CN104241798A - Resonant cavity for coaxial resonant filter and coaxial resonant filter - Google Patents

Abstract

The invention provides a resonant cavity for a filter used in the microwave field and a coaxial resonant filter. The height, the length and the width of the resonant cavity is 50 millimeters. The height of an outer guiding post in the cavity is 45 millimeters, the outer diameter is 16 millimeters, and the inner diameter is 14 millimeters. The diameter of an inner guiding post in the outer guiding post is from 6 millimeters to 10 millimeters. The coaxial resonant filter using the resonant cavity has the advantages that the internal insertion loss is low, the gradient of a pass band is high, and the Q value is high.

Description

For resonant cavity and the coaxial resonance filter of coaxial resonance filter

Technical field

The present invention relates to microwave technical field, particularly relate to a kind of resonant cavity for coaxial resonance filter and coaxial resonance filter.

Background technology

The develop rapidly of short-wave communication tedhnology and continuous maturation make filtering clutter particularly important.

Popularize today of development at mobile communications network, various microwave mobile communication network used band scope is close, mutually easily causes interference.As, GSM network frequency used and GSMI network close, if the system of both sides has fault to cause frequency departure, the fault such as very easily cause network to get lines crossed or to go offline.It is vital that the microwave filter of high-quality runs guarantee wireless communication networks health.

Summary of the invention

The invention provides a kind of resonant cavity and coaxial resonance filter, use the coaxial resonance filter of this resonant cavity to have Insertion Loss in band low, the advantage of the high and high q-factor of passband steepness.

Wherein in a kind of embodiment, described a kind of resonant cavity for coaxial resonance filter, the height of described resonant cavity, length and width are 50 millimeters, the height of outer guiding post in cavity is 45 millimeters, external diameter is 16 millimeters, internal diameter is 14 millimeters, and the diameter being located at the inner guiding post in outer guiding post is 6 millimeters to 10 millimeters.

Wherein in an embodiment, the degree of depth that described inner guiding post stretches into outer guiding post is adjustable.

Wherein in an embodiment, the cavity of described outer guiding post and described resonant cavity is formed in one structure.

Wherein in an embodiment, described inner guiding post is bolt, and the mode that inner guiding post is threaded connection is fixing on the cover board.

A kind of coaxial resonance filter, comprise multiple resonant cavity, the height of described resonant cavity, length and width are 50 millimeters, the height of outer guiding post in cavity is 45 millimeters, external diameter is 16 millimeters, internal diameter is 14 millimeters, and the diameter being located at the inner guiding post in outer guiding post is 6 millimeters to 10 millimeters.

Wherein in an embodiment, described passage comprises eight resonant cavitys, be respectively the first resonant cavity, second resonant cavity, 3rd resonant cavity, 4th resonant cavity, 5th resonant cavity, 6th resonant cavity, 7th resonant cavity, 8th resonant cavity, described first resonant cavity, second resonant cavity, 3rd resonant cavity, 4th resonant cavity, 5th resonant cavity, 6th resonant cavity, 7th resonant cavity, 8th resonant cavity is connected by window successively and is arranged into the array of 2*4, described first resonant cavity is directly connected by window with the 4th resonant cavity, described 5th resonant cavity is directly communicated with by window with the 8th resonant cavity.

Wherein in an embodiment, described resonant cavity, outer guiding post and cover plate are made by metallic aluminium.

Wherein in an embodiment, the outer surface of described resonant cavity, inner guiding post, outer guiding post and cover plate is all coated with silver or silver alloy.

Wherein in an embodiment, described coaxial resonance filter also comprises the adjusting rod of intersection's generation transmission zero of at least two resonant cavitys being located at passage.

Wherein in an embodiment, described adjusting rod shape is U-shaped.

Above-mentioned resonant cavity and coaxial resonance duplexer design according to electromagnetic transmission theory, can find out that to use the coaxial resonance duplexer of this resonant cavity to have Insertion Loss in band low by Electromagnetic Simulation and actual test result, the advantage of the high and high q-factor of passband steepness.

Accompanying drawing explanation

Fig. 1 is the coaxial resonance filter schematic diagram of an embodiment;

Fig. 2 is one of them cavity resonator structure schematic diagram of coaxial resonance filter shown in Fig. 1;

Fig. 3 be coaxial resonance filter signal shown in Fig. 1 by time test result schematic diagram.

Embodiment

Please refer to Fig. 1 and Fig. 2, an embodiment provides a kind of coaxial resonance filter 100.This coaxial resonance filter 100 comprises eight resonant cavitys.Signal transmissions cavity 110 is connected with external microwave circuit by connector 120 and connecting line 121, is used for transmitting and trap signal.

Eight resonant cavitys of passage are respectively the first resonant cavity 131, second resonant cavity 132, the 3rd resonant cavity 133, the 4th resonant cavity 134, the 5th resonant cavity 135, the 6th resonant cavity 136, the 7th resonant cavity 137, the 8th resonant cavity 138.First resonant cavity 131, second resonant cavity 132, the 3rd resonant cavity 133, the 4th resonant cavity 134, the 5th resonant cavity 135, the 6th resonant cavity 136, the 7th resonant cavity 137, the 8th resonant cavity 138 are connected by the window in metallic walls successively and are arranged into the array of 2*4.First resonant cavity 131 is directly connected with the 4th resonant cavity 134, and the 5th resonant cavity 135 is directly connected with the 8th resonant cavity 138.Their common wall has offered the groove of connection effect, the width of its middle slot is determined by the stiffness of coupling between resonant cavity, and stiffness of coupling is stronger, then the width of groove is larger.Like this, the cross-couplings between the first resonant cavity 131 and the 4th resonant cavity 134 will be better.In like manner, the cross-couplings between the 5th resonant cavity 135 and the 8th resonant cavity 138 will be better.Stiffness of coupling in resonant cavity also can go deep into the position adjustments of window by being located at the screw rod of window between cavity.

This coaxial resonance filter 100 employs altogether 8 resonant cavitys, and these 8 resonant cavitys form 2*4 matrix layout, create enough transmission zeros, can meet design needs.Because the resonant cavity number that this coaxial resonance filter uses is less and rationally distributed, so the small volume of this coaxial resonance filter.More transmission zero, also makes this coaxial resonance filter 100 achieve high selectivity, can play the effect reducing resonance progression, reduce insertion loss simultaneously.Certainly, the present invention does not limit the particular location of each resonant cavity, and those skilled in the art person suitably can adjust the position of resonant cavity, and it is still within protection scope of the present invention.

Be provided with outer guiding post 170 in the cavity of the resonant cavity of transmission channel and receive path, be provided with inner guiding post 180 in outer guiding post 170, the degree of depth that inner guiding post 180 stretches into outer guiding post 170 is adjustable.Inner guiding post 180 is herein bolt, and the mode that inner guiding post 180 is threaded connection is fixed on cover plate 190.That is, cover plate 190 is provided with screwed hole, inner guiding post 180 has the screw thread closed with the corresponding threaded holes on cover plate, and the mode that such inner guiding post 180 just can be threaded connection is fixing on the cover board.Meanwhile, part extend in outer guiding post 170 by inner guiding post 180.By the performance regulating inner guiding post 180 degree of depth stretched in outer guiding post 170 can adjust this coaxial resonance duplexer 100, the needs used with satisfied reality.

The height of the cavity of the resonant cavity of transmission channel and receive path, length and width are 50 millimeters, the height of outer guiding post in cavity is 45 millimeters, external diameter is 16 millimeters, internal diameter is 14 millimeters, the diameter being located at the inner guiding post in outer guiding post is 6 millimeters to 10 millimeters, and the diameter of inner guiding post 180 is 6 millimeters herein.The size of outer guiding post 170 is less, thus make the volume of resonant cavity not need to do comparatively large, thus while meeting performance requirement, reduce this coaxial resonance duplexer 100 volume further.

In this embodiment, the cavity of the resonant cavity of outer guiding post 170 and transmission channel and receive path is formed in one structure, and in other embodiments, outer guiding post 170 dismountablely can be fixed on the bottom of resonant cavity.Resonant cavity, outer guiding post 170 and cover plate 190 are made by metallic aluminium.The outer surface of resonant cavity, inner guiding post 180, outer guiding post 170 and cover plate is all coated with silver or silver alloy.The Q value of this coaxial resonance filter 100 can be improved like this, reduce pass band insertion loss, strengthen Out-of-band rejection.

This coaxial resonance filter 100 also comprises the adjusting rod of intersection's generation transmission zero of at least two resonant cavitys being located at passage.These adjusting rods are U-shaped adjusting rods 151 and 152.Concrete, the intersection of the first resonant cavity 131, second resonant cavity 132, the 3rd resonant cavity 133, the 4th resonant cavity 134 is provided with U-shaped adjusting rod 151, connect the first resonant cavity 131 and the 3rd resonant cavity 133, but U-shaped bar 151 does not contact the outer guiding post of the first resonant cavity 131 and the 3rd resonant cavity 133.The intersection of the 5th resonant cavity 135, the 6th resonant cavity 136, the 7th resonant cavity 137, the 8th resonant cavity 138 is also provided with U-shaped adjusting rod 152, connect the 5th resonant cavity 135 and the 7th resonant cavity 137, but U-shaped bar 152 does not contact the outer guiding post of the 5th resonant cavity 135 and the 7th resonant cavity 137.These U-shaped bars can realize magnetic cross-couplings, produce transmission zero, thus effectively improve the signal suppressing outside the passage band in this coaxial resonance filter 100.

Theoretical according to electromagnetic transmission, resonant cavity is along the height H in Electromagnetic Wave Propagation direction and resonance frequency f ₀relational expression is:

$H=\frac{c_0}{{4f}_0\sqrt{{\mathrm{\ϵ}}_r}}$

In addition, relational expression:

$\mathrm{CL}=\frac{2.745\×{10}^{-4}}{Z_0\×(D+O)}\×D\×O\×L\×{({\mathrm{\ϵ}}_r\×{\mathrm{\μ}}_c\×f)}^{1/2}\mathrm{dB}$

Give CL, ZO, D, O, L, ε _r, μ _c, f relation.

Wherein CL: conductor losses, Z ₀: characteristic impedance, D: the internal diameter of outer conductor, O: inner wire diameter, L: conductor length, ε _r: dielectric constant, μ _c: the relative magnetic flux of conductor, f: frequency

The characteristic impedance of coaxial line can be expressed as:

$Z_0=\frac{60}{\sqrt{{\mathrm{\ϵ}}_r}}\ln \frac{b}{a}$

In formula: a is the half of the outer guiding post external diameter in filter, and b is the half of cavity length.In addition, the selection principle of b and a meets following condition:

Maximum power capabilities condition: b/a > 1.65;

Minimal attenuation condition: b/a < 3.592.

According to above principle and according to Electromagnetic Simulation and actual test result, we find that band connection frequency is 50 millimeters at the height of the cavity of the desirable resonant cavity of 800-1000 megahertz, length and width, the height of outer guiding post in cavity is 45 millimeters, external diameter is 16 millimeters, internal diameter is 14 millimeters, and the diameter being located at the inner guiding post in outer guiding post is 6 millimeters to 10 millimeters.

Please refer to Fig. 3.This coaxial resonance filter 100 is mainly applicable to the application that band connection frequency is 800MHz to 900MHz.This coaxial resonance filter 100, according to general Chebyshev filters principle design, has in band and waits ripple, be with outer definite transmission controlled for zero point, the features such as Out-of-band rejection degree is good.The present invention uses Agilent network analyzer 8753E to test this coaxial resonance filter 100, as can be seen from test result: in the passband of this coaxial resonance filter 100, Insertion Loss is within-1.5dB, Out-of-band rejection is high, within the scope of Peak Jitter 0.5dB, meets instructions for use.Fig. 3 high frequency side steepness is comparatively large, and obviously, it is high that display is Q value in waveform turnover; In passband, waveform is straight, and it is little that display is Peak Jitter; And passband waveform reaches 0.5dB, illustrate that in band, Insertion Loss is low.In stopband, waveform is below-40dB, illustrates that Out-of-band rejection is high.So it is little that this coaxial resonance filter 100 has volume, in band, Insertion Loss is low, the advantage of the high and high q-factor of passband steepness.

The transmission channel of this coaxial resonance filter and receive path employ altogether 8 resonant cavitys, and these 8 resonant cavitys form approximate 2*4 matrix layout, create enough transmission zeros, can meet design needs.Because the resonant cavity number that this coaxial resonance filter uses is less and rationally distributed, compact conformation, so the small volume of this coaxial resonance filter, miniaturized needs can be met.

The above embodiment only have expressed several execution mode of the present invention, and it describes comparatively concrete and detailed, but therefore can not be interpreted as the restriction to the scope of the claims of the present invention.It should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection range of patent of the present invention should be as the criterion with claims.

Claims (10)

1. the resonant cavity for coaxial resonance filter, the height of described resonant cavity, length and width are 50 millimeters, the height of outer guiding post in cavity is 45 millimeters, external diameter is 16 millimeters, internal diameter is 14 millimeters, and the diameter being located at the inner guiding post in outer guiding post is 6 millimeters to 10 millimeters.

2. the resonant cavity for coaxial resonance filter according to claim 1, is characterized in that, the degree of depth that described inner guiding post stretches into outer guiding post is adjustable.

3. the resonant cavity for coaxial resonance filter according to claim 2, is characterized in that, the cavity of described outer guiding post and described resonant cavity is formed in one structure.

4. the resonant cavity for coaxial resonance filter according to claim 2, is characterized in that, described inner guiding post is bolt, and the mode that inner guiding post is threaded connection is fixing on the cover board.

5. a coaxial resonance filter, comprise multiple resonant cavity, the height of described resonant cavity, length and width are 50 millimeters, the height of outer guiding post in cavity is 45 millimeters, external diameter is 16 millimeters, internal diameter is 14 millimeters, and the diameter being located at the inner guiding post in outer guiding post is 6 millimeters to 10 millimeters.

6. coaxial resonance filter according to claim 5, it is characterized in that, described filter comprises eight resonant cavitys, eight resonant cavitys are respectively the first resonant cavity, second resonant cavity, 3rd resonant cavity, 4th resonant cavity, 5th resonant cavity, 6th resonant cavity, 7th resonant cavity, 8th resonant cavity, described first resonant cavity, second resonant cavity, 3rd resonant cavity, 4th resonant cavity, 5th resonant cavity, 6th resonant cavity, 7th resonant cavity, 8th resonant cavity is connected by window successively and is arranged into the array of 2*4, described first resonant cavity is directly connected by window with the 4th resonant cavity, described 5th resonant cavity is directly connected by window with the 8th resonant cavity.

7. coaxial resonance filter according to claim 6, is characterized in that, described resonant cavity, outer guiding post and cover plate are made by metallic aluminium.

8. coaxial resonance filter according to claim 7, is characterized in that, the outer surface of described resonant cavity, inner guiding post, outer guiding post and cover plate is all coated with silver or silver alloy.

9. coaxial resonance duplexer according to claim 8, is characterized in that, described coaxial resonance filter also comprises the adjusting rod of intersection's generation transmission zero of at least two resonant cavitys being located at passage.

10. coaxial resonance duplexer according to claim 9, is characterized in that, the shape of described adjusting rod is U-shaped.