An electromagnetic hybrid filter with a tuned structure

Abstract

The present invention discloses an electromagnetic hybrid filter with a tuning structure, comprising an upper cover plate (1), a lower cover plate (2) and a filter housing (3) located between the upper cover plate (1) and the lower cover plate (2); a cavity communicating with the upper and lower sides thereof is arranged in the filter housing (3); after the filter housing (3) is fixed to the upper cover plate (1) and the lower cover plate (2) respectively, the cavity is sealed by the upper cover plate (1) and the lower cover plate (2) to form an electromagnetic hybrid coupling resonant cavity; a plurality of metal rod resonators are arranged in sequence from left to right in the electromagnetic coupling resonant cavity, the metal rod resonator comprising an open circuit portion (4) located at the upper part of the metal rod resonator and a short circuit portion (5) located at the lower part of the metal rod resonator; the short circuit portions (5) of any two adjacent metal rod resonators are connected by a metal connecting rod (6). The present invention generates a transmission zero point through hybrid electromagnetic coupling, thereby reducing the order and volume of the filter.

Description

Technical Field

[0001] The invention relates to filters in the communication field, and in particular to an electromagnetic hybrid filter with a tuning structure. Background Art

[0002] Due to the vigorous development of information industry and wireless communication systems, microwave frequency bands are relatively crowded, frequency band resource division is more refined, and the frequency intervals allocated to various communication systems are getting denser, which puts higher requirements on the performance of filters. Therefore, designing filters with low cost, high performance, miniaturization, stability and reliability is one of the key links in the current microwave and millimeter wave communication field.

[0003] Traditional filters achieve transmission zeros by cross-coupling non-adjacent resonant cavities, and at least three resonators are required to achieve a transmission zero. This cross-coupling method is difficult to physically achieve for filters with linear cavity rows. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide an electromagnetic hybrid filter with a tuning structure, which generates transmission zeros through hybrid electromagnetic coupling and reduces the order and volume of the filter.

[0005] The objective of the present invention is achieved through the following technical solutions: an electromagnetic hybrid filter with a tuning structure, comprising an upper cover plate, a lower cover plate and a filter housing located between the upper cover plate and the lower cover plate; a cavity communicating with the upper and lower sides of the filter housing is provided in the filter housing, and after the filter housing is respectively fixed to the upper cover plate and the lower cover plate, the cavity is sealed by the upper cover plate and the lower cover plate to form an electromagnetic hybrid coupling resonant cavity;

[0006] A plurality of metal rod resonators are arranged in sequence from left to right in the electromagnetic coupling resonant cavity; the metal rod resonator comprises an open circuit portion located at the upper part of the metal rod resonator and a short circuit portion located at the lower part of the metal rod resonator; the width of the open circuit portion of the metal rod resonator is greater than the width of the short circuit portion, so in the metal rod resonator, the impedance of the open circuit portion is smaller than the short circuit portion, and in the entire metal rod resonator, the open circuit portion exhibits low impedance and the short circuit portion exhibits high impedance; the short circuit portions of any two adjacent metal rod resonators are connected by a metal connecting rod.

[0007] Preferably, the filter housing is fixed to the upper cover plate and the lower cover plate by fastening screws. The electromagnetic hybrid filter also includes a signal input connector, one end of which is connected to the leftmost metal rod resonator, and the other end of which passes through the left side wall of the filter housing and extends outside the filter housing. The electromagnetic hybrid filter also includes a signal output connector, one end of which is connected to the rightmost metal rod resonator, and the other end of which passes through the right side wall of the filter housing and extends outside the filter housing. A tuning position is provided in the open circuit portion of each of the metal rod resonators, and the tuning position is a tuning hole, a tuning notch or a tuning gap.

[0008] Preferably, the electromagnetic coupling filter further comprises a plurality of tuning screws I, the number of the tuning screws I is the same as that of the metal rod resonators and they correspond one to one, and each tuning screw I extends to the tuning position of the corresponding metal rod resonator through a through hole reserved for the tuning screw on the upper cover plate. The electromagnetic coupling filter further comprises a plurality of tuning screws II, each tuning screw II corresponds to two adjacent metal rod resonators, and the tuning screw II extends between the short-circuited parts of the corresponding two adjacent metal rod resonators through a through hole reserved for the tuning screw on the upper cover plate.

[0009] The beneficial effects of the present invention are as follows: the present invention generates a transmission zero point through hybrid electromagnetic coupling, reduces the order and volume of the filter, and is provided with a tuning structure to facilitate tuning during use. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a structural schematic diagram of the present invention;

[0011] Figure 2 A top view of the internal structure of the electromagnetic hybrid coupling resonant cavity of the present invention;

[0012] Figure 3 is a schematic diagram of the connection structure of any two adjacent metal rod resonators;

[0013] Figure 4 A schematic diagram of a tuning position in an embodiment;

[0014] Figure 5 is another schematic diagram of tuning positions in the embodiment;

[0015] Figure 6 The figure is a schematic diagram of the test results of this application.

[0016] In the figure, 1-upper cover, 2-lower cover, 3-filter housing, 4-open circuit part, 5-short circuit part, 6-metal connecting rod, 7-signal input connector, 8-signal output connector, 9-tuning screw I, 10-tuning screw II, 11-tuning position. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0018] The present invention utilizes hybrid electromagnetic coupling to achieve cross coupling without non-adjacent cavities. Two resonators can generate a transmission zero point, which reduces the order of the filter and enables the resonant cavities of the filter to be arranged in a straight line, effectively reducing the volume of the filter. At the same time, the cavity filter implemented by the hybrid electromagnetic coupling structure of the present application has the advantages of high reliability and convenient debugging, and can be used to replace the dielectric waveguide filter. Specifically:

[0019] like Figures 1 to 3 As shown, an electromagnetic hybrid filter with a tuning structure comprises an upper cover plate 1, a lower cover plate 2 and a filter housing 3 located between the upper cover plate 1 and the lower cover plate 2; a cavity communicating with the upper and lower sides thereof is arranged in the filter housing 3, and after the filter housing 3 is respectively fixed to the upper cover plate 1 and the lower cover plate 2, the cavity is sealed by the upper cover plate 1 and the lower cover plate 2 to form an electromagnetic hybrid coupling resonant cavity;

[0020] A plurality of metal rod resonators are arranged in sequence from left to right in the electromagnetic coupling resonant cavity; the metal rod resonator includes an open circuit portion 4 located at the upper part of the metal rod resonator and a short circuit portion 5 located at the lower part of the metal rod resonator; the width of the open circuit portion 4 of the metal rod resonator is greater than the width of the short circuit portion 5, so in the metal rod resonator, the impedance of the open circuit portion 4 is less than the short circuit portion 5, and in the entire metal rod resonator, the open circuit portion 4 exhibits low impedance and the short circuit portion 5 exhibits high impedance; the short circuit portions 5 of any two adjacent metal rod resonators are connected by a metal connecting rod 6.

[0021] For any two adjacent metal rod resonators, according to the field distribution, the electric field density of the low impedance part is large, and the magnetic field density of the high impedance part is large, that is, the open circuit part 4 with low impedance is mainly electrically coupled, and the short circuit part 5 with high impedance is mainly magnetically coupled, forming a hybrid electromagnetic coupling structure, thereby generating a transmission zero point; further, increasing the area of ​​the open circuit part of the two adjacent resonators or the closer the open circuit parts of the two resonators are, the greater the electric coupling, and vice versa. Increasing the position of the metal connecting rod will increase the magnetic coupling, and vice versa, the magnetic coupling will decrease. By adjusting the electric coupling and magnetic coupling, the position of the transmission zero can also be adjusted. The superposition of the electric coupling and magnetic coupling of the two resonators is the total coupling. If the total coupling is magnetic coupling, a transmission zero is generated at the high end of the filter passband (higher than the stopband with the maximum frequency of the filter passband); on the contrary, if the total coupling is electric coupling, a transmission zero is generated at the low end of the filter passband (lower than the stopband with the lowest frequency of the filter passband), and by adjusting the ratio of magnetic coupling to electric coupling, the position of the transmission zero at the low or high end of the filter can be further adjusted. A filter with a fixed transmission zero can be designed through reasonable electric coupling and magnetic coupling configuration.

[0022] In an embodiment of the present application, the filter housing 3 is fixed to the upper cover plate 1 and the lower cover plate 2 by fastening screws; one end of the short-circuit part 5 of the metal rod resonator is fixed to the open-circuit part 4, and the other end is fixed to the front inner wall of the filter housing; the width of the open-circuit part 4 and the short-circuit part 5 refers to the width from left to right. In addition, the thickness of the open-circuit part 4 from top to bottom may also be greater than the thickness of the short-circuit part from top to bottom.

[0023] The electromagnetic hybrid filter also includes a signal input connector 7, one end of which is connected to the leftmost metal rod resonator, and the other end of which passes through the left side wall of the filter housing 3 and extends outside the filter housing. The electromagnetic hybrid filter also includes a signal output connector 8, one end of which is connected to the rightmost metal rod resonator, and the other end of which passes through the right side wall of the filter housing 3 and extends outside the filter housing. A tuning position 11 is provided in the open circuit portion 4 of each of the metal rod resonators; the tuning position may be a tuning hole, a tuning notch or a tuning gap, wherein when the tuning position 11 is a tuning hole, as shown in Figure 2 As shown, when the tuning position 11 adopts the tuning notch, it is shown in Figure 4, and when the tuning position 11 adopts the tuning gap, it is shown in Figure 5.

[0024] The electromagnetic coupling filter also includes a plurality of tuning screws Ⅰ9, the number of the tuning screws Ⅰ9 is the same as that of the metal rod resonators and they correspond one to one. Each tuning screw Ⅰ9 extends through a through hole reserved for the tuning screw on the upper cover plate 1 to the tuning position of the corresponding metal rod resonator, so as to adjust the frequency of the resonator.

[0025] The electromagnetic coupling filter also includes a plurality of tuning screws II10, each tuning screw II10 corresponds to two adjacent metal rod resonators, and the tuning screw II10 extends through a through hole reserved for the tuning screw on the upper cover plate 1 to between the short-circuit parts 5 of the corresponding two adjacent metal rod resonators, so as to adjust the coupling amount between the resonators.

[0026] like Figure 6 As shown in the figure, it is a schematic diagram of the test results of the filter of the present application. The test is the return loss and insertion loss of the filter. It can be seen from the figure that the return loss of the filter is very good (greater than 20dB). This is because the filter has a tuning screw, which can correct the error as needed. In addition, any two resonators can form a hybrid electromagnetic coupling structure. In the embodiment of the present application, the filter has a total of 7 resonators, forming a total of 6 pairs of resonators that can generate transmission zeros; Figure 6 The filter generates a transmission zero point a at the low end of the passband (lower than the stopband with the lowest frequency of the filter passband), which is generated by three pairs of resonators in the filter with total electrical coupling, and the transmission zero points generated by these three pairs of resonators overlap to form transmission zero point a; two transmission zero points b and c are generated at the high end of the passband (higher than the stopband with the maximum frequency of the filter passband), and transmission zero point b is generated by a pair of resonators with total magnetic coupling; transmission zero point c is generated by the remaining two pairs of resonators with total magnetic coupling, and the transmission zero points generated by these two pairs of resonators overlap to form transmission zero point c. At the same time, the structure of the present application does not introduce a cross-coupling structure, so the filter structure is simple and easy to process.

[0027] The above is a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not depart from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. An electromagnetic hybrid filter with a tuning structure, Features: The filter housing (3) comprises an upper cover plate (1), a lower cover plate (2), and a filter housing (3) located between the upper cover plate (1) and the lower cover plate (2); a cavity communicating with the upper and lower sides of the filter housing (3) is provided in the filter housing (3); after the filter housing (3) is fixed to the upper cover plate (1) and the lower cover plate (2), the cavity is sealed by the upper cover plate (1) and the lower cover plate (2), thereby forming an electromagnetic hybrid coupling resonant cavity; A plurality of metal rod resonators are arranged in sequence from left to right in the electromagnetic hybrid coupling resonant cavity; the metal rod resonator comprises an open circuit portion (4) located at the upper part of the metal rod resonator and a short circuit portion (5) located at the lower part of the metal rod resonator; the width of the open circuit portion (4) of the metal rod resonator is greater than the width of the short circuit portion, so in the metal rod resonator, the impedance of the open circuit portion (4) is smaller than that of the short circuit portion (5); in the entire metal rod resonator, the open circuit portion (4) exhibits low impedance and the short circuit portion (5) exhibits high impedance; any two adjacent short circuit portions (5) of the metal rod resonators are connected by a metal connecting rod (6); The filter housing (3) is fixed to the upper cover plate (1) and the lower cover plate (2) by means of fastening screws; The electromagnetic hybrid filter further comprises a signal input connector (7), one end of the signal input connector (7) being connected to the leftmost metal rod resonator, and the other end of the signal input connector (7) penetrating the left side wall of the filter housing (3) and extending outside the filter housing.

2. The electromagnetic hybrid filter with a tuning structure according to claim 1, Features: The electromagnetic hybrid filter further comprises a signal output connector (8), one end of the signal output connector (8) being connected to the rightmost metal rod resonator, and the other end of the signal output connector (8) penetrating the right side wall of the filter housing (3) and extending outside the filter housing.

3. The electromagnetic hybrid filter with a tuning structure according to claim 1, Features: A tuning position (11) is provided in the open circuit portion (4) of each metal rod resonator, and the tuning position is a tuning hole, a tuning notch or a tuning gap.

4. The electromagnetic hybrid filter with a tuning structure according to claim 1, Features: The electromagnetic hybrid filter further comprises a plurality of tuning screws I (9), the number of the tuning screws I (9) being the same as the number of the metal rod resonators and corresponding one to one, and each tuning screw I (9) extending through a through hole reserved for the tuning screw on the upper cover plate (1) to a tuning position of the corresponding metal rod resonator.

5. The electromagnetic hybrid filter with a tuning structure according to claim 1, Features: The electromagnetic hybrid filter also includes a plurality of tuning screws II (10), each tuning screw II (10) corresponding to two adjacent metal rod resonators, and the tuning screw II (10) extends between the short-circuit parts (5) of the corresponding two adjacent metal rod resonators through a through hole reserved for the tuning screw on the upper cover plate (1).

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