US3657670A - Microwave bandpass filter with higher harmonics rejection function - Google Patents

Microwave bandpass filter with higher harmonics rejection function Download PDF

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Publication number
US3657670A
US3657670A US9926A US3657670DA US3657670A US 3657670 A US3657670 A US 3657670A US 9926 A US9926 A US 9926A US 3657670D A US3657670D A US 3657670DA US 3657670 A US3657670 A US 3657670A
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waveguide
distance
walls
narrow
cavity
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Susumu Kitazume
Osamu Kasuga
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NEC Corp
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Nippon Electric Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/16—Auxiliary devices for mode selection, e.g. mode suppression or mode promotion; for mode conversion
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/20—Frequency-selective devices, e.g. filters
    • H01P1/212—Frequency-selective devices, e.g. filters suppressing or attenuating harmonic frequencies

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  • ABSTRACT second harmonic Baraff Attorney-Mam & J angarathis [57] ABSTRACT second harmonic; and one or two adjustable screws disposed between the two susceptance elements in one or both waveguide wide walls to project into the interior of the cavity at a position which is one-twelth of the one-third waveguide wavelength susceptance element spacing and which is from an adjacent narrow waveguide wall one-third of the overall distance between the two narrow waveguide walls whereby thescrews are restricted to function as one or two capacitive elements only for the TE mode.
  • a travelling-wave tube is used as the power amplifier on the transmission side.
  • a travelling-wave tube has, however, inherent nonlinearity, due to which higher harmonics are inevitably generated at the amplification stage.
  • Such harmonic components are not only unnecessary to microwave communication but also undesirable for the system as a whole because it requires excessive power for transmission. Such undesirable components should therefore be removed.
  • a band pass filter is usually coupled to the output end of the TWT arnplifier for this purpose.
  • a conventional bandpass filter of the waveguide type is not capable of rejecting the higher harmonic components. It allows the undesirable higher n harmonics to pass therethrough together with the fundamental components.
  • a lowpass filter must be employed in addition to the bandpass filter.
  • a novel microwave bandpass filter which has sufficiently high rejection characteristic against second harmonic component, which is dominant among the higher harmonic components.
  • This invention is based on the fact that the higher harmonic components can be substantially suppressed by rejecting the second higher harmonic component, because higher-thansecond higher harmonics are very weak and can be neglected. Since the second higher harmonics are in the region where higher transmission modes of microwaves are concentrated, the second higher harmonics can be suppressed by eliminating the higher mode components.
  • FIG. 1 schematically shows a conventional bandpass filter
  • FIG. 2 is a waveform diagram showing the characteristics of the bandpass filter of FIG. 1;
  • FIGS. 3a-3f shows various modes possible in a bandpass filter of the rectangular waveguide type
  • FIG. 4 shows characteristic curves of the filter to illustrate the principle of this invention
  • FIG. 5 schematically shows a bandpass filter embodying this invention
  • FIG. 6 shows the characteristic curve of the filter-of FIG. 5.
  • FIG. 7 through 10 schematically show modifications of the embodiment in FIG. 5.
  • susceptance elements 11 and 11' each consisting of three rods disposed in perpendicular relation to the wide plane of a rectangular waveguide 10 for TE mode propagation, are disposed at an interval of one-half of the guide wavelength Ag (namely, Ag/2) to form a cavity resonator 12.
  • a plurality of resonators 12 and 13 are disposed in series at a spacing of Ag/4.
  • Each of the resonators 12 and 13 has tuning screw 14 for attaining the tuned state at each of the resonators l2 and 13.
  • This bandpass filter has the attenuation vs. frequency characteristic as seen from the curve in FIG. 2 that a bandpass filter consisting of a waveguide having a width a of the wide plane has its selectivity only in the range where the frequency is lower than the cutoff frequency fc for the TE, mode.
  • the cutoff frequency fc is approximately equal to c/a; where 0 denotes the velocity of light.
  • the bandpass filter has its selectivity only in the range where the frequency f is lower than fc In the region above f rnthe characteristics become indefinite, because the existence of possible higher modes disturbs the function of the filter.
  • the second harmonic 2f twice as high as the frequency f of the passband of the bandpass filter is higher than fc and included in the region where disturbance is caused.
  • FIG. 3(a) illustrates field intensity distributions (in absolute value) of the fundamental (or dominant) mode TE which is generally used as the desirable frequency of the passband of the filter.
  • FIGS. 3(b) through 3(f) illustrate higher modes I T8 T8 TE TE TE and TE respectively, of a bandpass filter consisting .of susceptance elements 21 and 21' each comprising three rods disposed in perpendicular relation to the wide plane of a rectangular waveguide 20. Let it be as sumed here that the long line of the cross-sectional rectangle of the rectangular waveguide lies in X-axis, the shorter line in Y-axis, and the longitudinal axis in Z-axis.
  • the electric field intensity distribution of the fundamental mode TE has a single sinusoidal hump each in X-Y plane and YZ plane (extending from the inductive rod 21 to 21).
  • the wavelength of the mode under consideration is the guide wavelength.
  • FIG. 3(b) shows a field intensity distribution of higher mode TE having a double sinusoidal hump in X-Y plane, and a single hump in Y-Z plane (extending from the inductive rod 21 to 21').
  • FIG. 3(c) shows a similar distribution of higher mode TE having a single sinusoidal hump in the X-Y plane, and a double hump in the Y-Z plane (extending from the inductive post 21 to 21').
  • the inner width measured in X direction of the rectangular waveguide 20 is a, and the axial length of the waveguide section or cavity defined by rod arrays 21 and 21' and measured in the Z-axis direction I.
  • the guide wavelength Ag of the electromagnetic wave propagated in the waveguide in the TE mode is expressed by The resonant frequency f at the cavity length is given, from Eqs. (1) and (2), by
  • FIG. 4 shows characteristic curves, which are the results of calculation from Equation (5).
  • Curve 31 shows the relationship between the resonant frequency f for the fundamental mode TE and the cavity length l normalized by the cutofi' frequency and cutoff wavelength for the TE mode itself.
  • Curve 32 shows the relationship between the resonant frequency f of a higher mode T13 and the cavity length I normalized by the cutoff frequency j and cutoff wavelength Ac of the fundamental mode TE Similarly, curves 33 through 37 show relationships between the resonant frequency f for higher modes TE TE TE TE, and TE respectively, and the cavity length normalized by the cutofi frequency f, and cutoff wavelength M for the fundamental wave TE mode.
  • a rectangular-waveguide-type bandpass filter is designed to operate with f/f value of the desirable (or fundamental) frequency of the passband in the range between 1.4 and 1.8.
  • f/f for the fundamental frequency value is between 1.4 and 1.63.
  • f/f for the fundamental frequency is in the range between 1.58 and 1.71. It is therefore apparent that second harmonic must be rejected in the f/f value range between 2.8 and 3.3 or between 3.1 and 3.6. To attain this objective, the resonance curves for the higher modes should never fall within this range. In FIG. 4, the hatched area satisfies this condition.
  • the area where l/M value lies in the range between 0.2 and 0.3 is favorable.
  • the reason for this is as follows: While the l/Ac values lie in the region between 0.3 and 0.6, curves 33, 35, and 36 respectively for TE TE and TE, modes are existent, this is not favorable to elimination of higher modes.
  • the resonant frequency for the fundamental mode TE corresponding to the fundamental frequency becomes lower than the desirable resonant frequency f, and very difficult to raise.
  • the resonant frequency for the fundamental frequency is unnecessarily high, and also difficult to lower. Therefore, by way of selecting the cavity length l to fall within this area, the second harmonic component can be rejected.
  • the higher mode TE it is sufficient for the higher mode TE to reduce its resonant frequency or to keep it unchanged.
  • the resonant frequency of T15 mode can be reduced by inserting a capacitive rod at a position except for on the line -15.
  • the cutoff frequency f normalized by the cutoff frequency f, for TE mode, f /f is equal to 2, which is well above the frequency region for TE mode ranging from 1.4 and L8.
  • the capacitive rod may be disposed anywhere.
  • the capacitive rod in order to lower the resonant frequency of the fundamental wave TE the capacitive rod must be disposed at such a point at which the field of the fundamental mode TE is maximum as the center position of the wide plane of the waveguide which forms the resonator with the susceptance elements.
  • the capacitive rod should be disposed on the center line A-A' of the cavity at which the field of the same mode is minimum as shown in FIG. 3(c).
  • the capacitive rods should be positioned on the trisectional lines B-B and C-C' on the major plane along the longitudinal axis at which the field of the mode is minimum as shown in FIG. 3(d).
  • the element is on the center line A-A' of the cavity and also the center line E-E' on the major plane of the rectangular waveguide, at the two lines the field is minimum as shown in FIG. 3(e).
  • the positions common to the conditions for these modes are D and D at which the center line A-A of the cavity are in crossed relation with the trisectional lines 8-8 and C-C as shown in FIG. 3(d).
  • the TE mode has no problem in rejecting the second harmonic component.
  • the length I of the cavity of the rectangular waveguide section is made equal to %Ag, in contrast to the corresponding length m of the conventional bandpass filter and adjustable capacitive elements (screws) 41 and 41 are installed at two points, respectively, at which the trisectional lines 42 and 42' on the major plane of the rectangular waveguide 40 intersect with the bisector 43 of the interval 1 between the induction rods 44 and 44'.
  • FIG. 6 shows the attenuation vs. frequency characteristics of the second-harmonic-rejecting bandpass filter of FIG. 5.
  • this filter is capable of rejecting the higher modes in the frequency region twice as high as the resonant frequencies for fundamental mode. More specifically, this filter rejects the higher modes in the region where f/f ranges from 2.8 to 3.6, while the f/f, value for the passband for fundamental wave ranges from 1.4 to 1.8. Thus, the second harmonic wave component is eliminated.
  • FIGS. 7 through 9 show modifications of the embodiment in FIG. 5. These modifications are based on the fact that, as described above, the higher mode TE may be left out of consideration if the second harmonic is to be rejected and, therefore, the structure of the bandpass filter need not be symmetrical.
  • FIG. 7 shows a modification of the embodiment in FIG. 5 wherein only one of the adjustable capacitive elements (screws) of FIG. 5 is used.
  • FIG. 7 embodies only the adjustable capacitive element 41 disposed at the intersection of the trisection line 42 and the bisector 43 in the manner of FIG. 5, the adjustable capacitive 41' in FIG. 5 being omitted in FIG. 7.
  • the essential dimensions in FIG. 7 being the same as corresponding dimensions in FIG. 5.
  • FIG. 8 shows another modification wherein one of the adjustable capacitive elements (screw) is installed at the trisectional in the opposing major surface of the waveguide.
  • FIG. 8 embodies the adjustable capacitive element 41 disposed at the intersection of the trisectional line 42 and the bisector 43 in one waveguide wide side in the manner of FIG. 5 but the ad justable capacitive element 41 is disposed at the intersection of the trisectional line 42' and the bisector 43 in the wide side of the waveguide opposite to that embodying the adjustable capacitive element 41.
  • the essential dimensions in FIG. 7 being the same as corresponding dimensions in FIG. 5.
  • FiG. 9 shows still another modification wherein two capacitive elements 41 and 41' are spaced on trisectional line 42 on opposite sides of bisector $3 in the vicinity of the position corresponding to that of the capacitive element 41 of FIG. 7.
  • the essential dimensions in FIG. 9 being identical with corresponding dimensions in FIG. 5.
  • the arrangements of FIGS. 5 and 8 may be modified by replacing the single capacitive element with a plurality of capacitive elements disposed at around the positions as in FIG. 5 or 8.
  • FIG. 10 shows an arrangement wherein the capacitive elements 41 and 41' are oppositely installed on the opposite major planes of the waveguide. Accordingly, in FIG. 10, element 4-1 is installed at the intersection of trisectional line 42 and bisector 43 in the upper major plane of the waveguide while element 41' is installed at the intersection of the trisectional line 42 and bisector 43 in the lower major plane of the waveguide, whereby the elements 41 and 41' are oppositely disposed in opposite major planes of the waveguide.
  • the essential dimensions in FIG. 10 are the same as corresponding dimensions in FIG. 5. The similar arrangement may be made in connection with FIGS. 5 and 7.
  • the rectangular waveguide employed in the above embodiment and modifications may be replaced by acircular or elliptic waveguide.
  • the number of the susceptance rods employed in the embodiment to define each stage of the filter may not necessarily be three. It may be two, four or any other arbitrary number.
  • these susceptance rods may be of window shape or any other shape.
  • variable capacitive element In the embodiment, two adjustable screws are employed as the variable capacitive element at symmetrical points on the major plane or planes. However, the number of the screws may be chosen arbitrarily. The positions of the capacitive ele ments may not necessarily be symmetrical.
  • a rectangular waveguide filter having a passband for transmitting electromagnetic waves including a fundamental frequency and attenuating a second harmonic or said fundamental frequency in a fundamental mode TE keeping resonant frequencies of modes higher than said mode TE outside of the region where the second harmonic of said fundamental frequency exists comprising:
  • a rectangular waveguide having narrow and wide opposite walls; two susceptance means spaced in mutually parallel relation interiorly of said waveguide in a direction lengthwise of said wide walls and disposed transversely to said narrow walls; each of said means consisting of a plurality of rods spaced in mutually parallel relation in a further direction perpendicular to said transverse direction; said rods and said waveguide forming a resonator cavity; said two means so spaced as to provide a distance of one-third waveguide wavelength between lengthwise axes of corresponding rods in said respective means for enabling said cavity to provide said filter passband to transmit said fundamental frequency band and to attenuate said second harmonic while preventing resonant frequencies of modes higher than said mode TE from coming into a frequency region including said second harmonic; and
  • said capacitive means comprises two adjustable screws having some spaced in mutually parallel relation in said one wide wall in a plane perpendicular to said narrow and wide walls, each screw adjusted to project one end into said cavity; said two screw axes spaced in two positions which include said firstmentioned position and are located said one-half of said one third waveguide wavelength distance between said two planes including said corresponding axes of said susceptance means and which include each of said two screw axes further located said one-third distance from said inner surface of an adjacent narrow wall and said two screw axes having said one-third distance therebetween.
  • said capacitive means comprises an adjustable screw disposed in said one wide wall to project one end into said cavity and having an axis in said position which is located said one-half of said one-third waveguide wavelength distance between said two planes including said two susceptance means corresponding axes and which is further located said one-third distance from said inner surface of said adjacent one narrow wall.
  • said capacitive means comprises two adjustable screws of which one is disposed in said one wide wall and a second in the opposite wide wall; said one and second screws adjusted to project respective one ends thereof into said cavity and having axes in said position which is located said one-half of said onethird waveguide wavelength distance between said two planes including said susceptance means corresponding axes and which is further located said one-third distance from inner surfaces of said respective narrow walls.
  • said capacitive means comprises two adjustable screws having axes spaced in mutually parallel relation in said one wide wall in a plane perpendicular to said wide walls and parallel to said narrow walls; said two screws adjusted to project corresponding ends into said cavity and to dispose opposing peripheral portions approximately at said position which is located said onehalf of said one-third waveguide wavelength distance between said two planes including said susceptance means corresponding axes and which is further located said one-third distance from said inner surface of said adjacent one narrow wall.
  • said filter means comprises two adjustable screws of which one is disposed in said one wide wall and a second in the opposite wide wall; said one and second screws adjusted to project respective one ends into said cavity and having axes in said position which is located said one-half of said one-third waveguide wavelength distance between said two planes including said two susceptance means corresponding axes and which is further located said one-third distance from said inner surface of said one narrow wall.
  • a rectangular waveguide filer having a passband for transmitting a band of electromagnetic waves including a fundamental frequency and attenuating at least a second harmonic of said fundamental frequency in a fundamental mode T5 comprising:
  • a rectangular waveguide having narrow and wide opposite walls; two susceptance means spaced in mutually parallel relation interiorly of said waveguide in a direction lengthwise of said wide walls and disposed transversely to said narrow walls; each of said means consisting of a plurality of rods spaced in mutually parallel relation in a further direction perpendicular to said transverse direction; said waveguide and said rods forming a resonator cavity for providing said passband to transmit said waves; said two means so spaced as to provide a distance of one-third waveguide wavelength between lengthwise axes of corresponding rods in said respective means for enabling said cavity to transmit said fundamental band and to'attenuate said second harmonic while preventing resonant frequencies of modes higher than said modefrom coming into a frequency region including said second harmonic; and
  • a rectangular waveguide filter having a passband for transmitting a band of electromagnetic waves including a fundamental frequency and attenuating at least a second harmonic of said fundamental frequency in a fundamental mode TE comprising:
  • each of said means consisting of a plurality of rods spaced in mutually parallel relation in a further direction perpendicular to said transverse direction; said waveguide and said rods forming a resonator cavity for transmitting said waves; said two means so spaced as to provide a distance of one-third waveguide wavelength between lengthwise axes of corresponding rods in said respective means for enabling said cavity to transmit said fundamental band and to attenuate said second harmonic while preventing resonant frequencies of modes higher than said fundamental mode from coming into a frequency region including said second harmonic; and
  • an adjustable screw disposed in one wide wall and adjusted to project one end into said cavity to function as a capacity only for said fundamental mode to provide said filter passbands; said screw having a lengthwise axis equidistantly located between two planes including lengthwise axes of said rods of said respective susceptance means at a distance of one-half of said onethird waveguide wavelength distance; said screw lengthwise axis further located from an inner surface of an adjacent narrow wall at one-third of an overall distance between inner surfaces of said narrow walls.
  • a rectangular waveguide filter having a passband for transmitting a band of electromagnetic waves including a fundamental frequency and attenuating at least a second harmonic of said fundamental frequency in a fundamental mode TE comprising:
  • each of said means consisting of a plurality of rods spaced in mutually parallel relation in a further direction perpendicular to said transverse direction; said waveguide and said rods forming a resonator cavity for transmitting said waves; said two means so spaced as to provide a distance of one-third waveguide wavelength between lengthwise axes of corresponding rods in said respective two means for enabling said cavity to transmit said fundamental band and to attenuate said second harmonic while preventing resonant frequencies of modes higher than said fundamental mode from coming into a frequency region including said second harmonic; and two adjustable screws of which one is disposed in one wide wall and a second in the opposite wide wall; said one and second screws adjusted to project respective one ends thereof into said cavity to function as capacities only for said fundamental mode to provide said filter passband; said two screws having lengthwise axes equidistantly located between two planes including
  • a rectangular waveguide filter having a passband for transmitting a band of electromagnetic waves including a fundamental frequency and attenuating at least a second harmonic of said fundamental frequency in a fundamental mode TE comprising:
  • each of said means consisting of a plurality of rods spaced in mutually parallel relation in a further direction perpendicular to said transverse direction; said waveguide and rods forming a resonator cavity for trans mitting said waves; said two means so spaced as to provide a distance of one-third waveguide wavelength between lengthwise axes of corresponding rods in said respective two means for enabling said cavity to transmit said fundamental band and to attenuate said second harmonic while preventing resonant frequencies of modes higher than said fundamental mode from coming into a frequency region including said second harmonic; and two adjustable screws spaced in mutually parallel relation in one wide wall and adjusted to project respective one ends thereof into said cavity to function as capacities only for said fundamental mode to provide said filter passband; said two screws having lengthwise axes disposed in parallel in a plane perpendicular to said wide walls and parallel to said narrow walls and also having oppos

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Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4607242A (en) * 1983-05-02 1986-08-19 Rockwell International Corporation Microwave filter
US4613989A (en) * 1984-09-28 1986-09-23 Cincinnati Microwave, Inc. Police radar warning receiver
US4686499A (en) * 1984-09-28 1987-08-11 Cincinnati Microwave, Inc. Police radar warning receiver with cantilevered PC board structure
US4990870A (en) * 1989-11-06 1991-02-05 The United States Of America As Represented By The Secretary Of The Navy Waveguide bandpass filter having a non-contacting printed circuit filter assembly
US5398009A (en) * 1991-09-18 1995-03-14 Fujitsu Limited Waveguide filter with coaxial/waveguide mode conversion
US20050270125A1 (en) * 2004-06-08 2005-12-08 Rockwell Scientific Licensing, Llc Tunable waveguide filter
US20080068112A1 (en) * 2006-09-14 2008-03-20 Yu David U L Rod-loaded radiofrequency cavities and couplers
WO2010036292A1 (en) * 2008-09-25 2010-04-01 Jefferson Science Associates, Llc Particle beam and crabbing and deflecting structure
US20150180103A1 (en) * 2013-12-19 2015-06-25 Mesaplexx Pty Ltd Filter
US9401537B2 (en) 2011-08-23 2016-07-26 Mesaplexx Pty Ltd. Multi-mode filter
US9406988B2 (en) 2011-08-23 2016-08-02 Mesaplexx Pty Ltd Multi-mode filter
US9843083B2 (en) 2012-10-09 2017-12-12 Mesaplexx Pty Ltd Multi-mode filter having a dielectric resonator mounted on a carrier and surrounded by a trench
US9882259B2 (en) 2013-02-21 2018-01-30 Mesaplexx Pty Ltd. Filter
US9972882B2 (en) 2013-02-21 2018-05-15 Mesaplexx Pty Ltd. Multi-mode cavity filter and excitation device therefor
US10109907B2 (en) 2013-02-21 2018-10-23 Mesaplexx Pty Ltd. Multi-mode cavity filter
CN108804762A (zh) * 2018-05-04 2018-11-13 中国电子科技集团公司第二十七研究所 微波高功率多次谐波滤波器的设计方法及多次谐波滤波器
CN108808200A (zh) * 2018-08-07 2018-11-13 中国航空工业集团公司雷华电子技术研究所 一种波导功率合成器及功率合成方法
US10256518B2 (en) 2017-01-18 2019-04-09 Nokia Solutions And Networks Oy Drill tuning of aperture coupling
US10283828B2 (en) 2017-02-01 2019-05-07 Nokia Solutions And Networks Oy Tuning triple-mode filter from exterior faces
US10476462B2 (en) 2016-08-03 2019-11-12 Nokia Solutions And Networks Oy Filter component tuning using size adjustment

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GB2213652A (en) * 1987-12-11 1989-08-16 Gary Raymond Cobb Waveguide filters using expanded joints

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Cited By (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4607242A (en) * 1983-05-02 1986-08-19 Rockwell International Corporation Microwave filter
US4613989A (en) * 1984-09-28 1986-09-23 Cincinnati Microwave, Inc. Police radar warning receiver
US4686499A (en) * 1984-09-28 1987-08-11 Cincinnati Microwave, Inc. Police radar warning receiver with cantilevered PC board structure
US4990870A (en) * 1989-11-06 1991-02-05 The United States Of America As Represented By The Secretary Of The Navy Waveguide bandpass filter having a non-contacting printed circuit filter assembly
US5398009A (en) * 1991-09-18 1995-03-14 Fujitsu Limited Waveguide filter with coaxial/waveguide mode conversion
US20050270125A1 (en) * 2004-06-08 2005-12-08 Rockwell Scientific Licensing, Llc Tunable waveguide filter
US7068129B2 (en) * 2004-06-08 2006-06-27 Rockwell Scientific Licensing, Llc Tunable waveguide filter
US20080068112A1 (en) * 2006-09-14 2008-03-20 Yu David U L Rod-loaded radiofrequency cavities and couplers
WO2010036292A1 (en) * 2008-09-25 2010-04-01 Jefferson Science Associates, Llc Particle beam and crabbing and deflecting structure
US9406988B2 (en) 2011-08-23 2016-08-02 Mesaplexx Pty Ltd Multi-mode filter
US9698455B2 (en) 2011-08-23 2017-07-04 Mesaplex Pty Ltd. Multi-mode filter having at least one feed line and a phase array of coupling elements
US9406993B2 (en) 2011-08-23 2016-08-02 Mesaplexx Pty Ltd Filter
US9401537B2 (en) 2011-08-23 2016-07-26 Mesaplexx Pty Ltd. Multi-mode filter
US9437916B2 (en) 2011-08-23 2016-09-06 Mesaplexx Pty Ltd Filter
US9437910B2 (en) 2011-08-23 2016-09-06 Mesaplexx Pty Ltd Multi-mode filter
US9559398B2 (en) 2011-08-23 2017-01-31 Mesaplex Pty Ltd. Multi-mode filter
US9843083B2 (en) 2012-10-09 2017-12-12 Mesaplexx Pty Ltd Multi-mode filter having a dielectric resonator mounted on a carrier and surrounded by a trench
US9882259B2 (en) 2013-02-21 2018-01-30 Mesaplexx Pty Ltd. Filter
US9972882B2 (en) 2013-02-21 2018-05-15 Mesaplexx Pty Ltd. Multi-mode cavity filter and excitation device therefor
US10109907B2 (en) 2013-02-21 2018-10-23 Mesaplexx Pty Ltd. Multi-mode cavity filter
US9614264B2 (en) * 2013-12-19 2017-04-04 Mesaplexxpty Ltd Filter
US20150180103A1 (en) * 2013-12-19 2015-06-25 Mesaplexx Pty Ltd Filter
US10476462B2 (en) 2016-08-03 2019-11-12 Nokia Solutions And Networks Oy Filter component tuning using size adjustment
US10256518B2 (en) 2017-01-18 2019-04-09 Nokia Solutions And Networks Oy Drill tuning of aperture coupling
US10283828B2 (en) 2017-02-01 2019-05-07 Nokia Solutions And Networks Oy Tuning triple-mode filter from exterior faces
CN108804762A (zh) * 2018-05-04 2018-11-13 中国电子科技集团公司第二十七研究所 微波高功率多次谐波滤波器的设计方法及多次谐波滤波器
CN108808200A (zh) * 2018-08-07 2018-11-13 中国航空工业集团公司雷华电子技术研究所 一种波导功率合成器及功率合成方法

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DE2006864B2 (de) 1974-11-21
GB1290448A (enrdf_load_stackoverflow) 1972-09-27
DE2006864A1 (de) 1971-02-18

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