CN204333186U - A hairpin cross-coupled bandpass filter - Google Patents

Abstract

The utility model discloses a kind of hair clip cross-coupling band pass filter, comprise and be spaced successively and be first of " U " shape, second, 3rd, 4th, 5th resonator, first resonator is connected with input, 5th resonator is connected with output, input comprises the first microstrip line connected successively, second microstrip line, 3rd microstrip line, the width that the width of the first microstrip line is greater than the second microstrip line is greater than the width of the 3rd microstrip line, output comprises the 4th microstrip line connected successively, 5th microstrip line, 6th microstrip line, the width that the width of the 4th microstrip line is less than the 5th microstrip line is less than the width of the 6th microstrip line, the base of the 5th resonator is connected with the 7th microstrip line.The utility model is on the basis that ensure that low insertion loss and low reflection loss, and reduce volume, compact conformation, size is less, is easy to integrated, reduces relative bandwidth, can effectively improve Out-of-band rejection performance in addition.

Description

A hairpin cross-coupled bandpass filter

technical field

The utility model belongs to the technical field of electronic communication, relates to a microwave filter, and more specifically relates to an improved hairpin cross-coupled bandpass filter.

Background technique

As a two-port microwave network, the microwave filter controls the working frequency band of the microwave system through its frequency selectivity. It is one of the most common components in systems such as radar, wireless communication, and microwave measurement. The performance of the communication system has a crucial impact. Divided by function, microwave filters can be divided into four types: low-pass, high-pass, band-pass, and band-stop. According to the type of components used, they can be divided into lumped parameter filters, microstrip filters, and crystal filters. Microstrip filters are widely used in engineering design because they are easy to integrate with other microwave circuits and realize the miniaturization of microwave systems.

Common microstrip bandpass filter structures include parallel coupling, hairpin, comb, and interdigitated. Existing filters have defects. For example, the parallel coupling line microwave filter has a large size because the parallel coupling nodes are cascaded in one direction; the comb line microwave filter needs to be grounded through holes, so that In some cases, errors will be introduced; if the interdigitated microwave filter analyzes the coupling between all resonators, the analysis will be very cumbersome, so in most cases, only the coupling between two resonators is considered. It is an approximate design, and the target can only be reached after a lot of work in the subsequent optimization process.

Contents of the invention

In order to solve the above problems, the utility model discloses an improved hairpin cross-coupled bandpass filter, which has a compact structure, is easy to integrate, and improves the out-of-band suppression performance without affecting the insertion loss and input and output standing wave coefficients.

In order to achieve the above object, the utility model provides the following technical solutions:

A hairpin cross-coupled bandpass filter, comprising a first resonator, a second resonator, a third resonator, a fourth resonator, and a fifth resonator arranged at intervals in sequence, and the five resonators are " U" shape, wherein the openings of the first resonator, the third resonator and the fifth resonator are upward, the openings of the second resonator and the fourth resonator are downward, and one resonant bar of the second resonator is located in the first resonator Between the two resonant bars of the fourth resonator, one resonant bar of the fourth resonator is located between the two resonant bars of the fifth resonator, the first resonator is connected to the input end, and the fifth resonator is connected to the output end connected, the input end includes a first microstrip line, a second microstrip line, and a third microstrip line connected in sequence, the width of the first microstrip line is greater than the width of the second microstrip line, and the width of the second microstrip line The width is greater than the width of the third microstrip line, and the output terminal includes the fourth microstrip line, the fifth microstrip line, and the sixth microstrip line connected in sequence, and the width of the fourth microstrip line is smaller than that of the fifth microstrip line Width, the width of the fifth microstrip line is smaller than the width of the sixth microstrip line, and the bottom edge of the fifth resonator is connected with the seventh microstrip line. the

Further, each resonator includes a bottom and two resonant strips vertically connected to the bottom, and the angle between the bottom and the outer edges of the two turning sections of the two resonant strips and the bottom is 45 degrees.

Specifically, the third microstrip line is connected to the first resonator, and the fourth microstrip line is connected to the fifth resonator.

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

On the basis of ensuring low insertion loss and low reflection loss, the hairpin cross-coupled bandpass filter provided by the utility model has the advantages of reduced volume, compact structure, small size and easy processing; These microstrip lines have different impedances due to their different widths, thereby reducing the relative bandwidth, and can effectively improve the out-of-band suppression performance.

Description of drawings

Fig. 1 is the structural representation of the hairpin cross-coupled bandpass filter provided by the utility model;

Fig. 2 is the S11 simulation result diagram of the hairpin cross-coupled filter;

Fig. 3 is the S21 simulation result diagram of the hairpin cross-coupled filter;

Figure 4 is a graph of the standing wave simulation results of the hairpin cross-coupling filter.

List of reference signs:

1-input terminal, 11-first microstrip line, 12-second microstrip line, 13-third microstrip line, 2-first resonator, 3-second resonator, 4-third resonator, 5-fourth resonator, 6-fifth resonator, 7-output, 71-fourth microstrip line, 72-fifth microstrip line, 73-sixth microstrip line, 8-seventh microstrip line , 9-turn segment.

Detailed ways

The utility model will be further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the utility model and are not intended to limit the scope of the utility model. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to the directions in the drawings, and the words "inner" and "outer ” refer to directions towards or away from the geometric center of a particular part, respectively.

As shown in Figure 1, a hairpin cross-coupled bandpass filter includes a first resonator 2, a second resonator 3, a third resonator 4, a fourth resonator 5, and a fifth resonator 6. Each resonator is U-shaped and arranged at intervals, wherein the first resonator 2, the third resonator 4, and the fifth resonator 6 open upward, and the second resonator 3 and fourth resonator 5 open downward. , wherein one resonant bar of the second resonator 3 is placed between two resonant bars of the first resonator 2, and one resonant bar of the fourth resonator 5 is placed between two resonant bars of the fifth resonator 6 . Through the above settings, the first resonator 2 and the second resonator 3 are hybrid coupling, the fourth resonator 5 and the fifth resonator 6 are hybrid coupling, the second resonator 3 and the third resonator 4, and the third resonator 4 and the fourth resonator 5 are magnetically coupled. The first resonator 2 is connected to the input terminal 1, and the fifth resonator 6 is connected to the output terminal 7. Both the input terminal 1 and the output terminal 7 are composed of three microstrip lines with different widths. Specifically, the input terminal 1 is composed of the first Microstrip line 11, the second microstrip line 12 and the third microstrip line 13, the input end 1 is connected to the third microstrip line 13, the first microstrip line 11, the second microstrip line 12 and the third microstrip line The width of the line 13 gradually decreases, that is, the width of the first microstrip line 11 is greater than the width of the second microstrip line 12, and the width of the second microstrip line is greater than the width of the third microstrip line. In this example, their width 1.12mm, 0.56mm, 0.16mm respectively, the output end is composed of the fourth microstrip line 71, the fifth microstrip line 72, the sixth microstrip line 73, the fourth microstrip line 71, the fifth microstrip line 72, The width of the sixth microstrip line 73 gradually increases, that is, the width of the fourth microstrip line 71 is smaller than the width of the fifth microstrip line 72, and the width of the fifth microstrip line 72 is smaller than the width of the sixth microstrip line 73. In this example, their widths are 0.16mm, 0.56mm, and 1.12mm respectively. Since the width of the microstrip lines at the input and output ends gradually changes, their impedances gradually change to form high and low impedance feeds. Compared with the uniform width of the microstrip line as the input and output ends, the passband of the bandpass filter can be narrowed. , the structure of the input and output terminals in the utility model can enable the filter to better screen and filter signals. The bottom of the fifth resonator 6 is also connected with a seventh microstrip line 8 perpendicular to the bottom. The insertion loss of a certain frequency of the filter can be changed by adjusting the length of the microstrip line 8, thereby effectively suppressing the generation of spurious passbands and avoiding affecting the performance of the filter.

The change of the transmission zero point of the bandpass filter can be achieved by adjusting the distance between the first resonator 2 and the second resonator 3 and the cross-coupling distance d between the fourth resonator 5 and the fifth resonator 6, D and S1, especially The electrical coupling is realized by the vertical distances d and D, and the length of the seventh microstrip line 8 . In this example, the size of the entire filter is 30.2mm*18.1mm, and it is made on a high-frequency radio frequency circuit board with a dielectric constant of 3.55. It has a compact structure and a small size. The width of the seventh microstrip line 8 is 1mm. The length is 2.38mm.

Each resonator is U-shaped, specifically including the bottom and two resonant strips vertically connected to the bottom. The angle between the bottom and the two turning sections of the two resonant strips and the bottom is 45 degrees, which can effectively reduce the Small reflection loss.

We tested the above-mentioned hairpin cross-coupled bandpass filter, and obtained the schematic diagrams of S11, S21 and standing wave simulation shown in Figure 2, Figure 3, and Figure 4 (in the passband, the larger the S21, the better it indicates that the passband The insertion loss is small, the smaller the S11, the better it indicates that the reflection loss is small. In the stop band, the smaller the S21, the better, and the larger the S11, the better). It can be seen from the figure that the insertion loss and reflection loss of the utility model are both small, which can meet the application requirements.

The technical means disclosed in the solution of the utility model are not limited to the technical means disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be pointed out that for those skilled in the art, some improvements and modifications can be made without departing from the principle of the utility model, and these improvements and modifications are also regarded as the protection scope of the utility model.

Claims (3)

1. A hairpin cross-coupled bandpass filter, characterized in that: comprise the first resonator, the second resonator, the third resonator, the fourth resonator, the fifth resonator arranged at intervals in sequence, the five resonators Each resonator is "U" shape, wherein, the opening of the first resonator, the third resonator and the fifth resonator is upward, the opening of the second resonator and the fourth resonator is downward, and one of the second resonator The resonant strip is located between two resonant strips of the first resonator, one resonant strip of the fourth resonator is located between two resonant strips of the fifth resonator, the first resonator is connected to the input terminal, and the first resonator is connected to the input terminal. The five resonators are connected to the output terminal, the input terminal includes the first microstrip line, the second microstrip line, and the third microstrip line connected in sequence, the width of the first microstrip line is greater than the width of the second microstrip line, The width of the second microstrip line is greater than the width of the third microstrip line, and the output terminal includes the fourth microstrip line, the fifth microstrip line, and the sixth microstrip line connected in sequence, and the width of the fourth microstrip line is less than The width of the fifth microstrip line is smaller than the width of the sixth microstrip line, and the bottom edge of the fifth resonator is connected with the seventh microstrip line. the 2. hairpin cross-coupled bandpass filter according to claim 1, is characterized in that: each resonator comprises base and two resonant bars that are connected vertically with base, and the two turning sections of base and two resonant bars The angle between the outer edge and the bottom edge is 45 degrees. 3. The hairpin cross-coupled bandpass filter according to claim 1 or 2, characterized in that: the third microstrip line is connected to the first resonator, and the fourth microstrip line is connected to the fifth resonator connected.