CN103094648A - Radio frequency reconfigurable band-pass filter with wide frequency and wide adjustment range of broadband - Google Patents

Abstract

The invention discloses a novel radio frequency reconfigurable band-pass filter with a wide frequency and a wide adjustment range of broadband. The reconfigurable filter comprises an upper-layer microstrip structure, a middle-layer medium substrate and the lower-layer grounded metal. The upper-layer microstrip structure is composed of an input port, an input feed network, a cross adjustable multimode resonator, an output feed network and an output port which are connected in succession. The input feed network and the output feed network are both composed of a blocking condenser and a 50-ohm microstrip line. The cross adjustable multimode resonator is composed of two microstrip lines which are perpendicular to each other and six varactors with two ends of the varactors connected. The input feed network and the output feed network tap feed electricity respectively from the two varactors with two ends of the varactors in series connection of the left side and the right side of the multimode resonator. The reconfigurable filter has the advantages of being wide in central frequency and adjustment range of bandwidth and good in passband stability, and being capable of being reconfigured the broadbands with different central frequencies or a narrow-band band-pass filter and can be used for the front end of the reconfigurable radio frequency.

Description

RF reconfigurable band pass filter with broadband and wide bandwidth adjustable range

Technical field

The present invention relates to a kind of novel radio frequency electrically adjusted band-pass filter based on variable capacitance diode, particularly a kind of RF reconfigurable band pass filter with broadband and wide bandwidth adjustable range.

Background technology

Electrically tunable filter is one of key technology of the aspects such as frequency hopping spread spectrum (FHSS) communication technology, unjammable radar, dynamic frequency allocation technology, multi function receiver, spurious emissions measurement.Since World War II, electrically tunable filter always is one of focus of various countries' research.Aspect this, some research reports have been arranged at present, the electrically tunable filter of various structures is suggested.But the fast development of radar and the communication technology has in recent years proposed higher performance requirement to tunable filter.

Modern ULTRA-WIDEBAND RADAR and radio communication require to adopt high performance restructural radio-frequency front-end.In order to take full advantage of and to merge various wireless channel and communication standard, radio-frequency front-end need to be operated on different frequency and bandwidth, and this just requires a kind of restructural radio-frequency front-end that has simultaneously frequency and bandwidth adjustment ability.Restructural filter (fully tunable filter) with frequency and bandwidth adjustment ability is the important component part of restructural radio-frequency front-end.This kind filter is one of the forward position of electrically tunable filter research and trend, only has in the world at present a small amount of bibliographical information (be no more than 10 pieces, and substantially all be published on Trans), but the following problem of ubiquity:

(1) the bandwidth adjustment scope is less, and due to the problem of structural design aspect, the restructural filter with frequency and bandwidth adjustment ability can only realize that all maximum is no more than 15% bandwidth.And the broadband connections technology is more ripe at present, and has entered the practical stage.Although the research of broadband filter is carried out for many years, and has obtained great successes, yet the development of broadband tunable filter is all at home and abroad extremely rare.Obviously maximum 15% bandwidth can not satisfy the demand of modern broadband communication system far away.

(2) when centre frequency or bandwidth variation, can not keep stable filtering performance.The filtering performance here comprises return loss, insertion loss, squareness factor, Out-of-band rejection degree etc.

For the little problem of bandwidth adjustment scope, though literature research the has been arranged wide electrically tunable filter of adjustable band in some broadbands, often can not freely control its centre frequency, be limited by very large in actual applications.Multimode resonator is proposed 2005 the time by Lei Zhu professor the earliest, owing to having comprised simultaneously a plurality of modes of resonance in single resonator, so be widely used in the design of broadband filter.But up to the present also there is no report is how multimode resonator to be applied to frequency and bandwidth all in adjustable restructural filter.

Up to the present the problem that keeps the stationary filtering performance during for centre frequency and bandwidth adjustment is also ideally to keep stable filtering performance about how when centre frequency and the bandwidth adjustment without any the research report.

Except these 2 common problems, it is large that the restructural filter that part has frequency and a bandwidth adjustment ability also exists insertion loss, and the control DC power supply that needs is many, and the problem such as volume is large.

In a word, need also in the design of present restructural filter to solve that the bandwidth adjustment scope is little, the problem aspect such as unstable properties when regulating.

Summary of the invention

The object of the present invention is to provide a kind of high-performance restructural band pass filter based on the adjustable multimode resonator of microstrip line, this restructural band pass filter can be realized having guaranteed simultaneously stable filtering performance up to 60% frequency-tuning range and 65% bandwidth.

the technical solution adopted for the present invention to solve the technical problems is: a kind of RF reconfigurable band pass filter with broadband and wide bandwidth adjustable range, the microstrip structure that comprises the upper strata, the grounded metal of interlayer substrate and lower floor, described upper strata microstrip structure is attached to interlayer plate upper surface, and the lower surface in intermediate layer is grounded metal, the upper strata microstrip structure comprises an adjustable microstrip line multimode resonator of cross, an input feeding network, output feeding network, an input port and an output port, the adjustable multimode resonator of cross comprises orthogonal two microstrip lines and six variable capacitance diodes, wherein the two ends of horizontal microstrip line connect respectively two variable capacitance diodes of series connection, the two ends of vertical microstrip line have connected respectively a variable capacitance diode, be specially: cross is adjustable, and the microstrip line multimode resonator comprises horizontal rectangular microstrip line and vertical rectangle microstrip line, one end series connection the first variable capacitance diode and the second variable capacitance diode of horizontal microstrip line, other end series connection the 3rd variable capacitance diode and the 4th variable capacitance diode of horizontal microstrip line, vertical microstrip line passes from the middle point vertical of horizontal microstrip line, one end of vertical microstrip line connects the 5th variable capacitance diode, the other end of vertical microstrip line connects the 6th variable capacitance diode, the input feeding network comprises capacitance and the 50 ohm of rectangular microstrip lines that connect in turn, and the output feeding network comprises capacitance and the 50 ohm of rectangular microstrip lines that connect in turn, the characteristic impedance of described input port and output port is all 50 ohm, input port is connected with the input feeding network, and output port is connected with the output feeding network, the input feeding network is from tap feed between the first variable capacitance diode of multimode resonator and the second variable capacitance diode, and the output feeding network is from tap feed between the 3rd variable capacitance diode of multimode resonator and the 4th variable capacitance diode, microstrip line multimode resonator left-right symmetric that described cross is adjustable, input feeding network, input port, output feeding network, output port are left-right symmetric and distribute.

In the above-mentioned RF reconfigurable band pass filter with broadband and wide bandwidth adjustable range, the vacant end of described variable capacitance diode all passes the interlayer substrate and is connected with the lower floor grounded metal.

In order further to realize purpose of the present invention, in the above-mentioned RF reconfigurable band pass filter with broadband and wide bandwidth adjustable range, the long 12～24mm of horizontal microstrip line in described cross is adjustable microstrip line multimode resonator, wide 0.5～2mm; The vertical wide 0.5～3mm of microstrip line is in the long 4～12mm of part above horizontal microstrip line, is in the long 1～6mm of part below horizontal microstrip line; The appearance of two capacitances in described feeding network value is identical and all more than 6pF.

The DIELECTRIC CONSTANT ε of described medium substrate _rBeing 2～10, is highly 0.2～1mm.

The present invention compared with prior art, its remarkable advantage is: 1) the present invention has designed the novel adjustable multimode resonator of microstrip line cross, utilize for the first time two series connection variable capacitance diodes to regulate the position of tap feed, make this restructural filter have very wide frequency and bandwidth adjustment scope, guaranteed simultaneously stable filtering performance; 2) the adjustable multimode resonator of microstrip line cross has three band inpolars of energy independent regulation, can realize wider bandwidth; In actual measurement, bandwidth can reach 65%, head and shoulders above existing electrically tunable filter, reached the standard of broadband connections; 3) use two series connection variable capacitance diodes to regulate the position of tap feed, make resonator flexibly and accurately carry out impedance matching with feeding network, all can keep the filtering characteristic of stable and consistent when making this restructural band pass filter be in any operating frequency and bandwidth; In actual measurement, return loss is stabilized in the 12dB left and right, and in passband, ripple is comparatively even; 4) the adjustable multimode resonator of microstrip line cross of design has two bands that can move with passband outer zero points, has greatly improved the selectivity of restructural filter; 5) owing to having adopted the tap feeding classification, do not exist in traditional structure energy is caused coupled structure than lossy, this restructural filter has less insertion loss, and in actual measurement, insertion loss is between 1 – 2dB; 6) owing to introducing adjustable multimode resonator, the present invention compares with the restructural filter with frequency bandwidth regulating power of same order, needs less control DC power supply; 7) the present invention compares with existing other designs, and the design of this restructural filter construction is more succinct, and volume is also less.

Description of drawings

Fig. 1 is the schematic diagram with high-performance restructural band pass filter of broadband and wide bandwidth adjustable range.

Fig. 2 is the schematic diagram of the above-mentioned adjustable multimode resonator of cross.

Fig. 3 a is that the pole and zero of the adjustable multimode resonator of cross in Fig. 2 is with C ₁The graph of a relation that changes.

Fig. 3 b is that the pole and zero of the adjustable multimode resonator of cross in Fig. 2 is with C ₂, C ₃The graph of a relation that changes.

Fig. 4 is the first variable capacitance diode 7, the second variable capacitance diode 8(or the 3rd variable capacitance diode 9, the 4th variable capacitance diode 10 of series connection) principle schematic of control inputs feeding network (or output feeding network) tap position.

Fig. 5 a is the transfer curve that bandwidth remains unchanged, centre frequency is regulated.

Fig. 5 b is the return loss plot that bandwidth remains unchanged, centre frequency is regulated.

Fig. 5 c is that centre frequency is constant, the transfer curve of bandwidth adjustment and return loss plot.

Embodiment

The present invention is further detailed explanation below in conjunction with accompanying drawing, but the scope of protection of present invention is not limited to the scope of lower example statement.

as shown in Figure 1, a kind of RF reconfigurable band pass filter with broadband and wide bandwidth adjustable range, the microstrip structure that comprises the upper strata, the grounded metal of interlayer substrate and lower floor, described upper strata microstrip structure is attached to interlayer plate upper surface, and the lower surface in intermediate layer is grounded metal, the upper strata microstrip structure comprises an adjustable microstrip line multimode resonator of cross, an input feeding network, output feeding network, an input port and an output port, the adjustable multimode resonator of cross comprises orthogonal two microstrip lines and six variable capacitance diodes, wherein the two ends of horizontal microstrip line connect respectively two variable capacitance diodes of series connection, the two ends of vertical microstrip line have connected respectively a variable capacitance diode, be specially: cross is adjustable, and the microstrip line multimode resonator comprises horizontal rectangular microstrip line 2 and vertical rectangle microstrip line 3, one end series connection the first variable capacitance diode 7 and the second variable capacitance diode 8 of horizontal microstrip line 2, other end series connection the 3rd variable capacitance diode 9 and the 4th variable capacitance diode 10 of horizontal microstrip line 2, vertical microstrip line 3 passes from the middle point vertical of horizontal microstrip line 2, one end of vertical microstrip line 3 connects the 5th variable capacitance diode 11, the other end of vertical microstrip line 3 connects the 6th variable capacitance diode 12, the input feeding network comprises capacitance 5 and the 50 ohm of rectangular microstrip lines 1 that connect in turn, and the output feeding network comprises capacitance 6 and the 50 ohm of rectangular microstrip lines 4 that connect in turn, the characteristic impedance of described input port and output port is all 50 ohm,

Input port is connected with the input feeding network, and output port is connected with the output feeding network; The input feeding network is from tap feed between the first variable capacitance diode 7 of multimode resonator and the second variable capacitance diode 8, and the output feeding network is from tap feed between the 3rd variable capacitance diode 9 of multimode resonator and the 4th variable capacitance diode 10; Microstrip line multimode resonator left-right symmetric that described cross is adjustable, input feeding network, input port, output feeding network, output port are left-right symmetric and distribute.

In the above-mentioned RF reconfigurable band pass filter with broadband and wide bandwidth adjustable range, the vacant end of described variable capacitance diode all passes the interlayer substrate and is connected with the lower floor grounded metal.

In the above-mentioned RF reconfigurable band pass filter with broadband and wide bandwidth adjustable range, the long 12～24mm of horizontal microstrip line 2 in described cross is adjustable microstrip line multimode resonator, wide 0.5～2mm; The vertical wide 0.5～3mm of microstrip line 3 is in the long 4～12mm of part above horizontal microstrip line, is in the long 1～6mm of part below horizontal microstrip line; The appearance of two capacitances in described feeding network value is identical and all more than 6pF.

The DIELECTRIC CONSTANT ε of described medium substrate _rBeing 2～10, is highly 0.2～1mm.

In conjunction with Fig. 2, above-mentioned cross is adjustable, and little concrete size with multimode resonator can be chosen according to following formula relation:

${\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HDA00002781716400031.png"\; state="\{\{state\}\}">C</figure-callout>}}_1=\frac{{\mathrm{<figure-callout\; id="1"\; label="Y"\; filenames="HDA00002781716400031.png"\; state="\{\{state\}\}">Y</figure-callout>}}_1}{2\mathrm{\&pi;}{f}_o}\cot \left(\frac{2\mathrm{\&pi;}{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="HDA00002781716400031.png"\; state="\{\{state\}\}">l</figure-callout>}}_1\sqrt{{\mathrm{\&epsiv;}}_r}}{c}{f}_o\right)$

${\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="HDA00002781716400011.png,HDA00002781716400031.png"\; state="\{\{state\}\}">C</figure-callout>}}_2=\frac{2{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HDA00002781716400031.png"\; state="\{\{state\}\}">C</figure-callout>}}_1\mathrm{\&pi;}{f}_{e1}{\mathrm{<figure-callout\; id="1"\; label="Z"\; filenames="HDA00002781716400031.png"\; state="\{\{state\}\}">Z</figure-callout>}}_1+\tan \left(\frac{2\mathrm{\&pi;}({\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="HDA00002781716400031.png"\; state="\{\{state\}\}">l</figure-callout>}}_1+l_2)\sqrt{{\mathrm{\&epsiv;}}_r}}{c}{f}_{e1}\right)}{\mathrm{\&pi;}{f}_{\mathrm{el}}{\mathrm{<figure-callout\; id="1"\; label="Z"\; filenames="HDA00002781716400031.png"\; state="\{\{state\}\}">Z</figure-callout>}}_1+2{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HDA00002781716400031.png"\; state="\{\{state\}\}">C</figure-callout>}}_1{\mathrm{\&pi;}}^2{f}_{e1}^2{\mathrm{<figure-callout\; id="1"\; label="Z"\; filenames="HDA00002781716400031.png"\; state="\{\{state\}\}">Z</figure-callout>}}_1^2\tan \left(\frac{2\mathrm{\&pi;}({\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="HDA00002781716400031.png"\; state="\{\{state\}\}">l</figure-callout>}}_1+l_2)\sqrt{{\mathrm{\&epsiv;}}_r}}{c}{f}_{e1}\right)}$

${\mathrm{<figure-callout\; id="3"\; label="C"\; filenames="HDA00002781716400011.png"\; state="\{\{state\}\}">C</figure-callout>}}_3=\frac{2{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HDA00002781716400031.png"\; state="\{\{state\}\}">C</figure-callout>}}_1\mathrm{\&pi;}{f}_{e2}{\mathrm{<figure-callout\; id="1"\; label="Z"\; filenames="HDA00002781716400031.png"\; state="\{\{state\}\}">Z</figure-callout>}}_1+\tan \left(\frac{2\mathrm{\&pi;}({\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="HDA00002781716400031.png"\; state="\{\{state\}\}">l</figure-callout>}}_1+l_3)\sqrt{{\mathrm{\&epsiv;}}_r}}{c}{f}_{e2}\right)}{\mathrm{\&pi;}{f}_{\mathrm{el}}{\mathrm{<figure-callout\; id="1"\; label="Z"\; filenames="HDA00002781716400031.png"\; state="\{\{state\}\}">Z</figure-callout>}}_1+2{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HDA00002781716400031.png"\; state="\{\{state\}\}">C</figure-callout>}}_1{\mathrm{\&pi;}}^2{f}_{e2}^2{\mathrm{<figure-callout\; id="1"\; label="Z"\; filenames="HDA00002781716400031.png"\; state="\{\{state\}\}">Z</figure-callout>}}_1^2\tan \left(\frac{2\mathrm{\&pi;}({\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="HDA00002781716400031.png"\; state="\{\{state\}\}">l</figure-callout>}}_1+l_3)\sqrt{{\mathrm{\&epsiv;}}_r}}{c}{f}_{e2}\right)}$

${\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="HDA00002781716400011.png,HDA00002781716400031.png"\; state="\{\{state\}\}">C</figure-callout>}}_2=\frac{{\mathrm{<figure-callout\; id="2"\; label="Y"\; filenames="HDA00002781716400011.png,HDA00002781716400031.png"\; state="\{\{state\}\}">Y</figure-callout>}}_2}{2\mathrm{\&pi;}{\mathrm{<figure-callout\; id="1"\; label="f\; TZ"\; filenames="HDA00002781716400031.png"\; state="\{\{state\}\}">f</figure-callout>}}_{\mathrm{TZ}}}\cot \left(\frac{2\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA00002781716400011.png,HDA00002781716400031.png"\; state="\{\{state\}\}">l</figure-callout>}}_2\sqrt{{\mathrm{\&epsiv;}}_r}}{c}{f}_{\mathrm{TZ}1}\right)$

${\mathrm{<figure-callout\; id="3"\; label="C"\; filenames="HDA00002781716400011.png"\; state="\{\{state\}\}">C</figure-callout>}}_3=\frac{{\mathrm{<figure-callout\; id="2"\; label="Y"\; filenames="HDA00002781716400011.png,HDA00002781716400031.png"\; state="\{\{state\}\}">Y</figure-callout>}}_2}{2\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="f\; TZ"\; filenames="HDA00002781716400011.png,HDA00002781716400031.png"\; state="\{\{state\}\}">f</figure-callout>}}_{\mathrm{TZ}}}\cot \left(\frac{2\mathrm{\&pi;}{\mathrm{<figure-callout\; id="3"\; label="l"\; filenames="HDA00002781716400011.png"\; state="\{\{state\}\}">l</figure-callout>}}_3\sqrt{{\mathrm{\&epsiv;}}_r}}{c}{f}_{\mathrm{TZ}2}\right)$

Y wherein ₁Be the characteristic admittance of horizontal rectangular microstrip line 2, Z ₁Characteristic impedance for horizontal rectangular microstrip line 2; l ₁Physical length for horizontal rectangular microstrip line 2; Y ₂Characteristic admittance for vertical rectangle microstrip line 3; l ₂That vertical rectangle microstrip line 3 is in the physical length of horizontal rectangular microstrip line 2 upper sections; l ₃It is the physical length of vertical rectangle microstrip line 3 part below horizontal rectangular microstrip line 2; C is light propagation velocity in a vacuum; f _o, f _e1, f _e2, f _TZ1, f _TZ2The resonance frequency at the zero point in the stopband of the outer the right of the zero point in the stopband of the outer left side of the limit on the right in the limit on the left side, passband in the limit in the middle of in passband, passband in corresponding Fig. 5, passband, passband respectively; C ₁The first variable capacitance diode 7, the second variable capacitance diode 8(or the 3rd variable capacitance diode 9, the 4th variable capacitance diode 10 of expression series connection) series capacitance; C ₂The capacitance that represents the 5th variable capacitance diode 11; C ₃The capacitance that represents the 6th variable capacitance diode 12; ε _rIt is the dielectric constant of above-mentioned medium substrate.

Fig. 3 has described variable capacitance diode in above-mentioned resonator to the relation that affects at three limits and two zero points.When the electric capacity value of variable capacitance diode was in A point and B point centre, this resonator can form one and have three limits and the bandpass characteristics at two zero points.In Fig. 3 a, f _o, f _e1, f _e2, f _TZ1, f _TZ2The resonance frequency at the zero point in the stopband of the outer the right of the zero point in the stopband of the outer left side of the limit on the right in the limit on the left side, passband in the limit in the middle of respectively in corresponding passband, passband, passband, passband; C ₁Represent the first variable capacitance diode 7, the second variable capacitance diode 8(or the 3rd variable capacitance diode 9, the 4th variable capacitance diode 10) series capacitance; In Fig. 3 b, f _o, f _e1, f _e2, f _TZ1, f _TZ2The resonance frequency at the zero point in the stopband of the outer the right of the zero point in the stopband of the outer left side of the limit on the right in the limit on the left side, passband in the limit in the middle of respectively in corresponding passband, passband, passband, passband; C ₂The capacitance that represents the 5th variable capacitance diode 11; C ₃The capacitance that represents the 6th variable capacitance diode 12.

When being operated in different center frequency and bandwidth due to the adjustable microstrip line multimode resonator of above-mentioned cross, need different external sort factors to be complementary with it, the variable capacitance diode that the present invention has designed pair of series carries out impedance matching.According to monograph " J.S.Hong and M.J.Lancaster, Microwave Filter for RF/Microwave Application, New York:John Wiley﹠amp; Sons, 2001. " design of filter of introducing in is theoretical, and for the filter of tap feed, the external component prime factor in the position of tap on resonator has considerable influence.As shown in Figure 4, at the series capacitance C that keeps the first variable capacitance diode 7, the second variable capacitance diode 8 ₁In constant situation, change the electric capacity of the first variable capacitance diode 7 and the second variable capacitance diode 8, just can equivalence move on resonator for the tap of feeding network, changed the external sort factor, can be for good coupling be provided between the resonator under different conditions and feeding network.

In the following embodiments, the high-performance restructural band pass filter that has 669MHz-1215MHz broadband and a wide bandwidth adjustable range is produced on that relative dielectric constant is 3.38, thickness 0.8128mm, fissipation factor be 0.0027 medium basically.Variable capacitance diode is all selected the silicon variable capacitance diode 1sv232 of Toshiba.

Embodiment: the high-performance restructural band pass filter with 669MHz-1215MHz broadband and wide bandwidth adjustable range.

Has the high-performance restructural band pass filter of 669MHz-1215MHz broadband and wide bandwidth adjustable range as shown in Figure 1.Design parameter is: the long 22mm of horizontal microstrip line 2, wide 1mm; The vertical wide 2mm of microstrip line 3 is in the long 7mm of part above horizontal microstrip line, is in the long 4.2mm of part below horizontal microstrip line; Two capacitances 5,6 capacitance equate and are 15pF; 50 ohm microstrip 1,4 length are not limit, wide 1.9mm.Fig. 5 has provided the result of utilizing the designed filter of above-mentioned parameter to carry out emulation and actual measurement, and wherein emulation and actual measurement are completed with the MS4624D vector network analyzer of the business electromagnetism ADS of simulation software of Agilent company and An Li company respectively.In order to show the performance characteristics of this filter, to show in two kinds of situation in this example, a kind of situation is the constant adjusting centre frequency of bandwidth, the constant adjusting bandwidth of frequency centered by another kind of situation.Shown in Fig. 5 a to be that this filter bandwidht is constant regulate centre frequency for 300MHz the time emulation and actual test transmission characteristic, transverse axis represents frequency, the longitudinal axis represents transmission characteristic | S ₂₁|, shown in Fig. 5 b to be that this filter bandwidht is constant regulate centre frequency for 300MHz the time emulation and actual test reflection characteristic, transverse axis represents frequency, the longitudinal axis represents return loss | S ₁₁|.Transmission characteristic and the reflection characteristic of emulation and actual test during remaining 1000MHz and regulate bandwidth for this filter center frequency shown in Fig. 5 c, transverse axis represents frequency, the left longitudinal axis represents transmission characteristic | S ₂₁|, the right longitudinal axis represents return loss | S ₁₁|.By this three width figure as seen, the band connection frequency tuning range of filter has 58% relative bandwidth adjustable range from 669MHz to 1215MHz, its absolute bandwidth adjustable range from 140MHz to 644MHz, corresponding relative bandwidth adjustable range from 14% to 64.4%.The frequency tuning range of this filter and bandwidth adjustment scope all surmount existing filter.The standard of general broadband connections is relative bandwidth more than 20%, and the bandwidth adjustment scope of this filter has realized the reconfigurable filter characteristic in broadband considerably beyond this standard.Under all working state, the excursion of insertion loss be 1dB to 2dB, return loss remains on about 12dB, and ripple is very even, so this filter has kept stable filtering characteristic in frequency and bandwidth adjustment.The outer squareness factor that has improved passband zero point of this filter band, satisfied in Modern Communication System optionally requirement of filter in addition.

The present invention proposes a kind of novel tunable filter structure based on adjustable multimode resonator, the frequency of controlling each mode of resonance by the variable capacitance diode in multimode resonator has realized very wide centre frequency and the adjustable range of bandwidth; And transfer the tap position of feeding network to control the external sort factor with the variable capacitance diode electricity of series connection, and then when being regulated, frequency and bandwidth kept stable filtering characteristic; In addition, this kind also possesses the advantages such as insertion loss is little, required direct current forces down, volume is little, structural design is simple based on the novel tunable filter structure of adjustable multimode resonator.

The above is only preferred embodiments of the present invention, and is in order to limit the present invention, within the spirit and principles in the present invention not all, any modification of doing, is equal to replacement, improvement etc., within all should being included in protection scope of the present invention.

Claims (5)

1. RF reconfigurable band pass filter with broadband and wide bandwidth adjustable range, it is characterized in that, the microstrip structure that comprises the upper strata, the grounded metal of interlayer substrate and lower floor, described upper strata microstrip structure is attached to interlayer plate upper surface, and the lower surface in intermediate layer is grounded metal;

the upper strata microstrip structure comprises an adjustable microstrip line multimode resonator of cross, an input feeding network, output feeding network, an input port and an output port, the adjustable multimode resonator of cross comprises orthogonal two microstrip lines and six variable capacitance diodes, wherein the two ends of horizontal microstrip line connect respectively two variable capacitance diodes of series connection, the two ends of vertical microstrip line have connected respectively a variable capacitance diode, be specially: cross is adjustable, and the microstrip line multimode resonator comprises horizontal rectangular microstrip line [2] and vertical rectangle microstrip line [3], one end series connection the first variable capacitance diode [7] and the second variable capacitance diode [8] of horizontal microstrip line [2], other end series connection the 3rd variable capacitance diode [9] and the 4th variable capacitance diode [10] of horizontal microstrip line [2], vertical microstrip line [3] passes from the middle point vertical of horizontal microstrip line [2], one end of vertical microstrip line [3] connects the 5th variable capacitance diode [11], the other end of vertical microstrip line [3] connects the 6th variable capacitance diode [12], the input feeding network comprises capacitance [5] and the 50 ohm of rectangular microstrip lines [1] that connect in turn, and the output feeding network comprises capacitance [6] and the 50 ohm of rectangular microstrip lines [4] that connect in turn, the characteristic impedance of described input port and output port is all 50 ohm,

Input port is connected with the input feeding network, and output port is connected with the output feeding network; The input feeding network is from tap feed between first variable capacitance diode [7] of multimode resonator and the second variable capacitance diode [8], exports feeding network from tap feed between the 3rd variable capacitance diode [9] of multimode resonator and the 4th variable capacitance diode [10]; Microstrip line multimode resonator left-right symmetric that described cross is adjustable, input feeding network, input port, output feeding network, output port are left-right symmetric and distribute.

2. the RF reconfigurable band pass filter with broadband and wide bandwidth adjustable range according to claim 1, is characterized in that, the vacant end of above-mentioned variable capacitance diode all passes the interlayer substrate and is connected with the lower floor grounded metal.

3. the RF reconfigurable band pass filter with broadband and wide bandwidth adjustable range according to claim 1 and 2, is characterized in that, the long 12～24mm of the horizontal microstrip line [2] in described cross is adjustable microstrip line multimode resonator, wide 0.5～2mm; The vertical wide 0.5～3mm of microstrip line [3] is in the long 4～12mm of part above horizontal microstrip line, is in the long 1～6mm of part below horizontal microstrip line; The appearance of two capacitances in described feeding network value is identical and all more than 6pF.

4. the RF reconfigurable band pass filter with broadband and wide bandwidth adjustable range according to claim 1 and 2, is characterized in that the DIELECTRIC CONSTANT ε of medium substrate _rBeing 2～10, is highly 0.2～1mm.

5. the RF reconfigurable band pass filter with broadband and wide bandwidth adjustable range according to claim 3, is characterized in that the DIELECTRIC CONSTANT ε of medium substrate _rBeing 2～10, is highly 0.2～1mm.

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