Bandwidth coding reconfigurable band-pass filter

Abstract

The bandwidth coding reconfigurable band-pass filter comprises a first layer of metal grounding plate, a second layer of dielectric substrate, a third layer of interdigital resonator, a fourth layer of dielectric substrate and a fifth layer of metal grounding plate which are stacked in sequence, a first-layer metal strip group is arranged in the first-layer metal grounding plate, and the left side and the right side of the first-layer metal strip group are connected with the first-layer metal grounding plate through a first-layer diode group; the third-layer interdigital resonator comprises a middle-layer metal grounding plate, the middle-layer metal grounding plate is connected with a resonator group, and the upper side and the lower side of the resonator group are connected with grounding coplanar waveguides through tapped strip lines respectively; a fifth layer metal strip group is arranged in the fifth layer metal grounding plate, and the left side and the right side of the fifth layer metal strip group are connected with the fifth layer metal grounding plate through a fifth layer diode group. According to the invention, the bandwidth adjustable range is large, the discrete bandwidth regulation and control capability is flexible, the dependence on tuning elements is weak, and the performance is excellent.

Description

Technical Field

[0001] The invention belongs to the technical field of active adjustable filters, and in particular relates to a bandwidth coded reconfigurable bandpass filter. Background Art

[0002] With the vigorous development of wireless communication technology and integrated circuit technology, the demand for small-sized, wide-band, and adjustable-band bandpass filters is becoming increasingly urgent. At the same time, due to the complex modern communication environment, narrowband systems are no longer applicable in some application scenarios, and there is an urgent need for wideband and narrowband switchable bandpass filters.

[0003] Active adjustable units such as PIN diodes and varactor diodes can change the equivalent circuit parameters of the filter by changing the capacitance value or branch length, thereby achieving the purpose of adjustment. At the same time, the stripline interdigital structure has the characteristics of compact size and fast roll-off speed, which is suitable for use in modern miniaturized integrated circuits.

[0004] PIN diodes have the characteristics of being turned on by forward voltage and cut off by reverse voltage. The on and off of the circuit can be switched by changing the bias voltage, thereby adjusting the equivalent electrical size, state and other characteristics of the microwave structure.

[0005] The interdigital stripline filter consists of TEM mode stripline resonators placed in parallel in the middle layer, and two layers of ground planes. The length of each resonator is one quarter wavelength, one end of the resonator is short-circuited and the other end is open-circuited. Adjacent resonant units are coupled through the field edge to achieve the bandpass effect. In 2018, Salman Arain et al. proposed a bandwidth reconfigurable filter with high-frequency suppression function in "Reconfigurable Bandwidth Bandpass Filter With Enhanced Out-of-Band Rejection Using π-Section-Loaded Ring Resonator" (IEEE Microwave and wireless component letters, vol. 28, no. 1, Jan 2018). PIN tubes are used to control the connection and disconnection of branches, so that the fractional bandwidth is extended from 39.5% to 90%. However, this type of filter generally has the problem of excessive dependence on the performance of tuning elements. In 2021, Fan et al. proposed a bandpass filter with adjustable bandwidth and center frequency in "Reconfigurable Bandpass Filter With Wide-Range Bandwidth and Frequency Control" (IEEE Transactions on circuits and systems, vol. 68, no. 6, Jun 2021). The filter is composed of a cascade of high-pass and low-pass filters, and the cutoff frequencies of the two filters are controlled by varactor diodes to adjust the upper and lower cutoff frequencies. However, the adjustable range of this type of filter is narrow, and due to the nonlinear distortion of the varactor diode, the passband performance is not ideal. In 2022, Ponnammal P. et al. proposed a switchable bandpass filter in "Miniaturized bandwidth reconfigurable microwave bandpass filter" (Microelectronics international: journal of ISHM--Europe, the Microelectronics Society--Europe, 17Jun 2022, Vol. 39, Issue 3, pages 121-131), using PIN diodes to switch the hexagonal ring and its peripheral bias network to achieve switching between narrow dual passband (center frequency 2.1GHz and 4.5GHz) and wide passband (2.1 to 5.9GHz). However, the structure has fewer adjustable states, and the microstrip structure has certain radiation losses. Summary of the invention

[0006] The object of the present invention is to provide a bandwidth-coded reconfigurable bandpass filter with a large adjustable bandwidth range, flexible discrete bandwidth control capability, weak dependence on tuning elements and superior performance.

[0007] To achieve the above object, the present invention provides a bandwidth-coded reconfigurable bandpass filter, comprising a first metal ground plate, a second dielectric substrate, a third interdigital resonator, a fourth dielectric substrate, and a fifth metal ground plate stacked in sequence;

[0008] The bandpass filter is provided with a grounding through hole which sequentially penetrates the first metal grounding plate, the second dielectric substrate, the third interdigital resonator, the fourth dielectric substrate and the fifth metal grounding plate;

[0009] A top layer through groove is provided in the middle of the first layer metal grounding plate, a first layer metal strip group is provided in the top layer through groove, and the left and right sides of the first layer metal strip group are connected to the first layer metal grounding plate through the first layer diode group;

[0010] The third-layer interdigital resonator includes a middle-layer metal ground plate, which is composed of concave ground plates that are symmetrically arranged and have openings facing each other. A resonator group is connected between the two concave ground plates. The upper and lower sides of the resonator group are respectively connected to a grounded coplanar waveguide through a tapped strip line, and the other end of the grounded coplanar waveguide is connected to the SMA head.

[0011] A bottom through groove is arranged in the middle of the fifth metal grounding plate, a fifth metal strip group is arranged in the bottom through groove, and the left and right sides of the fifth metal strip group are connected to the fifth metal grounding plate through the fifth diode group.

[0012] As a further solution of the present invention: the first layer of metal strip group includes a metal strip V, and metal strips IV and metal strips III are symmetrically distributed on the upper and lower sides of the metal strip V in sequence.

[0013] As a further solution of the present invention: the first layer diode group includes diode III, diode IV, and diode V, and the left and right sides of metal strips III, metal strips IV, and metal strips V are connected to the first layer metal ground plate through diodes III, diode IV, and diode V respectively.

[0014] As a further solution of the present invention: the resonator group includes a resonator IV, and resonators III, resonator II, and resonator I are symmetrically distributed on the upper and lower sides of resonator IV; the left end of resonator I is short-circuited and the right end is open, the right end of resonator II is short-circuited and the left end is open, and the left end of resonator III is short-circuited and the right end is open.

[0015] As a further solution of the present invention: the fifth-layer metal strip group includes metal strip I and metal strip II, and the bottom layer through groove is divided into upper and lower parts by a middle partition, and the metal strip I and metal strip II are symmetrically distributed in the upper and lower parts respectively; the fifth-layer diode group includes diode I and diode II, and the metal strip I and metal strip II are connected to the fifth-layer metal grounding plate on the left and right sides through diode I and diode II respectively.

[0016] As a further solution of the present invention: the lateral dimensions w of the first metal ground plane, the second dielectric substrate, the middle metal ground plane, the fourth dielectric substrate, and the fifth metal floor are all 10 mm, and the longitudinal dimensions l of the first metal ground plane and the second dielectric substrate are all 7.4 mm; the longitudinal dimensions p of the middle metal ground plane, the fourth dielectric substrate, and the fifth metal floor are all 11.4 mm;

[0017] The first metal floor, the third interdigital resonator, and the fifth metal floor have a thickness of 0.035 mm, and the second dielectric substrate and the fourth dielectric substrate have a relative dielectric constant of 3.55 and a thickness of 0.3 mm;

[0018] The diameter of the ground via is 0.2mm.

[0019] As a further solution of the present invention: the lateral dimension l of the top through groove is u The longitudinal dimension w is 7.644 mm. u 3.2mm;

[0020] The longitudinal distance g between the metal strip III and the first metal ground plane u is 0.436 mm, and the longitudinal distance d between metal strip III and metal strip IV is u is 0.179 mm, and the longitudinal distance d between metal strip IV and metal strip V l 0.16mm;

[0021] Transverse dimension S of metal strip III, metal strip IV, and metal strip V u Both are 6.944mm, vertical dimension w l Both are 0.33mm.

[0022] As a further solution of the present invention: the dimension lc between the openings of the two concave ground plates is 7.644 mm, and the longitudinal dimension w c 5mm;

[0023] The transverse dimension S0 of the grounded coplanar waveguide is 0.6 mm, the longitudinal dimension l1 is 1.5 mm, and the transverse spacing g0 between the grounded coplanar waveguide and the middle metal ground plate is 0.379 mm;

[0024] The lateral dimension w0 of the tapped stripline is 0.3 mm, and the longitudinal dimension l0 is 2.261 mm;

[0025] The lateral spacing d1 between resonator I and the middle metal ground plane is 0.121 mm, the lateral spacing d2 between resonator II and the middle metal ground plane is 1.147 mm, the lateral spacing d3 between resonator III and the middle metal ground plane is 1.122 mm, and the lateral spacing d4 between resonator IV and the middle metal ground plane is 1.113 mm;

[0026] The longitudinal spacing c1 between resonator I and resonator II is 0.08 mm, the longitudinal spacing c2 between resonator II and resonator III is 0.138 mm, and the longitudinal spacing c3 between resonator III and resonator IV is 0.171 mm;

[0027] The longitudinal dimension w0 of resonator I, resonator II, resonator III, and resonator IV is 0.3 mm.

[0028] As a further solution of the present invention: the lateral dimension l of the bottom through groove is d The longitudinal dimension w is 2.96 mm. d 3.03mm;

[0029] The longitudinal distance g between the metal strip I and the fifth metal ground plane l The longitudinal spacing g between metal strip II and the fifth metal ground plane is 0.085 mm. d is 0.05 mm, and the longitudinal distance d between metal strip I and metal strip II is d 0.67mm;

[0030] Transverse dimension S of metal strip I and metal strip II d Both are 2.3mm, vertical dimension w l Both are 0.33mm.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] A diode is used to control the connection between the metal strip and the grounding end to achieve switching between the non-grounded and grounded states. The metal strips are divided into 5 groups (3 groups on the first-layer metal grounding plate and 2 groups on the fifth-layer metal grounding plate). The strips in each group are in the same state, and the states between each group are different. By regulating the states of different metal strips on the first-layer metal grounding plate and the fifth-layer metal grounding plate, the purpose of discretely regulating the bandwidth is achieved.

[0033] According to the state combination between each group of strips, there are 16 combinations that meet the performance requirements, with absolute bandwidth (-3dB) ranging from 2.29GHz to 5.68GHz, relative bandwidth ranging from 38% to 90%, center frequencies all around 6GHz, a large adjustable bandwidth range, and flexible discrete bandwidth control capability; the filter uses SMA coaxial connectors for feeding, and both AC signal input and output are in the form of coplanar waveguides, and FPGA coding is used to control active devices; since the signal is concentrated between the ground plate and the transmission line, and the tuning element is at the ground plate, the dependence on the performance of the tuning element is not strong; compared with traditional active adjustable structures, the bandpass filter has the characteristics of a large adjustable bandwidth range, compact size (10mm×11.4mm), weak dependence on tuning elements, superior performance, and low processing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is an exploded diagram of the bandpass filter of the present invention;

[0035] Figure 2 It is a schematic diagram of the combined structure of the bandpass filter of the present invention;

[0036] Figure 3 It is a structural schematic diagram of the first metal ground plate of the bandpass filter of the present invention;

[0037] Figure 4 It is a schematic structural diagram of the third layer of interdigital resonators of the bandpass filter of the present invention;

[0038] Figure 5 It is a schematic structural diagram of the fifth metal ground plate of the bandpass filter of the present invention;

[0039] Figure 6 It is a schematic diagram of the dimensions of the first metal ground plate of the bandpass filter of the present invention;

[0040] Figure 7 It is a schematic diagram of the dimensions of the second dielectric substrate of the bandpass filter of the present invention;

[0041] Figure 8 It is a schematic diagram of the dimensions of the third layer of interdigital resonators of the bandpass filter of the present invention;

[0042] Fig. 9 It is a schematic diagram of the dimensions of the fourth dielectric substrate of the bandpass filter of the present invention;

[0043] Fig.10 It is a schematic diagram of the dimensions of the fifth metal ground plate of the bandpass filter of the present invention;

[0044] Fig.11 It is a schematic diagram of the port of the bandpass filter of the present invention using FPGA for feeding (the first metal ground plate);

[0045] Fig.12 It is a schematic diagram of the port of the bandpass filter of the present invention that uses FPGA for feeding (the fifth metal ground plate);

[0046] Fig.13 It is a performance parameter table (absolute bandwidth, center frequency, return loss) of 16 combinations of the bandpass filter of the present invention, wherein 1 represents diode conduction and 0 represents diode cutoff;

[0047] Fig.14 It is a schematic diagram of the coupling capacitance of two parallel coupled transmission lines a and b under the electric wall and magnetic wall;

[0048] Fig.15 is the equivalent circuit diagram of the resonant frequency of two coupled transmission lines;

[0049] Fig.16 is the simulated insertion loss S of the bandpass filter of the present invention 21 Parameter diagram, the horizontal axis represents frequency, the vertical axis represents S parameters, the unit is dB;

[0050] Fig.17 is the simulated return loss S of the bandpass filter of the present invention 11 Parameter diagram, the horizontal axis represents frequency, the vertical axis represents S parameters, the unit is dB.

[0051] In the figure: 1. first layer metal ground plane, 2. second layer dielectric substrate, 3. third layer interdigital resonator, 4. fourth layer dielectric substrate, 5. fifth layer metal ground plane, 6. grounding through hole, 7. top layer through slot, 8. diode III, 9. diode IV, 10. diode V, 11. metal strip III, 12. metal strip IV, 13. metal strip V, 14. resonator I, 15. resonator III, 16. tapped stripline, 17. grounded coplanar waveguide, 18. resonator II, 19. resonator IV, 20. middle layer metal ground plane, 21. bottom layer through slot, 22. diode II, 23. metal strip II, 24. metal strip I, 25. diode I. DETAILED DESCRIPTION

[0052] The present invention will be further described below by way of examples.

[0053] like Figures 1 to 5 As shown, a bandwidth-coded reconfigurable bandpass filter comprises a first metal ground plate 1, a second dielectric substrate 2, a third interdigital resonator 3, a fourth dielectric substrate 4, and a fifth metal ground plate 5, which are stacked in sequence;

[0054] The bandpass filter is provided with a grounding through hole 6 which sequentially penetrates the first metal grounding plate 1, the second dielectric substrate 2, the third interdigital resonator 3, the fourth dielectric substrate 4, and the fifth metal grounding plate 5;

[0055] A top through groove 7 is provided in the middle of the first metal grounding plate 1, a first metal strip group is provided in the top through groove 7, and the left and right sides of the first metal strip group are connected to the first metal grounding plate 1 through a first diode group;

[0056] The third interdigital resonator 3 includes a middle metal ground plate 20, which is composed of concave ground plates that are symmetrically arranged and have openings facing each other. A resonator group is connected between the two concave ground plates. The upper and lower sides of the resonator group are respectively connected to a grounded coplanar waveguide 17 through a tapped stripline 16. The other end of the grounded coplanar waveguide 17 is connected to the SMA head.

[0057] A bottom through slot 21 is provided in the middle of the fifth metal grounding plate 5 , and a fifth metal strip group is provided in the bottom through slot 21 . The left and right sides of the fifth metal strip group are connected to the fifth metal grounding plate 5 through a fifth diode group.

[0058] Further, such as Figure 3 As shown, the first layer of metal strip group includes a metal strip V13, and metal strips IV12 and III11 are symmetrically distributed on the upper and lower sides of the metal strip V13.

[0059] Furthermore, the first layer diode group includes diode III8, diode IV9, and diode V10, and the left and right sides of metal strips III11, metal strips IV12, and metal strips V13 are connected to the first layer metal ground plate 1 through diodes III8, diode IV9, and diode V10 respectively.

[0060] Further, such as Figure 4 As shown, the resonator group includes resonator IV19, and resonator III15, resonator II18, and resonator I14 are symmetrically distributed on the upper and lower sides of resonator IV19; the left end of resonator I14 is short-circuited and the right end is open, the right end of resonator II18 is short-circuited and the left end is open, and the left end of resonator III15 is short-circuited and the right end is open.

[0061] Further, such as Figure 5 As shown, the fifth-layer metal strip group includes metal strip I24 and metal strip II23, and the bottom through groove 21 is divided into upper and lower parts by a partition in the middle, and the metal strip I24 and metal strip II23 are symmetrically distributed in the upper and lower parts respectively; the fifth-layer diode group includes diode I25 and diode II22, and the left and right sides of the metal strip I24 and metal strip II23 are connected to the fifth-layer metal ground plate 5 through diode I25 and diode II22 respectively.

[0062] Further, such as Figures 6 to 10 As shown, the transverse dimensions w of the first metal ground plane 1, the second dielectric substrate 2, the middle metal ground plane 20, the fourth dielectric substrate 4, and the fifth metal floor are all 10 mm, and the longitudinal dimensions l of the first metal ground plane 1 and the second dielectric substrate 2 are all 7.4 mm; the longitudinal dimensions p of the middle metal ground plane 20, the fourth dielectric substrate 4, and the fifth metal floor are all 11.4 mm;

[0063] The first metal floor, the third interdigital resonator 3, and the fifth metal floor have a thickness of 0.035 mm, and the second dielectric substrate 2 and the fourth dielectric substrate 4 have a relative dielectric constant of 3.55 and a thickness of 0.3 mm;

[0064] The diameter of the ground through hole 6 is 0.2 mm.

[0065] Furthermore, the lateral dimension l of the top through groove 7 is u The longitudinal dimension w is 7.644 mm. u 3.2mm;

[0066] The longitudinal distance g between the metal strip III11 and the first metal grounding plate 1 u is 0.436 mm, and the longitudinal distance d between the metal strip III11 and the metal strip IV12 is u The longitudinal distance d between the metal strip IV12 and the metal strip V13 is 0.179 mm. l 0.16mm;

[0067] Transverse dimensions S of metal strips III11, IV12 and V13 u Both are 6.944mm, vertical dimension w l Both are 0.33mm.

[0068] Furthermore, the opening dimension lc of the two concave ground plates is 7.644 mm, and the longitudinal dimension w c 5mm;

[0069] The transverse dimension S0 of the grounded coplanar waveguide 17 is 0.6 mm, the longitudinal dimension l1 is 1.5 mm, and the transverse spacing g0 between the grounded coplanar waveguide 17 and the middle metal ground plate 20 is 0.379 mm;

[0070] The lateral dimension w0 of the tapped stripline 16 is 0.3 mm, and the longitudinal dimension l0 is 2.261 mm;

[0071] The lateral spacing d1 between the resonator I14 and the middle metal grounding plate 20 is 0.121 mm, the lateral spacing d2 between the resonator II18 and the middle metal grounding plate 20 is 1.147 mm, the lateral spacing d3 between the resonator III15 and the middle metal grounding plate 20 is 1.122 mm, and the lateral spacing d4 between the resonator IV19 and the middle metal grounding plate 20 is 1.113 mm;

[0072] The longitudinal spacing c1 between resonator I14 and resonator II18 is 0.08 mm, the longitudinal spacing c2 between resonator II18 and resonator III15 is 0.138 mm, and the longitudinal spacing c3 between resonator III15 and resonator IV19 is 0.171 mm;

[0073] The longitudinal dimension w0 of resonator I14, resonator II18, resonator III15, and resonator IV19 is 0.3 mm.

[0074] Furthermore, the lateral dimension l of the bottom through groove 21 is d The longitudinal dimension w is 2.96 mm. d 3.03mm;

[0075] The longitudinal distance g between the metal strip I24 and the fifth metal grounding plate 5 l The longitudinal distance g between the metal strip II23 and the fifth metal grounding plate 5 is 0.085 mm. d The longitudinal distance d between the metal strip I24 and the metal strip II23 is 0.05 mm. d 0.67mm;

[0076] Transverse dimension S of metal strip I24 and metal strip II23 d Both are 2.3mm, vertical dimension w l Both are 0.33mm.

[0077] like Fig.13 As shown, the size limitation of the above structure ensures that the bandpass filter has 16 combinations with excellent passband performance, with absolute bandwidth (-3dB) ranging from 2.29GHz to 5.68GHz, relative bandwidth ranging from 38% to 90%, center frequency around 6GHz, wide adjustable bandwidth range, and flexible discrete bandwidth control capability.

[0078] The filter works as follows:

[0079] The signal is fed into the grounded coplanar waveguide 17 of the third-layer interdigital resonator 3 through the SMA head, and then fed into the grounded coplanar waveguide 17 at the other end after passing through resonator I14, resonator II18, resonator III15, resonator IV19, resonator III15, resonator II18, and resonator I14, and then output through SMA.

[0080] At the same time, Fig.11 and Fig.12 As shown, FPGA is used to control the on-off of the diode group of the first metal grounding plate 1 and the fifth metal grounding plate 2 to form different on-off combinations to change the self-capacitance and mutual capacitance of the coupled transmission line, thereby changing the bandwidth of the filter and realizing the function of discrete adjustable bandwidth. Specifically, the 10 output GPIO ports of the FPGA are connected to the corresponding 10 ports of the filter (port1-port10), and the port order corresponds to the coding order. Port1 is always connected to a low level. When other ports are connected to a high level, the diode corresponding to the port is turned on (the corresponding metal strip is grounded); when other ports are connected to a low level, the diode corresponding to the port is turned off (the corresponding metal strip is not grounded), thereby controlling the state of the metal strip to achieve the purpose of coding and regulating the bandwidth of the filter. For example: to ground the metal strips I24 and V13, and the others are not grounded, you only need to turn on the diodes I25 and V10, that is, port 1 is connected to a low level, and port 6, port 7, and port 8 are connected to a high level. At this time, the encoding is: 0000011100000000 (0700), and so on.

[0081] The specific theory is as follows:

[0082] The relationship between the bandwidth and coupling coefficient of the coupled filter is as follows:

[0083]

[0084] where k nm is the coupling coefficient between the nth resonator and the mth resonator, BW is the absolute bandwidth of the filter, f0 is the center frequency of the filter, g n g m is the low-pass prototype coefficient. For parallel coupled transmission lines, the coupling coefficient k nm It is inversely proportional to the spacing S between adjacent transmission lines, and the coupling coefficient k is easily obtained nm With C nm It is directly proportional to C nn Inversely proportional.

[0085] like Fig.14 The figure shows the coupling capacitance diagram of two parallel coupled transmission lines a and b under the electric wall and magnetic wall, where the mutual capacitance satisfies the relationship: C ab =4(C fo '-C fe '), where C fo ' is the mutual coupling capacitance of the two transmission lines under the electric wall, C fe' is the edge capacitance when another coupling line exists under the magnetic wall; the self-capacitance of transmission line a (or b) satisfies: C a =4(C f +C p +C fe '), where C f is the fringe capacitance of a single transmission line in an uncoupled state, C p is the capacitance of a single transmission line to ground.

[0086] After the first metal grounding plate 1 and the fifth metal grounding plate 5 are grooved, if the metal strips of the first metal grounding plate 1 and the fifth metal grounding plate 5 are not grounded, the strip line loses the metal ground, which will cause the edge capacitance C fe 'decreases; at the same time, due to C p With C f The decrease of the self-capacitance of a single transmission line reduces, resulting in the mutual coupling capacitance C of the two transmission lines fo 'Increase. Eventually, the mutual capacitance C ab Increases, expanding the bandwidth of the filter.

[0087] If the metal strips of the first metal grounding plate 1 and the fifth metal grounding plate 5 are grounded, the strip line has a metal ground, which is the opposite of the ungrounded state. Therefore, by controlling the diode connecting the metal grounding plate and the metal strip, the grounding state of the metal strip can be changed, and the bandwidth of the filter can be flexibly adjusted.

[0088] Taking the resonant frequency of two coupled transmission lines as an example, the equivalent circuit diagram is as follows: Fig.15 As shown;

[0089] Where L and C represent the self-inductance and self-capacitance of a single transmission line, C m Represents the coupling capacitor, and its high-frequency and low-frequency resonant frequencies can be expressed as:

[0090]

[0091] When the metal strip of the first metal ground plane 1 is not grounded, the mutual capacitance C m increases, the self-capacitance C decreases, and the mutual capacitance C m The increase is greater than the decrease in self-capacitance C. Therefore, the high-frequency resonant frequency f m Increase, low frequency resonance frequency f e decreases, and f e The reduction is slightly lower than f m The increase in the bandwidth results in an increase in the center frequency and a slight shift to higher frequencies.

[0092] like Fig.16 The simulation S 21 In the parameter diagram, the horizontal axis represents the frequency and the vertical axis represents the S parameter in dB. Fig.17 The simulation S 11 Parameter diagram, the horizontal axis represents frequency, the vertical axis represents S parameters, the unit is dB.

[0093] Fig.16 and Fig.17 Figure 2 is the S parameter diagram of 6 main states among the 16 states. The triangular solid line represents the S parameter when all diodes are turned on; the square solid line represents the S parameter when diode group II is disconnected and other tube groups are turned on; the circular solid line represents the S parameter when diode group I, diode group II, and diode group V are disconnected, and other tube groups are turned on; the inverted triangle solid line represents the S parameter when diode group I, diode group IV, and diode group V are disconnected, and other tube groups are turned on; the star solid line represents the S parameter when diode group III, diode group IV, and diode group V are disconnected, and other tube groups are turned on; the diamond solid line represents the S parameter diagram when all diodes are cut off.

[0094] It can be seen that the center frequencies of the six curves are all around 6 GHz, and the -3dB bandwidths range from 2.29 GHz to 5.68 GHz. 21 All above -1dB, return loss S 11 All are below -10dB, with good performance and a wide adjustable range.

Claims

1. A bandwidth coded reconfigurable bandpass filter, characterized in that: It comprises a first metal grounding plate (1), a second dielectric substrate (2), a third interdigital resonator (3), a fourth dielectric substrate (4), and a fifth metal grounding plate (5) which are stacked in sequence; The bandpass filter is provided with a grounding through hole (6) which sequentially penetrates the first metal grounding plate (1), the second dielectric substrate (2), the third interdigital resonator (3), the fourth dielectric substrate (4), and the fifth metal grounding plate (5); A top through groove (7) is provided in the middle of the first metal grounding plate (1), a first metal strip group is provided in the top through groove (7), and the left and right sides of the first metal strip group are connected to the first metal grounding plate (1) via a first diode group; The third interdigital resonator (3) comprises a middle metal ground plate (20), the middle metal ground plate (20) is composed of concave ground plates that are symmetrically arranged and have openings facing each other, a resonator group is connected between the two concave ground plates, and the upper and lower sides of the resonator group are respectively connected to a grounded coplanar waveguide (17) through a tapped stripline (16), and the other end of the grounded coplanar waveguide (17) is connected to an SMA head; A bottom through groove (21) is provided in the middle of the fifth metal grounding plate (5), a fifth metal strip group is provided in the bottom through groove (21), and the left and right sides of the fifth metal strip group are connected to the fifth metal grounding plate (5) via a fifth diode group.

2. A bandwidth coded reconfigurable bandpass filter according to claim 1, characterized in that: The first layer of metal strip group includes a metal strip V (13), and metal strips IV (12) and III (11) are symmetrically distributed on the upper and lower sides of the metal strip V (13).

3. A bandwidth coded reconfigurable bandpass filter according to claim 2, characterized in that: The first layer diode group comprises a diode III (8), a diode IV (9), and a diode V (10). The left and right sides of the metal strips III (11), IV (12), and V (13) are connected to the first layer metal ground plate (1) through the diodes III (8), IV (9), and V (10), respectively.

4. A bandwidth coded reconfigurable bandpass filter according to claim 1, characterized in that: The resonator group comprises a resonator IV (19), and resonators III (15), II (18), and I (14) are symmetrically distributed on the upper and lower sides of the resonator IV (19); the left end of the resonator I (14) is short-circuited and the right end is open-circuited, the right end of the resonator II (18) is short-circuited and the left end is open-circuited, and the left end of the resonator III (15) is short-circuited and the right end is open-circuited.

5. The bandwidth coded reconfigurable bandpass filter according to claim 1, characterized in that: The fifth layer of metal strip group includes metal strip I (24) and metal strip II (23), and the bottom layer through groove (21) is divided into upper and lower parts by a partition in the middle, and the metal strip I (24) and metal strip II (23) are symmetrically distributed in the upper and lower parts respectively; the fifth layer of diode group includes diode I (25) and diode II (22), and the left and right sides of the metal strip I (24) and metal strip II (23) are connected to the fifth layer of metal ground plate (5) through diode I (25) and diode II (22) respectively.

6. A bandwidth coded reconfigurable bandpass filter according to claim 2, characterized in that: The transverse dimensions w of the first metal grounding plate (1), the second dielectric substrate (2), the middle metal grounding plate (20), the fourth dielectric substrate (4), and the fifth metal floor are all 10 mm, and the longitudinal dimensions l of the first metal grounding plate (1) and the second dielectric substrate (2) are all 7.4 mm; the longitudinal dimensions p of the middle metal grounding plate (20), the fourth dielectric substrate (4), and the fifth metal floor are all 11.4 mm; The first metal floor, the third interdigital resonator (3), and the fifth metal floor have a thickness of 0.035 mm, and the second dielectric substrate (2) and the fourth dielectric substrate (4) have a relative dielectric constant of 3.55 and a thickness of 0.3 mm. The diameter of the grounding through hole (6) is 0.2 mm.

7. A bandwidth coded reconfigurable bandpass filter according to claim 6, characterized in that: The lateral dimension l of the top through groove (7) u The longitudinal dimension w is 7.644 mm. u 3.2mm; The longitudinal distance g between the metal strip III (11) and the first metal grounding plate (1) u is 0.436 mm, and the longitudinal distance d between the metal strip III (11) and the metal strip IV (12) is u is 0.179 mm, and the longitudinal distance d between the metal strip IV (12) and the metal strip V (13) is l 0.16mm; The transverse dimension S of the metal strip III (11), the metal strip IV (12), and the metal strip V (13) u Both are 6.944mm, vertical dimension w l Both are 0.33mm.

8. A bandwidth coded reconfigurable bandpass filter according to claim 4, characterized in that: The opening dimension lc of the two concave ground plates is 7.644 mm, and the longitudinal dimension w c 5mm; The transverse dimension S0 of the grounded coplanar waveguide (17) is 0.6 mm, the longitudinal dimension l1 is 1.5 mm, and the transverse spacing g0 between the grounded coplanar waveguide (17) and the middle metal ground plate (20) is 0.379 mm; The lateral dimension w0 of the tapped stripline (16) is 0.3 mm, and the longitudinal dimension l0 is 2.261 mm; The lateral distance d1 between the resonator I (14) and the middle metal grounding plate (20) is 0.121 mm, the lateral distance d2 between the resonator II (18) and the middle metal grounding plate (20) is 1.147 mm, the lateral distance d3 between the resonator III (15) and the middle metal grounding plate (20) is 1.122 mm, and the lateral distance d4 between the resonator IV (19) and the middle metal grounding plate (20) is 1.113 mm; The longitudinal spacing c1 between resonator I (14) and resonator II (18) is 0.08 mm, the longitudinal spacing c2 between resonator II (18) and resonator III (15) is 0.138 mm, and the longitudinal spacing c3 between resonator III (15) and resonator IV (19) is 0.171 mm; The longitudinal dimension w0 of resonator I (14), resonator II (18), resonator III (15), and resonator IV (19) is 0.3 mm.

9. The bandwidth coded reconfigurable bandpass filter according to claim 5, characterized in that: The transverse dimension l of the bottom through groove (21) d The longitudinal dimension w is 2.96 mm. d 3.03mm; The longitudinal distance g between the metal strip I (24) and the fifth metal grounding plate (5) l The longitudinal distance g between the metal strip II (23) and the fifth metal grounding plate (5) is 0.085 mm. d is 0.05 mm, and the longitudinal distance d between the metal strip I (24) and the metal strip II (23) is d 0.67mm; The transverse dimension S of the metal strip I (24) and the metal strip II (23) d Both are 2.3mm, vertical dimension w l Both are 0.33mm.

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