CN104241743A - Millimeter wave filter adopting frequency selectivity coupling for suppressing fundamental waves - Google Patents

Abstract

The invention discloses a millimeter wave filter which uses frequency selective coupling to suppress the fundamental wave, which comprises an upper microstrip structure, a middle dielectric substrate and a lower ground metal plate. The filter is composed of two resonators and two feed lines, the two resonators are left and right symmetrical, and the feed lines are also left and right symmetrical. Each resonator includes a main transmission microstrip line open at both ends, and an open stub line loaded at the midpoint of the half-wavelength main transmission line. This center-loaded resonator has two resonant modes or resonant paths. The resonant path of the fundamental wave is a longer half-wavelength resonant path. Due to the introduction of a symmetrical feeding method, selective electromagnetic coupling is generated, thereby suppressing The passband of the fundamental wave, while only the high passband is retained. The invention has the characteristics of easy processing and manufacturing in the 30G frequency band, wide band resistance, good selectivity of the pass band and no redundant circuits.

Description

A Millimeter Wave Filter Using Frequency Selective Coupling to Suppress Fundamental Wave

technical field

The invention relates to a millimeter-wave band-pass filter, in particular to a millimeter-wave filter that suppresses the fundamental wave, has a large size, and can be realized by PCB plate-making technology and adopts frequency selective coupling to suppress the fundamental wave.

Background technique

With the development of millimeter wave engineering, the application of millimeter wave is developing towards higher frequency bands, and new problems have also been encountered. For example, higher frequency means smaller circuit size, which makes circuit processing difficult and high manufacturing cost. Therefore, there is an urgent demand for millimeter-wave filters with lower cost, larger size, and easier processing.

At present, many researchers have used many techniques for the design of millimeter-wave bandpass filters, among which there are several typical methods. The first method is to design millimeter-wave bandpass filters using low-temperature co-fired ceramic technology (LTCC) with multilayer structure and high manufacturing precision, such as S. W. Wong, Z. N. Chen, and Q. X. Chu, (2012), 'Microstrip-line millimeter-wave bandpass filter using interdigital coupled-line', Electron Lett. , 48, pp. 224-225. The second method is to use COMS (bulk complementary metal oxide semiconductor) to design millimeter-wave bandpass filters, such as B. Yang, E. Skafidas, and R. J. Evans, (2012), 'Slow-wave slot microstrip using a slow-wave structure transmission line and bandpass filter for compact millimeter-wave integrated circuits on bulk complementary metal oxide semiconductor', IET Microw. Antennas Propag ., 6, pp. 1548-1555. and H. -R. Lin, C. -Y. Hsu, H. -R. Chuang, and C. -Y. Chen, (2012), 'A 77-GHz miniaturized slow-wave SIR bandpass filter fabricated using 0.18-um standard CMOS technology', Microwave Opt Technol Lett ., 54, pp . 1063–1066. and S. -C. Chang, Y. -M. Chen, S. -F. Chang, Y. -H. Jeng, C. -L. Wei, C. -H. Huang, using step impedance resonators, and C. -P. Jeng, (2010), 'Compact millimeter-wave CMOS bandpass filters using grounded pedestal stepped-impedance technique', IEEE Trans Microw Theory Tech ., 58, pp. 3850-3858. The third method is to use dielectric integrated waveguide technology (SIW) and integrated passive device technology (IPD) to design millimeter-wave bandpass filters, such as C. Y. Hsiao, S. S. H. Hsu, and D. C. Chang, (2011), 'A compact V- band bandpass filter in IPD technology', IEEE Microw Wireless Compon. Lett ., 21, pp. 531-533. and X. P. Chen, and K. Wu, (2012) 'Self-packaged millimeter-wave substrate integrated waveguide filter with asymmetric frequency response', IEEE Trans Compon Package Manufact Tech ., 2, pp. 775-782. The planar microstrip line structure can be realized by the PCB plate-making technology adopted in the present invention.

At this stage, mmWave bandpass filters have attracted a lot of attention. Such as J. –H. Lee, S. Pinel, J. Laskar, and M. M. Tentzeris, (2007), 'Design and development of advanced cavity-based dual-mode filters using low-temperature co-fired ceramic technology for V-band gigabit wireless systems', IEEE Trans Microw Theory Tech ., 55, pp. 1869-1879. However, it adopts LTCC technology, which is difficult to process and high in production cost. In order to solve this problem, the present invention provides a new millimeter-wave bandpass filter capable of suppressing the fundamental wave with a large size.

the

Contents of the invention

The object of the present invention is to overcome the above-mentioned shortcomings in the prior art, and provide a millimeter-wave bandpass filter that uses frequency selective coupling to suppress the fundamental wave.

For realizing the object of the present invention, the technical scheme adopted in the present invention is as follows:

A millimeter-wave filter that uses frequency selective coupling to suppress the fundamental wave, including an upper microstrip structure, an intermediate dielectric substrate, and a lower grounded metal plate; the upper microstrip structure is attached to the upper surface of the intermediate dielectric substrate, and the lower grounded metal plate Attached to the lower surface of the intermediate dielectric substrate; the upper microstrip structure includes two feeders and two resonators; the two resonators are centrally symmetrical and have the same structure, and the resonators are equivalent to half a wavelength when they work in the low passband The resonator is also equivalent to a half-wavelength resonator when it works in the high-pass band, but the two resonance paths are different. One of the feed lines of the filter is divided into two at the input port, and they are loaded symmetrically along the center The outer edge of the resonator is coupled and fed, and the other feed line is divided into two paths at the output port, and the coupled feed is carried out symmetrically along the other center-loaded resonator.

The above-mentioned millimeter-wave filter that uses frequency selective coupling to suppress the fundamental wave, the resonator includes a half-wavelength main transmission line and an open-circuit stub line loaded at the center of the resonator, wherein the half-wavelength main transmission microstrip line is partly composed of a fourth microstrip The strip line, the fifth microstrip line, the sixth microstrip line, the eighth microstrip line and the ninth microstrip line are connected in sequence, one end of the fourth microstrip line and one end of the ninth microstrip line are open, and the other One end is respectively connected with the two ends of the microstrip line, and the open stub line loaded in the center of the sixth microstrip line is the seventh microstrip line, one end of which is connected in the middle of the half-wavelength main transmission line, and the other end is open. When the resonator works in the low passband, the resonant path is half of the corresponding low passband formed by the fourth microstrip line, the fifth microstrip line, the sixth microstrip line, the eighth microstrip line, and the ninth microstrip line. The wavelength path, when working in the high-pass band, the resonant path is the half-wavelength path corresponding to the high frequency composed of the fourth microstrip line, the fifth microstrip line, half of the sixth microstrip line and the seventh microstrip line.

The above millimeter-wave filter that uses frequency selective coupling to suppress the fundamental wave, the electrical length L of the half-wavelength main transmission line of each resonator is half the wavelength corresponding to the fundamental resonant frequency f ₁ ; L/2 + L ₁ is _Half of the wavelength λ corresponding to the high resonance frequency f of the double bandpass filter, L1 is the length _of the seventh microstrip line; the length L of the half-wavelength main transmission microstrip line is the fourth microstrip line, the fifth microstrip line The sum of the lengths of the strip line, the sixth microstrip line, the eighth microstrip line and the ninth microstrip line.

In the millimeter-wave filter that uses frequency selective coupling to suppress the fundamental wave, the half-wavelength main transmission line of the resonator is composed of the fourth microstrip line, the fifth microstrip line, the sixth microstrip line, the eighth microstrip line and the fourth microstrip line. Nine microstrip lines are connected in sequence, and the two resonators are symmetrical about the central axis, forming two back-to-back E-shaped structures.

In the above-mentioned millimeter wave filter that uses frequency selective coupling to suppress the fundamental wave, one of the feed lines is composed of the first microstrip line, the second microstrip line, the third microstrip line, and the nineteenth microstrip line. One end of a microstrip line is open, the other end is connected to one end of the second microstrip line, the other end of the second microstrip line is connected to one end of the third microstrip line, the other end of the third microstrip line is open, and one end of the nineteenth microstrip line The other end is vertically lapped at the center of the second microstrip line; the other feeder line is composed of the tenth microstrip line, the eleventh microstrip line, the twelfth microstrip line, and the twentieth microstrip line. One end of the tenth microstrip line is open, the other end is connected to one end of the eleventh microstrip line, the other end of the eleventh microstrip line is connected to one end of the twelfth microstrip line, the other end of the twelfth microstrip line is open circuited, One end of the microstrip line is open, and the other end is vertically lapped at the center of the eleventh microstrip line; the feeder line connected after the input port is divided into two paths, one of which includes half of the first microstrip line and the second microstrip line ; The other way includes the third microstrip line and the other half of the second microstrip line; wherein there is a gap of 0.1 ± 0.05 mm between the first microstrip line and the eighth microstrip line of the half-wavelength main transmission line to realize parallel coupling; There is a gap of 0.1±0.05 mm between the third microstrip line and the fifth microstrip line of the half-wavelength main transmission line to realize parallel coupling; there is a gap between the second microstrip line, the fourth microstrip line and the ninth microstrip line A gap of 0.1±0.05 mm is used to achieve parallel coupling.

In the above-mentioned millimeter-wave filter that uses frequency selective coupling to suppress the fundamental wave, the feed line connected before the output port is divided into two paths, one path includes half of the tenth microstrip line and the eleventh microstrip line; the other path includes The other half of the twelfth microstrip line and the eleventh microstrip line.

The above-mentioned millimeter-wave filter that uses frequency selective coupling to suppress the fundamental wave, the passband of the filter is fixed at 30 GHz, and has a good suppression level in a wide range of frequency bands; the length of the first microstrip line is 1.1±0.02mm, the width is 0.2±0.02mm, the length of the second microstrip line is 4.2±0.02mm, the width is 0.2±0.02mm, the length of the third microstrip line is 1.1±0.02mm, and the width is 0.2±0.02 mm, the nineteenth microstrip line is connected to the input port, its characteristic impedance is 50Ω, the length is 1.3±0.02mm, and the width is 0.8±0.03mm, the length of the fourth microstrip line is 1.2±0.04mm, and the width is 0.2±0.02mm mm, the length of the fifth microstrip line is 0.8±0.01mm, the width is 0.2±0.02mm, the length of the sixth microstrip line is 3.6±0.01mm, and the width is 0.2±0.02mm, the length of the seventh microstrip line is 0.6±0.05mm, the width is 0.2±0.02mm, the length of the eighth microstrip line is 0.8±0.01mm, the width is 0.2±0.02mm, the length of the ninth microstrip line is 1.2±0.04mm, and the width is 0.2±0.02 mm, the length of the tenth microstrip line is 1.1±0.02mm, the width is 0.2±0.02mm, the length of the eleventh microstrip line is 4.2±0.02mm, and the width is 0.2±0.02mm, the width of the twelfth microstrip line The length is 1.1±0.02mm, the width is 0.2±0.02mm, the twentieth microstrip line is connected to the output port, its characteristic impedance is 50Ω, the length is 1.3±0.02mm, the width is 0.8±0.03mm, the first microstrip line and The spacing between the eighth microstrip line is 0.1+0.05mm, the spacing between the third microstrip line and the fifth microstrip line is 0.1±0.05mm, between the second microstrip line, the fourth microstrip line and the ninth microstrip line The spacing is 0.1±0.05 mm.

Compared with the prior art, the present invention has the following advantages:

(1) Both ends of the half-wavelength main transmission line are open, the center is loaded with open-circuit stub lines, and two resonators are used to realize the function of dual-mode resonance.

(2) Due to the use of dual-mode resonators and selective coupling, the fundamental resonant frequency is suppressed, so the filter is considered large in size at the operating frequency and is easy to process. The size of the whole circuit is 0.37lg'0.58lg, and lg is the wavelength corresponding to the low frequency.

(3) Selective coupling is used to suppress the fundamental wave, the stop band range is very wide, no additional circuit is introduced between the feeder line and the resonator, and the structure is simple.

Description of drawings

Figure 1 is a structural diagram of a millimeter-wave filter that uses frequency-selective coupling to suppress the fundamental wave.

Figure 2a is a schematic diagram of the microstrip line coupling region of the electromagnetic coupling structure for selective coupling and suppression of the fundamental wave,

Figure 2b is a schematic diagram of odd and even mode voltages on the feeder;

Fig. 2c is a schematic diagram of odd and even mode voltages in the partial coupling region of the resonator.

Fig. 3 is a schematic diagram of a millimeter wave filter that uses frequency selective coupling to suppress the fundamental wave.

Fig. 4 is the simulation result diagram of the asymmetry of the feeding port, and the fundamental wave is not suppressed.

Figure 5 is a plot of the insertion loss of the simulated and tested filter.

Figure 6 is a plot of the return loss of the simulated and tested filter.

Fig. 7 is a diagram of insertion loss of a simulated and tested filter for a local low passband.

Fig. 8 is a return loss diagram of a simulated and tested filter for a local low passband.

specific implementation plan

The present invention will be described in further detail below in conjunction with the accompanying drawings, but the scope of protection claimed by the present invention is not limited to the scope of the following examples.

As shown in Figure 1, the millimeter wave filter that uses frequency selective coupling to suppress the fundamental wave (implemented using a simple and low-cost process such as PCB plate making) includes the upper microstrip structure, the middle dielectric substrate and the lower ground metal plate; The upper microstrip structure is attached to the upper surface of the intermediate dielectric substrate, and the lower ground metal plate is attached to the lower surface of the intermediate dielectric substrate; it is characterized in that: the upper microstrip structure includes two feed lines and two resonators; the two resonators are The central axis is symmetrical and has the same structure. The resonator is equivalent to a half-wavelength resonator when it works in the low-pass band, and it is also equivalent to a half-wavelength resonator when it works in the high-pass band, but the two resonance paths are different; the filter One of the feeding lines of the resonator is divided into two ways at the input port, and the coupling feeding is carried out symmetrically along the outer edge of the center-loaded resonator; the other feeding line is divided into two ways at the output port, respectively symmetrically along the other Center-loaded resonators for coupling feed.

In the above-mentioned millimeter-wave filter using frequency selective coupling to suppress the fundamental wave, the resonator includes a half-wavelength main transmission line and an open stub line loaded at the center of the resonator. Among them, the half-wavelength main transmission microstrip line is formed by sequentially connecting the fourth microstrip line, the fifth microstrip line, the sixth microstrip line, the eighth microstrip line and the ninth microstrip line, and the fourth microstrip line One end and one end of the ninth microstrip line are all open, and the other end is connected to the two ends of the microstrip line; In the middle of the transmission line, the other end is open.

The above-mentioned millimeter-wave filter that uses frequency selective coupling to suppress the fundamental wave can be seen from the analysis of odd and even modes. In the odd mode, the middle of the half-wavelength main transmission line is equivalent to grounding, corresponding to the low passband, and is a half-wavelength resonator; The electrical length corresponding to the length L of the half-wavelength main transmission line of the resonator is half of the wavelength corresponding to the low resonance frequency f ₁ of the millimeter-wave bandpass filter; Half of the transmission line is connected to the seventh microstrip line 7, which corresponds to the high-pass band when it resonates, and is a half-wavelength resonator. That is, 1/2 L + L ₁ is 1/2 of the wavelength λ corresponding to the high resonance frequency f ₂ of the millimeter-wave bandpass filter, and L ₁ is the length of the seventh microstrip line 7; the half-wavelength main transmission micro The stripline length L is the sum of the lengths of the fourth microstrip line 4, the fifth microstrip line 5, the sixth microstrip line 6, the eighth microstrip line 8 and the ninth microstrip line ₉ ; the resonant frequency f is determined by the microstrip line The sum L of the lengths of the fourth microstrip line 4, the fifth microstrip line 5, the sixth microstrip line 6, the eighth microstrip line 8 and the ninth microstrip line 9 determines the low resonance to be suppressed After the frequency f ₁ , then the sum L of the lengths of the fourth microstrip line 4, the fifth microstrip line 5, the sixth microstrip line 6, the eighth microstrip line 8 and the ninth microstrip line 9 corresponds to a half wavelength The length of L can be determined by the characteristic of L; when the high resonance frequency f ₂ is determined, the length of 1/2L+L ₁ is also determined, and then the length of L ₁ can be determined. Due to the symmetrical feeding method adopted at the midpoint of the second microstrip line 2, the voltage on the feeder line composed of the first microstrip line 1, the second microstrip line 2 and the third microstrip line 3 is related to the feeding Points are distributed as even functions when the odd and even modes resonate. As shown in Figure 2a, in order to suppress the fundamental resonance, the selective coupling method is used to select the appropriate coupling area between the feeder line and the main resonator, in Figure 2b it is from AA' to BB' and from CC' to DD ' shown in the two regions; as shown in Fig. 2c, at the odd-mode resonant frequency f ₁ , the voltages of the two regions are distributed as an odd function with respect to the midpoint of the main microstrip line, so the coupling factor is zero in the selected coupling region, suppressing The signal is transmitted from the feed line to the resonator, and the fundamental resonant frequency is suppressed; at the even-mode resonant frequency f ₂ , the voltages of the two regions are distributed as an even function with respect to the midpoint of the main microstrip line, so in the selected coupling The coupling factor in the region is not zero, and its coupling strength can be obtained by controlling the coupling gap to an appropriate value.

For the millimeter-wave filter that uses frequency selective coupling to suppress the fundamental wave, the half-wavelength main transmission line of the resonator is composed of the fourth microstrip line 4, the fifth microstrip line 5, the sixth microstrip line 6, and the eighth microstrip line. The line 8 and the ninth microstrip line 9 are connected in sequence, and the two resonators are symmetrical about the central axis, forming two back-to-back E-shaped structures.

In the millimeter wave filter using frequency selective coupling to suppress the fundamental wave, one of the feed lines is composed of the first microstrip line 1, the second microstrip line 2, the third microstrip line 3, and the nineteenth microstrip line 19 components, one end of the first microstrip line 1 is open, the other end is connected to one end of the second microstrip line 2, the other end of the second microstrip line 2 is connected to one end of the third microstrip line 3, and the other end of the third microstrip line 3 Open circuit, one end of the nineteenth microstrip line 19 is open circuit, and the other end is vertically lapped at the center of the second microstrip line 2; the other feeder line consists of the tenth microstrip line 10, the eleventh microstrip line 11, the One end of the tenth microstrip line 10 is open, the other end is connected to one end of the eleventh microstrip line 11, the other end of the eleventh microstrip line 11 is connected to the twelfth microstrip line One end of the strip line 12 is connected, the other end of the twelfth microstrip line 12 is open, one end of the twentieth microstrip line 20 is open, and the other end is vertically lapped at the center of the eleventh microstrip line 11; The feeding lines are divided into two paths, one path includes the first microstrip line 1 and half of the second microstrip line 2 ; the other path includes the third microstrip line 2 and the other half of the second microstrip line 2 . As an example, there is a gap of 0.1±0.05 mm between the first microstrip line 1 and the eighth microstrip line 8 of the half-wavelength main transmission line to realize parallel coupling; the third microstrip line 3 and the fifth half-wavelength main transmission line There is a gap of 0.1±0.05 mm between the microstrip lines 5 to achieve parallel coupling; there is a gap of 0.1±0.05 mm between the second microstrip line 2 and the fourth microstrip line 4 and the ninth microstrip line 9 to achieve parallel coupling coupling.

The feeder line connected before the output port is divided into two paths, one path includes half of the tenth microstrip line 10 and the eleventh microstrip line 11; the other path includes the twelfth microstrip line 12 and the eleventh microstrip line The other half of 11.

As an example, the passband of the filter is fixed at 30 GHz, and has a good suppression level in a wide range of frequency bands; the length of the first microstrip line 1 is 1.1 ± 0.02 mm, and the width is 0.2 ± 0.02 mm, The length of the second microstrip line 2 is 4.2±0.02mm, and the width is 0.2±0.02mm. The length of the third microstrip line 3 is 1.1±0.02mm, and the width is 0.2±0.02mm. The nineteenth microstrip line 19 is connected to The input port has a characteristic impedance of 50Ω, a length of 1.3±0.02mm, and a width of 0.8±0.03mm. The length of the fourth microstrip line 4 is 1.2±0.04mm, and the width is 0.2±0.02mm. The fifth microstrip line 5 The length is 0.8±0.01mm, the width is 0.2±0.02mm, the length of the sixth microstrip line 6 is 3.6±0.01mm, the width is 0.2±0.02mm, the length of the seventh microstrip line 7 is 0.6±0.05mm, The width is 0.2±0.02mm, the length of the eighth microstrip line 8 is 0.8±0.01mm, and the width is 0.2±0.02mm, the length of the ninth microstrip line 9 is 1.2±0.04mm, and the width is 0.2±0.02mm. The tenth microstrip line 10 has a length of 1.1±0.02mm and a width of 0.2±0.02mm, the eleventh microstrip line 11 has a length of 4.2±0.02mm and a width of 0.2±0.02mm, and the twelfth microstrip line 12 The length is 1.1±0.02mm, the width is 0.2±0.02mm, the twentieth microstrip line 20 is connected to the output port, its characteristic impedance is 50Ω, the length is 1.3±0.02mm, the width is 0.8±0.03mm, the first microstrip line The distance between 1 and the eighth microstrip line 8 is 0.1+0.05mm, the distance between the third microstrip line 3 and the fifth microstrip line 5 is 0.1±0.05mm; the second microstrip line 2 and the fourth microstrip line 4 And the spacing between the ninth microstrip lines 9 is 0.1±0.05 mm.

Example

The structure of a millimeter-wave filter that uses frequency selective coupling to suppress the fundamental wave is shown in Figure 1, and the relevant dimensions are shown in Figure 3 below; the thickness of the dielectric substrate is 0.254mm, the relative permittivity is 2.2, and the loss angle The tangent is 0.0009; the E-shaped structure of the resonator can facilitate the design of selective coupling feeding structure; the size parameters of each microstrip line of the filter are as follows: L ₁ =1.06±0.01mm, L ₂ =0.6±0.01mm, L ₃ =1.16±0.01mm, L ₄ = L5 =1.515±0.01mm, L ₆ =1.385±0.01mm, L ₇ =0.65±0.01mm, g ₁ =0.15±0.01mm, g ₂ =0.1±0.01mm, W ₁ =0.2±0.01mm, W ₂ =0.77±0.01mm, W ₃ =0.2±0.01mm, W ₄ =0.2±0.01mm, select the respective length and width of these microstrip lines to obtain the desired input/output Impedance characteristics, in-band transmission characteristics and out-of-band attenuation characteristics.

Fig. 4 is the simulation result diagram of asymmetric feed port under the condition of other parameters being constant; the dotted line represents the simulation result of insertion loss S ₂₁ , and the solid line represents the simulation result of return loss S ₁₁ ; it can be seen from the figure , when the feeding port is asymmetrical, the fundamental resonance passband is not suppressed, when the feeding port is symmetrical, the fundamental resonance passband is well suppressed, showing good out-of-band suppression characteristics; Figure 5 and Figure 6 respectively It is the simulation result of S ₂₁ (insertion loss) and S ₁₁ (return loss) of the large-sized millimeter-wave bandpass filter that suppresses the fundamental wave designed according to the above parameters; the horizontal axis in the output characteristic curve represents the frequency, and the vertical Axes represent transfer characteristics , The dotted line is the simulation result, and the solid line is the test result; the test result in Figure 5 shows that the center frequency of the passband is 30.2 GHz, and the insertion loss is 2.5dB, which is different from the simulation insertion loss of 1.1dB because the 50 The loss and the loss of the SMA head on the port, there are transmission zeros on both sides of the passband, which greatly improves the selectivity of the filter; because the fundamental resonant frequency is suppressed, a good out-of-band suppression characteristic is obtained. The frequency is lower than 29GHz and in the frequency range from 33GHz to 50GHz, the return loss is lower than -20dB; in order to show the passband characteristics and the effect of out-of-band suppression more clearly, Figure 7 intercepts the partial graphics in Figure 5, and its test insertion The loss is -2.5dB, the simulation insertion loss is -1.1dB, and the relative bandwidth of -3dB is 4.6%; Figure 6 shows the transmission characteristics It can be seen from the figure that the simulated passband return loss is better than -23dB; in order to see the effect of the passband return loss S ₁₁ more clearly, Fig. 8 intercepts the partial passband graph in Fig. 6, The test result shows that the passband return loss is better than -11dB, and the test result is basically consistent with the simulation result. The simulation and test are completed by using the full-wave electromagnetic simulation software IE3D and E5071C network analyzer respectively.

The simulation and actual measurement results of the embodiment show that the fundamental resonant frequency can be well suppressed by the above design, and no additional circuit is introduced, the resonant frequency has a relatively large circuit size, and it is easy to process and manufacture in the 30G frequency band, and the passband Choose good features.

The above descriptions are only preferred examples of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (8)

1. adopt frequency selectivity coupling to carry out a millimeter wave filter for Fundamental wave suppression, comprise upper-layer micro-strip structure, interlayer substrate and lower floor's grounding plate; Upper-layer micro-strip structure is attached to interlayer upper surface of base plate, and lower floor's grounding plate is attached to interlayer base lower surface; It is characterized in that: upper-layer micro-strip structure comprises two feed lines and two resonators; Two resonators are formed symmetrical, and structure is identical, and resonator works is equivalent to half-wave resonator when lower passband, are also equivalent to half-wave resonator when being operated in upper passband, and the resonant path of resonator when upper passband and lower passband work is different; A wherein feed line of described filter punishes into two-way at input port, carries out couple feed symmetrically respectively along the outward flange of center loaded resonator; An other feed line punishes into two-way at output port, carries out couple feed symmetrically respectively along another center loaded resonator.

2. employing frequency selectivity coupling according to claim 1 carrys out the millimeter wave filter of Fundamental wave suppression, it is characterized in that described resonator comprises the open circuit minor matters line that a half-wavelength main transmission line and are carried in this resonator central, wherein half-wavelength main transmission microstrip line part is connected in sequence by the 4th microstrip line, the 5th microstrip line, the 6th microstrip line, the 8th microstrip line and the 9th microstrip line, all open a way in one end of 4th microstrip line and one end of the 9th microstrip line, the other end is connected with the two ends of microstrip line respectively; The open circuit minor matters line being carried in the 6th microstrip line center is the 7th microstrip line, and its one end is connected to the centre of half-wavelength main transmission line, and the other end is opened a way.

3. employing frequency selectivity coupling according to claim 2 carrys out the millimeter wave filter of Fundamental wave suppression, it is characterized in that the half-wavelength path of the corresponding lower passband that resonator works resonant path when lower passband is the 4th microstrip line, the 5th microstrip line, the 6th microstrip line, the 8th microstrip line, the 9th microstrip line form, when being operated in upper passband resonant path be the 4th microstrip line, the high-frequency half-wavelength path of correspondence that forms of a half-sum the 7th microstrip line of the 5th microstrip line, the 6th microstrip line.

4. employing frequency selectivity coupling according to claim 2 carrys out the millimeter wave filter of Fundamental wave suppression, it is characterized in that the length of the half-wavelength main transmission line of each resonator lelectrical length fundamental resonant frequency f ₁the half of corresponding wavelength; l/2+ l ₁for the high resonance frequency of described twin band pass filter f ₂the half of corresponding wavelength X, l ₁be the length of the 7th microstrip line; Half-wavelength main transmission microstrip line length lit is the length sum of the 4th microstrip line, the 5th microstrip line, the 6th microstrip line, the 8th microstrip line and the 9th microstrip line.

5. employing frequency selectivity coupling according to claim 2 carrys out the millimeter wave filter of Fundamental wave suppression, it is characterized in that the half-wavelength main transmission line part of resonator is connected in sequence by the 4th microstrip line, the 5th microstrip line, the 6th microstrip line, the 8th microstrip line and the 9th microstrip line, two resonators about formed symmetrical, in two back-to-back E shape structures.

6. employing frequency selectivity coupling according to claim 2 carrys out the millimeter wave filter of Fundamental wave suppression, described in it is characterized in that, wherein one article of feed line is made up of the first microstrip line, the second microstrip line, the 3rd microstrip line, the 19 microstrip line, first microstrip line one end open circuit, the other end is connected with second microstrip line one end, the second microstrip line other end is connected with the 3rd microstrip line one end, 3rd microstrip line other end open circuit, 19 microstrip line one end open circuit, the other end is vertically overlapped on the center of the second microstrip line; Another article feed line is made up of the tenth microstrip line, the 11 microstrip line, the 12 microstrip line, the 20 microstrip line, tenth microstrip line one end open circuit, the other end is connected with the 11 microstrip line one end, the 11 microstrip line other end is connected with the 12 microstrip line one end, 12 microstrip line other end open circuit, 20 microstrip line one end open circuit, the other end is vertically overlapped on the center on the 11 microstrip line; Feed line after being connected on input port is divided into two-way, and wherein a road comprises the half of the first microstrip line and the second microstrip line; Another road comprises second half of the 3rd microstrip line and the second microstrip line; Wherein there is the gap of 0.1 ± 0.05 mm to realize parallel coupling between the first microstrip line and the 8th microstrip line of half-wavelength main transmission line; The gap of 0.1 ± 0.05 mm is had to realize parallel coupling between 3rd microstrip line and the 5th microstrip line of half-wavelength main transmission line; The gap of 0.1 ± 0.05 mm is had to realize parallel coupling between second microstrip line and the 4th microstrip line and the 9th microstrip line.

7. employing frequency selectivity coupling according to claim 2 carrys out the millimeter wave filter of Fundamental wave suppression, and the feed line before being connected on output port described in it is characterized in that is divided into two-way, and a road comprises the half of the tenth microstrip line and the 11 microstrip line; Another road comprises second half of the 12 microstrip line and the 11 microstrip line.

8. employing frequency selectivity coupling according to claim 7 carrys out the millimeter wave filter of Fundamental wave suppression, it is characterized in that, the passband of described filter is fixed on 30GHz, the length of the first microstrip line is 1.1 ± 0.02mm, width is 0.2 ± 0.02mm, the length of the second microstrip line is 4.2 ± 0.02mm, width is 0.2 ± 0.02mm, the length of the 3rd microstrip line is 1.1 ± 0.02mm, width is 0.2 ± 0.02mm, 19 microstrip line connects input port, its characteristic impedance is 50 Ω, length is 1.3 ± 0.02mm, width is 0.8 ± 0.03mm, the length of the 4th microstrip line is 1.2 ± 0.04mm, width is 0.2 ± 0.02mm, the length of the 5th microstrip line is 0.8 ± 0.01mm, width is 0.2 ± 0.02mm, the length of the 6th microstrip line is 3.6 ± 0.01mm, width is 0.2 ± 0.02mm, the length of the 7th microstrip line is 0.6 ± 0.05mm, width is 0.2 ± 0.02mm, the length of the 8th microstrip line is 0.8 ± 0.01mm, width is 0.2 ± 0.02mm, the length of the 9th microstrip line is 1.2 ± 0.04mm, width is 0.2 ± 0.02mm, the length of the tenth microstrip line is 1.1 ± 0.02mm, width is 0.2 ± 0.02mm, the length of the 11 microstrip line is 4.2 ± 0.02mm, width is 0.2 ± 0.02mm, the length of the 12 microstrip line is 1.1 ± 0.02mm, width is 0.2 ± 0.02mm, 20 microstrip line connects output port, its characteristic impedance is 50 Ω, length is 1.3 ± 0.02mm, width is 0.8 ± 0.03mm, the spacing of the first microstrip line and the 8th microstrip line is the spacing of 0.1+0.05mm the 3rd microstrip line and the 5th microstrip line is 0.1 ± 0.05mm, spacing between second microstrip line and the 4th microstrip line and the 9th microstrip line is 0.1 ± 0.05 mm.