CN108183294A - Broadband dual-mode bandpass filter based on line of rabbet joint resonator - Google Patents

Abstract

The invention discloses a wideband dual-mode bandpass filter based on a slot line resonator, which includes a dielectric substrate and a metal layer located on the upper layer of the dielectric substrate; the metal layer includes a rectangular ring resonator and two input/output ports, and the rectangular ring The rectangular resonator is a slot line etched on the metal layer, and the center of the rectangular ring resonator coincides with the center of the metal layer; the two input/output ports adopt the CPW orthogonal feeding method, and are respectively arranged on the adjacent two sides of the rectangular slot line ring resonator midpoint position. The CPW orthogonal feeding method of the present invention produces two transmission poles in the passband, and produces a transmission zero at the low cutoff frequency and the high cutoff frequency, which effectively improves the passband selection performance of the filter; the wideband filter The design of the device is simple, the structure is compact, the processing is convenient, the passband performance is stable, and the passband selectivity is good.

Description

Wideband dual-mode bandpass filter based on slot line resonator

technical field

The invention relates to wideband filter technology, in particular to a wideband dual-mode bandpass filter based on slot line resonators.

Background technique

With the rapid development of modern communication technology and microwave radio frequency applications, people have higher and higher expectations for wireless communication equipment: it is required to further improve integration and reduce costs while ensuring the performance of communication systems. Microwave transmission line is the basis of realizing microwave devices, and its size and performance directly affect the size and performance of components. Traditional microwave transmission lines mainly include coaxial lines, waveguides, and striplines. Among them, striplines represented by microstrip lines have become mainstream transmission lines due to their simple structure and easy integration. However, after years of development, the potential of using microstrip lines to further improve devices has become smaller and smaller. Different from the conventional microstrip line, the slot line is a slot etched on the upper metal layer of the dielectric board, and it is a transmission line that can be integrated planarly. Compared with the microstrip line, the slot line has the following advantages:

(1) On the same substrate, compared with the traditional stripline structure, the slot line with the same characteristic impedance is easier to process.

(2) The metal surface that can be integrated in the structure has good integrability.

(3) The slot line structure formed by etching on the metal ground plate can effectively improve the circuit performance without increasing the plane size.

As a single-plane transmission structure, slotlines have attracted more and more attention due to their coplanarity and special electrical properties. The planar slot line structure not only has the characteristics of easy manufacture without drilling, but also has lower radiation and resistance loss. Therefore, compared with the microstrip line resonator, the slot line resonator designed based on the planar slot line structure has a higher quality factor under the same size. The structure of the slot line itself is similar to that of the CPW transmission line, and it is also easy to connect with the CPW transmission line to form a feed structure.

In 2008, Professor Zhang Xiuyin of City University of Hong Kong proposed a filter based on slot line resonators in the paper "Uniplanar Bandpass Filter Using Slotline Resonators and CPW Feeding Lines", which includes two coupled open-loop slot line resonators and uses two CPW transmission lines The resonator is fed, and the filter is coupled through two open loops, but the final effect bandwidth is not wide enough and the structure is relatively complicated.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings and deficiencies in the prior art, and provide a wideband dual-mode bandpass filter based on slot line resonators.

The technical solution for realizing the object of the present invention is: a wideband dual-mode bandpass filter based on a slot line resonator, including a dielectric substrate and a metal layer located on the upper layer of the dielectric substrate;

The metal layer includes a rectangular ring resonator and two input/output ports, the rectangular ring resonator is a groove line etched on the metal layer, and the center of the rectangular ring resonator coincides with the center of the metal layer; the two input/output ports are the first input/output port and the second input/output port respectively, one of which is used as an input port and the other is an output port;

The first input/output port and the second input/output port adopt the CPW orthogonal feeding method, and are respectively arranged at midpoints of two adjacent sides of the rectangular slot line ring resonator.

Compared with the prior art, the present invention has the following advantages: (1) the present invention adopts CPW quadrature at the midpoint position of the adjacent two sides of the rectangular groove line ring resonator by etching the rectangular groove line on the metal layer of the upper layer of the dielectric plate. Feed mode, design a broadband filter with stable passband performance, good passband selectivity, and simple structure. This broadband filter is especially suitable for broadband wireless communication systems with international high standards; (2) the present invention uses CPW positive The cross-feed rectangular slot line ring resonator structure makes the present invention have a wider bandwidth, which can reach a relative bandwidth of 22.5%, and the absolute bandwidth reaches 684MHz (@3.0GHz); (3) the CPW transmission line adopted in the present invention is orthogonal Feed mode can respectively produce a transmission zero point on the upper and lower sides of the passband, which improves the selectivity of the passband; (4) the broadband filter in the present invention has fully utilized the space of the groove line on the metal plate, effectively The volume of the device is reduced, the topology is simple, the circuit model is compact, and the space utilization rate is high.

Description of drawings

FIG. 1 is a schematic structural diagram of a wideband dual-mode bandpass filter of the present invention.

Fig. 2 is a schematic diagram of the upper metal structure of the broadband dual-mode bandpass filter of the present invention.

Fig. 3 is a schematic diagram of the frequency response of the broadband dual-mode bandpass filter of the present invention.

Detailed ways

The structural representation of the wideband dual-mode bandpass filter of the present invention is as shown in Figure 1, the passband characteristic of this wideband dualmode bandpass filter is stable, the passband selectivity is good, and this wideband filter consists of a dielectric substrate, located on the upper layer of the dielectric plate composed of metal layers.

Referring to FIG. 2, the metal layer 4 includes a rectangular ring resonator and an input/output port. The rectangular ring resonator is a rectangular ring groove line etched on the metal layer, and the center of the rectangular ring resonator coincides with the center of the metal layer; There are two input/output ports, namely the first input/output port and the second input/output port, one of which is used as an input port and the other is an output port;

The first input/output port and the second input/output port adopt the CPW orthogonal feeding method, and are respectively arranged at midpoints of two adjacent sides of the rectangular slot line ring resonator.

The first input/output port and the second input/output port separate the rectangular slot line ring resonator into a first slot line 3 and a second slot line 5;

The first input/output port includes the first CPW transmission line 1, and the second input/output port includes the second CPW transmission line 2; the position of the first CPW transmission line 1 and the second CPW transmission line 2 are orthogonal, and the first CPW transmission line 1 and the second CPW transmission line The outer periphery of the CPW transmission line 2 is respectively etched with a third slot line and a fourth slot line; the third slot line communicates with one end of the first slot line 3 and the second slot line 5 respectively, and the fourth slot line communicates with the first slot line 3 and the second slot line 5 respectively. The other end of the second groove line 5 is connected.

Take the center origin of the metal layer horizontally to the right as 0°, rotate counterclockwise, the first CPW transmission line 1 is in the direction of 180°, the second CPW transmission line 2 is in the direction of 270°, the first CPW transmission line 1 and the second CPW transmission line 2 embedded in the rectangular slot line ring resonator;

The depth of the first CPW transmission line 1 and the second CPW transmission line 2 embedded in the slot line of the rectangular slot line ring resonator accounts for one sixth to one third of the side length of the rectangular ring resonator.

The first CPW transmission line 1 and the second CPW transmission line 2 have the same length and the same width, and are not in contact with each other.

The width of the first groove line to the fourth groove line is 0.3-0.5 mm.

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

Example

The structure of the wideband dual-mode bandpass filter based on the slot line resonator in this embodiment is shown in Figure 1. The intermediate layer dielectric plate is Rogers RT/droid 6010/6010LM(tm), the thickness is 0.635mm, and the relative permittivity is 10.2, the loss tangent is 0.0023. Use the 3D electromagnetic simulation software HFSS based on the finite element method to optimize the structure of the wideband dual-mode bandpass filter based on the slot line resonator proposed by the present invention, and finally obtain the dimensions of the slot line on the filter metal plate and the CPW transmission line The parameters are as follows: the length and width of the rectangular dielectric plate are both equal to 30mm; the width of the rectangular slot line ring resonator engraved on the upper metal layer 4 of the dielectric plate is W2=0.4mm; the width of the first CPW transmission line 1 and the second CPW transmission line 2 is W1=1.2mm; the lengths of the first CPW transmission line 1 and the second CPW transmission line 2 are both L3=12.8mm; the length of the first slot line 3 is L1=29.8mm, and the length of the second slot line 5 is L2=8.6mm; The depth of two CPW transmission lines inserted into the rectangular annular slot is L4=3.5mm; the width of the slot and the insertion depth of the CPW transmission line are reasonably selected to obtain optimal in-band transmission characteristics and band selectivity.

FIG. 3 is a graph of simulation results of bandwidth S parameters of the slot line resonator-based wideband dual-mode bandpass filter in this embodiment. As can be seen from Fig. 3, the wideband dual-mode bandpass filter of the present invention has an operating frequency band of 1GHz to 5GHz, a central operating frequency at 3.14GHz, an absolute operating bandwidth of 684MHz, and a 3dB relative bandwidth of 22.5%. The insertion loss is kept within 0.5dB, and the return loss is kept below -10dB. There is a transmission zero at the upper side of the passband at 2.57GHz and at the lower side of 4.32GHz, so the attenuation slope of the low cutoff edge of the passband is 264.5dB/GHz, and the attenuation slope of the high cutoff edge is 54.8dB/GHz, which has a good passband With optional performance.

While meeting the requirements of broadband wireless communication frequency band, the present invention has wider working bandwidth, smaller insertion loss, better passband performance and higher passband selectivity.

Claims (6)

1. a kind of broadband dual-mode bandpass filter based on line of rabbet joint resonator, which is characterized in that including medium substrate and positioned at Jie The metal layer on matter substrate upper strata；

The metal layer includes rectangular ring resonator and two input/output end ports, and rectangular ring resonator is on metal layer The line of rabbet joint of etching, rectangular ring resonator central are overlapped with metal layer center；Two input/output end ports are respectively first defeated Enter/output port and the second input/output end port, as input port, another is output port for one of them；

First input/output end port, the second input/output end port are separately positioned on rectangle using CPW orthogonal feed modes The point midway on the adjacent both sides of line of rabbet joint ring resonator.

2. the broadband dual-mode bandpass filter according to claim 1 based on line of rabbet joint resonator, which is characterized in that first is defeated Enter/rectangular ring resonator is divided into first line of rabbet joint (3) and second line of rabbet joint (5) by output port, the second input/output end port；

First input/output end port includes the first CPW transmission lines (1), and the second input/output end port includes the 2nd CPW transmission lines (2)；First CPW transmission lines (1) and the 2nd CPW transmission lines (2) position are orthogonal, and the first CPW transmission lines (1) and the 2nd CPW are passed Defeated line (2) periphery is etched with the third line of rabbet joint and the 4th line of rabbet joint respectively；The third line of rabbet joint respectively with first line of rabbet joint (3) and second line of rabbet joint (5) one end connection, the other end of the 4th line of rabbet joint respectively with first line of rabbet joint (3) and second line of rabbet joint (5) connect.

3. the broadband dual-mode bandpass filter according to claim 2 based on line of rabbet joint resonator, which is characterized in that first In one end of CPW transmission lines (1) and the 2nd CPW transmission lines (2) insertion rectangular channel wire loop resonator, embedded depth accounts for straight-flanked ring / to three/6ths of the shape resonator length of side.

4. the broadband dual-mode bandpass filter according to claim 3 based on line of rabbet joint resonator, which is characterized in that first CPW transmission lines (1) are identical and of same size with the length of the 2nd CPW transmission lines (2).

5. the broadband dual-mode bandpass filter according to claim 4 based on line of rabbet joint resonator, which is characterized in that first CPW transmission lines (1) and the 2nd CPW transmission lines (2) are not in contact with each other.

6. the broadband dual-mode bandpass filter based on line of rabbet joint resonator according to claim 2-5 any one, feature It is, the width of the line of rabbet joint of first line of rabbet joint~the 4th is 0.3~0.5mm.