CN203983428U - A kind of microstrip filter based on electromagnetism hybrid coupled - Google Patents

Abstract

The utility model discloses a microstrip filter based on electromagnetic hybrid coupling, which comprises a microstrip plate, and also includes a grounded metallized through hole arranged on the microstrip plate, a first resonator, a second resonator, a third Resonator, input port feeder and output port feeder, one end of the first, second and third resonator is connected to the metallized through hole, the first resonator and the third resonator are symmetrical with the second resonator as the center line It is set that the input port feeder and the output port feeder are arranged symmetrically outside the first resonator and the third resonator respectively. The microstrip filter of the utility model can adjust the intensity of magnetic coupling and electric coupling, and furthermore, can flexibly control the bandwidth of the filter, and has small volume.

Description

A Microstrip Filter Based on Electromagnetic Hybrid Coupling

technical field

The utility model relates to a microwave filter, in particular to a microstrip filter based on electromagnetic hybrid coupling.

Background technique

In recent years, the rapid development of wireless communication, the popularity of 3G technology, and the arrival of 4G all indicate that wireless technology will usher in a peak period of vigorous development. At the same time, with the popularity of wireless electronic products in people's lives, miniaturization and low cost have become the trend of electronic products. On the other hand, with the rapid development of electronic information, the increasingly scarce spectrum resources are becoming more and more scarce. In order to improve the communication capacity and reduce the signal crosstalk between adjacent channels, higher requirements are put forward for the selectivity and integration of filters. The microstrip filter meets these requirements.

As an important device in the microwave communication system, the microstrip filter has been widely used in commercial and military fields due to its miniaturized structure and high performance. For example, microwave filters are used for mobile communications, satellite communications , radar, electronic warfare, and long-distance remote sensing.

In the prior art, in July 2009, Chu Qingxin and Wang Huan applied to disclose the patent of "Controllable Electromagnetic Coupling Microstrip Split Ring Resonator Filter", which uses a microstrip split ring resonator, but the electrical coupling and magnetic coupling are intertwined, not independent.

In May 2012, Ouyang Xiao of South China University of Technology published a master's degree thesis entitled "Research on Hybrid Electromagnetic Coupling Filters", using a hybrid electromagnetic coupling split-loop filter, in which the electrical coupling and magnetic coupling cannot be adjusted independently.

Therefore, there is a need to design a new microstrip filter with controllable electrical coupling and magnetic coupling.

Utility model content

The purpose of the utility model is to overcome the shortcomings and deficiencies of the prior art, and provide a microstrip filter based on electromagnetic hybrid coupling, which has the characteristics of flexible design, small size, low cost and good characteristics, and by introducing controllable Electric coupling and magnetic coupling can flexibly control the bandwidth, and can adjust the filter bandwidth in a large range.

The purpose of this utility model is achieved through the following technical solutions:

A microstrip filter based on electromagnetic hybrid coupling, including a microstrip plate, and also includes a grounded metallized through hole arranged on the microstrip plate, a first resonator, a second resonator, a third resonator, and an input port Feed line and output port feed line, one end of the first, second, and third resonators is connected to the metallized through hole, the first resonator and the third resonator are arranged symmetrically with the second resonator as the center line, and the input port feed line and the output port feeder are arranged symmetrically outside the first resonator and the third resonator respectively.

The first resonator, the second resonator, and the third resonator are quarter-wavelength short-circuit resonators, and the input port of the input port feeder and the output port of the output port feeder are respectively located in the first resonator, the third resonator A quarter of the resonator length near the open end of the resonator.

The open end of the second resonator is formed by parallel connection of two sections of transmission lines. The size of the second resonator can be shortened.

The open-circuit ends of the first resonator and the third resonator, and the ports of the input port feeder and the output port feeder are all folded into an L shape. The volume of the microstrip filter can be reduced.

The ports of the feeder for the input port and the feeder for the output port are all matched impedances of 50 ohms.

The microstrip board is a double-sided copper-clad microstrip board, the microstrip filter is fabricated on one side of the microstrip board in the form of a printed circuit board, and the other side of the microstrip board is grounded.

The metallized through hole is connected to the grounding side of the microstrip board through soldering tin.

Compared with the prior art, the utility model has the following advantages and beneficial effects:

1. The external quality factor of the microstrip filter can be adjusted by changing the length of the input port feeder, the output port feeder, and the coupling between the feeder and the resonator.

2. The three quarter resonators share a ground via (that is, a metallized via). Changing the size of the via can effectively control the strength of the magnetic coupling, thereby controlling the filter bandwidth; the first resonator and the second resonator There is electrical coupling between the open-circuit ends of the resonators, and between the open-circuit ends of the third resonator and the second resonator, and adjusting the gap between them can effectively control the electrical coupling. Adjusting the strength of magnetic coupling and electrical coupling can flexibly control the bandwidth of the filter.

3. The utility model introduces an independently controllable electrical coupling at the open end of the resonator, and the electrical coupling and magnetic coupling can cancel each other out. This structure is very suitable for designing a narrowband bandpass filter.

4. Since the filter has a microstrip structure, it is small in size, light in weight, low in cost, and suitable for industrial mass production, so the filter has the advantages of simple structure and low production cost.

Description of drawings

Fig. 1 is a structural representation of a microstrip filter based on electromagnetic hybrid coupling described in the utility model;

Fig. 2 is the structural parameter annotation figure of microstrip filter described in Fig. 1;

Fig. 3 is the microstrip filter described in Fig. 1 in the return loss simulation result figure of different through-hole diameters;

Fig. 4 is the insertion loss simulation result diagram of the microstrip filter described in Fig. 1 under different through-hole diameters;

Fig. 5 is a diagram of the simulation results of diameter return loss of the microstrip filter described in Fig. 1 under different coupling gaps;

FIG. 6 is a diagram showing the insertion loss simulation results of the microstrip filter shown in FIG. 1 under different coupling gaps.

Detailed ways

The utility model will be further described in detail below in conjunction with the embodiments and accompanying drawings, but the implementation of the utility model is not limited thereto.

As shown in Figures 1 and 2, a microstrip filter based on electromagnetic hybrid coupling includes a microstrip plate 1, and also includes a grounded metallized through hole 3, a first resonator 4, and a second resonator 4 disposed on the microstrip plate 1. Resonator 5, third resonator 6, input port feeder 10 and output port feeder 2, one end of the first, second, third resonator is connected with metallized through hole 3, first resonator 4, third resonator The resonator 6 is symmetrically arranged with the second resonator 5 as the center line, and the input port feeder 10 and the output port feeder 2 are respectively symmetrically arranged outside the first resonator 4 and the third resonator 6;

The first resonator 4, the second resonator 5, and the third resonator 6 are quarter-wavelength short-circuit resonators, and the input port of the input port feeder 10 and the output port of the output port feeder 2 are respectively located at the first resonance 4 and the third resonator 6 are close to a quarter of the length of the resonator at the open end;

The open end of the second resonator 5 is formed by parallel connection of two sections of transmission lines 7 and 8, and there is a gap 9 between the transmission lines 7 and 8 at both ends and the first resonator 4 and the third resonator 6;

The open ends of the first resonator 4 and the third resonator 6, as well as the ports of the input port feeder 10 and the output port feeder 2 are all folded into an L shape;

The ports of the input port feeder and the output port feeder are 50 ohm matching impedance;

The microstrip board 1 is a double-sided copper-clad microstrip board, and the microstrip filter is fabricated on one side of the microstrip board 1 in the form of a printed circuit board, and the other side of the microstrip board is grounded;

The metallized through hole 3 is connected to the grounded side of the microstrip board 1 through solder.

Use three-dimensional simulation software ZELAND IE3D to simulate the filter, the relative dielectric constant of the microstrip substrate used in the filter designed by the utility model is 2.55, and the medium height is 0.8, as shown in Figure 2, the main structural parameters of the filter are: L2 =13.05mm, L3=2.50mm, L4=1.15mm, W1=1mm, W2=0.15mm. In addition, L1 is the length of the input port feeder, L5 is the length of the third resonator, L6 is the length of the transmission line 8, S1 is the gap between the input port feeder and the first resonator, S2 is the gap between the transmission line 7 and the first resonator, W3 is the width of the output port feeder, and D is the diameter of the metallized through hole.

Figure 3 and Figure 4 show the simulation results of the scattering parameters of the filter under different hole diameters, and Figure 3 shows the simulation results of the return loss of the microstrip filter at different hole diameters, the center frequency is 3GHz, and the horizontal axis represents the actual The signal frequency of the new microstrip filter, the vertical axis represents the return loss of the filter (S11), and the return loss represents the relationship between the input power of the port signal and the reflected power of the signal. The corresponding mathematical function is as follows: Reflected power/incident power==20*log|S11|. Figure 4 shows the simulation results of the insertion loss (S21) of the microstrip filter under different hole diameters. The insertion loss represents the relationship between the input power of a signal and the output power of another port signal. The corresponding mathematical function is: output Power/input power (dB) = 20*log|S21|.

It can be seen from Figure 3 and Figure 4 that: increasing the radius D of the through hole, the magnetic coupling between the resonators becomes smaller, and the filter bandwidth becomes narrower.

Figures 5 and 6 show the simulation results of the scattering parameters of the (S2) filter under different coupling gaps, and its center frequency is 3GHz. Figure 5 is the simulation result of return loss, and Figure 6 is the simulation result of insertion loss. From Figure 5 and Figure 6, it can be seen that reducing the coupling gap S2 will increase the electrical coupling between resonators, which can offset part of the magnetic coupling, and the filter bandwidth will become larger. narrow.

The above-mentioned embodiment is a preferred implementation mode of the present utility model, but the implementation mode of the present utility model is not limited by the above-mentioned embodiment, and any other changes, modifications and substitutions made without departing from the spirit and principle of the present utility model , combination, and simplification, all should be equivalent replacement methods, and are all included in the protection scope of the present utility model.

Claims (7)

1. the microstrip filter based on electromagnetism hybrid coupled, comprise micro-band plate, it is characterized in that: also comprise the plated-through hole, the first resonator, the second resonator, the 3rd resonator, input port feeder line and the output port feeder line that are arranged on the ground connection on micro-band plate, one end of described first, second, third resonator is connected with plated-through hole, the first resonator, the 3rd resonator line centered by the second resonator are symmetrical arranged, and input port feeder line, output port feeder line are symmetricly set on respectively the outside of the first resonator, the 3rd resonator.

2. the microstrip filter based on electromagnetism hybrid coupled according to claim 1, it is characterized in that: described the first resonator, the second resonator, the 3rd resonator are quarter-wave short circuit resonator, the output port of the input port of input port feeder line and output port feeder line lays respectively at the first resonator, the 3rd resonator 1/4th resonator length places near open end.

3. the microstrip filter based on electromagnetism hybrid coupled according to claim 1, is characterized in that: the open end of the second described resonator is formed in parallel by two sections of transmission lines.

4. the microstrip filter based on electromagnetism hybrid coupled according to claim 1, is characterized in that: the first described resonator, the open end of the 3rd resonator, and the port of input port feeder line, output port feeder line is all folded into L shaped.

5. the microstrip filter based on electromagnetism hybrid coupled according to claim 1, is characterized in that: described input port feeder line, the port of output port feeder line are the matched impedance of 50 ohm.

6. the microstrip filter based on electromagnetism hybrid coupled according to claim 1, it is characterized in that: described micro-band plate is the micro-band plate of double-sided copper-clad, described microstrip filter is produced on the one side of micro-band plate in the mode of printed circuit board (PCB), the another side ground connection of micro-band plate.

7. the microstrip filter based on electromagnetism hybrid coupled according to claim 6, is characterized in that: described plated-through hole is connected with micro-one side with plate earthing by scolding tin.