Dual-band bandpass filter with independently controllable cutoff frequencies based on effective artificial surface plasmons

Abstract

The application provides a double-passband band-pass filter with independently controllable cutoff frequency based on effective artificial surface plasmon, which comprises a dielectric substrate, the upper and lower surfaces of the dielectric substrate are respectively formed with a dielectric substrate top layer and a dielectric substrate bottom layer, the dielectric substrate top layer is provided with a first microstrip line, a second microstrip line, an equivalent artificial surface plasmon double-passband band-pass filter based on a mixed substrate integrated waveguide structure, a third microstrip line and a fourth microstrip line, one end of the first microstrip line is a feeding port and is connected with a ground metal layer through a first microwave high-frequency connector joint, the other end of the first microstrip line is sequentially connected with a metal ground layer through the second microstrip line, the equivalent artificial surface plasmon double-passband band-pass filter based on the mixed substrate integrated waveguide structure, the third microstrip line, the fourth microstrip line and a second microwave high-frequency connector joint; the application can realize a band-pass filter with a wide passband, low loss, independently controllable cutoff frequency, stable stopband and deep out-of-band suppression capability.

Description

Technical Field

[0001] This invention relates to a dual-passband bandpass filter with an independently controllable cutoff frequency based on effective artificial surface plasmons, belonging to the field of filter technology. Background Technology

[0002] With the continuous development of modern communication systems, dual-band bandpass filters have been extensively studied using various design methods. For example, Yuxia Mo et al. implemented a microstrip dual-band bandpass filter based on a single improved step impedance resonator to achieve miniaturization and high selectivity, but the passband (including center frequency and bandwidth) of the filter was difficult to control. WeiJiang et al. designed a filter with high selectivity and a wide stopband using a step impedance resonator loaded with an open / short-circuit stub. Although the filter achieved independently adjustable bandwidth, unfortunately, the passband center frequency could not be controlled independently.

[0003] In summary, the aforementioned dual-bandpass filters cannot simultaneously achieve independently controllable passband center frequency and bandwidth. Azita M. Moattari et al. implemented a tri-bandpass filter to obtain a flexible and controllable passband. However, the passband selectivity and isolation enhancement are still insufficient, and the bandpass filter has a relatively narrow stopband bandwidth. The design process of all these proposed dual-bandpass filters is often cumbersome and complex, and may be difficult to meet the requirements of high data rates, high transmission capacity, and multiplexing due to their narrow bandwidth. Therefore, simultaneously realizing a dual-passband bandpass filter with a simple design process, high selectivity, independently controllable cutoff frequency, and wide stopband remains a challenging task.

[0004] Surface plasmon polaritons (SPPs) are surface-propagating electromagnetic (EM) waves confined at the interface between a metal and a dielectric. Due to the strong localization of the surface field, SPPs can overcome the diffraction limit, achieving subwavelength confinement, high-frequency cutoff, and wide bandwidth, which has greatly promoted plasmonic devices. However, natural SPPs cannot be excited in the low-frequency range of GHz to THz. Until 2004, Pendry et al. proposed designing SPPs operating in the microwave or terahertz band using periodic structural surface designs. Since then, various surface plasmon filters have been reported due to flexible dispersion engineering by shaping artificial grooves or holes in metals. Cui et al. constructed a tunable frequency suppression device using a metamaterial-based electric resonance and impedance mismatch electric field coupling unit structure tightly coupled with artificial surface plasmon polaritons (SSPPs). However, all these proposed dual-band filters lack both bandwidth and independent tunability within the dual bands. Furthermore, many artificial SPP transmission structures are open or semi-open, inevitably resulting in radiation losses and high insertion losses in the associated filters.

[0005] In recent years, another SPP-like concept has been proposed in the microwave field. This concept is based on the utilization of the well-known electromagnetic mode structure dispersion in parallel-plate waveguide structures filled only with positive permittivity materials. That is, if a parallel-plate waveguide is divided into two parts by an array of wires placed along a plane perpendicular to the plate, and if these parts are filled with different materials, the two parts exhibit effective permittivity of opposite signs within a certain range. This results in SPP phenomena at the interface within a frequency range. These mode dispersion-induced effective surface plasmons (ESPPs) differ from traditional artificial surface plasmons because ESPPs are not generated by the corrugations of a metallic structure. This method has been applied to substrate integrated waveguides (SIWs), and the implemented configuration demonstrates the potential for microwave frequency filtering applications. ESPPs are used to generate a dual-band effect in substrate integrated waveguides. The effective permittivity of the three sub-substrate integrated waveguide structures exhibits opposite signs within a specific frequency range, providing two distinct SPP-like propagation paths with high isolation, thus generating dual-bandpass characteristics in a multilayer waveguide. However, the proposed dual-band filter still cannot independently control the cutoff frequency, and has a narrow passband, high insertion loss, and low stopband stability.

[0006] The above-mentioned issues should be considered and resolved during the design process of dual-passband bandpass filters. Summary of the Invention

[0007] The purpose of this invention is to provide a dual-passband bandpass filter with an independently controllable cutoff frequency based on effective artificial surface plasmons, which solves the problems in the prior art where the cutoff frequency of the mid-passband and the out-of-band cutoff frequency cannot be independently controlled, the insertion loss is high, and the stability of the stopband needs to be improved.

[0008] The technical solution of this invention is:

[0009] A dual-passband bandpass filter with an independently controllable cutoff frequency based on an effective artificial surface plasmon polariton (ASP) comprises a dielectric substrate. The top and bottom surfaces of the dielectric substrate are respectively formed as a top layer and a bottom layer. The top layer of the dielectric substrate is provided with a first microstrip line, a second microstrip line, an equivalent artificial surface plasmon polariton dual-passband bandpass filter based on a hybrid substrate integrated waveguide structure, a third microstrip line, and a fourth microstrip line. One end of the first microstrip line is a feed port and is connected to a ground metal layer through a first microwave high-frequency connector. The other end of the first microstrip line is sequentially connected to the second microstrip line, the equivalent artificial surface plasmon polariton (ASP) based on the hybrid substrate integrated waveguide structure, and the third microstrip line. The dual-pass bandpass filter, third microstrip line, fourth microstrip line, and second microwave high-frequency connector are connected to the metal grounding layer. The equivalent artificial surface plasmon dual-pass bandpass filter based on the hybrid substrate integrated waveguide structure includes a substrate integrated waveguide, a first metal pillar layer, a dielectric cavity layer, a second metal pillar layer, an air cavity layer, and a copper-clad layer arranged sequentially from bottom to top. The grounding metal layer, substrate integrated waveguide, first metal pillar layer, dielectric cavity layer, second metal pillar layer, air cavity layer, and copper-clad layer are each provided with two rows of cylindrical through holes and fixed by positioning screws. The inner walls of the cylindrical through holes are copper-clad, forming side electric walls. The bottom layer of the dielectric substrate is completely covered by the grounding metal layer.

[0010] Furthermore, the metal pillar layer one includes a dielectric layer one and a plurality of metal pillars one arranged at intervals in the middle of the dielectric layer one, and the metal pillars one are disposed between two rows of cylindrical through holes in the metal pillar layer one.

[0011] Furthermore, the dielectric is provided with a number of air gaps, the sidewalls of which are covered by copper sheets to form the sidewalls of the metal pillars. The upper and lower ends of the copper sheets are respectively provided with upper metal strips and lower metal strips. The copper sheets and the corresponding upper and lower metal strips together form the metal pillars.

[0012] Furthermore, the upper metal strips are spaced apart at the bottom of the dielectric cavity layer, and the lower metal strips are spaced apart at the top of the substrate integrated waveguide.

[0013] Furthermore, the dielectric cavity layer includes a dielectric substrate and a first rectangular air groove, with the first rectangular air groove having copper-covered sidewalls at both ends of the dielectric substrate.

[0014] Furthermore, the second metal pillar layer includes a second dielectric, a U-shaped copper sheet, a top metal strip, and a bottom metal strip. The second dielectric has several spaced air gaps, which are all located between two rows of cylindrical through holes in the second metal pillar layer. The sidewalls of the air gaps are covered with copper sheets, and the upper and lower ends of the copper sheets are respectively provided with top metal strips and bottom metal strips. The copper sheets, together with the corresponding top and bottom metal strips, form the second metal pillar. The bottom metal strips are spaced apart at the top of the dielectric cavity layer, and the top metal strips are spaced apart within the U-shaped copper sheet.

[0015] Furthermore, the air cavity layer includes a second dielectric substrate, and a second rectangular air groove is provided in the middle of the first dielectric substrate, with the sidewalls of the second rectangular air groove covered with copper.

[0016] Furthermore, the second and third microstrip lines are symmetrically arranged trumpet-shaped tapered microstrip lines, while the first and fourth microstrip lines are elongated strips.

[0017] Furthermore, the lower cutoff frequency of the lower passband is controlled by adjusting the width of the two rows of cylindrical vias in the substrate integrated waveguide; that is, as the width of the two rows of cylindrical vias in the substrate integrated waveguide increases, the lower cutoff frequency of the lower passband decreases. The upper cutoff frequency of the lower passband is independently controlled by adjusting the width of the two rows of cylindrical vias in the first metal pillar layer; that is, as the width of the two rows of cylindrical vias in the first metal pillar layer increases, the upper cutoff frequency of the lower passband decreases.

[0018] Furthermore, the lower cutoff frequency of the high-pass band is controlled by adjusting the width of the two rows of cylindrical vias in the dielectric cavity layer; that is, as the width of the two rows of cylindrical vias in the dielectric cavity layer increases, the lower cutoff frequency of the high-pass band decreases. Similarly, the upper cutoff frequency of the high-pass band is independently controlled by adjusting the width of the two rows of cylindrical vias in the second metal pillar layer; that is, as the width of the two rows of cylindrical vias in the second metal pillar layer increases, the upper cutoff frequency of the high-pass band decreases. Finally, the upper cutoff frequency of the high-stop band is controlled by adjusting the width of the two rows of cylindrical vias in the air cavity layer; that is, as the width of the two rows of cylindrical vias in the air cavity layer increases, the upper cutoff frequency of the high-stop band decreases.

[0019] The beneficial effects of this invention are:

[0020] I. This dual-passband bandpass filter with an independently controllable cutoff frequency based on effective artificial surface plasmons introduces a sandwich structure into the ESPP in the substrate integrated waveguide to excite the ESSPP mode, thereby independently controlling the cutoff frequency of the dual-passband bandpass filter. It can achieve bandwidth, low loss, independently controllable cutoff frequency, stopband stability and deep out-of-band suppression capability.

[0021] II. Unlike traditional resonant mode dual-band bandpass filters, the proposed bandpass filter using rectangular waveguide technology typically features low insertion loss, wide passband, and high power processing capability, and can be extended to millimeter waves.

[0022] Third, this dual-passband bandpass filter based on effective artificial surface plasmons with independent controllable cutoff frequencies, compared with the ESPP dual-frequency bandpass filter, has multiple cutoff frequencies determined for each layer of the equivalent artificial surface plasmon dual-passband bandpass filter based on a hybrid substrate integrated waveguide structure, which can ensure independent passband and out-of-band control. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of a dual-passband bandpass filter with an independently controllable cutoff frequency based on effective artificial surface plasmons according to an embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram of the back structure of a dual-passband bandpass filter with an independently controllable cutoff frequency based on an effective artificial surface plasmon resonance in an embodiment.

[0025] Figure 3 This is a schematic diagram of the decomposed structure of a dual-passband bandpass filter with an independently controllable cutoff frequency based on an effective artificial surface plasmon resonance in an embodiment.

[0026] Figure 4 This is a physical schematic diagram of a dual-passband bandpass filter with an independently controllable cutoff frequency based on an effective artificial surface plasmon resonance (ASPR).

[0027] Figure 5 The width W of the two rows of cylindrical vias in the substrate integrated waveguide in the embodiment is... Ⅴ A schematic diagram illustrating the effect on the lower cutoff frequency of the lower passband.

[0028] Figure 6 The width W of the two rows of cylindrical through holes in the first metal column layer in the embodiment is... Ⅳ A schematic diagram illustrating the effect on the upper cutoff frequency of the lower passband.

[0029] Figure 7 The width W of the two rows of cylindrical through holes in the dielectric cavity layer in the embodiment is... Ⅲ A schematic diagram illustrating the effect on the lower cutoff frequency of the high-pass band.

[0030] Figure 8 The width W of the two rows of cylindrical through holes in the second metal column layer in the embodiment is... Ⅱ A schematic diagram illustrating the effect on the upper cutoff frequency of the high-pass band.

[0031] Figure 9 The width W of the two rows of cylindrical through holes in the air cavity layer in the embodiment is... Ⅰ A schematic diagram illustrating the effect on the upper cutoff frequency of the high stopband.

[0032] Figure 10 This is a schematic diagram of the S-parameters of a dual-passband bandpass filter with an independently controllable cutoff frequency based on effective artificial surface plasmons, simulated and measured at 2-12 GHz.

[0033] Wherein: 1-dielectric substrate, 2-ground metal layer, 3-first microstrip line, 4-second microstrip line, 5-equivalent artificial surface plasmon dual-passband bandpass filter based on hybrid substrate integrated waveguide structure, 6-third microstrip line, 7-fourth microstrip line, 8-positioning screw, 9-cylindrical through hole, 10-first microwave high-frequency connector, 11-second microwave high-frequency connector;

[0034] 51-Substrate integrated waveguide, 52-Metal pillar layer one, 53-Dielectric cavity layer, 54-Metal pillar layer two, 55-Air cavity layer, 56-Copper cladding layer;

[0035] 521-Dielectric material one, 522-Air gap one, 523-Copper sheet one, 524-Lower metal strip;

[0036] 531-Dielectric substrate one, 532-First rectangular gas groove;

[0037] 541-Dielectric material two, 542-Air gap two, 543-Copper sheet two, 544-U-shaped copper sheet, 545-Top metal strip, 546-Bottom metal strip;

[0038] 551 - Dielectric substrate two, 552 - Second rectangular gas groove. Detailed Implementation

[0039] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Example

[0040] A dual-passband bandpass filter with an independently controllable cutoff frequency based on effective artificial surface plasmons, such as... Figure 1 and Figure 2The substrate includes a dielectric substrate 1, with a top layer and a bottom layer formed on its upper and lower surfaces, respectively. The top layer is provided with a first microstrip line 3, a second microstrip line 4, an equivalent artificial surface plasmon dual-passband filter 5 based on a hybrid substrate integrated waveguide structure, a third microstrip line 6, and a fourth microstrip line 7. One end of the first microstrip line 3 is a feed port connected to a ground metal layer 2 via a first microwave high-frequency connector 10. The other end of the first microstrip line 3 is connected sequentially to the second microstrip line 4, the equivalent artificial surface plasmon dual-passband filter 5 based on a hybrid substrate integrated waveguide structure, the third microstrip line 6, the fourth microstrip line 7, and the second microstrip line 7. The high-frequency connector 11 connects to the metal grounding layer 2; the equivalent artificial surface plasmon dual-passband bandpass filter 5 based on the hybrid substrate integrated waveguide structure includes a substrate integrated waveguide 51, a first metal pillar layer 52, a dielectric cavity layer 53, a second metal pillar layer 54, an air cavity layer 55, and a copper-clad layer 56 arranged sequentially from bottom to top. The grounding metal layer 2, the substrate integrated waveguide 51, the first metal pillar layer 52, the dielectric cavity layer 53, the second metal pillar layer 54, the air cavity layer 55, and the copper-clad layer 56 are each provided with two rows of cylindrical through holes 9 and fixed by positioning screws 8. The inner walls of the cylindrical through holes 9 are copper-clad, forming side electric walls. The bottom layer of the dielectric substrate is completely covered by the grounding metal layer 2.

[0041] This dual-passband bandpass filter with an independently controllable cutoff frequency, based on effective artificial surface plasmons, introduces a sandwich structure into the ESPP in the substrate integrated waveguide 51 to excite the ESSPP mode, thereby independently controlling the cutoff frequency of the dual-passband bandpass filter. It can achieve bandwidth, low loss, independently controllable cutoff frequency, stopband stability, and deep out-of-band suppression capability.

[0042] like Figure 3 The metal pillar layer 52 includes a dielectric layer 521 and a plurality of metal pillars 521 spaced apart in the middle of the dielectric layer 521, with the metal pillars 521 positioned between two rows of cylindrical through holes 9. The dielectric layer 521 has a plurality of air gaps 522 spaced apart, each 2 mm wide. The sidewalls of the air gaps 522 are covered with copper sheets 523 forming the sidewalls of the metal pillars 522. Upper metal strips and lower metal strips 524 are respectively provided at the upper and lower ends of the copper sheets 523, forming the metal pillars 521. The upper metal strips are spaced apart at the bottom of the dielectric cavity layer 53, and the lower metal strips 524 are spaced apart at the top of the substrate integrated waveguide 51. Individual control of the upper cutoff frequency of the lower passband is achieved by controlling the width of the two rows of cylindrical through holes in the metal pillar layer 52.

[0043] The dielectric cavity layer 53 includes a dielectric substrate 531 and a first rectangular air groove 532. The dielectric substrate 531 has first rectangular air grooves 532 with copper-covered sidewalls at both ends. The lower cutoff frequency of the high-pass band can be individually controlled by controlling the width of the two rows of cylindrical vias in the dielectric cavity layer 53.

[0044] The second metal pillar layer 54 includes a second dielectric 541, a U-shaped copper sheet 544, a top metal strip 545, and a bottom metal strip 546. The second dielectric 541 has several spaced air gaps 542, each 2mm wide, located between two rows of cylindrical through holes 9 in the second metal pillar layer 544. The sidewalls of the air gaps 542 are covered by copper sheets 543. The upper and lower ends of each copper sheet 543 have top metal strips 545 and bottom metal strips 546, respectively. The copper sheets 543, along with their corresponding top and bottom metal strips 545, together form the second metal pillar. The bottom metal strips 546 are spaced apart at the top of the dielectric cavity layer 53, and the top metal strips 545 are spaced apart within the U-shaped copper sheet 544. Individual control of the upper cutoff frequency of the high-pass band is achieved by controlling the width of the two rows of cylindrical through holes in the second metal pillar layer 544.

[0045] The air cavity layer 55 includes a second dielectric substrate 551. A second rectangular air groove 552 is provided in the middle of the first dielectric substrate 531, and the sidewalls of the second rectangular air groove 552 are covered with copper. The upper cutoff frequency of the high stopband can be individually controlled by controlling the width of the two rows of cylindrical through holes in the air cavity layer 55.

[0046] Both sides of the substrate integrated waveguide 51 have microstrip lines that transition into each other, namely the second microstrip line 4 and the third microstrip line 6. The second microstrip line 4 and the third microstrip line 6 are symmetrically arranged horn-shaped tapered microstrip lines. The first microstrip line 3 and the fourth microstrip line 7 are elongated strips. The first microstrip line 3, the second microstrip line 4, the third microstrip line 6, and the fourth microstrip line 7 form the transition lines of the substrate integrated waveguide, serving to achieve good feeding, reduce losses, and obtain better S-axis characteristics. 11 parameter.

[0047] This dual-passband bandpass filter, based on effective artificial surface plasmons and featuring independently controllable cutoff frequencies, controls the lower cutoff frequency of the lower passband by adjusting the width of the two rows of cylindrical vias in the substrate integrated waveguide 51. Specifically, as the width of the two rows of cylindrical vias in the substrate integrated waveguide 51 increases, the lower cutoff frequency of the lower passband decreases. Similarly, the upper cutoff frequency of the lower passband is independently controlled by adjusting the width of the two rows of cylindrical vias in the metal pillar layer 52. In other words, as the width of the two rows of cylindrical vias in the metal pillar layer 52 increases, the upper cutoff frequency of the lower passband decreases.

[0048] This dual-passband bandpass filter, based on effective artificial surface plasmons and featuring independently controllable cutoff frequencies, controls the lower cutoff frequency of the high-pass band by adjusting the width of the two rows of cylindrical vias in the dielectric cavity layer 53. Specifically, increasing the width of the two rows of cylindrical vias in the dielectric cavity layer 53 continuously decreases the lower cutoff frequency of the high-pass band. Similarly, controlling the width of the two rows of cylindrical vias in the second metal pillar layer 54 independently controls the upper cutoff frequency of the high-pass band. Likewise, increasing the width of the two rows of cylindrical vias in the second metal pillar layer 54 continuously decreases the upper cutoff frequency of the high-pass band. Finally, controlling the width of the two rows of cylindrical vias in the air cavity layer 55 controls the upper cutoff frequency of the high-stopband.

[0049] The copper-clad layer 56 is used to prevent electromagnetic wave leakage and has a small thickness. At the same time, each layer of the hybrid substrate integrated waveguide 51 has two rows of cylindrical through-holes 9 with copper clad inner walls to form the side electric walls of the substrate integrated waveguide 51, so as to achieve a good transmission effect similar to that of a rectangular waveguide.

[0050] This dual-passband bandpass filter, based on an effective artificial surface plasmon resonance (ASPR) and featuring an independently controllable cutoff frequency, receives a signal fed into the system via a first microwave high-frequency connector 10. The signal then passes through a first microstrip line 3, a second microstrip line 4, and an equivalent ASPR dual-passband bandpass filter 5 based on a hybrid substrate integrated waveguide structure. The filtered signal is then extracted via a third microstrip line 6, a fourth microstrip line 7, and a second microwave high-frequency connector 11. This completes the entire filtering process.

[0051] This dual-passband bandpass filter, based on effective artificial surface plasmons (SPPs) with independently controllable cutoff frequencies, reveals its operating mechanism through the dispersion relation of ESSPP modes supported on the transmission line. To obtain the dispersion relation, the structure is divided into five layers: a substrate integrated waveguide 51, a first metal pillar layer 52, a dielectric cavity layer 53, a second metal pillar layer 54, and an air cavity layer 55. In the first frequency range, the substrate integrated waveguide 51 and all dielectric cavities have negative effective permittivity, thus no propagation occurs. In the second and fourth frequency ranges, ESSPP modes can be supported, and it exhibits the same behavior as true SPPs, heading towards infinity at specific frequencies called surface plasmon frequencies fSP1 and fSP2. In the second range, ESSPPs propagate along the first metal pillar of the first metal pillar layer 52. Similarly, in the third frequency range, ESSPP propagation propagates along the metal pillars of the second metal pillar layer 54. Since the proposed structure can support SPP-like propagation in two different frequency ranges, this provides possibilities for designing dual-band filters.

[0052] like Figure 4This invention relates to a dual-passband bandpass filter with an independently controllable cutoff frequency based on an effective artificial surface plasmon polariton. The top layer of the dielectric substrate comprises a first microstrip line 3, a second microstrip line 4, and an equivalent artificial surface plasmon dual-passband bandpass filter 5 based on a hybrid substrate integrated waveguide structure. One end of the first microstrip line 3 serves as the filter's feed port and is connected to a grounded metal layer 2 via a microwave high-frequency connector. The other end of the first microstrip line 3 sequentially passes through the second microstrip line 4, the equivalent artificial surface plasmon polariton dual-passband bandpass filter 5 based on a hybrid substrate integrated waveguide structure, and then through a third microstrip line 6, a fourth microstrip line 7, and the microwave high-frequency connector to complete the dual-band signal transmission and filtering process. This invention achieves a wide passband, low loss, independently controllable cutoff frequency, stable stopband, and deep out-of-band rejection capability.

[0053] Unlike traditional resonant mode dual-band bandpass filters, the proposed bandpass filter using rectangular waveguide technology typically features low insertion loss, wide passband, and high power handling capability, and can be extended to millimeter waves.

[0054] This dual-passband bandpass filter based on effective artificial surface plasmons with independently controllable cutoff frequencies, compared to the ESPP dual-band bandpass filter, features a uniquely defined cutoff frequency for each of the substrate integrated waveguide 51, metal pillar layer 52, dielectric cavity layer 53, metal pillar layer 54, and air cavity layer 55, ensuring independent passband and out-of-band control. Due to the completely independent and controllable cutoff frequencies, the proposed filter can be extended to design tri-band or even quad-band bandpass filters.

[0055] This dual-passband bandpass filter, based on effective artificial surface plasmons and featuring independently controllable cutoff frequencies, is implemented as a hybrid substrate integrated waveguide 51. Each of the five layers possesses an inherent effective dielectric constant, which depends on its width and the filling dielectric material. The independent selection of the geometric parameters of each layer or the corresponding dielectric material provides a high degree of freedom for arbitrarily positioning the passband in the spectrum.

[0056] This dual-passband bandpass filter with an independently controllable cutoff frequency, based on effective artificial surface plasmons, is implemented using a hybrid substrate integrated waveguide 51 structure. It meets the requirements of low cost and thin configuration, has strong scalability, and exhibits excellent in-band characteristics and selectivity as confirmed by measurement results.

[0057] The simulation and experimental verification results of the embodiments are as follows:

[0058] like Figures 5-9The changes in the cutoff frequency corresponding to the width of each layer of the substrate integrated waveguide 51, metal pillar layer 1 52, dielectric cavity layer 53, metal pillar layer 2 54 and air cavity layer 55 are respectively shown.

[0059] Figure 5 The width W of the two rows of cylindrical through holes in the substrate integrated waveguide 51 in the embodiment is... Ⅴ A schematic diagram illustrating the effect on the lower cutoff frequency of the lower passband. (From...) Figure 5 It can be seen that as the width of the two rows of cylindrical vias in the substrate integrated waveguide 51 increases, the lower cutoff frequency of the lower passband decreases continuously.

[0060] Figure 6 The width W of the two rows of cylindrical through holes in the metal pillar layer 52 in the embodiment is... Ⅳ A schematic diagram illustrating the effect on the upper cutoff frequency of the lower passband. (From...) Figure 6 It can be seen that as the width of the two rows of cylindrical through holes in the metal column layer 52 increases, the upper cutoff frequency of the lower passband decreases continuously.

[0061] Figure 7 The width W of the two rows of cylindrical through holes in the dielectric cavity layer 53 in the embodiment is... Ⅲ A schematic diagram illustrating the effect on the lower cutoff frequency of the high-pass band. (From...) Figure 7 It can be seen that as the width of the two rows of cylindrical through holes in the dielectric cavity layer 53 increases, the lower cutoff frequency of the high-pass band decreases continuously.

[0062] Figure 8 The width W of the two rows of cylindrical through holes in the metal pillar layer 54 in the embodiment is... Ⅱ A schematic diagram illustrating the effect on the upper cutoff frequency of the high-pass band. (From...) Figure 8 It can be seen that as the width of the two rows of cylindrical through holes in the metal column layer 54 increases, the upper cutoff frequency of the high-pass band decreases continuously.

[0063] Figure 9 The width W of the two rows of cylindrical through holes in the air cavity layer 55 in the embodiment is... Ⅰ A schematic diagram illustrating the effect on the upper cutoff frequency of the high stopband. (From...) Figure 9 It can be seen that as the width of the two rows of cylindrical through holes in the air cavity layer 55 increases, the upper cutoff frequency of the high resistance band decreases continuously.

[0064] Figure 10 This is a schematic diagram of the S-parameters of a dual-passband bandpass filter with an independently controllable cutoff frequency based on effective artificial surface plasmons, as simulated and measured at 2-12 GHz. Figure 10As can be seen, this dual-passband bandpass filter based on effective artificial surface plasmons with independently controllable cutoff frequencies exhibits edge selectivity within the passband (4.8-6.5 GHz, 7-9.8 GHz) and stable stopband (6.5-7 GHz, 9.8-12 GHz) in both simulation and measurement results, with low insertion losses of 0.6 dB and 0.7 dB, respectively. Theoretical analysis and simulations demonstrate its ability to achieve independently controllable cutoff frequencies, a consistently stable stopband, and deep out-of-band suppression.

[0065] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dual-passband bandpass filter with an independently controllable cutoff frequency based on effective artificial surface plasmons, comprising a dielectric substrate, wherein a top dielectric substrate and a bottom dielectric substrate are respectively formed on the upper and lower surfaces of the dielectric substrate, characterized in that: The top layer of the dielectric substrate is provided with a first microstrip line, a second microstrip line, an equivalent artificial surface plasmon dual-passband bandpass filter based on a hybrid substrate integrated waveguide structure, a third microstrip line, and a fourth microstrip line. One end of the first microstrip line is a feed port and is connected to the ground metal layer through a first microwave high-frequency connector. The other end of the first microstrip line is sequentially connected through the second microstrip line, the equivalent artificial surface plasmon dual-passband bandpass filter based on a hybrid substrate integrated waveguide structure, the third microstrip line, the fourth microstrip line, and the second microwave high-frequency connector. Metal grounding layer; The equivalent artificial surface plasmon dual-passband bandpass filter based on the hybrid substrate integrated waveguide structure includes, from bottom to top, a substrate integrated waveguide, a first metal pillar layer, a dielectric cavity layer, a second metal pillar layer, an air cavity layer, and a copper cladding layer. The grounding metal layer, the substrate integrated waveguide, the first metal pillar layer, the dielectric cavity layer, the second metal pillar layer, the air cavity layer, and the copper cladding layer are each provided with two rows of cylindrical through holes and fixed by positioning screws. The inner walls of the cylindrical through holes are copper-clad, forming side electric walls. The bottom layer of the dielectric substrate is completely covered by the grounding metal layer. The lower cutoff frequency of the lower passband is controlled by adjusting the width of the two rows of cylindrical vias in the substrate integrated waveguide. That is, as the width of the two rows of cylindrical vias in the substrate integrated waveguide increases, the lower cutoff frequency of the lower passband decreases. The upper cutoff frequency of the lower passband is independently controlled by adjusting the width of the two rows of cylindrical vias in the first metal pillar layer. That is, as the width of the two rows of cylindrical vias in the first metal pillar layer increases, the upper cutoff frequency of the lower passband decreases. The lower cutoff frequency of the high-pass band is controlled by adjusting the width of the two rows of cylindrical vias in the dielectric cavity layer; that is, as the width of the two rows of cylindrical vias in the dielectric cavity layer increases, the lower cutoff frequency of the high-pass band decreases. Similarly, the upper cutoff frequency of the high-pass band is independently controlled by adjusting the width of the two rows of cylindrical vias in the second metal pillar layer; that is, as the width of the two rows of cylindrical vias in the second metal pillar layer increases, the upper cutoff frequency of the high-pass band decreases. Likewise, the upper cutoff frequency of the high-stop band is controlled by adjusting the width of the two rows of cylindrical vias in the air cavity layer; that is, as the width of the two rows of cylindrical vias in the air cavity layer increases, the upper cutoff frequency of the high-stop band decreases.

2. The dual-passband bandpass filter with an independently controllable cutoff frequency based on effective artificial surface plasmons as described in claim 1, characterized in that: The metal pillar layer includes a dielectric and a plurality of metal pillars spaced apart in the middle of the dielectric, and the metal pillars are located between two rows of cylindrical through holes in the metal pillar layer.

3. The dual-passband bandpass filter with an independently controllable cutoff frequency based on effective artificial surface plasmons as described in claim 2, characterized in that: The dielectric is provided with several air gaps. The sidewalls of the air gaps are covered with copper sheets to form the sidewalls of the metal pillars. The upper and lower ends of the copper sheets are respectively provided with upper metal strips and lower metal strips. The copper sheets and the corresponding upper and lower metal strips together form the metal pillars.

4. The dual-passband bandpass filter with an independently controllable cutoff frequency based on effective artificial surface plasmons as described in claim 3, characterized in that: The upper metal strips are spaced apart at the bottom of the dielectric cavity layer, and the lower metal strips are spaced apart at the top of the substrate integrated waveguide.

5. The dual-passband bandpass filter with an independently controllable cutoff frequency based on effective artificial surface plasmons as described in any one of claims 1-4, characterized in that: The dielectric cavity layer includes a dielectric substrate and a first rectangular air groove. The first rectangular air groove with copper-covered sidewalls is provided at both ends of the dielectric substrate.

6. The dual-passband bandpass filter with an independently controllable cutoff frequency based on effective artificial surface plasmons as described in any one of claims 1-4, characterized in that: The second metal pillar layer includes a second dielectric, a U-shaped copper sheet, a top metal strip, and a bottom metal strip. The second dielectric has several spaced air gaps, which are located between two rows of cylindrical through holes in the second metal pillar layer. The sidewalls of the air gaps are covered with copper sheets. The upper and lower ends of the copper sheets are respectively provided with top and bottom metal strips. The copper sheets, together with the corresponding top and bottom metal strips, form the second metal pillar. The bottom metal strips are spaced apart at the top of the dielectric cavity layer, and the top metal strips are spaced apart within the U-shaped copper sheet.

7. The dual-passband bandpass filter with an independently controllable cutoff frequency based on effective artificial surface plasmons as described in any one of claims 1-4, characterized in that: The air cavity layer includes a dielectric substrate two, and a second rectangular air groove is provided in the middle of the dielectric substrate one. The sidewalls of the second rectangular air groove are covered with copper.

8. The dual-passband bandpass filter with an independently controllable cutoff frequency based on effective artificial surface plasmons as described in any one of claims 1-4, characterized in that: The second and third microstrip lines are symmetrically arranged trumpet-shaped tapered microstrip lines, while the first and fourth microstrip lines are elongated strips.

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