030] Figure 4 Scan horizontal 30° far field pattern of waveguide structure electromagnetic surface wave beam scanning array of embodiment of the present application;

[0031] Figure 5 Scan horizontal 45° far field pattern of waveguide structure electromagnetic surface wave beam scanning array of embodiment of the present application;

[0032] Figure 6 Front view schematic diagram of waveguide structure electromagnetic surface wave beam scanning array of embodiment of the present application using double-ridge waveguide structure;

[0033] Figure 7 Front view schematic diagram of waveguide structure electromagnetic surface wave beam scanning array of embodiment of the present application using orthogonal ridge waveguide structure;

[0034] Figure 8 Front view schematic diagram of waveguide structure electromagnetic surface wave beam scanning array of embodiment of the present application using square waveguide structure;

[0035] Figure 9 Double dielectric substrate schematic diagram of multi-layer electromagnetic surface structure of embodiment of the present application;

[0036] Figure 10 Three dielectric substrate schematic diagram of multi-layer electromagnetic surface structure of embodiment of the present application;

[0037] Figure 11 Double-frequency dual-polarized metal pattern schematic diagram of multi-layer electromagnetic surface structure of embodiment of the present application. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.

[0039] Reference Figure 1 , Figure 2 , Figure 3 As shown in the figure, the novel waveguide structure electromagnetic surface wave beam scanning array provided by the embodiment of the present application comprises a multi-layer electromagnetic surface structure 7 and a waveguide structure 8; the electromagnetic surface structure 7 comprises a plurality of array-arranged electromagnetic surface units, and the multi-layer electromagnetic surface structure 7 is separated by a dielectric layer between layers; adjacent electromagnetic surface units are isolated by the waveguide structure 8.

[0040] In one embodiment, the electromagnetic surface structure 7 comprises a dielectric substrate 1 and a periodic array of metal patterns printed on both sides of the dielectric substrate 1; the metal pattern printed on the front side of the dielectric substrate 1 is composed of an inner solid metal patch 2, an outer square metal ring 3, and a vertical bias line 5, a varactor diode 4 is symmetrically loaded between the inner solid metal patch 2 and the outer square metal ring 3, the vertical bias line 5 is connected to the outer square metal ring 3 for changing the electromagnetic characteristics of the transmitted wave; the metal pattern printed on the back side of the dielectric substrate 1 is a horizontally biased line 6; the vertical bias line 5 and the horizontally biased line 6 are used to provide a bias voltage for the varactor diode 4; by adjusting the capacitance of the varactor diode 4 by changing the bias voltage of the varactor diode 4, a transmitted wave with different progressive phase differences is obtained, and an effective electronic scanning beam is realized. The varactor diode 4 is symmetrically loaded between the metal patterns on the front side of the dielectric substrate 1, and the loading direction is the same as the polarization direction of the incident wave.

[0041] In one embodiment, the dielectric substrate material of the multilayer electromagnetic surface structure is Rogers RO4350B, and the relative dielectric constant is 3.48; the interlayer dielectric layer of the multilayer electromagnetic surface structure is Rogers RT6010, and the relative dielectric constant is 10.2, forming an alternating distribution of high and low dielectric constant materials, eliminating the parasitic resonant cavity mode existing in the electromagnetic surface structure, and greatly reducing the profile height of the electromagnetic surface, realizing a profile height of about half a wavelength.

[0042] The waveguide structure adopts a closed structure, the electromagnetic surface unit is placed inside the waveguide structure, electromagnetic waves are fed into one end of the waveguide structure, and electromagnetic waves are radiated to the free space from the other end, the electric field intensity on the waveguide wall is zero, thereby realizing isolation of the electromagnetic surface units and minimizing the mutual coupling and transverse radiation between the electromagnetic surface units. By designing the size of the waveguide structure, single-mode transmission of electromagnetic waves in the target frequency band is ensured, and grating lobes in the scanning beam are avoided.

[0043] In one embodiment, the length and width of the cavity of the waveguide structure 8 are A and B respectively, where A < λ0 / 2 and B < λ0 / 2, to avoid grating lobes in the scanning beam, and λ0 is the minimum free space wavelength of the transmitted or received electromagnetic wave. The electromagnetic wave mode propagating in the waveguide structure is TE mn , m and n represent the mode number, and the main mode cutoff frequency is where v is the phase velocity, by adjusting the length A and the width B of the cavity, the target frequency f satisfies f c <f<f h , f h is the cutoff frequency of the high-order mode, and single-mode transmission of electromagnetic waves in the target frequency band is ensured.

[0044] The waveguide structure is a ridge waveguide structure or a dielectric-filled waveguide structure, and the ridge waveguide structure includes a single-ridge waveguide structure, a double-ridge waveguide structure or a cross-ridge waveguide structure.

[0045] In one embodiment, the selected waveguide structure 8 is a single-ridge waveguide structure, and the single-ridge waveguide structure has a long side A of 12.0 mm, a short side B of 9.5 mm, a metal ridge width s of 4.2 mm and a metal ridge height h of 4.0 mm.

[0046] The leftmost unit in the array is the 0th unit, and in order to realize beam angle deflection θ, the transmitted wave and the phase shift γ generated by the electromagnetic surface unit spaced by n periods n The phase shift γ can be calculated by the following formula:

[0047]

[0048] where λ0 is the minimum free-space wavelength of the transmitted or received electromagnetic wave, p is the period size, n is a natural number, and k0 is the propagation constant, so that the phase shift γ can be calculated. n The phase shift a required by each electromagnetic surface unit n = -γ n + α0 + 2πi, where α0 is the phase shift required by the 0th unit. In practice, when the bias voltage of the varactor tube of the x-direction i th unit is Vi, the capacitance value of the varactor tube is Ci, and the generated phase shift is Φ i , the bias voltage of the varactor tube of the jth unit is Vj, the capacitance value of the varactor tube is Cj, and the generated phase shift is Φ j When Φ j - Φ i = γ j-i + 2πm, where m is a natural number, the transmitted wave is still a plane wave, and the beam deflection angle is θ.

[0049] The waveguide structure electromagnetic surface beam scanning array of the application is simulated by using electromagnetic simulation software, and simulation results are obtained by setting different capacitance values as shown in Figure 4 、 Figure 5 It can be seen from the analysis Figure 4 that at the frequency point 11.7 GHz, the main beam direction is deflected by 30°, the gain is 18.2 dBi, and the sidelobe level is -12.4 dB. Figure 5 It can be seen from the analysis that at the frequency point 11.7 GHz, the main beam direction is deflected by 45°, the gain is 17.4 dBi, and the sidelobe level is -12.8 dB. It can be seen that the waveguide structure electromagnetic surface beam scanning array of the application has the characteristics of high gain and low sidelobe.

[0050] Reference Figure 6 , Figure 7 As shown in FIG. 4, the ridge waveguide structure can also be a double-ridge waveguide structure or an orthogonal ridge waveguide structure, and similarly, the electromagnetic surface unit is placed in the center of the double-ridge waveguide or the center of the orthogonal ridge waveguide. Figure 8 As shown in FIG. 5, the waveguide structure can also be a dielectric-filled waveguide structure, and in this case, a dielectric is filled between layers, and the dielectric constant of the dielectric is higher than that of the electromagnetic surface structure dielectric substrate, so as to ensure the transmission of electromagnetic waves and reduce the profile height of the multi-layer electromagnetic surface structure.

[0051] Reference Figure 9 , Figure 10 As shown in FIG. 6, the electromagnetic surface structure can be a multi-layer structure, and the number of metal patterns is one more than the number of dielectric substrates 1. When the dielectric substrate 1 is two layers, the metal pattern is three layers, and the outer two layers are loaded with varactor tubes, and the middle layer provides a bias voltage for the varactor diode. When the dielectric substrate 1 is three layers, the metal pattern is four layers, and the outer two layers are loaded with varactor tubes, and one of the middle two layers provides a bias voltage for the varactor diode, and the other layer is a matching layer to expand the operating bandwidth of the electromagnetic surface structure.

[0052] Reference Figure 11 As shown in FIG. 7, the electromagnetic surface structure can work in dual polarization, and two varactor diodes are loaded in the horizontal direction and the vertical direction, respectively. The varactor diode in the horizontal direction can control the incident electromagnetic wave in the horizontal direction, and the varactor diode in the vertical direction can control the incident electromagnetic wave in the vertical direction. The varactor diodes in the two directions do not interfere with each other, and the electromagnetic waves in the orthogonal polarization directions can be controlled.

[0053] The above is the specific implementation of the embodiments of the present application, and those skilled in the art can manufacture the waveguide structure electromagnetic surface beam scanning array of the present application by applying the disclosed method and some alternative ways without creative labor. The waveguide structure electromagnetic surface beam scanning array of the present application has the characteristics of low cost, low power consumption, easy processing, and easy implementation, and can be used in high-performance portable satellite communication, low-slow-small target detection, etc. However, the embodiments of the present application are not limited by the above embodiments, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application shall be equivalent replacement ways, and all shall be included in the protection scope of the present application.

Claims

1. A waveguide structure electromagnetic surface wave beam scanning array, characterized in that, The beam scanning array comprises a multilayer electromagnetic surface structure and a waveguide structure, the electromagnetic surface structure comprises a plurality of arrayed electromagnetic surface units, the multilayer electromagnetic surface structure is separated by a dielectric layer, and adjacent electromagnetic surface units are isolated by the waveguide structure; the waveguide structure adopts a closed structure, the electromagnetic surface units are placed in the waveguide structure, one end of the waveguide structure feeds electromagnetic waves, the other end radiates electromagnetic waves to the free space, the electric field intensity on the waveguide wall is zero, thereby realizing isolation of the electromagnetic surface units and minimizing the mutual coupling and transverse radiation between the electromagnetic surface units.

2. The waveguide structure electromagnetic surface wave beam scanning array of claim 1, wherein, Each layer of the electromagnetic surface structure comprises a dielectric substrate and a periodically arranged metal pattern printed on the front and back surfaces of the dielectric substrate; The metal pattern printed on the front surface of the dielectric substrate comprises an inner solid metal patch, an outer square metal ring and a vertical bias line, a variable capacitance diode is symmetrically loaded between the inner solid metal patch and the outer square metal ring, the vertical bias line is connected with the outer square metal ring and is used for changing the electromagnetic characteristics of the transmitted wave; The metal pattern printed on the back surface of the dielectric substrate is a horizontal bias line; The vertical bias line and the horizontal bias line are used for providing a bias voltage for the variable capacitance diode; by changing the bias voltage of the variable capacitance diode to adjust the capacitance of the variable capacitance diode, a transmitted wave with different progressive phase differences is obtained, thereby realizing effective electronic scanning beam.

3. The waveguide structure electromagnetic surface wave beam scanning array of claim 1, wherein, Each layer of the electromagnetic surface structure comprises a plurality of dielectric substrates, a periodically arranged metal pattern is arranged between adjacent dielectric substrates, a periodically arranged metal pattern with symmetrically loaded variable capacitance diodes is arranged on the outer sides of the outermost two dielectric substrates, at least one intermediate layer metal pattern provides a bias voltage for the variable capacitance diode, and other intermediate layer metal patterns expand the working bandwidth of the electromagnetic surface structure.

4. A waveguide structure electromagnetic surface wave beam scanning array according to claim 2 or 3, wherein, The dielectric constant of the dielectric layer between the multilayer electromagnetic surface structure layers is higher than the dielectric constant of the dielectric substrate of the electromagnetic surface structure, thereby forming an alternating distribution of high and low dielectric constant materials, eliminating the parasitic resonant cavity mode of the electromagnetic surface structure, and greatly reducing the profile height of the electromagnetic surface.

5. The waveguide structure electromagnetic surface wave beam scanning array of claim 2 or 3, wherein, The variable capacitance diode is loaded in the horizontal direction or the vertical direction, and the loading direction is the same as the polarization direction of the incident wave.

6. The waveguide structure electromagnetic surface wave beam scanning array of claim 2 or 3, wherein, The variable capacitance diode is loaded in the horizontal direction and the vertical direction at the same time, the variable capacitance diode in the vertical direction is used for regulating the incident electromagnetic wave with vertical linear polarization, the variable capacitance diode in the horizontal direction is used for regulating the incident electromagnetic wave with horizontal linear polarization, and the orthogonal direction variable capacitance diode is used for simultaneously controlling the electromagnetic wave with orthogonal direction polarization.

7. The waveguide structure electromagnetic surface wave beam scanning array of claim 1, wherein, The waveguide structure is a ridge waveguide structure or a dielectric-filled waveguide structure, and the ridge waveguide structure comprises a single-ridge waveguide structure, a double-ridge waveguide structure and an orthogonal ridge waveguide structure.

8. The waveguide structure electromagnetic surface wave beam scanning array of claim 1, wherein, The waveguide structure is realized by directly processing a waveguide cavity with metal or by using a metalized via instead of a metal waveguide wall.

9. The waveguide structure electromagnetic surface wave beam scanning array of claim 1, wherein, By designing the size of the waveguide structure, the electromagnetic wave is ensured to be single-mode transmitted in the target frequency band, and the grating lobes are avoided in the scanning beam, specifically: the cavity length and width of the waveguide structure are A and B respectively, wherein A < λ0 / 2, B < λ0 / 2, the grating lobes are avoided in the scanning beam, wherein λ0 is the minimum free space wavelength of the transmitted or received electromagnetic wave; in the waveguide structure, the electromagnetic wave mode propagating is TE mn , m, n represent mode numbers, the main mode cutoff frequency wherein v is the phase velocity, by adjusting the cavity length A and width B, so that the target frequency f satisfies f c <f<f h , f h is the high-order mode cutoff frequency, and the electromagnetic wave is ensured to be single-mode transmitted in the target frequency band.

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