CN213212346U - Ultra-wideband band-pass filter - Google Patents
Ultra-wideband band-pass filter Download PDFInfo
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- CN213212346U CN213212346U CN202022580015.3U CN202022580015U CN213212346U CN 213212346 U CN213212346 U CN 213212346U CN 202022580015 U CN202022580015 U CN 202022580015U CN 213212346 U CN213212346 U CN 213212346U
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Abstract
The utility model discloses an ultra wide band pass filter, including low pass module and high pass module, the low pass module includes: a defective microstrip structure and is equivalent to an RLC parallel circuit; the high-pass module is a semi-lumped high-pass module, comprising: the first high-pass microstrip transmission line and the second high-pass microstrip transmission line are provided with a surface-mounted capacitor. The utility model provides an ultra wide band pass filter, utilize the first vertical groove of seting up, the vertical groove of second, the vertical groove of third and transverse groove have changed the electric current route, the electric current route length has been increased, utilize the additional inductance effect of defect microstrip structure, and the wide stop band of corresponding low pass module and the characteristic of slow wave, band pass filter's bandwidth has been enlarged, combine to introduce the semi-lumped high pass module of SMD electric capacity, ultra wide band pass filter has been formed, the volume of wave filter has been reduced to the appearance value size through controlling SMD electric capacity, the miniaturization of wave filter has been realized.
Description
Technical Field
The utility model relates to a communication filter technical field especially relates to an ultra wide band pass filter.
Background
In the field of radio frequency communication, a filter is widely used as a frequency selection device, and in a base station for performing signal transmission and reception in a communication system, the filter is used for selecting a communication signal and filtering out clutter or interference signals outside the frequency of the communication signal.
A band-pass filter refers to a filter that passes frequency components in a certain frequency range, but attenuates frequency components in other ranges to an extremely low level, as opposed to the concept of a band-stop filter. An example of an analog bandpass filter is a resistor-inductor-capacitor circuit (RLC circuit). These filters may also be generated using a low pass filter in combination with a high pass filter.
Ultra Wide Band (UWB) technology is a new type of wireless communication technology. It makes the signal have a bandwidth of the order of GHz by directly modulating an impulse with very steep rise and fall times. The ultra-wideband technology solves the major problems of the traditional wireless technology in the aspect of transmission for many years, and has the advantages of insensitivity to channel fading, low power spectral density of transmitted signals, low interception capability, low system complexity, capability of providing positioning accuracy of a few centimeters and the like.
The patent of invention with publication number CN105024124A discloses a microstrip ultra wide band pass filter based on a novel multi-stub multimode resonator, as shown in fig. 1 and fig. 2, which includes the following patterns in a metal upper cladding layer I of a microstrip: input feed 1, tapered impedance transmission line segment 11, short circuit transmission line segment 12, open circuit transmission line segment 14, open circuit transmission line segment 15, open circuit transmission line segment 16, open circuit transmission line segment 31, transmission line segment 32, intermediate short circuit transmission line segment 33, metalized via 34, open circuit transmission line segment 35, open circuit transmission line segment 36, open circuit transmission line segment 37, open circuit transmission line segment 38, open circuit transmission line segment 39, open circuit transmission line segment 26, open circuit transmission line segment 25, open circuit transmission line segment 24, short circuit transmission line segment 22, tapered impedance transmission line segment 21, and output feed 2. Wherein: two ends of the middle short-circuit transmission line section 33 are connected with two ends of the transmission line section 32 to form a closed ring; the open transmission line node 31, the open transmission line node 35, the open transmission line node 36, the open transmission line node 37, the open transmission line node 38 and the open transmission line node 39 are respectively connected to the transmission line node 32, which form a multi-branch multi-mode resonator, and the input feeder 1 is coupled with the multi-mode resonator through a graded impedance transmission line node 11 and the connected open transmission line node 15 and open transmission line node 16. The output feed 2 is energy coupled to the multimode resonator through a graded impedance transmission line segment 21, and then through open transmission line segments 25 and 26 connected thereto. To improve input impedance matching, a short-circuited transmission line node 12 and an open-circuited transmission line node 14 are connected at the input feed 1. To improve output impedance matching, a short-circuited transmission line segment 22 and an open-circuited transmission line segment 24 are connected at the output feed 2.
The utility model discloses a utility model patent that grant publication number is CN203871450U discloses an ultra wide band pass filter with trap point, as shown in fig. 3, it includes medium base plate 1, form in the sculpture circuit layer 3 of medium base plate upper surface and the ground metal layer 2 that forms in medium base plate lower surface, wherein sculpture circuit layer 3 includes two 50 ohm match lines 4, four sections coupling microstrip lines 5, a ladder impedance line 6 and a resonance ring 7, this resonance ring 7 is squarely, be located upper portion in the sculpture circuit layer 3, ladder impedance line 6 is located resonance ring 7 and is connected with resonance ring 7 under, ladder impedance line 6 is the open circuit line, constitute on loading the low impedance line by one section high impedance line. The two 50-ohm matching lines 4 are symmetrically distributed on the left side and the right side of the joint of the stepped impedance line 6 and the resonance ring 7, and one side, close to the joint of the stepped impedance line 6 and the resonance ring 7, of each 50-ohm matching line 4 is connected with two sections of coupling microstrip lines 5. The resonance ring 7 has the function of generating a wider bandwidth, and the positions of the resonance modes can be adjusted by adjusting the length, the width and the impedance of the resonance ring 7 so as to be uniformly distributed in a passband range, thereby realizing the passband bandwidth of 3.1-10.6.
The bandpass filters disclosed in the above two patents can achieve ultra-wideband, but they have a common drawback: the size is too large and the degree of miniaturization is insufficient.
It can be seen that the prior art is still in need of improvement and development.
SUMMERY OF THE UTILITY MODEL
In view of the not enough of above-mentioned prior art, the utility model aims at providing an ultra wide band pass filter aims at solving among the prior art ultra wide band pass filter oversize, problem that the miniaturization degree is not enough.
The technical scheme of the utility model as follows:
an ultra-wideband bandpass filter comprising: the low-pass module is provided with a transverse groove, the lower end of the transverse groove is sequentially communicated with a first longitudinal groove, a second longitudinal groove and a third longitudinal groove from left to right, the first longitudinal groove and the second longitudinal groove are provided with a first defective microstrip transmission line, a second defective microstrip transmission line is arranged between the second longitudinal groove and the third longitudinal groove, and the first longitudinal groove, the second longitudinal groove, the third longitudinal groove, the transverse groove, the first defective microstrip transmission line and the second defective microstrip transmission line are combined to form a defective microstrip structure and enable the low-pass module to be equivalent to an RLC parallel circuit; the high-pass module is a semi-lumped high-pass module, comprising: the antenna comprises a first high-pass microstrip transmission line and a second high-pass microstrip transmission line, wherein a surface-mounted capacitor is arranged between the first high-pass microstrip transmission line and the second high-pass microstrip transmission line.
The effect of above-mentioned scheme lies in: the cascade connection of the low-pass module and the high-pass module can realize the basic function of the band-pass filter (that is, only signals with specific frequency are allowed to pass), but the ultra-wideband effect cannot be realized only by the cascade connection of the low-pass module and the high-pass module. The utility model discloses utilize first longitudinal groove, second longitudinal groove, third longitudinal groove and the transverse groove of seting up to change the current path, increased the current path length, utilize the additional inductance effect of defect microstrip structure to and the characteristic of the wide stop band of corresponding low pass module and slow wave, enlarged band-pass filter's bandwidth, specifically, along with the increase of transverse groove length, additional inductance grow, resonant frequency moves to the low frequency; as the width of the second longitudinal groove increases, the additional capacitance decreases and the resonance frequency moves to a high frequency; as the width of the lateral slot increases, the additional effect shows an inductive behavior, with the resonance behavior shifting towards lower frequencies; therefore, the utility model discloses an above-mentioned defect microstrip structure has enlarged band pass filter's bandwidth, combines to introduce the semi-lumped high pass module of SMD electric capacity, has formed ultra wide band pass filter, and in addition, the volume of ultra wide band pass filter has been reduced to the appearance value size through controlling SMD electric capacity, has realized ultra wide band pass filter's miniaturization.
In a further preferred scheme, one side of the low-pass module is connected with a half-wavelength short-circuit branch microstrip transmission line, one end of the half-wavelength short-circuit branch microstrip transmission line, which is far away from the low-pass module, is provided with a first round hole, the dielectric plate is provided with a first metal column, the first metal column penetrates through the dielectric plate and is connected with the metal patch, and the first round hole is matched with the first metal column.
The effect of above-mentioned scheme lies in: by adjusting the structural size of the half-wavelength short-circuit branch microstrip transmission line, a transmission zero point can be introduced into the upper sideband, so that an ultra-wideband of 3.1GHz to 10.6GHz is generated, the bandwidth of the ultra-wideband filter is further expanded, and meanwhile, the in-band frequency selectivity of the ultra-wideband band-pass filter can be improved, so that the relative bandwidth of the ultra-wideband band-pass filter reaches 131%.
In a further preferred scheme, the half-wavelength short-circuit stub microstrip transmission line is in an L shape.
The effect of above-mentioned scheme lies in: the ultra-wideband band-pass filter is loaded with the L-shaped half-wavelength short-circuit branch microstrip transmission line, so that the size of the ultra-wideband band-pass filter can be reduced (if the half-wavelength short-circuit branch microstrip transmission line is in a straight shape, the width of the ultra-wideband band-pass filter is inevitably increased, and the space utilization rate of the ultra-wideband band-pass filter is insufficient), and the miniaturization degree of the ultra-wideband band-pass filter is further improved.
In a further preferred aspect, the low pass module further includes: the microstrip antenna comprises a first microstrip feeder line, a first microstrip transmission line and a second microstrip transmission line which are sequentially arranged from left to right, wherein the first longitudinal groove, the second longitudinal groove, the third longitudinal groove and the transverse groove are all arranged on the first microstrip transmission line.
The effect of above-mentioned scheme lies in: the first microstrip transmission line is provided with the groove to form a defective microstrip structure, so that the structure processing of the low-pass module equivalent RLC parallel circuit is convenient, simple and reliable, and the low-pass module can realize the function of signal interception higher than a specific frequency band under a small volume.
In a further preferred scheme, the upper end of the first transmission microstrip line is connected with an open-circuit stub microstrip transmission line in a butting manner, and the open-circuit stub microstrip transmission line is rectangular.
The effect of above-mentioned scheme lies in: the in-band frequency selectivity of the ultra-wideband band-pass filter can be improved by adjusting the structural size of the open-circuit branch microstrip transmission line.
In a further preferred aspect, the high-pass module further comprises: the second microstrip transmission line is a common transmission line of the high-pass module and the low-pass module.
The effect of above-mentioned scheme lies in: the second microstrip transmission line can reduce the use of one microstrip, thereby reducing the size of the ultra-wideband band-pass filter and further improving the miniaturization of the ultra-wideband band-pass filter.
In a further preferred embodiment, the first high-pass microstrip transmission line and the second high-pass microstrip transmission line are both L-shaped, and the first high-pass microstrip transmission line and the second high-pass microstrip transmission line are arranged in mirror symmetry.
The effect of above-mentioned scheme lies in: the first high-pass microstrip transmission line and the second high-pass microstrip transmission line are bent into an L shape, so that the size of the ultra-wideband band-pass filter can be reduced, and the miniaturization of the ultra-wideband band-pass filter is further improved.
In a further preferred embodiment, the high-pass module is equivalent to an LC series circuit, which has two inductors and a capacitor connected in parallel with the two inductors, and the two inductors are grounded.
The effect of above-mentioned scheme lies in: through the arrangement of the preferred scheme, the two grounded inductors form the L-shaped resonator, so that the notch band is generated by adding the L-shaped resonator under the condition that the total size of the ultra-wideband band-pass filter is almost the same, and the notch can work in the X-band by controlling the length of the L-shaped resonator.
In a further preferred aspect, the high-pass module further comprises: the third high-pass microstrip transmission line is provided with a second round hole, the dielectric plate is provided with a second metal column, the second metal column penetrates through the dielectric plate and is connected with the metal patch, the second round hole is matched with the second metal column, and the first high-pass microstrip transmission line and the second high-pass microstrip transmission line are grounded through the third high-pass microstrip transmission line and the second metal column.
The effect of above-mentioned scheme lies in: the matching relation of the second round hole and the second metal column ensures that the third high-pass microstrip transmission line can be tightly attached to the second metal column, so that the reliability of inductor grounding is ensured; and secondly, the third high-pass microstrip transmission line is quickly positioned and installed through the matching relation of the second round hole and the second metal column.
In a further preferred embodiment, the third high-pass microstrip transmission line is integrally formed with the first high-pass microstrip transmission line and the second high-pass microstrip transmission line, and is an "n" type with right-angled corners.
The effect of above-mentioned scheme lies in: the third high-pass microstrip transmission line is integrally formed with the first high-pass microstrip transmission line and the second high-pass microstrip transmission line, so that the third high-pass microstrip transmission line, the first high-pass microstrip transmission line and the second high-pass microstrip transmission line can be integrally formed, and the third high-pass microstrip transmission line, the first high-pass microstrip transmission line and the second high-pass microstrip transmission line are extremely simple; and set up the third high-pass microstrip transmission line for the corner is "n" type of right angle, then make things convenient for processing of three, during production, directly excise unnecessary material on the basis of rectangle sheetmetal can.
In a further preferred scheme, the patch capacitor is packaged by an SMD (surface mounted device), and the capacitance value is 0.5pF of Murata GRM18 capacitor.
In a further preferred embodiment, the dielectric plate is a rectangular parallelepiped, the dielectric body has a size of 12.6mm × 8.3mm × 0.508mm, and is made of Rogers RT/duroid 5880 material having a dielectric constant of 2.2 and a loss tangent of 0.0009.
Compared with the prior art, the utility model provides an ultra wide band pass filter, include: the low-pass module is provided with a transverse groove, the lower end of the transverse groove is sequentially communicated with a first longitudinal groove, a second longitudinal groove and a third longitudinal groove from left to right, the first longitudinal groove and the second longitudinal groove are provided with a first defective microstrip transmission line, a second defective microstrip transmission line is arranged between the second longitudinal groove and the third longitudinal groove, and the first longitudinal groove, the second longitudinal groove, the third longitudinal groove, the transverse groove, the first defective microstrip transmission line and the second defective microstrip transmission line are combined to form a defective microstrip structure and enable the low-pass module to be equivalent to an RLC parallel circuit; the high-pass module is a semi-lumped high-pass module, comprising: the antenna comprises a first high-pass microstrip transmission line and a second high-pass microstrip transmission line, wherein a surface-mounted capacitor is arranged between the first high-pass microstrip transmission line and the second high-pass microstrip transmission line. The utility model provides an ultra wide band pass filter utilizes first longitudinal groove, second longitudinal groove, third longitudinal groove and the transverse groove of seting up to change the electric current route, has increased electric current route length, utilizes the additional inductance effect of defect microstrip structure to and the characteristic of the wide stop band of corresponding low pass module and slow wave, has enlarged band width of band pass filter, specifically speaking, along with the increase of transverse groove length, additional inductance grow, resonant frequency moves to the low frequency; as the width of the second longitudinal groove increases, the additional capacitance decreases and the resonance frequency moves to a high frequency; as the width of the lateral slot increases, the additional effect shows an inductive behavior, with the resonance behavior shifting towards lower frequencies; therefore, the utility model discloses an above-mentioned defect microstrip structure has enlarged band pass filter's bandwidth, combines to introduce the semi-lumped high pass module of SMD electric capacity, has formed ultra wide band pass filter, and in addition, the volume of ultra wide band pass filter has been reduced to the appearance value size through controlling SMD electric capacity, has realized ultra wide band pass filter's miniaturization.
Drawings
Fig. 1 is a perspective view of CN105024124A in the prior art.
Figure 2 is a front view of CN105024124A in the prior art.
Fig. 3 is a perspective view of CN203871450U in the prior art.
Fig. 4 is a front view of an ultra-wideband band-pass filter according to a preferred embodiment of the present invention.
Fig. 5 is a schematic structural diagram of a filtering module used in the ultra-wideband band-pass filter of the present invention.
Fig. 6 is a circuit diagram of an equivalent RLC parallel circuit of the mid-low pass module of the present invention.
Fig. 7 is a graph comparing transmission coefficient curves of filters provided with defective microstrip structures and filters without defective microstrip structures.
Fig. 8 is a schematic diagram showing the comparison of the transmission coefficients of the filter in the case of the half-wavelength short-circuited stub-free microstrip transmission line and the case of the half-wavelength short-circuited stub-added microstrip transmission line.
FIG. 9 is the utility model discloses the S of well ultra wide band pass filter11And S21Graph is shown.
Fig. 10 is a group delay curve diagram of the ultra-wideband band-pass filter of the present invention.
Fig. 11 is a diagram illustrating critical parameter dimensions of the middle filter module according to the present invention.
Fig. 12 is an equivalent LC series circuit diagram of the high pass module in the preferred embodiment of the present invention.
Fig. 13 is a graph comparing the full-wave simulation of the mid-low pass module and the response curve of its equivalent RLC parallel circuit.
Detailed Description
The utility model provides an ultra wide band pass filter, for making the utility model discloses a purpose, technical scheme and effect are clearer, clear and definite, and it is right that the following refers to the attached drawing and lifts the example the utility model discloses further detailed description. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The utility model provides an ultra wide band pass filter, as shown in FIG. 4, ultra wide band pass filter includes: the metal patch 100, the dielectric plate 200 and the filter module 300 are sequentially arranged from bottom to top, wherein the structures of the metal patch 100 and the dielectric plate 200 are the prior art (the parameters will be described in detail below), and are not described herein again; the filtering module 300 is used for cooperating with the metal patch 100 and the dielectric plate 200 to realize the setting function and effect of the ultra-wideband band-pass filter; the basic function of the ultra-wideband band-pass filter provided by the present invention is the same as that of the band-pass filter in the prior art, and all the functions are to pass the frequency component in a certain frequency range, but attenuate the frequency components in other ranges to an extremely low level.
The same as the prior art, the filtering module 300 of the present invention also includes a low-pass module and a high-pass module, and filters the signal higher than the designated frequency through the low-pass module, and filters the signal lower than the designated frequency through the high-pass module, so as to only allow the signal in the designated frequency range to pass through.
However, the low-pass modules (in the preferred embodiment, 311 to 314, 312a, 312b, 312c, 312d and 330, specifically as shown in FIG. 5, and since 330 is a common transmission line for the low-pass module and the high-pass module in the preferred embodiment, it is indicated here by the independent reference numeral 330) and the high-pass modules (in the preferred embodiment, 321 to 325, specifically as shown in FIG. 5, it is noted that the dotted line in FIG. 5 does not really exist, and is added for clearly defining the transmission lines in the following description of the present invention) are different from the prior art in the first place: as shown in fig. 5, the transverse groove 312d has been opened to the low pass module in the present invention, the lower end of the transverse groove 312d is sequentially communicated with the first longitudinal groove 312a, the second longitudinal groove 312b and the third longitudinal groove 312c from left to right, the first longitudinal groove 312a and the second longitudinal groove 312b are provided with the first defective microstrip transmission line, the second defective microstrip transmission line is provided between the second longitudinal groove 312b and the third longitudinal groove 312c, and the first longitudinal groove 312a, the second longitudinal groove 312b, the third longitudinal groove 312c, the transverse groove 312d, the first defective microstrip transmission line and the second defective microstrip transmission line jointly form the defective microstrip structure, and the low pass module is equivalent to the RLC parallel circuit (the RLC parallel circuit is shown in fig. 6).
The RLC parallel circuit is derived by using ABCD matrix derivation, and the matrix equation is as follows:
wherein Z is0Is port impedance, when ZG＝ZL＝Z0When Y is 1/R + j (ω C-1/ω L)), since the defective microstrip structure has a band-stop response, its transfer function can be described as:
S21(ω)＝2Z0/(2Z0+1/Y)
since the RLC circuit oscillates, the electric field energy is equal to the magnetic energy, Z is 1/Y is R (resistance value), and thus the resistance value R is obtained:
R＝2Z0(1/|S21(ω)|-1)/f＝fr
from Q ═ ω rCR and BW ═ fr/Q, capacitance C and inductance L can be obtained:
C＝1/(2πR*BW)
L＝1/((2πfr)2C)
according to the above formula, the figure of merit is proportional to the C value, but the sideband selectivity of the bandstop response is not large, so the utility model introduces a correction factor β from adjusting the sideband selectivity:
C＝(1*(1+β))/(2πR*BW)
according to the formula, the initial parameter value is calculated to obtain: r3881' Ω, β 1.5, C0.25 pF, and L1.0132 nH, so as to obtain the parameter values of the equivalent RLC parallel circuit of the low pass module, and perform circuit simulation based on the parameter values, as can be seen from fig. 13, the circuit response has good consistency with the full-wave simulation of the ultra-wideband band-pass filter.
Specifically, the present invention changes the current path by the first longitudinal slot 312a, the second longitudinal slot 312b, the third longitudinal slot 312c and the transverse slot 312d (taking the structure shown in fig. 5 as an example, under the condition that the above-mentioned groove is not opened, the current path of the low-pass module part is the first microstrip feeder 311, the first microstrip transmission line 312 and the second microstrip transmission line 330, and at most, the equivalent resistance is generated due to the change of the microstrip transmission line size, and the equivalent RLC parallel circuit is not generated; after the above-mentioned groove is opened, the first microstrip feeder 311, the first microstrip transmission line 312, the second microstrip transmission line 330, the first defective microstrip transmission line, the second defective microstrip transmission line and the above-mentioned groove will be equivalent to the RLC parallel circuit, thereby realizing the low-pass filtering function under the small volume); specifically, as the length of the transverse slot 312d increases, the additional inductance becomes greater and the resonant frequency shifts to a lower frequency; as the width of the second longitudinal groove 312b increases, the additional capacitance decreases and the resonance frequency shifts to a high frequency; as the width of the lateral slot 312d increases, the additional effect shows an inductive characteristic, with the resonance characteristic moving towards lower frequencies; therefore, the utility model discloses an above-mentioned defect microstrip structure has enlarged band pass filter's bandwidth, combines to introduce SMD electric capacity 323's semi-lumped high pass module, has formed ultra wide band pass filter. In addition, the defected microstrip structure has the characteristic of a slow wave stop band, and the in-band high-frequency performance of the ultra-wideband band-pass filter can be improved.
Fig. 7 is a graph showing a comparison of transmission coefficient curves of a filter provided with a defective Microstrip Structure and a non-Defective Microstrip Structure (DMS), which can be found by the comparison to have a wide stop-band low-pass characteristic, thereby improving the in-band selectivity of the filter by adjusting the size of the defective Microstrip Structure.
In practical implementation, the first longitudinal slot 312a, the second longitudinal slot 312b, the third longitudinal slot 312c and the transverse slot 312d are opened in the first microstrip transmission line 312.
The utility model provides a high pass module is semi-lumped high pass module, as shown in FIG. 5, it includes: the microstrip transmission line comprises a first high-pass microstrip transmission line 321 and a second high-pass microstrip transmission line 322, wherein a patch type capacitor 323 is arranged between the first high-pass microstrip transmission line 321 and the second high-pass microstrip transmission line 322. The sideband of the ultra-wideband band-pass filter can move to low frequency by controlling the capacitance value of the patch capacitor 323, so that the size of the ultra-wideband band-pass filter can be reduced, and the miniaturization of the ultra-wideband band-pass filter is realized.
In specific implementation, the chip capacitor 323 adopts an SMD package structure, and has a capacitance value of 0.5pF Murata GRM18 capacitor.
As the utility model discloses the preferred embodiment of ground, low pass module one side is connected with half wavelength short circuit minor matters microstrip transmission line 313, half wavelength short circuit minor matters microstrip transmission line 313 deviates from low pass module one end and has seted up first round hole, be provided with first metal post 340 on the dielectric plate, first metal post 340 run through the dielectric plate and with the metal patch is connected, first round hole with first metal post 340 looks adaptation, half wavelength short circuit minor matters microstrip transmission line 313 is through the cooperation ground connection of first round hole with first metal post 340.
By adjusting the structural size of the half-wavelength short-circuit branch microstrip transmission line 313, a transmission zero can be introduced into the upper sideband, so that an ultra-wideband of 3.1GHz to 10.6GHz is generated, the bandwidth of the ultra-wideband filter is further expanded, and meanwhile, the in-band frequency selectivity of the ultra-wideband band-pass filter can be improved, so that the relative bandwidth of the ultra-wideband band-pass filter reaches 131%. Fig. 8 shows a schematic diagram of the comparison of transmission coefficients of the filter in the case of no half-wavelength short-circuit branch microstrip transmission line 313 and the case of adding the half-wavelength short-circuit branch microstrip transmission line 313 (the dotted line is the transmission coefficient curve of no half-wavelength short-circuit branch microstrip transmission line 313, and the transmission coefficient curve of adding the half-wavelength short-circuit branch microstrip transmission line 313 is realized).
Further, the half-wavelength short-circuit branch microstrip transmission line 313 is in an L shape; the ultra-wideband band-pass filter is loaded with the L-shaped half-wavelength short-circuit branch microstrip transmission line 313, so that the size of the ultra-wideband band-pass filter can be reduced, and the miniaturization degree of the ultra-wideband band-pass filter is further improved.
Preferably, the low pass module further comprises: the first microstrip feeder 311, the first microstrip transmission line 312 and the second microstrip transmission line 330 are sequentially arranged from left to right, and the first longitudinal slot 312a, the second longitudinal slot 312b, the third longitudinal slot 312c and the transverse slot 312d are all arranged on the first microstrip transmission line 312. The first microstrip transmission line 312 is provided with a groove to form a defective microstrip structure, so that the structure processing of the low-pass module equivalent RLC parallel circuit is convenient, simple and reliable, and the low-pass module can realize the function of signal interception higher than a specific frequency band under a small volume.
In addition, the upper end of the first transmission microstrip line is connected with an open-circuit stub microstrip transmission line 314 in an abutting manner, and the open-circuit stub microstrip transmission line 314 is rectangular. The in-band frequency selectivity of the ultra-wideband band-pass filter can be improved by adjusting the structural size of the open-circuit branch microstrip transmission line 314.
According to another aspect of the present invention, the high pass module further comprises: a second microstrip transmission line 330 and a second microstrip feed line 325, wherein the second microstrip transmission line 330 is a common transmission line for the high-pass module and the low-pass module. The second microstrip transmission line 330 can be shared to reduce the use of one microstrip, thereby reducing the size of the ultra-wideband band-pass filter and further improving the miniaturization of the ultra-wideband band-pass filter.
Further, the first high-pass microstrip transmission line 321 and the second high-pass microstrip transmission line 322 are both L-shaped, and the first high-pass microstrip transmission line 321 and the second high-pass microstrip transmission line 322 are arranged in mirror symmetry. The first high-pass microstrip transmission line 321 and the second high-pass microstrip transmission line 322 are bent into an L shape, so that the size of the ultra-wideband band-pass filter can be reduced, and the miniaturization of the ultra-wideband band-pass filter is further improved.
Preferably, the high-pass module is equivalent to an LC series circuit (as shown in fig. 12, details of which are not repeated), the LC series circuit has two inductors and a capacitor connected in parallel with the two inductors, and the two inductors are grounded. Through the arrangement of the preferred scheme, the two grounded inductors form the L-shaped resonator, so that the notch band is generated by adding the L-shaped resonator under the condition that the total size of the ultra-wideband band-pass filter is almost the same, and the notch can work in the X-band by controlling the length of the L-shaped resonator.
Preferably, the high pass module further comprises: a third high-pass microstrip transmission line 324, wherein a second circular hole is formed in the third high-pass microstrip transmission line 324, a second metal pillar 350 is disposed on the dielectric plate, the second metal pillar 350 penetrates through the dielectric plate and is connected to the metal patch, the second circular hole is matched with the second metal pillar 350, and the first high-pass microstrip transmission line 321 and the second high-pass microstrip transmission line 322 are grounded through the third high-pass microstrip transmission line 324 and the second metal pillar 350. The matching relationship between the second circular hole and the second metal pillar 350, i.e., the third high-pass microstrip transmission line 324 can be tightly attached to the second metal pillar 350, thereby ensuring the reliability of the inductor grounding; secondly, the third high-pass microstrip transmission line 324 is positioned and installed quickly through the matching relationship between the circular holes and the cylinders.
In specific implementation, the third high-pass microstrip transmission line 324 is integrally formed with the first high-pass microstrip transmission line 321 and the second high-pass microstrip transmission line 322, and is an "n" type with right-angled corners. The third high-pass microstrip transmission line 324 is integrally formed with the first high-pass microstrip transmission line 321 and the second high-pass microstrip transmission line 322, so that the three can be integrally formed, and the three are very simple and convenient to produce and install and have high reliability; the third high-pass microstrip transmission line 324 is arranged to be an n-type with right-angled corners, so that the processing of the third high-pass microstrip transmission line, the third high-pass microstrip transmission line and the third high-pass microstrip transmission line is convenient, and when the third high-pass microstrip transmission line, the third high-pass microstrip transmission line and the third high-pass microstrip transmission.
In summary, in an embodiment of the present invention, an ultra-wideband band-pass filter includes: connected from left to right in turn: a first microstrip feed line 311, a first microstrip transmission line 312, a second microstrip transmission line 330, a first high-pass microstrip transmission line 321, a patch capacitor 323, a second high-pass microstrip transmission line 322, and a second microstrip feed line 325, the upper side band of the first microstrip transmission line 312 is provided with a half-wavelength short-circuit stub microstrip transmission line 313 (grounded) and an open-circuit stub microstrip transmission line 314, the first high-pass microstrip transmission line 321 and the second high-pass microstrip transmission line 322 are connected to a third high-pass microstrip transmission line 324, the first microstrip feed line 311 and the second microstrip feed line 325 are rectangular metal patches, and in addition, the first microstrip transmission line 312, the second microstrip transmission line 330, the first high-pass microstrip transmission line 321 and the second high-pass microstrip transmission line 322 are not rectangular metal patches either, the half-wavelength short-circuited stub microstrip transmission line 313, the first high-pass microstrip transmission line 321, and the second high-pass microstrip transmission line 322 are electrically connected to the metal patch 100 (considered as being grounded). The utility model provides an ultra wide band pass filter is convenient for batch production, and low cost, easily with other circuit integrations.
As shown in fig. 9, the utility model provides an ultra wide band pass filter's passband frequency range is 3.1GHz to 10.6GHz, and relative bandwidth reaches 131%, and insertion loss is less than 1dB in the passband, and return loss all is greater than 22dB in 3.1GHz and 10.6 GHz's frequency band, and the in-band selectivity is all good outward, and the rectangle coefficient is 1.2(25dB-bandwidth/3 dB-bandwidth). As shown in fig. 10, the group delay of the ultra-wideband band-pass filter provided by the present invention is better than 0.6 ns in the whole passband.
As shown in fig. 11, the key parameters in the embodiments provided by the present invention are shown in the following table (please look at the reference numerals of fig. 11 and the following table values, the unit is mm):
| L1 | W1 | L2 | W2 | L3 | W3 | L4 | D | L6 | W6 | R1 |
| 0.8 | 1.3 | 1.6 | 0.2 | 0.8 | 2.1 | 0.2 | 1.1 | 7.2 | 1.2 | 0.4 |
| L7 | W7 | L9 | W9 | L10 | L11 | W11 | L12 | W12 | R2 | |
| 1 | 0.6 | 5.2 | 0.3 | 4 | 1.6 | 1.6 | 2 | 3.2 | 0.15 |
it is to be understood that the invention is not limited to the above-described embodiments, and that modifications and variations may be made by those skilled in the art in light of the above teachings, and all such modifications and variations are intended to be included within the scope of the invention as defined in the appended claims.
Claims (10)
1. An ultra-wideband bandpass filter comprising: the low-pass module is provided with a transverse groove, the lower end of the transverse groove is sequentially communicated with a first longitudinal groove, a second longitudinal groove and a third longitudinal groove from left to right, the first longitudinal groove and the second longitudinal groove are provided with a first defective microstrip transmission line, a second defective microstrip transmission line is arranged between the second longitudinal groove and the third longitudinal groove, and the first longitudinal groove, the second longitudinal groove, the third longitudinal groove, the transverse groove, the first defective microstrip transmission line and the second defective microstrip transmission line jointly form a defective microstrip structure and enable the low-pass module to be equivalent to an RLC parallel circuit; the high-pass module is a semi-lumped high-pass module, comprising: the antenna comprises a first high-pass microstrip transmission line and a second high-pass microstrip transmission line, wherein a surface-mounted capacitor is arranged between the first high-pass microstrip transmission line and the second high-pass microstrip transmission line.
2. The ultra-wideband band-pass filter according to claim 1, wherein one side of the low-pass module is connected with a half-wavelength short-circuit branch microstrip transmission line, one end of the half-wavelength short-circuit branch microstrip transmission line, which is far away from the low-pass module, is provided with a first round hole, the dielectric plate is provided with a first metal post, the first metal post penetrates through the dielectric plate and is connected with the metal patch, and the first round hole is matched with the first metal post.
3. The ultra-wideband bandpass filter of claim 2 wherein the half-wavelength short-circuited stub microstrip transmission line is L-shaped.
4. The ultra-wideband bandpass filter of claim 1, wherein the low pass module further comprises: the microstrip antenna comprises a first microstrip feeder line, a first microstrip transmission line and a second microstrip transmission line which are sequentially arranged from left to right, wherein the first longitudinal groove, the second longitudinal groove, the third longitudinal groove and the transverse groove are all arranged on the first microstrip transmission line.
5. The ultra-wideband bandpass filter of claim 4, wherein the first microstrip transmission line has an open stub microstrip transmission line abutted thereon, and the open stub microstrip transmission line is rectangular.
6. The ultra-wideband bandpass filter of claim 1, wherein the high-pass module further comprises: the second microstrip transmission line is a common transmission line of the high-pass module and the low-pass module.
7. The ultra-wideband bandpass filter of claim 6 wherein the first high-pass microstrip transmission line and the second high-pass microstrip transmission line are both L-shaped, and the first high-pass microstrip transmission line and the second high-pass microstrip transmission line are arranged in mirror symmetry.
8. The ultra-wideband bandpass filter of claim 7 wherein the high-pass module is equivalent to an LC series circuit having two inductors and a capacitor, and wherein the two inductors are grounded.
9. The ultra-wideband bandpass filter of claim 8, wherein the high-pass module further comprises: the third high-pass microstrip transmission line is provided with a second round hole, the dielectric plate is provided with a second metal column, the second metal column penetrates through the dielectric plate and is connected with the metal patch, the second round hole is matched with the second metal column, and the first high-pass microstrip transmission line and the second high-pass microstrip transmission line are grounded through the third high-pass microstrip transmission line and the second metal column.
10. The ultra-wideband bandpass filter of claim 9 wherein the third high-pass microstrip transmission line is formed integrally with the first and second high-pass microstrip transmission lines and is "n" shaped with right angles at its corners.
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