A variable ferroelectric dielectric resonator based controllable filter

Abstract

The application discloses a controllable filter based on a variable ferroelectric medium resonator. The filter comprises a medium plate, a metal microstrip arranged on the surface of the medium plate, an artificial plasmon section arranged in the middle part of the metal microstrip, and a transition section and a co-planar waveguide section connected to the two ends of the artificial plasmon section respectively; metal grounds are arranged on the two sides of the connection area of the transition section and the co-planar waveguide section of the metal microstrip; the metal microstrip extends from the middle part to the two ends until the position where the transition section and the co-planar waveguide section are connected, and circular-arc grooves are symmetrically distributed on the metal microstrip; the circular-arc grooves in the middle part of the metal microstrip are further connected to a variable ferroelectric medium resonator assembly. The application solves the problem that the working spectrum of a traditional SSPPs filter is fixed, the filter cannot be dynamically and real-timely controlled, and the filter cannot adapt to the needs of a complex electromagnetic environment, and the filter can be real-timely regulated and controlled. Moreover, the reflection problem caused by the structural mutation of the waveguide circuit structure can be solved through optimization.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of mobile communication technology, and particularly relates to a controllable filter based on a cylindrical variable ferroelectric medium resonator. BACKGROUND

[0002] In the field of microwave mobile communication, Spoof Surface Plasmonic Polaritons (SSPPs) filter based on artificial planar plasmonic material has attracted much attention due to its ultra-thin planar structure and the ability to control its dispersion characteristics by adjusting the size of the unit. However, the current SSPPs device is still analog in nature, and once its geometric structure is designed and processed, its working spectrum structure is fixed and cannot be dynamically and real-time controlled, which cannot adapt to complex application environments. For example, in the frequency division multiplexing communication system, the tunable channel filter needs to independently tune the low-end and high-end cutoff frequencies of the band-pass waveguide to realize the reconfigurability of the passband. This growing demand for real-time adjustable systems promotes the research on dynamic adjustable, switchable and active structure SSPPs devices. In addition, due to the mismatch between the traditional microstrip electromagnetic signal and the SSPPs electromagnetic mode, it is difficult to effectively feed in and output the electromagnetic signal. Traditional microwave / THz waveband circuits are composed of two metal transmission lines, such as microstrip lines or coplanar waveguide structures (CPWs). Therefore, in order to efficiently convert the waveguide mode of the traditional transmission line to the plasmonic waveguide mode of the SSPPs, a new matching conversion is needed. SUMMARY

[0003] The present application aims to provide a controllable microwave filter based on a ferroelectric medium resonator. The present application solves the problem of electromagnetic wave reflection caused by the structural mutation of the SSPPs controllable filter, and realizes the dynamic and flexible control of the frequency band of the controllable filter.

[0004] The technical scheme of the present application is a controllable filter based on a ferroelectric medium resonator, comprising a medium plate, a metal microstrip provided on the surface of the medium plate, an artificial plasmon section in the middle part of the metal microstrip, and a transverse section and a co-planar waveguide section connected at both ends of the artificial plasmon section; the metal microstrip is provided with a gradually changing metal ground on both sides of the connection area of the transverse section and the co-planar waveguide section, and the gradually changing equation is an exponential equation X(t) = L1 + L2 * t, y(t) = h + g + (w - h - g) * (exp(a * t) - 1) / (exp(a) - 1), (0 <= t <= 1), wherein the parameter a = 8; the metal microstrip gradually extends from the middle part to both ends until the position where the transverse section and the co-planar waveguide section are connected, and is symmetrically provided with a circular-arc groove; the circular-arc groove in the middle part of the metal microstrip is further connected with a variable ferroelectric medium resonant assembly.

[0005] In the aforementioned controllable filter based on a ferroelectric medium resonator, the variable ferroelectric medium resonant assembly comprises a cylindrical resonator base, and the top of the cylindrical resonator base is covered with a ferroelectric film; the bottom of the cylindrical resonator base is connected with the circular-arc groove in the middle part of the metal microstrip.

[0006] In the aforementioned controllable filter based on a ferroelectric medium resonator, the ferroelectric film is connected with a finger electrode during actual pressure application.

[0007] In the aforementioned controllable filter based on a ferroelectric medium resonator, the cylindrical resonator base is composed of lanthanum aluminate single crystal.

[0008] In the aforementioned controllable filter based on a ferroelectric medium resonator, the gap f between the two circular-arc grooves symmetrically distributed on the bottom of the cylindrical resonator base is 0.1 mm; the circular-arc groove is composed of three curves, which are respectively: a first curve with a parameter equation X(t) = d + ch / 2 * cost, Y(t) = h - ch / 2 + ch / 2 * sint (pi / 2 <= t <= 3pi / 2); a second curve with a parameter equation X(t) = d + d1 * cost, Y(t) = h - ch / 2 + ch / 2 * sint (pi / 2 <= t <= 3pi / 2); and a third curve with a parameter equation X(t) = d + ch / 2 * cost, Y(t) = h - ch / 2 + ch / 2 * sint (-pi / 2 <= t <= -acos(d / ch)), wherein the parameter d is 2.2, the parameter d1 is 1.7, the depth ch of the groove is 3 mm, and the half width h of the metal microstrip is 3.2 mm.

[0009] In the aforementioned controllable filter based on a ferroelectric medium resonator, the coupling gap g between the co-planar waveguide section and the metal ground is 0.14 mm.

[0010] In the aforementioned controllable filter based on a ferroelectric medium resonator, the thickness u of the cylindrical resonator base is 0.5 mm, and the thickness i of the ferroelectric film is 0.036 mm.

[0011] In the aforementioned controllable filter based on ferroelectric medium resonator, the variable ferroelectric medium resonant component is in real time regulated by an applied voltage.

[0012] Beneficial effects

[0013] Compared with the prior art, the application utilizes the artificial plasmonic structure formed by the metal and the metal microstrip with the circular-arc groove distributed, converts the electromagnetic mode into the SSPPs electromagnetic mode, solves the problem of electromagnetic wave reflection caused by the structure mutation by using the variable ferroelectric medium resonant component, changes the dielectric constant of the variable ferroelectric medium resonant component by adding an external voltage to the ferroelectric film, realizes the real-time regulation of the frequency selection frequency of the controllable filter, and finally realizes the flexible control of the frequency selection frequency band of the controllable filter.

[0014] The application effectively solves the problem of difficult effective feeding and output of electromagnetic signals in the controllable filter caused by the groove type of the metal microstrip. The groove type of the metal microstrip of the existing controllable filter structure is generally a rectangular structure with the same direction, while the groove type of the metal microstrip of the controllable filter is a circular-arc groove with symmetry in the middle, and a variable ferroelectric resonant component is added in the two opposite directions of the circular arc in the middle of the metal microstrip, effectively solving the influence caused by the fact that most of the electromagnetic waves are reflected due to the structure mutation. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is the dispersion curve and the electric field energy field diagram of the two-unit structure of the controllable filter of the application;

[0016] Figure 2 is the overall structure schematic diagram of the controllable filter of the application

[0017] Figure 3 is the parameter schematic diagram of the controllable filter of the application;

[0018] Figure 4 is the schematic diagram of the ferroelectric medium resonator of the controllable filter of the application;

[0019] Figure 5 is the S 11 Parameter curve change characteristic with the dielectric constant of the ferroelectric film;

[0020] Figure 6 is the S 21 Parameter curve change characteristic with the dielectric constant of the ferroelectric film;

[0021] Figure 7 is the schematic diagram of the interdigital electrode of the application and the equivalent circuit diagram;

[0022] Figure 8 Electric field distribution diagram in the normal direction of the controllable filter of the present invention when er=600 and operating frequency 8GHz.

[0023] Figure 9 The electric field distribution diagram in the normal direction of the controllable filter of the present invention when er=600 and the operating frequency is 16GHz.

[0024] Reference numerals: 1-Dielectric substrate, 2-Metallic microstrip, 21-Artificial plasmon segment, 22-Transition segment, 23-Coplanar waveguide segment, 3-Metallic ground, 4-Circular arc groove, 5-Variable ferroelectric dielectric resonator assembly, 51-Cylindrical resonator substrate, 52-Ferroelectric film. Detailed Implementation

[0025] Example 1. A controllable filter based on a variable ferroelectric resonator, configured as follows: Figures 1-6 As shown, the device includes a dielectric substrate 1, a metal microstrip 2 on the surface of the dielectric substrate 1, an artificial plasmon segment 21 in the middle of the metal microstrip 2, and two ends of the artificial plasmon segment 21 connected to a coplanar waveguide segment 23 via transition segments 22. The metal microstrip 2 has a gradient metal ground 3 on both sides of the connection area between the transition segment 22 and the coplanar waveguide segment 23, with the gradient equations being exponential equations X(t)=L1+L2*t, y(t)=h+g+(whg)*(exp(a*t)-1)(exp(a)-1), (0≤t≤1), where parameter a=8. The metal microstrip 2 extends gradually from the middle to both ends until the position where the transition segment connects to the coplanar waveguide segment, and symmetrically distributed arc-shaped grooves 4 are formed by three curve segments, which are: the first arc segment parameter equation X(t)... The parametric equations for the second arc segment are: X(t) = d + d1 * cost, Y(t) = h - ch / 2 + ch / 2 * sint (π / 2 ≤ t ≤ 3π / 2); X(t) = d + d1 * cost, Y(t) = h - ch / 2 + ch / 2 * sint (π / 2 ≤ t ≤ 3π / 2); X(t) = d + d1 * cost, Y(t) = h - ch / 2 + ch / 2 * sint (-π / 2 ≤ t ≤ -acos(d / ch)), where parameter d is 2.2, parameter d1 is 1.7, and the groove depth ch is 3mm; the half-width h of the metal microstrip 2 is 3.2mm; the arc-shaped groove 4 in the middle of the metal microstrip 2 is also connected to the variable ferroelectric resonator assembly 5.

[0026] The aforementioned variable ferroelectric resonator assembly 5 includes a cylindrical resonator substrate 51, the top of which is covered with a ferroelectric film 52; the bottom of the cylindrical resonator substrate 51 is connected to the arc-shaped groove 4 in the middle of the metal microstrip 2.

[0027] The aforementioned ferroelectric film 52 is actually pressurized through an interdigital electrode, see [link to documentation]. Figure 6 .

[0028] The aforementioned cylindrical resonator substrate 51 is made of lanthanum aluminate single crystal (LaAlO3).

[0029] The gap f between the two symmetrically distributed circular arc grooves 4 at the bottom of the aforementioned cylindrical resonator substrate 51 is 0.1 mm.

[0030] The depth ch of the aforementioned circular arc groove is 3 mm; the half width h of the metal microstrip 2 is 3.2 mm.

[0031] The coupling gap g between the aforementioned coplanar waveguide section 23 and the metal ground 3 is 0.14 mm.

[0032] The thickness u of the aforementioned cylindrical resonator substrate 51 is 0.5 mm, and the thickness i of the ferroelectric film 52 is 0.036 mm.

[0033] The aforementioned variable ferroelectric medium resonator assembly adjusts its dielectric constant by an applied voltage.

[0034] Specifically, the controllable filter according to the present application is further described below with the parameters in Table 1.

[0035] Table 1

[0036]

[0037]

[0038] The medium plate of the controllable filter uses Rogers RT5880 substrate with a dielectric constant of 2.2, and the variable ferroelectric medium resonator assembly 5 is made of lanthanum aluminate single crystal (LaAlO3) used in the cylindrical resonator substrate 51, and a ferroelectric film 52, and the remaining metal materials are all copper Cu. The dielectric constant of the ferroelectric film 52 can be changed by applying a voltage to the interdigital electrode (equivalent to a metal microstrip), and the resonator in its circuit is equivalent to a variable capacitor, which can change the capacitance value by changing the dielectric constant (ε r = f(V)). Figure 7 The scattering characteristics under different dielectric constants can be obtained in this way (as shown in Figure 4 and 5 ). Figure 5 S 11 is the return loss, that is, how much energy is reflected back to the source. By optimizing the dielectric constant of the resonator, the energy reflected back can be reduced, and the effect is obvious at 8 GHz. Figure 6 S 21For insertion loss, it shows how much energy is transmitted, by adjusting the dielectric constant of the resonator, the frequency band of the filter can be effectively controlled, increasing the dielectric constant of the resonator can make the frequency band decrease, and the transmitted energy increases, the effect is obvious at 8GHz, the electric field distribution diagram in the normal direction when working is shown in Figure 8 It can be seen that the electromagnetic energy passes through the entire waveguide structure smoothly, and at 16GHz, the electromagnetic energy is blocked. Thus, through a controllable filter based on a ferroelectric medium resonator, the problem of the fixed working frequency spectrum structure of the traditional SSPPs filter after the geometric structure design and processing is completed, which cannot be dynamically and real-time controlled, cannot adapt to the needs of complex electromagnetic environment, so as to realize flexible control of the frequency band of the filter. Moreover, the reflection problem caused by the sudden change of the waveguide structure can also be solved by optimizing the waveguide circuit structure. Figure 1 The dispersion curves of the two unit structures of the left and right circular arcs can be seen that the wave vectors, impedance of the two unit structures are consistent, and the microwave energy field is also similar, so the left and right unit structures are linked together, and the energy reflection of the entire controllable filter is relatively low.

Claims

1. A variable ferroelectric dielectric resonator based controllable filter, characterized by, The application relates to a medium plate (1), wherein a metal microstrip (2) is arranged on the surface of the medium plate (1), the middle part of the metal microstrip (2) is an artificial plasmon section (21), the two ends of the artificial plasmon section (21) are connected with coplanar waveguide sections (23) through transition sections (22), the metal microstrip (2) is provided with gradually-changing metal ground (3) on the two sides of the connection area of the transition sections (22) and the coplanar waveguide sections (23), the metal microstrip (2) is provided with symmetrical circular-arc grooves (4) extending from the middle part to the two ends until the position where the transition sections and the coplanar waveguide sections are connected, and the circular-arc grooves (4) in the middle part of the metal microstrip (2) are connected with variable ferroelectric medium resonator assemblies (5); The variable ferroelectric medium resonator assembly (5) comprises a cylindrical resonator base (51), and the top of the cylindrical resonator base (51) is covered with a ferroelectric film (52); the bottom of the cylindrical resonator base (51) is connected with the circular-arc grooves (4) in the middle part of the metal microstrip (2); The surface layer of the ferroelectric film (52) is attached with a layer of interdigital electrode for applying bias voltage in actual work; The cylindrical resonator base (51) is composed of lanthanum aluminate single crystal; The gap f between the two symmetrical circular-arc grooves (4) at the bottom of the cylindrical resonator base (51) is 0.1 mm; the circular-arc groove (4) is composed of three curve sections, namely, the first curve section with the parameter equation X(t)=d+ch / 2*cost, Y(t)=h-ch / 2+ch / 2*sint, pi / 2<=t<=3pi / 2; the second curve section with the parameter equation X(t)=d+d1*cost, Y(t)=h-ch / 2+ch / 2*sint, pi / 2<=t<=3pi / 2; and the third curve section with the parameter equation X(t)=d+ch / 2*cost, Y(t)=h-ch / 2+ch / 2*sint, -pi / 2<=t<=-acos(d / ch), wherein the parameter d is 2.2, the parameter d1 is 1.7, the depth ch of the groove is 3 mm, and the half width h of the metal microstrip (2) is 3.2 mm; The coupling gap g between the coplanar waveguide section (23) and the metal ground (3) is 0.14 mm; The thickness u of the cylindrical resonator base (51) is 0.5 mm, and the thickness i of the ferroelectric film (52) is 0.036 mm.

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