CN204257789U - A kind of Ka band broadband band pass filter - Google Patents

A kind of Ka band broadband band pass filter Download PDF

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Publication number
CN204257789U
CN204257789U CN201420806324.XU CN201420806324U CN204257789U CN 204257789 U CN204257789 U CN 204257789U CN 201420806324 U CN201420806324 U CN 201420806324U CN 204257789 U CN204257789 U CN 204257789U
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waveguide
band
frequency
pass filter
broadband
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CN201420806324.XU
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Chinese (zh)
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汪灏
武华锋
张思明
杨斐
雷国忠
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Xian Electronic Engineering Research Institute
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Xian Electronic Engineering Research Institute
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Abstract

The utility model relates to a kind of Ka band broadband band pass filter, the method for designing that application cut-off waveguide is theoretical, low-pass filtering is theoretical and waveguide gradual change theory combines, and apply this kind of method for designing and devise a kind of Ka wave band 32-40GHz waveguide broad-band filter, when waveguide port broadside is selected, in length one timing, should ensure that cut-off frequency is less than the low frequency of filter passband, need again to ensure low frequency Out-of-band rejection.In the property gradual transition of waveguide width sideline, frequency higher than and close to waveguide cutoff frequency time, guide wavelength is close to endless, and waveguide impedance and standard waveguide mouth impedanoe ratio are close to infinitely great.The utility model realizes the filtering performance in electronic countermeasures middle width strip transmitter and broadband transmitting-receiving subassembly.

Description

A kind of Ka band broadband band pass filter
Technical field
The invention belongs to ECM (Electronic Countermeasures) field, be specifically related to a kind of Ka band broadband band pass filter.
Background technology
In Millimeter wave countermeasure equipment, the generation that broadband millimeter-wave transmits comes from frequency multiplication and the mixing of low frequency signal, therefore attached various spurious signal, in wideband transmitter, broadband transmitting-receiving subassembly, we need to adopt broadband filter to suppress harmonic wave and spurious signal.At millimeter wave frequency band, filter has the structure such as micro-band, SIW, waveguide.Microstrip filter and SIW filter (substrate integral wave guide filter) due to loss excessive, be not suitable for the output filtering of millimeter wave broadband transmitter, broadband transmitting-receiving subassembly; Waveguide filter has the advantages such as power capacity is large, loss is little, passband is wide, is suitable for the wideband filtered application of millimeter wave broadband transmitter, broadband transmitting-receiving subassembly.In waveguide bandpass filter, traditional structure is the mode that waveguide resonator and coupled structure combine, and this fabric bandwidths is maximum reaches about 15%, when bandwidth is wide, crosses senior general be difficult to realize due to difficulty of processing.In order to the waveguide broad-band band pass filter of design bandwidth 22%, we propose to apply the method for designing design millimeter wave broadband waveguide filter that cut-off waveguide is theoretical, low-pass filtering is theoretical and waveguide gradual change theory combines.
Summary of the invention
The technical problem solved
In order to avoid the deficiencies in the prior art part, the present invention proposes a kind of Ka band broadband band pass filter applying cut-off waveguide, realizes the filtering performance in electronic countermeasures middle width strip transmitter and broadband transmitting-receiving subassembly.
Technical scheme
A kind of Ka band broadband band pass filter, is characterized in that comprising waveguide lowpass and waveguide transition line; Connect waveguide transition line at the two ends of waveguide lowpass, the broadside size Selection of connectivity port must meet condition: basic mode TE 10mould cut-off frequency is less than the low frequency of filter passband, and basic mode TE 10mould cut-off frequency is higher than the outer low frequency inhibition point of band; And higher mode TE 20mould cut-off frequency leads to high frequency points higher than band, basic mode TE 10mould cut-off frequency is lower than the low frequency of filter passband; The narrow limit size Selection of connectivity port must meet condition: higher mode TE 11mould cut-off frequency higher than band passband high-frequency suppressing point, and meets the requirement of working ability; The size of another port of waveguide transition line matches with the bore of the standard waveguide be connected.
Broadside size and the narrow limit size of described waveguide transition line convert simultaneously, and waveguide width limit linear gradient formula is as follows:
Γ f 0 = 1 2 ∫ z = 0 z = L 0 e - 2 jz ( 2 π λ 1 - ( λ 2 ( a 0 + z a - a 0 L 0 ) ) 2 ) d dz ln ( 1 Z 0 × b 0 + z b - b 0 L 0 a 0 + z a - a 0 L 0 × 1 1 - ( λ 2 ( a 0 + z a - z 0 L 0 ) ) 2 ) dz
Wherein: a, b, be the waveguide port before conversion, a 0, b 0, be the waveguide port after conversion, L 0for the length of waveguide transition line, λ is frequency f 0the air wavelength at place.
Described waveguide transition line and waveguide lowpass connecting portion are provided with a chamfering r.
Described chamfering r is 0.5mm.
The low frequency of described filter passband is 32GHz.
Described outer low frequency inhibition point 30GHz.
Described band passband high-frequency suppressing point 40GHz.
The length of described waveguide transition line is 25mm.
Beneficial effect
A kind of Ka band broadband band pass filter applying cut-off waveguide that the present invention proposes, proposes the Novel Filter method for designing in conjunction with cut-off waveguide theory, low-pass filtering theory and waveguide gradual change theory.When applying cut-off waveguide and being theoretical, control the size of nonstandard waveguide port, application of low-pass Theoretical Design waveguide lowpass, and transform to standard waveguide mouth by waveguide width sideline property grading structure.The present invention, when waveguide port broadside is selected, in length one timing, should ensure that cut-off frequency is less than the low frequency of filter passband, needs again to ensure low frequency Out-of-band rejection.In the property gradual transition of waveguide width sideline, frequency higher than and close to waveguide cutoff frequency time, guide wavelength is close to endless, and waveguide impedance and standard waveguide mouth impedanoe ratio are close to infinitely great.A kind of Ka wave band of the present invention 32-40GHz waveguide broad-band filter, realizes the filtering performance in electronic countermeasures middle width strip transmitter and broadband transmitting-receiving subassembly.
Accompanying drawing explanation
Fig. 1: waveguide broad-band bandpass filter structures figure
1-standard waveguide, 2-waveguide transition line, 3-waveguide lowpass.
Fig. 2: waveguide width sideline property graded junction composition
Fig. 3: waveguide low-pass filter structure figure
Fig. 4: waveguide broad-band band pass filter simulation result figure
Embodiment
Now in conjunction with the embodiments, the invention will be further described for accompanying drawing:
In the present invention, waveguide broad-band band pass filter comprises waveguide port selection, the transition of waveguide transition line, waveguide low-pass filter structure three aspects.Waveguide port will ensure that the outer low frequency of band pass filter band suppresses, and therefore applies cut-off waveguide theoretical, ensure during design waveguide mouth broadside size the cut-off frequency of waveguide higher than and away from the outer low frequency inhibition point of band; When signal enters the waveguide segment identical with waveguide port broadside, will pass through smoothly higher than cut-off frequency signal, lower than cut-off frequency signal, namely waveguide has serious mismatch by showing forceful electric power resistance, and reflection causes very greatly most of power not transmit and to decay.And the size that decays is relevant with the length of cut-off waveguide to the size of propagation constant imaginary part.Propagation constant imaginary part is larger, waveguide length is longer, fixed frequency decays larger.When waveguide port broadside is less, propagation constant imaginary part is larger; Waveguide port broadside is less, and waveguide cutoff frequency is larger.Therefore, when waveguide port broadside is selected, in length one timing, should ensure that cut-off frequency is less than the low frequency of filter passband, need again to ensure low frequency Out-of-band rejection.
In the property gradual transition of waveguide width sideline, frequency higher than and close to waveguide cutoff frequency time, guide wavelength is close to endless, and waveguide impedance and standard waveguide mouth impedanoe ratio are close to infinitely great.Therefore in this regard, waveguide cutoff frequency need away from frequency low in filter passband.The design of waveguide port broadside will consider above three aspects.In the property gradual transition of waveguide width sideline, during waveguide transition, waveguide width limit converts simultaneously, and waveguide width limit linear gradient formula is as follows:
Γ f 0 = 1 2 ∫ z = 0 z = L 0 e - 2 jz ( 2 π λ 1 - ( λ 2 ( a 0 + z a - a 0 L 0 ) ) 2 ) d dz ln ( 1 Z 0 × b 0 + z b - b 0 L 0 a 0 + z a - a 0 L 0 × 1 1 - ( λ 2 ( a 0 + z a - z 0 L 0 ) ) 2 ) dz
Wherein: a, b, be the waveguide port before conversion, a 0, b 0, be the waveguide port after conversion, L 0for the length of waveguide transition line, λ is frequency f 0the air wavelength at place.
By theory deduction pole location and simulation optimization transition length designed in conjunction, ensure that the feasibility of transition.
When according to low pass filter Theoretical Design low pass filter, realize by inductance capacitance.In waveguide lowpass, these go out waveguide lowpass by waveguide height low-impedance line Approximate Design.Now when low pass filter waveguide height Low ESR is similar to, be that the impedance of applying basic mode is similar to reactance component, therefore Narrow Wall of Waveguide limit is maximum, and minimum dimension is suitable, ensure that the impact of higher mode is unlikely to various numerical value and far departs from evaluation when applying waveguide basic mode, ensure processing request again.Therefore, under reactance original cost numerical value is determined, waveguide port impedance is as normalized impedance value, and the narrow limit of waveguide port is selected to ensure above two aspects.Under port is suitable, design applicable waveguide lowpass.
Specific embodiment:
If Fig. 1 is Ka wave band waveguide broad-band bandpass filter structures.Its structure comprises the Ka wave band standard waveguide mouth at two ends, is of a size of a × b, realizes interconnected by this standard waveguide mouth and outside.Be L by length 0the limit linear transformation of waveguide width realize standard waveguide mouth and transform to nonstandard waveguide mouth, be of a size of a 0× b 0, as shown in Figure 2.With the waveguide lowpass that this nonstandard waveguide mouth design cut-off frequency is 40GHz, as shown in Figure 3.
Nonstandard waveguide mouth broadside a 0design synthesis considers following aspect:
1 is theoretical according to cut-off waveguide, basic mode TE 10mould cut-off frequency is less than the low frequency of filter passband, is namely in this case less than 32GHz.
2 is theoretical according to cut-off waveguide, basic mode TE 10mould cut-off frequency is higher than the outer low frequency inhibition point 30GHz of band, and TE 10mould cut-off frequency is selected to ensure that low frequency suppresses index request.Higher by frequency, low frequency inhibition is better.
3 is theoretical according to cut-off waveguide, higher mode TE 20mould cut-off frequency, higher than band passband high frequency points 40GHz, ensures that in passband be single mode.And higher mode TE 20mould cut-off frequency is higher, and single mode transport frequency band is wider, and effect is better.
4 according to waveguide width sideline property gradual transition, and because operating frequency is the closer to by frequency, guide wavelength is more close to endless, and waveguide impedance is close to infinity.For ensureing that transition is smooth, basic mode TE 10mould cut-off frequency need be less than the low frequency of filter passband, and be namely in this case less than 32GHz, and cut-off frequency is less, in passband, transition effect is better.
The narrow limit b of nonstandard waveguide mouth 0design synthesis considers following aspect:
1 according to single mode transport requirement, and the narrow limit of any waveguide segment ensures higher mode TE 11mould cut-off frequency higher than and away from band passband high-frequency suppressing point 40GHz.
The 2 narrow limits of any waveguide segment meet working ability.
In the limit linear transformation of waveguide width, by theory deduction pole location and simulation optimization transition length L designed in conjunction 0, ensure that the feasibility of transition.
At this nonstandard waveguide mouth a 0× b 0design cut-off frequency is in the waveguide lowpass of 40GHz, according to chebyshev comprehensively in conjunction with the high Low ESR reactance principle of equal effects, is specifically of a size of 17 rank.The size on every rank as shown in Figure 3.
Utilize Ansoft HFSS electromagnetic simulation software, adopt waveguide broad-band band pass filter form shown in Fig. 1 to carry out simulation optimization to parameters, parameter optimization result is as shown in table 1.
As Fig. 4, simulation result shows: filter passband bandwidth 32-40GHz, echo S11<-20dB in passband band, during f=30GHz, during degree of suppression >=38dB, f=42GHz, and degree of suppression >=23dB.
Table 1 Ka band broadband filter parameter
a b a 0 b 0 L 0 r b 1 b 2 b 3 b 4 b 5 b 6
7.112 3.556 4.85 1 25 0.5 0.74 2.5 0.4 2.5 0.4 2.5
b 7 b 8 b 9 l 1 l 2 l 3 l 4 l 5 l 6 l 7 l 8 l 9
0.4 2.5 0.4 0.77 1.02 0.82 1.35 0.98 1.40 1.04 1.39 1.06
Unit is mm.

Claims (8)

1. a Ka band broadband band pass filter, is characterized in that comprising waveguide lowpass and waveguide transition line; Connect waveguide transition line at the two ends of waveguide lowpass, the broadside size Selection of connectivity port must meet condition: basic mode TE 10mould cut-off frequency is less than the low frequency of filter passband, and basic mode TE 10mould cut-off frequency is higher than the outer low frequency inhibition point of band; And higher mode TE 20mould cut-off frequency leads to high frequency points higher than band, basic mode TE 10mould cut-off frequency is lower than the low frequency of filter passband; The narrow limit size Selection of connectivity port must meet condition: higher mode TE 11mould cut-off frequency higher than band passband high-frequency suppressing point, and meets the requirement of working ability; The size of another port of waveguide transition line matches with the bore of the standard waveguide be connected.
2. a kind of Ka band broadband band pass filter according to claim 1, is characterized in that: broadside size and the narrow limit size of described waveguide transition line convert simultaneously, and waveguide width limit linear gradient formula is as follows:
&Gamma; f 0 = 1 2 &Integral; z = 0 z = L 0 e - 2 jz ( 2 &pi; &lambda; 1 - ( &lambda; 2 ( a 0 + z a - a 0 L 0 ) ) 2 ) d dz 1 n ( 1 Z 0 &times; b 0 + z b - b 0 L 0 a 0 + z a - a 0 L 0 &times; 1 1 - ( &lambda; 2 ( a 0 + z a - a 0 L 0 ) ) 2 ) dz
Wherein: a, b, be the waveguide port before conversion, a 0, b 0, be the waveguide port after conversion, L 0for the length of waveguide transition line, λ is frequency f 0the air wavelength at place.
3. a kind of Ka band broadband band pass filter according to claim 1, is characterized in that: described waveguide transition line and waveguide lowpass connecting portion are provided with a chamfering r.
4. a kind of Ka band broadband band pass filter according to claim 3, is characterized in that: described chamfering r is 0.5mm.
5. a kind of Ka band broadband band pass filter according to claim 1, is characterized in that: the low frequency of described filter passband is 32GHz.
6. a kind of Ka band broadband band pass filter according to claim 1, is characterized in that: described outer low frequency inhibition point 30GHz.
7. a kind of Ka band broadband band pass filter according to claim 1, is characterized in that: described band passband high-frequency suppressing point 40GHz.
8. a kind of Ka band broadband band pass filter according to claim 1, is characterized in that: the length of described waveguide transition line is 25mm.
CN201420806324.XU 2014-12-18 2014-12-18 A kind of Ka band broadband band pass filter Withdrawn - After Issue CN204257789U (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104466320A (en) * 2014-12-18 2015-03-25 西安电子工程研究所 Ka wave band broadband band-pass filter utilizing cut-off waveguide
CN104882652A (en) * 2015-06-12 2015-09-02 四川迈格酷科技有限公司 Ultra-wide-band terahertz wave filter
CN105680123A (en) * 2016-01-11 2016-06-15 中国电子科技集团公司第十研究所 EHF frequency band millimeter wave cut-off waveguide band-pass filter
CN115084810A (en) * 2022-07-21 2022-09-20 西南应用磁学研究所(中国电子科技集团公司第九研究所) Miniaturized high-frequency high-order mode harmonic suppression waveguide filter

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104466320A (en) * 2014-12-18 2015-03-25 西安电子工程研究所 Ka wave band broadband band-pass filter utilizing cut-off waveguide
CN104466320B (en) * 2014-12-18 2017-05-10 西安电子工程研究所 Ka wave band broadband band-pass filter utilizing cut-off waveguide
CN104882652A (en) * 2015-06-12 2015-09-02 四川迈格酷科技有限公司 Ultra-wide-band terahertz wave filter
CN105680123A (en) * 2016-01-11 2016-06-15 中国电子科技集团公司第十研究所 EHF frequency band millimeter wave cut-off waveguide band-pass filter
CN105680123B (en) * 2016-01-11 2018-05-25 中国电子科技集团公司第十研究所 EHF frequency range millimeter wave cut-off waveguide bandpass filters
CN115084810A (en) * 2022-07-21 2022-09-20 西南应用磁学研究所(中国电子科技集团公司第九研究所) Miniaturized high-frequency high-order mode harmonic suppression waveguide filter
CN115084810B (en) * 2022-07-21 2022-12-02 西南应用磁学研究所(中国电子科技集团公司第九研究所) Miniaturized high-frequency high-order mode harmonic suppression waveguide filter

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