CN103972623B - A kind of waveguide filter based on electromagnetic induced transparency - Google Patents

Abstract

The invention discloses a waveguide filter based on electromagnetic induction transparency. Input ports and signal output ports, the metal microstrip structure on the front of the dielectric substrate has a rectangular metal ring, an out-of-band suppression sheet, two rows of metallized through holes and grounding extension strips, and the metal microstrip structure on the back of the dielectric substrate has two symmetrical C-shaped resonant structure and grounded epitaxy. The rectangular metal ring on the front of the dielectric substrate and the two symmetrical C-shaped resonant structures on the back of the dielectric substrate interact to produce two passbands of the inductive transparent window and the magnetic inductive transparent window, that is, the electromagnetic induction transparent effect is formed. The waveguide filter has a transmission zero in the upper and lower sidebands of the passband, has high selectivity, and is compact and easy to design.

Description

A waveguide filter based on electromagnetic induction transparency

technical field

The invention relates to microwave and millimeter wave filter design technology, in particular to a new method for waveguide filter design.

Background technique

Waveguide filters have been widely used in many microwave and millimeter wave systems due to their small loss and large power capacity. There are various implementation techniques such as direct coupled resonators, evanescent mode waveguide filters, multimode waveguide filters, and E-plane waveguide filters. Among them, the direct coupling resonant cavity design method has flexible design, good square coefficient and low loss, but its processing is more complicated, the cost is high, and it is not easy to carry out mass production. The E-plane waveguide filter is simple to process, low in cost, suitable for mass production, and more flexible in design, but the traditional E-plane waveguide filter must be multi-staged in order to obtain excellent filter performance, which inevitably causes The overall size of the filter is larger. Of course, researchers have also made necessary improvements, including the insertion of double diaphragms on the E-plane (see F. Arndt, J. Bornemann, R. Vahldieck, et al. E-plane Integrated Circuit Filters with Improved Stopband Attenuation (short Papers )[J].Microwave Theory and Techniques,IEEE Transactionson,1984,32(10),1391-1394.) Although the stopband characteristics of its filter have been improved, this kind of filter still needs to be cascaded in multiple stages, and the volume is still relatively bigger. In addition, although domestic research progress is relatively backward, there are still some new research results. In 2009, Wu Weitao, Liang Changhong, Zhai Botao and Wen Haibin studied the E-plane filter loaded with periodic ridge waveguide (see Wu Weitao, Liang Changhong, Zhai Botao, etc. The E-plane filter loaded with periodic ridge waveguide [C], 2009 National Microwave and Millimeter Wave Conference, 2009, 51-52.) conducted research, the filter is based on the E-film sheet waveguide filter, and proposed a high A selective filter implementation scheme combines the waveguide and the ridge waveguide inserted with the E-mask sheet filter, and embeds a periodic ridge waveguide structure in the middle of the half-wave resonator of the E-mask sheet filter. The E-plane waveguide filter overcomes the shortcomings of traditional filters, and has the characteristics of fast out-of-band attenuation and smaller size than traditional E-plane waveguide filters. cascade.

In the design of the E-plane waveguide filter, multi-level cascading is inevitably required to increase the volume, so it is necessary to study and design a new type of waveguide filter to achieve better performance with a smaller structural size. filtering performance.

The EIT (Electromagnetically induced transparency) effect is an important research point in quantum science. Usually, the transmittable passband of a signal generated by the transmission medium due to the characteristics of the electromagnetically induced transparency effect is very narrow. Many applications based on the EIT effect appear in the field of quantum science. In recent years, some scholars have studied that non-quantum structures such as lumped circuit components and split resonant rings can be used to realize the EIT effect (see Guo Xiaoying, Yang Jing, Li Jian, et al. Experimental research on electromagnetic induction-like transparency in RLC circuits[J ]. Shanxi University Journal (Natural Science Edition), 2012(1): 68-74.).

Since the EIT effect can produce a transparent passband characteristic, it is conceivable that a bandpass filter can be designed using this electromagnetically induced transparent EIT effect. Therefore, the present invention will use the EIT effect to design a novel E-plane waveguide filter, which has the advantages of high squareness coefficient, small loss, compact structure, and flexible design. This kind of electromagnetic induction transparency (EIT) effect in this field of quantum science is effectively applied to the design of waveguide filters in the millimeter wave band, which will enrich the concept of filter design, add new theories, and provide a certain degree for the design of filters and other devices. It has theoretical and practical guiding significance.

Contents of the invention

In order to improve the performance of the E-plane waveguide filter, multi-level cascading has been carried out in the existing research design, which inevitably caused relatively large defects. Therefore, it is necessary to invent a new type of E-plane waveguide filter. It overcomes the need for cascading, and achieves better filtering performance with a smaller structure size.

In order to achieve the above object, technical scheme of the present invention is:

A waveguide filter based on electromagnetic induction transparency, comprising an upper cavity (1) constituting a standard rectangular waveguide, a lower cavity, a dielectric substrate inserted between the upper cavity and the lower cavity of the standard rectangular waveguide, a signal input port and Signal output port; the metal microstrip structure on the front of the dielectric substrate has a rectangular metal ring, an out-of-band suppression sheet, two rows of metallized through holes and a grounding epitaxial strip, and the metal microstrip structure on the back of the dielectric substrate has two symmetrical C-shaped resonances structure and ground extension strip;

By adjusting the structural size of the rectangular metal ring and two symmetrical C-shaped resonant structures, they can generate a strong interaction in a certain frequency band and then generate two passband windows of the electric induction transparent window and the magnetic induction transparent window, that is, form the electromagnetic induction Transparency effect; the waveguide filter realized by using this effect has a transmission zero in the upper and lower sidebands of the passband. Its specific design is to reasonably design the size of the rectangular metal ring and the two symmetrical C-shaped resonant structures, so that the positions of the two passbands of the electric induction transparent window and the magnetic induction transparent window are adjusted, so that the two transparent passbands are close to and overlap , so as to form a band-pass filtering characteristic with excellent performance, and realize a waveguide filter based on the EIT concept. Since the electromagnetic induction transparent window is produced by electric resonance and magnetic resonance, the upper and lower sidebands of the transparent passband of the filter are respectively introduced. A transmission zero effectively improves the square coefficient of the waveguide filter;

The signal input port and output port are directly composed of standard rectangular waveguides, and the signal does not need to pass through any metal microstrip structure transition directly from the input port to the metal microstrip structure on the front and back of the dielectric substrate, and then output from the output port; the back of the dielectric substrate Two symmetrical C-shaped resonant structures, the length of the upper and lower arms of the C-shaped can be changed from 0mm, so that the position of the inductively induced transparent passband and the magnetically induced transparent passband can be flexibly adjusted and designed;

The out-of-band suppression sheet with a certain out-of-band suppression effect on the front of the dielectric substrate is directly connected to the upper and lower waveguide walls of the waveguide through the substrate epitaxial tape, and its width can be 0 mm; The grounded epitaxy structures are of the same size and are connected by two rows of metallized vias. It should be noted in the design that when the duty ratio of the rectangular metal ring is small, the out-of-band suppression sheet can be designed reasonably, which can improve the stop-band suppression performance of the electromagnetic induction transparent waveguide filter, and when the duty ratio of the rectangular metal ring is large When , the structure will be very small, and its improved performance is limited, so the structure can be removed for simplicity of design, that is, the width becomes 0.

The present invention adopts a standard metal rectangular waveguide with low loss, which is composed of upper and lower cavities and a dielectric substrate is inserted into its E surface, and the rectangular metal ring structure on the front of the dielectric substrate produces an eigenmode called a low-Q mode. The mode is generated by the coupling effect of the rectangular metal ring and the external input field, resulting in stronger absorption, that is, a wider stop band can be generated in the standard rectangular waveguide. At the same resonance frequency point, the greater the height of the rectangular metal ring The lower the quality factor, the lower the quality factor of the stop band should be selected in the design of the utility model. The two symmetrical C-shaped resonant structures on the back of the dielectric substrate interact with the rectangular metal ring on the front of the dielectric substrate to generate electrical resonance and magnetic resonance in the presence of an input field, which correspond to the inductively transparent transparent Pass band and magnetic induction transparent pass band, that is, the effect of electromagnetic induction transparency. In addition, since the essence of electromagnetic induction transparent pass band is the effect of electromagnetic resonance, according to the theory of electromagnetic resonance, there will be a lower sideband and The upper sideband of the magnetically induced transparent passband has a characteristic of zero points, and these two zero points have a very important influence on the design of waveguide filters with high squareness coefficients. Reasonably design a rectangular metal ring and two symmetrical C-shaped resonant structures, where the value of L of the upper and lower arm lengths of the two symmetrical C-shaped resonant structures can change from 0, and we can obtain a bandpass EIT waveguide filter that meets the requirements . In addition, in the design, we should pay special attention to make the inductive induction transparent passband be located in the lower sideband of the magnetic induction transparent passband, and adjust the structure size, so that the two originally separated electromagnetic induction transparent passbands can approach and overlap to form a more transparent passband. Broadband electromagnetic induction transparent passband. Finally, the out-of-band suppression sheet with a certain out-of-band suppression effect can be flexibly applied in the design. When the duty ratio of the rectangular metal ring is small, the out-of-band suppression sheet can be designed reasonably, which can improve the performance of the electromagnetic induction transparent waveguide filter. Stop band suppression performance, and when the duty ratio of the rectangular metal ring is large, the structure will be small, and its improved performance is limited, so the structure can be removed for simplicity of design, that is, the width becomes 0.

Advantage of the present invention and beneficial effect:

(1) The present invention adopts the waveguide filter design of electromagnetic induction transparency (EIT) concept design, which has excellent performances such as high square coefficient and miniaturization.

(2) The present invention adopts a rectangular ring, an out-of-band suppressing metal sheet and two symmetrical C-shaped resonant structures. The structure is simple, the design is flexible and convenient, and it is easy to design.

(3) The out-of-band suppression sheet directly connected to the waveguide wall used in the present invention has a certain optimization function of out-of-band suppression and is flexible in design.

(4) Compared with the traditional waveguide filter design method, the present invention adopts a new design concept, successfully applies the EIT effect to the waveguide filter design, and realizes a waveguide filter with excellent performance.

Description of drawings

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is a three-dimensional schematic diagram of the structure of the transparent waveguide filter based on electromagnetic induction provided by the present invention.

Fig. 2 is a schematic diagram of the front structure of the substrate of the waveguide filter based on electromagnetic induction transparency provided by the present invention.

Fig. 3 is a schematic diagram of the backside structure of the substrate of the waveguide filter based on electromagnetic induction transparency provided by the present invention.

Fig. 4 is a comparison diagram of simulation and test results of an example of a waveguide filter based on electromagnetic induction transparency provided by the present invention.

detailed description

As shown in Figure 1, Figure 2, and Figure 3, a waveguide filter based on electromagnetic induction transparency includes an upper cavity 1 and a lower cavity 2 that constitute a standard rectangular waveguide, and are inserted into the upper cavity 1 and the lower cavity of the standard rectangular waveguide. The dielectric substrate 3 between the chambers 2, the signal input port 4 and the signal output port 5; the metal microstrip structure on the front of the dielectric substrate 3 has a rectangular metal ring 31, an out-of-band suppression sheet 32, and two rows of metallized through holes 33 and a grounded epitaxial strip 34, the metal microstrip structure on the back of the dielectric substrate 3 has two symmetrical C-shaped resonant structures 35 and a grounded epitaxial strip 36;

The rectangular metal ring 31 on the front of the dielectric substrate 3 and the two symmetrical C-shaped resonant structures 35 on the back of the dielectric substrate 3 interact to generate two passbands of the electric resonance transparent window and the magnetic resonance transparent window, thereby forming an electromagnetic induction transparent effect; The waveguide filter realized by this effect has a transmission zero in the upper and lower sidebands of the passband;

By adjusting the structural dimensions of the rectangular metal ring 31 and the two symmetrical C-shaped resonant structures 35, they generate a strong interaction in a certain frequency band and then generate two passband windows of the electric induction transparent window and the magnetic induction transparent window, namely forming Electromagnetic induction transparency effect; the waveguide filter realized by using this effect has a transmission zero point in the upper and lower sidebands of the passband.

The signal input port 4 and output port 5 are directly composed of standard rectangular waveguides, the signal does not need to pass through any metal microstrip structure transition, and is directly applied to the metal microstrip structure on the front and back of the dielectric substrate 3 by the input port 4, and then output by the output port 5 ; Two symmetrical C-shaped resonant structures 35 on the back of the dielectric substrate 3, the length of the C-shaped upper and lower arms can be changed from 0mm;

The out-of-band suppression sheet 32 with a certain out-of-band suppression effect on the front of the dielectric substrate 3 is directly connected to the upper and lower waveguide walls of the waveguide via the substrate extension tape 34, and its width can be 0 mm; It has the same structural size as the ground extension strip 34 on the front surface of the dielectric substrate 3 , and is connected through two rows of metallized through holes 33 .

As an example, a waveguide filter based on electromagnetic induction transparency is designed, fabricated, and tested. The standard rectangular waveguide is WR-28 (7.112mm*3.556mm) working in the Ka band. The dielectric substrate selected in the simulation design is Rogers RT/duroid5880 with a dielectric constant of 2.2, a thickness of 0.254mm, and a loss tangent of 0.0009, where The dimensions of the circuit structure on the dielectric substrate are respectively, the height of the rectangular metal ring 31 is 3mm, the width is 2mm, the height of the symmetrical C-shaped resonant structure 35 on the back of the substrate is 3mm, and the distance between the outer edges of the symmetrical C-shaped resonant structure 35 is 2mm , the value of L and the width of the out-of-band suppression sheet are 0mm, and the width of all metal strips is 0.2mm. The test results show that the new waveguide filter designed with the electromagnetic induction transparency (EIT) effect has a high square coefficient, low loss, excellent out-of-band suppression, low processing cost, and is easy to mass-produce, and the waveguide filter The design is flexible and convenient. In addition, the error in simulation and actual measurement is mainly due to the fact that the dielectric constant of the substrate used in the experiment is not a constant of 2.2 in the Ka band, and its value is actually less than 2.2. In addition, due to factors such as processing accuracy and actual operation, The frequency of the test results is shifted to high frequency.

Claims (4)

1. A transparent waveguide filter based on electromagnetic induction, comprising an upper cavity (1) and a lower cavity (2) forming a standard rectangular waveguide, inserted into the upper cavity (1) and lower cavity (2) of a standard rectangular waveguide ) between the dielectric substrate (3), the signal input port (4) and the signal output port (5); it is characterized in that: the front and back sides of the dielectric substrate (3) also have a metal microstrip structure; the dielectric substrate (3) The metal microstrip structure on the front side of the dielectric substrate (3) includes a rectangular metal ring (31) located in the center of the front side of the dielectric substrate (3), and out-of-band suppression sheets ( 32), the front grounded epitaxial strip (34) directly connected to the out-of-band suppression sheet (32); the metal microstrip structure on the back of the dielectric substrate (3) includes a metal microstrip structure located in the center of the back of the dielectric substrate (3) and facing the rectangular metal ring Two symmetrical C-shaped resonant structures (35) and the backside grounded epitaxial strip (36) opposite to the position of the front grounded epitaxial strip (34); The contours of the left and right sides of the rectangular metal ring (31) coincide; the front grounding extension strip (34) and the back grounding extension strip (36) are directly connected through two rows of metallized through holes (33) running through the entire substrate. 2. A kind of waveguide filter based on electromagnetic induction transparency according to claim 1, characterized in that: by adjusting the structural dimensions of the rectangular metal ring (31) and two symmetrical C-shaped resonant structures (35), it is A strong interaction occurs in a certain frequency band to generate two passband windows of the electric induction transparent window and the magnetic induction transparent window, that is, the electromagnetic induction transparency effect is formed; the waveguide filter realized by using this effect has the upper and lower sidebands of the passband respectively There is a transmission zero. 3. A transparent waveguide filter based on electromagnetic induction according to claim 1, characterized in that: said signal input port (4) and output port (5) are directly formed by standard rectangular waveguides, and the signal does not need to go through any The metal microstrip structure transition is directly applied to the metal microstrip structure on the front and back of the dielectric substrate (3) by the input port (4), and then output by the output port (5); the two symmetrical C-shaped resonances on the back of the dielectric substrate (3) Structure (35), the upper and lower arm length of its C type can start to change from 0mm. 4. A kind of waveguide filter based on electromagnetic induction transparency according to claim 1, characterized in that: the out-of-band suppression sheet (32) with a certain out-of-band suppression effect on the front side of the dielectric substrate (3) is directly connected to the The front ground extension strip (34) is connected with the upper and lower waveguide walls of the standard rectangular waveguide.