CA1130400A - Filter for microwaves - Google Patents
Filter for microwavesInfo
- Publication number
- CA1130400A CA1130400A CA332,993A CA332993A CA1130400A CA 1130400 A CA1130400 A CA 1130400A CA 332993 A CA332993 A CA 332993A CA 1130400 A CA1130400 A CA 1130400A
- Authority
- CA
- Canada
- Prior art keywords
- filter
- housing
- cavities
- coupling
- bottom wall
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- 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
- H01P1/201—Filters for transverse electromagnetic waves
- H01P1/205—Comb or interdigital filters; Cascaded coaxial cavities
- H01P1/2053—Comb or interdigital filters; Cascaded coaxial cavities the coaxial cavity resonators being disposed parall to each other
Abstract
FILTER FOR MICROWAVES
Abstract of the Disclosure A filter for microwaves includes a plurality of resona-tor cavities each having a housing formed unitarily with a respective resonance rod. The neighbouring resonator cavities are coupled together by means of a coupling window formed in the wall separating the cavities and a coupling loop, and a hole communicating with the coupling window is formed in the bottom plate of the filter.
Abstract of the Disclosure A filter for microwaves includes a plurality of resona-tor cavities each having a housing formed unitarily with a respective resonance rod. The neighbouring resonator cavities are coupled together by means of a coupling window formed in the wall separating the cavities and a coupling loop, and a hole communicating with the coupling window is formed in the bottom plate of the filter.
Description
113C~400 The present invention relates to filters for microwaves.
Figure 2 of the accompanying drawings illustrates a conventional filter for microwaves. Double superheterodyne tuners often include microwave filters such as that illustrated in Fig. 2, wherein reference numeral 20 represents a housing portion for a plutality of resonator cavities 21 to 23. The individual resonator cavities 21 to 23 each have respective resonance rods 21_ to 23_ having end portions extending through respective openings formed in the bottom wall of the housing 20 and adapted to be fastened thereto by a respective nut.
Coupling windows 26 are formed respectively in wall 24 between the resonator cavities 21 and 22, and the wall 25 between the resonator cavities 22 and 23. Further, coupling loops 27 are provided in the resona-tor cavities 21 to 23 to thereby couple the resonator cavities by means of the coupling windows 26 and the coupling loops 27. Moreover, referring to Fig. 2 (B) a cover 28 is brought into contact with the side of the housing 20 for covering the side of each resonator cavity to thereby provide the entire housing for the resonator cavities 21 to 23.
Holes 29 for the coupling loops 27 are formed in portions of the resonator cavities 21 and 23 and a bolt 30 is often provided for adjusting the resonance frequency of each cavity.
With the conventional filters for microwaves as mentioned above, the resonance rods 21a to 23a are typically fastened to the housing 20 by nuts, and the housing for the resonator cavities 21 to 23 typically has been formed by the housing of the tuner and the separate cover 28. When the device is constructed as mentioned above, however, it is difficult to bring the cover 28 reliably into proper contact with the housing 20 of the tuner. In addition, fastening of the cover must be attained by using many screws. Furthermore, the resonance rods 21_ to 23_, which are required to satisfy major ws/ ., 113~400 requirements for resonance of the resonators 21 to 23, are not formed together with ~he tuner housing 20 as a unitary structure.
Therefore, the contact at the base portions of the resonance rods 21a and 23a may lose stability and, since the base portions will be normally subjec-ted to the greatest high-frequency potential, this loss of stability can become extremely worrisome.
Importantly, the transmission losses can become great when the filter is resonated at ultrahigh frequencies o~, for example, 2 to 3 GHz and further, the resonance frequency may be changed by mechanical vibration and impact, making it difficult to obtain the frequency characteristics desired for the filter.
Accordingly, an object of the present invention is to provide a microwave filter which minimizes transmission losses and always exhibits the frequency characteristics desired without increasing the cost or complexity of the filter.
According to the present invention, a filter for signals in the microwave frequencies comprises a housing forming a plurality of resonator cavities separated by respective side walls therebetween. The housing includes a bottom wall and each of the cavities has a respective resonance rod formed unitarily with the bottom wall. Means including windows are formed in the side walls for coupling the cavit~es together.
Coupling loops extend respectively into the two end resonator cavities at locations therein aajacent the bottom wall and holes are formed in the bottom wall at locations adjacent the coupling loops. Other features and advantages of the present invention will become apparent in view of the following detailed description of an illustrative embodiment and accompanying drawings, in which:
Fig. 1 is a circuit diagram of a double superheterodyne tuner to which is applied a microwave filter according to the present invention;
! ` ~
WS/j, ' 1~3(~40C~
Figs. 2A and 2B are diagrams to illustrate a conventional filter for microwaves;
Figs. 3A and 3B illustrate a microwave filter according to an embodimen-t of the present invention, wherein the 3A is an upper plan view, 3B is a cross-sectional view taken along the line A-A' of Fig. 3A, and Fig. 3C is a side view.
Fig. 1 is a circuit diagram of a double superheterodyne tuner having a microwave filter. The tuner includes an antenna 1, -3a-ws/
113~400 ., an amplifier 2, a first mixer 3, a variable oscillator 4, a first .~ intermediate frequency filter 5 made up of a filter for micro-waves, a second mixer 6, a fixed oscillator 7, a second inter-, mediate frequency filter 8, a second intermediate Erequency I amplifier 9, an output terminal 10, a distributor 11, a distri-¦ butor 12, a synthesizer 13, a phase locked loop (PPL) ~ixer 14, a low-pass filter 15, a PLL block 16, an IC board 17, an IC board !
18, and an IC board 19.
The IC board 17 includes the circuits necessary to add ¦ the input signals fro~ the antenna 1 to the amplifier 2, to mix in the first mixer 3 the output of the amplifier with a portion of the output of the variable oscillator 4 distributea by the distributor 11, and to direct the resultiny mixed output of the l! mixer 3 to the first intermediate frequency filter 5.
I The IC board 18 includes the circuits necessary to mix~
¦Iby way of the second mixer 6, the first intermediate frequency .
¦ signals leaving the first intermediate ~requency filter 5 togetherl llwith a portion of the output of the fixed oscillator 7 distributed :
~Iby the distributor 12, to direct the mixed output to the second 1l intermediate frequency filter 8, and to amplify by means of the amplifier 9 the second intermediate frequency signals produced by the second intermediate -Lrequency fil-ter 8 thereby to produce the amplified output at the terminal 10.
ill The IC board 19 includes the circuits necessary to synthesize, by means of the synthes~zer 13, a porti.on of the out-put of the variable oscillator 4 distributed by the distributor ;11 in the IC board 17 and a portion of the output of the fixed ~oscillator 7 distributed by the disbributor 12 in t:he IC board 18.
;Further, the lC board 19 has circuitry to convert the output of the synthesi~er 13 through the PLL mixer 14, and tc, select, from the converted output and by means of the low-pass fi.lter 15, only :low frequencies correspondiny to the li~iting frequency of a 113~400 1, frequency divider incorporated in the PLL bloc~ 16, as will be described more fully below. The Ic board 19 also includes cir-cuitry to pass the output of the low-pass filter 15 to the PLL
¦ bloc~ 16 to thereby control the variable oscillator 4 in the IC
, board 17.
The PLL block 16 is typical of known PLL arrangements and includes a variable frequency divider, a progr~m switch, a phase detector, a reference signal generator and a low-pass filtel.
1 The PLL circuit is established by a closed circuit including the ~l PLL block 16 and the abovementioned variable oscillator 4, PLL
¦I mixer 14, and low-pass filter 15.
¦l In receiving a desired channel, if the difference between a frequency of the variable oscillator 4 and a frequency Il of the fixea oscillator is maintained at a constant value, the ~'l output of the terminal 10 is always maintained constant.
¦l A double superheterodyne tuner can therefore be obtained by connecting the abovementioned IC boards 17, 18 and 19 with the first intermediate frequency filter 5, which serves I as a microwave filter, as illustrated.
~ The microwave filter of the present invention is illustrated in Fig. 3 and includes a housing 31 contalning a plurality of resonator cavities 32 to 34. The resonator cavities 32 to 34 each have respective resonance rods 32a to 34a that are li formed together with the housing 31 as a unitary structure, as ~ shown most clearly in Fig. 3B.
The housing and unitary resonance rods are ~referably die cast from an aluminum alloy to provide a housing with low surface resistance. The alloy may have either of the ~wo compositionsset forth below.
Composition Cu 0.6%
Fe 1.3 51 1.0 to 13.
:; 11304V~ i ;~n 0.3 r~s 0.1 Zn 0.5 , ~i 0.5 j Sn 0.1 Al remainder omposition B
Cu 2.0 to 4.5%
Il Fe 1.3 1 Si 10.5 to 12.0 ~n 0.5 ~9 0.3 Zn 1,0 ¦ Ni 0.5 l' Sn 0.35 Al remainder Further, a coupling window 37 i5 formed in the housing Il wall 35 between the resonator cavity 32 and the resonator cavity ¦~ 33, and a coupling window is also formed in the housing wall 36 ¦, between the resonator cavity 33 and the resonator cavity 34.
1 Coupling loops 38 are disposed in the resonator cavity 32 and in ¦ the resonator cavity 34, whereby the resonator cavities are ~ I coupled by means of the coupling windows 37 and the coupling loops l` lll 38. Furthermore, as shown in Fig. 3B, the bottom wall 31a is ~I provided with a hole 39 communicating with the coupling window 37 ~f the wall 35, and, although not shown in the drawings, a ¦I similar hole in the bottom wall 31a communicates similarily with the coupling window in the housing wall 36. In the resonator llcavities 32 and 34, a hole 40 is formed in the bottom wall 31a 11 and is positioned outside of the respective holes communicating ' with the walls 35 and 36. A groove 41 is formed in the side wall 31b and the coupling loop 38 runs through the hole 40 and the groove 41. Reference numerals 17, 18 and 19 represent lC boards ;corresponding to the IC boards having the same reEerence numerals ~
Fig. 1. The input signals from the IC board 17 are introduced from the coupling loop 38 on the right side of Fig. 3A, and are subsequently fed to the IC board 18 through the coupling loop 38 located on the left side. Reference numeral 42 den~tes connection 113Q9~00 lines connecting the IC boards together.
As mentioned in the foregoing, the filter for micro-waves of the present invention comprises resonator cavities 32 to 1 34 having resonance rods 32a to 34a and Lhe housing 31 as a I unitary structure, wherein the neighbouring resonators are coupled together by means of the coupling windows 37 formed in the walls 35 and 36 separating the resonator cavities, and the coupling loop 38, and the holes 39 communicated with the coupling ~ windows 37 formed in the bottom wall 31_. Therefore, even when ¦¦ mechanical vibration or impact is imparted to the filter, the ¦I contacting states of the resonance rods 32a to 34a can be stably ¦ maintained with respect to the housing 31. Consequently, transmission losses can be minimized, and the resonating state ~ can be stably maintained even in the high frequency band of 2 to 1 3 GHz making it possible to obtain any preset frequency character-¦ istics. Besides, the coupling loop 38 can be easily adjusted through the hole 39 communicated with the coupling window 37 !I With the thus constructed filter for microwaves of the present :
¦ invention, the number of parts and the assembling steps can be greatly reduced, to increase consistancy in guality.
"
',
Figure 2 of the accompanying drawings illustrates a conventional filter for microwaves. Double superheterodyne tuners often include microwave filters such as that illustrated in Fig. 2, wherein reference numeral 20 represents a housing portion for a plutality of resonator cavities 21 to 23. The individual resonator cavities 21 to 23 each have respective resonance rods 21_ to 23_ having end portions extending through respective openings formed in the bottom wall of the housing 20 and adapted to be fastened thereto by a respective nut.
Coupling windows 26 are formed respectively in wall 24 between the resonator cavities 21 and 22, and the wall 25 between the resonator cavities 22 and 23. Further, coupling loops 27 are provided in the resona-tor cavities 21 to 23 to thereby couple the resonator cavities by means of the coupling windows 26 and the coupling loops 27. Moreover, referring to Fig. 2 (B) a cover 28 is brought into contact with the side of the housing 20 for covering the side of each resonator cavity to thereby provide the entire housing for the resonator cavities 21 to 23.
Holes 29 for the coupling loops 27 are formed in portions of the resonator cavities 21 and 23 and a bolt 30 is often provided for adjusting the resonance frequency of each cavity.
With the conventional filters for microwaves as mentioned above, the resonance rods 21a to 23a are typically fastened to the housing 20 by nuts, and the housing for the resonator cavities 21 to 23 typically has been formed by the housing of the tuner and the separate cover 28. When the device is constructed as mentioned above, however, it is difficult to bring the cover 28 reliably into proper contact with the housing 20 of the tuner. In addition, fastening of the cover must be attained by using many screws. Furthermore, the resonance rods 21_ to 23_, which are required to satisfy major ws/ ., 113~400 requirements for resonance of the resonators 21 to 23, are not formed together with ~he tuner housing 20 as a unitary structure.
Therefore, the contact at the base portions of the resonance rods 21a and 23a may lose stability and, since the base portions will be normally subjec-ted to the greatest high-frequency potential, this loss of stability can become extremely worrisome.
Importantly, the transmission losses can become great when the filter is resonated at ultrahigh frequencies o~, for example, 2 to 3 GHz and further, the resonance frequency may be changed by mechanical vibration and impact, making it difficult to obtain the frequency characteristics desired for the filter.
Accordingly, an object of the present invention is to provide a microwave filter which minimizes transmission losses and always exhibits the frequency characteristics desired without increasing the cost or complexity of the filter.
According to the present invention, a filter for signals in the microwave frequencies comprises a housing forming a plurality of resonator cavities separated by respective side walls therebetween. The housing includes a bottom wall and each of the cavities has a respective resonance rod formed unitarily with the bottom wall. Means including windows are formed in the side walls for coupling the cavit~es together.
Coupling loops extend respectively into the two end resonator cavities at locations therein aajacent the bottom wall and holes are formed in the bottom wall at locations adjacent the coupling loops. Other features and advantages of the present invention will become apparent in view of the following detailed description of an illustrative embodiment and accompanying drawings, in which:
Fig. 1 is a circuit diagram of a double superheterodyne tuner to which is applied a microwave filter according to the present invention;
! ` ~
WS/j, ' 1~3(~40C~
Figs. 2A and 2B are diagrams to illustrate a conventional filter for microwaves;
Figs. 3A and 3B illustrate a microwave filter according to an embodimen-t of the present invention, wherein the 3A is an upper plan view, 3B is a cross-sectional view taken along the line A-A' of Fig. 3A, and Fig. 3C is a side view.
Fig. 1 is a circuit diagram of a double superheterodyne tuner having a microwave filter. The tuner includes an antenna 1, -3a-ws/
113~400 ., an amplifier 2, a first mixer 3, a variable oscillator 4, a first .~ intermediate frequency filter 5 made up of a filter for micro-waves, a second mixer 6, a fixed oscillator 7, a second inter-, mediate frequency filter 8, a second intermediate Erequency I amplifier 9, an output terminal 10, a distributor 11, a distri-¦ butor 12, a synthesizer 13, a phase locked loop (PPL) ~ixer 14, a low-pass filter 15, a PLL block 16, an IC board 17, an IC board !
18, and an IC board 19.
The IC board 17 includes the circuits necessary to add ¦ the input signals fro~ the antenna 1 to the amplifier 2, to mix in the first mixer 3 the output of the amplifier with a portion of the output of the variable oscillator 4 distributea by the distributor 11, and to direct the resultiny mixed output of the l! mixer 3 to the first intermediate frequency filter 5.
I The IC board 18 includes the circuits necessary to mix~
¦Iby way of the second mixer 6, the first intermediate frequency .
¦ signals leaving the first intermediate ~requency filter 5 togetherl llwith a portion of the output of the fixed oscillator 7 distributed :
~Iby the distributor 12, to direct the mixed output to the second 1l intermediate frequency filter 8, and to amplify by means of the amplifier 9 the second intermediate frequency signals produced by the second intermediate -Lrequency fil-ter 8 thereby to produce the amplified output at the terminal 10.
ill The IC board 19 includes the circuits necessary to synthesize, by means of the synthes~zer 13, a porti.on of the out-put of the variable oscillator 4 distributed by the distributor ;11 in the IC board 17 and a portion of the output of the fixed ~oscillator 7 distributed by the disbributor 12 in t:he IC board 18.
;Further, the lC board 19 has circuitry to convert the output of the synthesi~er 13 through the PLL mixer 14, and tc, select, from the converted output and by means of the low-pass fi.lter 15, only :low frequencies correspondiny to the li~iting frequency of a 113~400 1, frequency divider incorporated in the PLL bloc~ 16, as will be described more fully below. The Ic board 19 also includes cir-cuitry to pass the output of the low-pass filter 15 to the PLL
¦ bloc~ 16 to thereby control the variable oscillator 4 in the IC
, board 17.
The PLL block 16 is typical of known PLL arrangements and includes a variable frequency divider, a progr~m switch, a phase detector, a reference signal generator and a low-pass filtel.
1 The PLL circuit is established by a closed circuit including the ~l PLL block 16 and the abovementioned variable oscillator 4, PLL
¦I mixer 14, and low-pass filter 15.
¦l In receiving a desired channel, if the difference between a frequency of the variable oscillator 4 and a frequency Il of the fixea oscillator is maintained at a constant value, the ~'l output of the terminal 10 is always maintained constant.
¦l A double superheterodyne tuner can therefore be obtained by connecting the abovementioned IC boards 17, 18 and 19 with the first intermediate frequency filter 5, which serves I as a microwave filter, as illustrated.
~ The microwave filter of the present invention is illustrated in Fig. 3 and includes a housing 31 contalning a plurality of resonator cavities 32 to 34. The resonator cavities 32 to 34 each have respective resonance rods 32a to 34a that are li formed together with the housing 31 as a unitary structure, as ~ shown most clearly in Fig. 3B.
The housing and unitary resonance rods are ~referably die cast from an aluminum alloy to provide a housing with low surface resistance. The alloy may have either of the ~wo compositionsset forth below.
Composition Cu 0.6%
Fe 1.3 51 1.0 to 13.
:; 11304V~ i ;~n 0.3 r~s 0.1 Zn 0.5 , ~i 0.5 j Sn 0.1 Al remainder omposition B
Cu 2.0 to 4.5%
Il Fe 1.3 1 Si 10.5 to 12.0 ~n 0.5 ~9 0.3 Zn 1,0 ¦ Ni 0.5 l' Sn 0.35 Al remainder Further, a coupling window 37 i5 formed in the housing Il wall 35 between the resonator cavity 32 and the resonator cavity ¦~ 33, and a coupling window is also formed in the housing wall 36 ¦, between the resonator cavity 33 and the resonator cavity 34.
1 Coupling loops 38 are disposed in the resonator cavity 32 and in ¦ the resonator cavity 34, whereby the resonator cavities are ~ I coupled by means of the coupling windows 37 and the coupling loops l` lll 38. Furthermore, as shown in Fig. 3B, the bottom wall 31a is ~I provided with a hole 39 communicating with the coupling window 37 ~f the wall 35, and, although not shown in the drawings, a ¦I similar hole in the bottom wall 31a communicates similarily with the coupling window in the housing wall 36. In the resonator llcavities 32 and 34, a hole 40 is formed in the bottom wall 31a 11 and is positioned outside of the respective holes communicating ' with the walls 35 and 36. A groove 41 is formed in the side wall 31b and the coupling loop 38 runs through the hole 40 and the groove 41. Reference numerals 17, 18 and 19 represent lC boards ;corresponding to the IC boards having the same reEerence numerals ~
Fig. 1. The input signals from the IC board 17 are introduced from the coupling loop 38 on the right side of Fig. 3A, and are subsequently fed to the IC board 18 through the coupling loop 38 located on the left side. Reference numeral 42 den~tes connection 113Q9~00 lines connecting the IC boards together.
As mentioned in the foregoing, the filter for micro-waves of the present invention comprises resonator cavities 32 to 1 34 having resonance rods 32a to 34a and Lhe housing 31 as a I unitary structure, wherein the neighbouring resonators are coupled together by means of the coupling windows 37 formed in the walls 35 and 36 separating the resonator cavities, and the coupling loop 38, and the holes 39 communicated with the coupling ~ windows 37 formed in the bottom wall 31_. Therefore, even when ¦¦ mechanical vibration or impact is imparted to the filter, the ¦I contacting states of the resonance rods 32a to 34a can be stably ¦ maintained with respect to the housing 31. Consequently, transmission losses can be minimized, and the resonating state ~ can be stably maintained even in the high frequency band of 2 to 1 3 GHz making it possible to obtain any preset frequency character-¦ istics. Besides, the coupling loop 38 can be easily adjusted through the hole 39 communicated with the coupling window 37 !I With the thus constructed filter for microwaves of the present :
¦ invention, the number of parts and the assembling steps can be greatly reduced, to increase consistancy in guality.
"
',
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A filter for signals in the microwave frequencies, comprising a housing forming a plurality of resonator cavities separated by respective side walls therebetween, said housing including a bottom wall and each of said cavities having a respective resonance rod formed unitarily with said bottom wall, means including windows formed in said side walls for coupling said cavities together, coupling loops extending respectively into the two end resonator cavities at locations therein adjacent said bottom wall, and holes formed in said bottom wall at locations adjacent said coupling loops.
2. A filter according to claim 1, said housing and said resonance rods being die cast from an aluminum alloy.
3. A filter according to claim 1, said holes being formed contiguous to the windows leading to the respective end resonator cavities.
4. A filter according to claim 2, said holes being formed contiguous to the windows leading to the respective end resonator cavities.
5. A filter according to claim 3 or 4, said coupling loops extending through respective elongate grooves in said housing.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP106318/78 | 1978-08-02 | ||
| JP1978106318U JPS5827526Y2 (en) | 1978-08-02 | 1978-08-02 | Microwave filter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1130400A true CA1130400A (en) | 1982-08-24 |
Family
ID=14430604
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA332,993A Expired CA1130400A (en) | 1978-08-02 | 1979-08-01 | Filter for microwaves |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US4275369A (en) |
| JP (1) | JPS5827526Y2 (en) |
| CA (1) | CA1130400A (en) |
| DE (1) | DE2928346C2 (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5924167Y2 (en) * | 1978-12-28 | 1984-07-18 | アルプス電気株式会社 | Microwave filter |
| JPS55146701U (en) * | 1979-04-09 | 1980-10-22 | ||
| US4661998A (en) * | 1983-09-22 | 1987-04-28 | Matsushita Electric Industrial Co. Ltd. | Double superheterodyne tuner |
| 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 |
| JPH07111928B2 (en) * | 1986-09-12 | 1995-11-29 | 株式会社日立製作所 | Ignition coil for internal combustion engine |
| DE3722713B3 (en) | 1987-07-09 | 2019-08-14 | Siemens Aktiengesellschaft | Pulse Doppler radar method |
| DE3722716B3 (en) | 1987-07-09 | 2019-08-14 | Siemens Aktiengesellschaft | Pulsdopller radar method |
| JPH01127224U (en) * | 1988-02-23 | 1989-08-31 | ||
| US5329687A (en) * | 1992-10-30 | 1994-07-19 | Teledyne Industries, Inc. | Method of forming a filter with integrally formed resonators |
| US5777534A (en) * | 1996-11-27 | 1998-07-07 | L-3 Communications Narda Microwave West | Inductor ring for providing tuning and coupling in a microwave dielectric resonator filter |
| US5781085A (en) * | 1996-11-27 | 1998-07-14 | L-3 Communications Narda Microwave West | Polarity reversal network |
| US6559740B1 (en) | 2001-12-18 | 2003-05-06 | Delta Microwave, Inc. | Tunable, cross-coupled, bandpass filter |
| CN210430091U (en) * | 2019-09-23 | 2020-04-28 | 深圳市安拓浦科技有限公司 | Antenna oscillator and planar antenna |
| CN113036366A (en) * | 2019-12-25 | 2021-06-25 | 深圳市大富科技股份有限公司 | Communication system and filter thereof |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2247803C3 (en) * | 1972-09-29 | 1979-01-11 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Coupling arrangement |
| AT330883B (en) * | 1973-09-17 | 1976-07-26 | Kraftwerk Union Ag | DEVICE FOR COOLING EXCITING CURRENT LINES IN LIQUID-COOLED TURBOGENERATOR ROTORS |
| JPS5348062B2 (en) * | 1973-11-20 | 1978-12-26 | ||
| US3955161A (en) * | 1974-08-05 | 1976-05-04 | General Dynamics Corporation | Molded waveguide filter with integral tuning posts |
| JPS5145967U (en) * | 1974-10-02 | 1976-04-05 | ||
| JPS51128244A (en) * | 1975-04-30 | 1976-11-09 | Nec Corp | Step connector of semi-coaxial multiple band pass filter |
| JPS5242608A (en) * | 1975-09-30 | 1977-04-02 | P S Concrete | Method of building underground continuous wall |
| US4037182A (en) * | 1976-09-03 | 1977-07-19 | Hughes Aircraft Company | Microwave tuning device |
-
1978
- 1978-08-02 JP JP1978106318U patent/JPS5827526Y2/en not_active Expired
-
1979
- 1979-07-13 DE DE2928346A patent/DE2928346C2/en not_active Expired
- 1979-07-27 US US06/061,415 patent/US4275369A/en not_active Expired - Lifetime
- 1979-08-01 CA CA332,993A patent/CA1130400A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| US4275369A (en) | 1981-06-23 |
| JPS5524834U (en) | 1980-02-18 |
| JPS5827526Y2 (en) | 1983-06-15 |
| DE2928346A1 (en) | 1980-02-21 |
| DE2928346C2 (en) | 1985-04-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |