CN203644913U - Trapped-wave frequency-band ultra-wide band-pass filter based on terminal-short-circuit cross resonator - Google Patents

Abstract

The utility model discloses a trapped-wave frequency-band ultra-wide band-pass filter based on a terminal-short-circuit cross resonator, and the filer comprises the cross resonator, three metalized through holes disposed at tail ends of three stub lines of the cross resonator, and a parallel coupling feeder-line structure. The filter provided by the utility model employs the design of distribution-parameter micro-strip lines. The filter provided by the utility model is light in weight, is high in reliability, is excellent in performance, is good in temperature stability, is low in cost of batch production, is especially suitable for the corresponding microwave communication, a digital radar, military and civil multi-mode and multipath communication system terminals, and corresponding systems which have strict requirements for the weight, performance and reliability.

Description

Trap frequency range ultra wide band bandpass filter based on the cross resonator of terminal short circuit

Technical field

The utility model belongs to microwave and millimeter wave technical field, particularly a kind of trap frequency range ultra wide band bandpass filter based on the cross resonator of terminal short circuit.

Background technology

2002, (the Federal Communications Commission of FCC, FCC) allow 3.1GHz～10.6GHz frequency range civilian, be with a branch of dawn to the development of the communications field, academia and industrial quarters have been carried out the research to super-broadband tech in ultra-wideband devices in high gear subsequently.Super-broadband tech is extensive application in military affairs, civilian radio communication, the develop rapidly of wireless communication system proposes more arduous requirement to existing system, especially for wireless transmission receiving system, the compatibling problem between radio ultra wide band system and existing communication system more and more comes into one's own.And filter is requisite critical elements in super broad band radio communication system, play the significant role that isolates useful signal.For the impact that existing wireless system brings within the scope of 3.1GHz～10.6GHz, can not be ignored, be for example applied to C-band and X-band and the WLAN signal of satellite communication.For fear of with the existing phase mutual interference of communicating by letter, all effectively suppress the how logical ultra-wide band filter disturbing in the urgent need to the high stop-band filter of function admirable and in whole ultra wide band range.Therefore, research have trap frequency range ultra wide band bandpass filter in whole ultra wide band range very important meaning.Lot of domestic and international scholar is studied this, finds that they mainly can classify as three kinds at trap frequency band method for designing: loading open stub method, asymmetric I/O coupled method and loading have other resonator method of controllable transmission zero points.Use the intrinsic transmission zero of multimode resonator self and no longer additionally use the trap method for designing of the resonators such as other such as open stub be not also mentioned and discuss.Not yet find correlative study and the report of the trap frequency range ultra wide band bandpass filter based on the cross resonator of terminal short circuit.

Utility model content

The trap frequency range ultra wide band bandpass filter based on the cross resonator of terminal short circuit that the purpose of this utility model is to provide that a kind of volume is little, lightweight, reliability is high, is easy to processing, cost is low.

The technical scheme that realizes the utility model object is: a kind of trap frequency range ultra wide band bandpass filter based on the cross resonator of terminal short circuit, comprise cross resonator, four microstrip lines of this cross resonator are respectively the first microstrip line along clockwise direction, the second microstrip line, the 3rd microstrip line, the 4th microstrip line, the first microstrip line is positioned at the top, wherein the second microstrip line and the 4th microstrip line are about y axial symmetry, the end of the first microstrip line arranges the first plated-through hole, the end of the second microstrip line arranges the second plated-through hole, the end of the 4th microstrip line arranges the 3rd plated-through hole, the 6th microstrip line and the 7th microstrip line are coupled with the 3rd microstrip line simultaneously, the 6th microstrip line one end is connected with the 5th microstrip line, the 5th microstrip line other end is connected with first input end, the 7th microstrip line one end is connected with the 8th microstrip line, the 8th microstrip line other end is connected with the first output.

Compared with prior art, its remarkable advantage is the utility model: (1) the utility model can produce according to self structure trap frequency range in passband; (2) in-band insertion loss is little; (3) group delay is smooth; (4) adopt microstrip structure, circuit structure is simple, and volume is little, lightweight, is easy to processing, and technique is simply ripe; (5) utilize the consistency of micro-production in enormous quantities with processing technology, obtain high finished product rate and low cost.

Below in conjunction with specific embodiment, the utility model is done to comparatively detailed description.

Brief description of the drawings

Fig. 1 is the cross resonator equivalent circuit diagram of terminal short circuit of the trap frequency range ultra wide band bandpass filter of the utility model based on the cross resonator of terminal short circuit.

Fig. 2 is that zero limit of the cross resonator of short circuit termination of the trap frequency range ultra wide band bandpass filter of the utility model based on the cross resonator of terminal short circuit is with impedance ratio k ₁and k ₂change curve.

Fig. 3 is the structure chart of the trap frequency range ultra wide band bandpass filter of the utility model based on the cross resonator of terminal short circuit.

Fig. 4 is that the relative bandwidth of the trap frequency range ultra wide band bandpass filter of the utility model based on the cross resonator of terminal short circuit is with impedance Z ₃change curve (Z ₄=100 Ω).

Fig. 5 is that the trap frequency range centre frequency of the trap frequency range ultra wide band bandpass filter of the utility model based on the cross resonator of terminal short circuit is with the change curve of the cross resonator minor matters of terminal short circuit length.

Fig. 6 is emulation and the measured result S parameter of the trap frequency range ultra wide band bandpass filter of the utility model based on the cross resonator of terminal short circuit.

Embodiment

The utility model discloses a kind of trap frequency range ultra wide band bandpass filter based on the cross resonator of terminal short circuit, comprise cross resonator, four articles of microstrip lines of this cross resonator are respectively the first microstrip line 1, the second microstrip line 2, the 3rd microstrip line 3, the 4th microstrip line 4 along clockwise direction, the first microstrip line 1 is positioned at the top, wherein the second microstrip line 2 and the 4th microstrip line 4 are about y axial symmetry, and the end of the first microstrip line 1 arranges the first plated-through hole V ₁, the end of the second microstrip line 2 arranges the second plated-through hole V ₂, the end of the 4th microstrip line 4 arranges the 3rd plated-through hole V ₃the 6th microstrip line 6 and the 7th microstrip line 7 are coupled with the 3rd microstrip line 3 simultaneously, the 6th microstrip line 6 one end are connected with the 5th microstrip line 5 one end, the 5th microstrip line 5 other ends are connected with first input end Port1, the 7th microstrip line 7 one end are connected with the 8th microstrip line 8 one end, and the 8th microstrip line 8 other ends are connected with the first output Port2; The length of the first microstrip line 1 is less than the length of the 3rd microstrip line 3.

The end of described the first microstrip line 1 arranges the first plated-through hole V ₁, the end of the second microstrip line 2 arranges the second plated-through hole V ₂, the end of the 4th microstrip line 4 arranges the 3rd plated-through hole V ₃, these plated-through holes are used for ground connection.

The size of described dimension of microstrip line, plated-through hole size and coupling space is adjustable.

Described the 5th microstrip line 5 and the 8th microstrip line 8 are on same straight line, and this straight line is parallel with the second microstrip line 2.

The impedance of the 5th microstrip line 5 and the 8th microstrip line 8 equates, is 50 Ω or 75 Ω.

The 4th microstrip line 4 that this filter transmission zero is corresponding and the electrical length of the 3rd microstrip line 3 meet respectively following formula:

${\mathrm{\θ}}_2={\tan }^{-1}\left(\frac{-2Z_1{Z}_3\tan {\mathrm{\θ}}_1\tan {\mathrm{\θ}}_3}{Z_2{Z}_3\tan {\mathrm{\θ}}_3+Z_1{Z}_2\tan {\mathrm{\θ}}_1}\right)$

${\mathrm{\&theta;}}_3={\tan }^{-1}\left(\frac{-Z_1{\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="HDA0000420370230000012.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2\tan {\mathrm{\&theta;}}_1\tan {\mathrm{\&theta;}}_2}{Z_2{Z}_3\tan {\mathrm{\&theta;}}_2+2Z_1{Z}_3\tan {\mathrm{\&theta;}}_1}\right)$

In formula, meaning of parameters is Z ₁the characteristic impedance of the 3rd microstrip line 3, Z ₂the characteristic impedance of the 4th microstrip line 4, Z ₃the characteristic impedance of the first microstrip line 1, θ ₁the electrical length of the 3rd microstrip line 3, θ ₂the electrical length of the 4th microstrip line 4, θ ₃it is the electrical length of the first microstrip line 1.

Below in conjunction with accompanying drawing, the utility model is described in further detail.

In conjunction with Fig. 1, Fig. 3, the trap frequency range ultra wide band bandpass filter of the utility model based on the cross resonator of terminal short circuit, is respectively θ by electrical length ₁, θ ₂, θ ₃, θ ₄microstrip line form cross resonator; There is plated-through hole in three stub end of resonator, be used for ground connection; Adopt parallel coupling feeder line structure at input/output terminal.Particularly, the utility model comprises cross resonator, four articles of microstrip lines of this cross resonator are respectively the first microstrip line 1, the second microstrip line 2, the 3rd microstrip line 3, the 4th microstrip line 4 along clockwise direction, the first microstrip line 1 is positioned at the top, wherein the second microstrip line 2 and the 4th microstrip line 4 are about y axial symmetry, and the end of the first microstrip line 1 arranges the first plated-through hole V ₁, the end of the second microstrip line 2 arranges the second plated-through hole V ₂, the end of the 4th microstrip line 4 arranges the 3rd plated-through hole V ₃the 6th microstrip line 6 and the 7th microstrip line 7 are coupled with the 3rd microstrip line 3 simultaneously, the 6th microstrip line 6 one end are connected with the 5th microstrip line 5, the 5th microstrip line 5 other ends are connected with first input end Port1, the 7th microstrip line 7 one end are connected with the 8th microstrip line 8, and the 8th microstrip line 8 other ends are connected with the first output Port2.

The trap frequency range ultra wide band bandpass filter of the utility model based on the cross resonator of terminal short circuit, its operation principle is summarized as follows: the utility model designs based on the cross resonator of terminal short circuit, so we first discuss the cross resonator principle of terminal short circuit.1) the cross resonator of terminal short circuit as shown in Figure 1, itself has two transmission poles and a transmission zero, and its input impedance and zero limit can be expressed as:

$Z_{\mathrm{in}2}=j\frac{Z_1{Z}_2{Z}_3+Z_1({\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="HDA0000420370230000012.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2+2Z_3)}{Z_1({\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="HDA0000420370230000012.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2+2Z_3)\cot \mathrm{\&theta;}-Z_2{Z}_3\tan \mathrm{\&theta;}}---\left(1\right)$

${\mathrm{<figure-callout\; id="1"\; label="f\; Bp"\; filenames="HDA0000420370230000012.png"\; state="\{\{state\}\}">f</figure-callout>}}_{\mathrm{Bp}}=\frac{2f_0}{\mathrm{\&pi;}}{\tan }^{-1}\left(\sqrt{\frac{Z_1({\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="HDA0000420370230000012.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2+2Z_3)}{Z_2{Z}_3}}\right)---\left(2\right)$

${\mathrm{<figure-callout\; id="2"\; label="f\; Bp"\; filenames="HDA0000420370230000012.png"\; state="\{\{state\}\}">f</figure-callout>}}_{\mathrm{Bp}}=\frac{2f_0}{\mathrm{\&pi;}}{\tan }^{-1}(-\sqrt{\frac{Z_1({\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="HDA0000420370230000012.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2+2Z_3)}{Z_2{Z}_3}})---\left(3\right)$

f _Bz1=f ₀ (4)

Wherein f _{Β p1,2}and f _{Β z1}represent respectively transmission pole and the zero frequency of this resonator, Z ₁, Z ₂, Z ₃, Z ₄, θ ₁, θ ₂, θ ₃, θ ₄respectively characteristic impedance and the electrical length of the 3rd microstrip line 3, the 4th microstrip line 4, the first microstrip line 1 and the second microstrip line 2.If k ₁=Z ₂/ Z ₁, k ₂=Z ₃/ Z ₁, Fig. 2 has provided its zero limit with impedance ratio k ₁and k ₂change curve, work as k ₁constant and k ₂become large or k ₂constant k ₁when increase, two transmission poles are by gradually away from the transmission zero that is positioned at centre frequency place.

2) disturb with the signal that suppresses other communication system for the intrinsic transmission zero of the better cross resonator of control terminal short circuit, applicant will discuss θ ₁≠ θ ₂≠ θ ₃(θ ₂=θ ₄) situation under the characteristic of the ultra-wide band filter that designs based on this quasi resonant oscillator.Our research emphasis generates needed trap frequency band at intrinsic zero point of the cross resonator of short circuit by being placed on how to utilize now.Work as θ ₁≠ θ ₂≠ θ ₃time, the input impedance of resonator as shown in Figure 1 can be expressed as:

$Z_{\mathrm{in}2}=j{Z}_1\frac{Z_2{Z}_3\tan {\mathrm{\&theta;}}_2\tan {\mathrm{\&theta;}}_3+Z_1{\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="HDA0000420370230000012.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2\tan {\mathrm{\&theta;}}_1\tan {\mathrm{\&theta;}}_2+2Z_1{Z}_3\tan {\mathrm{\&theta;}}_1\tan {\mathrm{\&theta;}}_3}{Z_1{\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="HDA0000420370230000012.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2\tan {\mathrm{\&theta;}}_2+2Z_1{Z}_3\tan {\mathrm{\&theta;}}_3-Z_2{Z}_3\tan {\mathrm{\&theta;}}_1\tan {\mathrm{\&theta;}}_2\tan {\mathrm{\&theta;}}_3}---\left(5\right)$

The insertion loss S of filter ₂₁for:

$S_{21A}=\frac{Y_{\mathrm{oddA}}-Y_{\mathrm{evenA}}}{(Y_0+Y_{\mathrm{oddA}})(Y_0+Y_{\mathrm{evenA}})}---\left(6\right)$

Wherein:

$Y_{\mathrm{oddA}}=\frac{2\mathrm{jA}\sin {\mathrm{\&theta;}}_1\cos {\mathrm{\&theta;}}_1}{{\mathrm{<figure-callout\; id="2"\; label="A"\; filenames="HDA0000420370230000012.png"\; state="\{\{state\}\}">A</figure-callout>}}^2{\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="HDA0000420370230000012.png"\; state="\{\{state\}\}">cos</figure-callout>}}^2{\mathrm{\&theta;}}_1-B^2}---\left(7\right)$

$Y_{\mathrm{evenA}}=\frac{Y_{\mathrm{rA}}A\sin \left(2{\mathrm{\&theta;}}_1\right)+4j{\sin }^2{\mathrm{\&theta;}}_1}{A\sin \left(2{\mathrm{\&theta;}}_1\right)+j{Y}_{\mathrm{rA}}(B^2-A^2{\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="HDA0000420370230000012.png"\; state="\{\{state\}\}">cos</figure-callout>}}^2{\mathrm{\&theta;}}_1)}---\left(8\right)$

$Y_{\mathrm{rA}}=\frac{1}{2}{Y}_{\mathrm{in}2}=\frac{1}{2Z_{\mathrm{in}2}}---\left(9\right)$

Can find out, work as Z _in2=0 o'clock, formula (8) can replace with:

$Y_{\mathrm{evenA}}=\frac{A\sin \left(2{\mathrm{\&theta;}}_1\right)}{j(B^2-A^2{\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="HDA0000420370230000012.png"\; state="\{\{state\}\}">cos</figure-callout>}}^2{\mathrm{\&theta;}}_1)}---\left(10\right)$

Wherein, A=Z _oe+ Z _oo, B=Z _oe-Z _oo.Obviously, the strange mould input admittance Y in it and formula (7) _oddAequate, that is to say that now we can obtain the transmission zero of filter.Simplifying can be in the hope of the short circuit minor matters electrical length corresponding to transmission zero after calculating:

${\mathrm{\&theta;}}_2={\tan }^{-1}\left(\frac{-2Z_1{Z}_3\tan {\mathrm{\&theta;}}_1\tan {\mathrm{\&theta;}}_3}{Z_2{Z}_3\tan {\mathrm{\&theta;}}_3+Z_1{\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="HDA0000420370230000012.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2\tan {\mathrm{\&theta;}}_1}\right)---\left(11\right)$

${\mathrm{\&theta;}}_3={\tan }^{-1}\left(\frac{-Z_1{\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="HDA0000420370230000012.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2\tan {\mathrm{\&theta;}}_1\tan {\mathrm{\&theta;}}_2}{Z_2{Z}_3\tan {\mathrm{\&theta;}}_2+2Z_1{Z}_3\tan {\mathrm{\&theta;}}_1}\right)---\left(12\right)$

It is emphasized that the θ in the design ₁electrical length be corresponding 90 ° of filter center frequency all the time.Fig. 4 is the change curve with minor matters impedance based on terminal short circuit cross resonator ultra wide band bandpass filter relative bandwidth, can find out by the impedance of rational adjusting filter minor matters, the bandwidth of filter is changed in the larger context, and relative bandwidth increase the change along with minor matters impedance greatly.

According to formula (11) and (12), Fig. 5 has provided l _a1when=6.2mm, filter trap frequency range is with the situation of change of the minor matters length of terminal short circuit cross resonator.P point in figure represents to work as θ ₁=θ ₂=θ ₃=θ ₄time, the trap of filter will appear at centre frequency place.

The utility model has carried out repeatedly implementing experiment, below the experiment situation of brief description embodiment:

Embodiment is that centre frequency is the fixed trap frequency range ultra wide band bandpass filter based on the cross resonator of terminal short circuit of 6.65GHz.Applicant's processing and fabricating a fixed trap frequency range ultra wide band bandpass filter based on the cross resonator of terminal short circuit, the dielectric-slab using is RO4003(ε _r=3.38, h=0.508mm), the detailed dimensions of filter is that length and the width of the first microstrip line 1 is respectively l _a3=3.2mm, w _a3=0.3mm, length and the width of the second microstrip line 2 and the 4th microstrip line 4 are respectively l _a2=11.5mm, w _a2=0.4mm, length and the broadband of the 3rd microstrip line 3 are respectively l _a1=6.2mm, w _c2=0.1mm, the 6th microstrip line 6 and the 7th microstrip line 7 length and width are respectively l _a1=6.2mm, w _c1=0.2mm, the 6th microstrip line 6 and the 3rd microstrip line 3 coupling spaces are s=0.08mm, and the 7th microstrip line 7 and the 3rd microstrip line 3 coupling spaces are s=0.08mm, and the 5th microstrip line 5 and the 8th microstrip line 8 are all 50 Ω microstrip lines.The emulation of this filter and measured result S parameter provide in Fig. 6.Can see the centre frequency f of filter ₀=6.65GHz, free transmission range be 3.5GHz to 9.8GHz, relative bandwidth is 94.7%, minimum insertion loss is that the return loss in 0.8dB and passband is better than 10dB.On it, to be greater than the Out-of-band rejection frequency range of 20dB be that 10.5GHz is to 18GHz to stopband.Four transmission poles of filter lay respectively at 3.7GHz, 6.5GHz, and 8.3GHz and 9.1GHz have two transmission zeros at 1.9GHz and 10.8GHz place near filter cutoff frequency simultaneously.Under the help of the intrinsic transmission zero of the cross resonator of terminal short circuit, a trap frequency range that is positioned at 5.8GHz is devised, its centre frequency inhibition ability is greater than 30dB, will well suppress the signal of the communication systems such as WLAN (wireless local area network) to the noise jamming of ultra-wideband communications.The structure of whole filter is also very compact, only has 23.6 × 11.1mm ²(0.36 λ _g ², λ _grepresent guide wavelength corresponding to filter center frequency).The group delay of filter is very smooth, and the group delay in passband is about 0.45ns.

The foregoing is only embodiment of the present utility model, not in order to limit the utility model, all within the utility model spirit and principle, any amendment of making, be equal to replacement, improvement etc., within all should being included in the utility model protection range.

Claims (5)

1. the trap frequency range ultra wide band bandpass filter based on the cross resonator of terminal short circuit, it is characterized in that, comprise cross resonator, four articles of microstrip lines of this cross resonator are respectively the first microstrip line (1), the second microstrip line (2), the 3rd microstrip line (3), the 4th microstrip line (4) along clockwise direction, the first microstrip line (1) is positioned at the top, wherein the second microstrip line (2) is with the 4th microstrip line (4) about y axial symmetry, and the end of the first microstrip line (1) arranges the first plated-through hole V ₁, the end of the second microstrip line (2) arranges the second plated-through hole V ₂, the end of the 4th microstrip line (4) arranges the 3rd plated-through hole V ₃the 6th microstrip line (6) and the 7th microstrip line (7) are coupled with the 3rd microstrip line (3) simultaneously, the 6th microstrip line (6) one end is connected with the 5th microstrip line (5) one end, the 5th microstrip line (5) other end is connected with first input end Port1, the 7th microstrip line (7) one end is connected with the 8th microstrip line (8) one end, and the 8th microstrip line (8) other end is connected with the first output Port2; The length of the first microstrip line (1) is less than the length of the 3rd microstrip line (3).

2. the trap frequency range ultra wide band bandpass filter based on the cross resonator of terminal short circuit according to claim 1, is characterized in that: the end of the first microstrip line (1) arranges the first plated-through hole V ₁, the end of the second microstrip line (2) arranges the second plated-through hole V ₂, the end of the 4th microstrip line (4) arranges the 3rd plated-through hole V ₃, these plated-through holes are used for ground connection.

3. the trap frequency range ultra wide band bandpass filter based on the cross resonator of terminal short circuit according to claim 1, is characterized in that: the size of described dimension of microstrip line, plated-through hole size and coupling space is adjustable.

4. the trap frequency range ultra wide band bandpass filter based on the cross resonator of terminal short circuit according to claim 1, it is characterized in that: the 5th microstrip line (5) and the 8th microstrip line (8) are on same straight line, and this straight line is parallel with the second microstrip line (2).

5. the trap frequency range ultra wide band bandpass filter based on the cross resonator of terminal short circuit according to claim 1, is characterized in that: the impedance of the 5th microstrip line (5) and the 8th microstrip line (8) equates, is 50 Ω or 75 Ω.

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