US2866595A - Ultra-high frequency band separating filters - Google Patents
Ultra-high frequency band separating filters Download PDFInfo
- Publication number
- US2866595A US2866595A US642517A US64251757A US2866595A US 2866595 A US2866595 A US 2866595A US 642517 A US642517 A US 642517A US 64251757 A US64251757 A US 64251757A US 2866595 A US2866595 A US 2866595A
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- US
- United States
- Prior art keywords
- guides
- guide
- coupling
- band
- section
- 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 - Lifetime
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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
- H01P1/213—Frequency-selective devices, e.g. filters combining or separating two or more different frequencies
Definitions
- the present invention relates to branching filters for use with a wave guide for the separation of waves, the frequencies of which cover wide frequency bands in. the range of centimeter waves.
- frequency bands can, for example, be those of channel groups of carrier wave systems.
- a filter according to the invention can separate a first frequency band, hereinafter called lower band and covering the range of 3,000 to 5,000 megacycles per second from a second frequency band, hereinafter called upper band and covering the range of 7,000 to 10,000 megacycles per second.
- the lower limit of the lower band and the upper limit of the upper band will be called the outer frequency limits of the frequency bands to be separated.
- the upper limit of the lower band and the lower limit of the upper band will be called the inner frequency limits.
- the band separating filters which are provided in accordance with the objects of the invention, may be of a type in which the two signal bands are received from anysource of waves at the input of a main wave guide of rectangular cross-section propagating a TE mode wave and in which the signals of the lower frequency band are further transmitted in the same form towards the output of this main guide, while the signals of the upper frequency band are derived towards a secondary guide also of rectangular cross-section and coupled to the said main guide along a certain length thereof by slots provided in the lateral walls of the two guides.
- the filters provided in. accordance with the invention obviate this draw-back by 'a particular choice of so-called I guides of rectangular cross-section.
- a band separating filter adapted to be inserted in a main wave guide of rectangular crosssection in which two signal groups, the frequencies of which cover respectively a lower frequency band and an upper frequency band, separated by a frequency-interval, propagate according to the TE mode.
- the filter comprises a length of the main guide at the input of which the two signal groups are applied and at the output of which the signals of said lower band are received,
- the filter is further characterized in that the dimensions of thecross-sections of the coupling guides vary progressively along the length of the main guide, so that their characteristic impedances have a maximum value in the middle and a minimum value at the; ends of the length.
- Filters provided by the invention thus consist of one or more directional couplers-withmultiple couplingscomposed of main and secondary guides and of coupling
- These couplers differ from those known in the art in that the cut-off frequency of the coupling guides is comprised between the inner limits of the frequency bands to be separated. They also differ from previously known couplersin the provision of certain devices for the connection of the secondary guides deriving the energy of'the waves of the upper frequency band. Owing to their symmetry, these devices avoid the formation of higher propagation modes which would otherwise be likely to appear. 7
- a filter of the invention contains only one secondary" guide coupled to the main guide, as explained above.
- the filter of the invention consists of amain guide and ofasecondary guide with parallel axes.
- These guides having equal cut-off frequencies lower than the l'owestfrequency of the waves used and are coupled by a plurality of rectangular crosssection coupling guides, the axes of which are parallel between themselves and perpendicular to those of the two" guides which they couple.
- the cut off fre'quencies of the, coupling guides are all equal between themselves with a common value comprised between the inner limits of the frequencybands to be separated.
- the waves of the upper band are transferred from the main guide across the coupling guide to thesecondary guide, while the waves of' the lower band remain in. the main guide at'the input of which they were applied;
- the longer sides of the cross-sections of the coupling guides are thus perpendicular to the direction of'the longitudinal currents in the walls of both the main and secondary guides.
- the coupling guidesv dov not have. the same. characteristic impedance.
- the value of this impedance is lowat-i the extremities of the coupling length; on the other hand, it
- the main guide in which the lower band waves propagate must have a square cross-section such as when two systems of waves with perpendicular polarization directions are to be used simultaneously.
- experience shows that transmission of the upper band through the coupling system is not properly efiected, as higher propagation modes appear in the square cross-section guide for the considered frequency band.
- various, methods can be used, either each one separately or all simultaneously, as described hereunder:
- the coupled main andsecondary guides may be provided with plates of dielectric material, the planes of which are parallel to the electric field, which concentrates the field lines in the neighborhood of the opening of the coupling guides.
- the electromagnetic power stored in the dielectric plates'then increases with the frequency of the wave, which allows the improving of the coupling between the main and secondary guides and the coupling guides for the sole upper band.
- the main guide may be coupled to two rectangular secondary guides, the smaller sides of the cross-sections of which are equal to half their longer sides; coupling is then effected by several guides.
- the assembly thus formed has a plane of geometric symmetry passing through one of the median lines of the cross-section of the square cross-section guide.
- the junction piece for the two guides should thus be an E-type T, i. e. the plane of which is parallel to the electric field 'in the threebranches of the T.
- Fig. 1 shows the transversal section of a coupling device with a rectangular input guide in accordance with the invention, through line l-1 of Fig. 2;
- Fig. 2 shows a longitudinal section of this device through line 2--2 of Fig. 1;
- Fig. 3 shows a longitudinal section of this device through line 3-3 of Fig. l;
- Fig. 4 shows. a first variant of the coupling device, in which theinputguide has a square cross-section
- Fig. 5 shows a second variant of the coupling device of Fig. 4.
- the simplest embodiment of the invention i. e. that which makes use of a main guide and of only one secondary guide, has not been shown in the annexed drawings.
- this embodiment may be constituted by half of the more complex system of Fig. 4 obtained by cutting the latter along plane 20, 21, 22. The details of the so obtained system are shown in Figs. 1, 2 and 3.
- the two rectangular main and secondary guides 1 and 2 respectively, propagate waves according to the TE mode.
- Guide 1 is the input wave guide.
- the two guides 1 and 2 have rectangular cross-sections, the normally shorter sides of which are at most equal to their longer sides.
- the waves of the upper band pass as a whole from guide 1 to guide 2.
- the main guides 1 and 2 have the same cut-ofii frequency, which is lower than the lower limit of the lower frequency band to be separated. Considering the above mentioned values 35,000 and 7-10,000 megacycles per second for the limits of the bands, it is possible, for instance, to take 2,700 mc./s. as the cut-oif frequency of the guides 1 and 2.
- the guides 1 and 2 are connected by the coupling guides 4 and 5 which are to be seen in longitudinal section in Figs. 1 and 2 and in transversal section in Fig. 3.
- the coupling guides have a common cut-off frequency comprised between the inner limits of the frequency bands to be separated and may be, for instance, equal to 6,200 megacycles per second in the example described.
- the panes of the longer sides of the coupling guides 4 and 5 cut the direction of the longitudinal currents caused in the walls by the waves TE propagated in the guides 1 and 2. Therefore, only waves having frequencies pertaining to the upper band can transmit electromagnetic energy through the coupling guides 4 and 5, owing to the choice of their cut-off frequencies.
- the particular coupling guides 4 situated close to the ends of the coupling length of the main guide have their shorter sides smaller than the shorter sides of guides 5, situated near the middle of this coupling length.
- the spacing between the successive coupling guides is approximately equal to one quarter of the phase wave length in the guide 1 for a wave having the middle fre quency of the upper band.
- the coupling is directional owing to the fact that the partial waves transmitted through the various coupling guides are in phase in the guide 2 for a certain direction of propogation in that guide and in phase opposition for the other propagation direction.
- the spacing of the coupling guides is chosen to be slightly less than one centimeter.
- the coupling guides cannot trans fer any energy. At the input of these guides there is just found a rapidly damped evanescent wave.
- the reactive energy contained in the wave propagated in the guide may be considered as localized in small inductances in series in the conductors of the two-wire line equivalent to the guide.
- These inductances could, for instance, be spaced by an inductance per unit length of the line thus obtained results in an increase of its characteristic impedance, i. e.
- the guides 4 situated near to theends of the coupling length have the same cut-off frequency .as guides 5 situated near the middle of this length; .but'they have a smaller thickness, so, that they contain less reactive energy and consequently their characteristic impedance is intermediate that of guides 1 and 2 loaded by the coupling guides 5 and that of the unloaded guides 1 and 2.
- the characteristic impedance is obtained.
- the waves of the upper band pass through the coupling guides from guide 1 to guide 2, or in the opposite direction.
- the optimum number of the coupling guides can be determined by experimentation. The efficiency of the coupling increases. with the number of coupling guides, reaches unity value and thereafter decreases when this number is further increased.
- this number can be from twelve to sixteen for coupling guides of approximately five millimeters. in thickness and of a length substantially equal to an odd number of quarter wavelengths for the average. frequency of the upper band.
- the tests have been particularly conclusive when both main and secondary guides have the same rectangular section with the smaller side of their cross-sections approximately equal tohalf their longer side.
- plates 6 and 7 of" dielectric material are put inside the guides 1 and 2, in their median planes and parallel to the direction of the electric polarization of the waves.
- the plate which is thicker in the neighborhood of the openings, concentrates more energy in the corresponding region.
- the dielectric plates may have tapered ends 8 and 9 as shown in Fig. 2. Practically, this concentration device for electromagnetic energy functions well, but a fine adjustment may be used. Therefore, it is preferable to use the filtering system shown in Fig. 4.
- the device includes an input section 10 of a main guide of square cross-section, rectangular crosssection secondary guides 11 and 12 arranged on both sides of the square guide 10. They preferably have their longer side equal to that of the square guide and their shorter side equal to half that of the square guide.
- guide 11 is ctn plecl to "section 10 by several rectangular guides 17.
- guide 12 is coupled to section 10 by several rectangular guides 18.
- the waves of the upper band enter through section 10.
- the electromagnetic energy passes into guides 11 and 12 and is then collected by the T-junction 14 through the intermediary of the elbows 15 and 16 respectively connected -to the guides 11 and 12.
- the plane of the axes. of the three branches of this T-junction is parallel to the electric field; it is, therefore, a T of the type designated E-plane.
- the unused ends of guides 11 and, 12, seen in Fig. 4 at the upper part of these, guides, are preferablyclosed on matched dissipating terminations so as to avoid any reflection.
- the coupling guides 17' and 18 present the same construction particularities as the coupling guides 4 and 5 considered in connection withFigs. l, 2 and 3; their common cut-off frequency is chosen between the inner limits of the frequency bands to be separated.
- the plane passing through points 20, 21, 22 placed in the middle plane of the guide of square cross-section is a plane of geometric symmetry for the whole of the guides, the elbows and the T-junction.
- a wave of the type TE entering the system of Fig. 4 and polarized in the direction of the arrow 13 is antisymmetric with respect tothe plane of geometric symmetry. The antisymmetry will necessarily be kept in the course of propagation. Therefore, whatever the wave frequency may i be, the electrical field at all points of the plane 20, 21,
- Waves that are polarized perpendicularly to the arrow 13 do not transmit energy to the coupling guides 17 and 18, whatever their frequencies may be, as for these waves the openings of these guides appear like slots parallel to the current lines.
- the reference numbers 10 to 22 relate to the same elements as those elements designated by the same numbers in Fig. 4.
- the coupling guides 17 and 18 collect the wave energy of the upper band polarized in the direction of arrow 13 and direct it towards the E-plane type T- junction 19 through the intermediary of guides 25 and 26.
- a band separating filter adapted to be inserted in a main wave guide of rectangular cross-section in which two signal groups, the frequencies of which respectively cover a lower frequency band and an upper frequency band separated by a frequency interval, propagate according to the TE mode, said filter comprising a length of said main guide at the input of which said two signal groups are applied and at the output of which the signals of said lower band are received at least one secondary wave guide receiving the signals of said upper band and being of rectangular cross-section, said secondary guide having its axis parallel to that of said main guide and being coupled to the latter said guide by a first series of slots distributed along said length of said main guide and provided in its walls and by a second series of slots provided in the walls of the longer sides of said secondary guide or, guides, and coupling assesses wave guides, the slots of said first and secondary series being connected in pairs by said coupling wave guides, said coupling wave guides having a rectangular cross-section equal to the surface of both of the slots to which they are connected and axes which are perpendicular to those of said main and
- a filter as claimed in claim 1 comprising a T-junction and an even number of secondary guides and wherein said secondary guides are grouped in pairs and the two guides of a same pairare coupled to a common utilization circuit by said T-junction; said T-junction comprising three lengths of rectangular cross-section guides, with the plane containing the three axes of said guide lengths beingparallel to the direction of the electric field in the secondary guides of said pair.
- a filter as claimed in claim 1 comprising one main and one secondary guide wherein the cross-sections of latter said guides are equal between themselves and wherein for each one of said cross-sections, the length of its longer side is substantially twice that of its shorter side.
- a filter as claimed in claim 1 comprising a main guide of square crosssection and two secondary guides with equal rectangular cross-sections, the longer side of said cross-sections being equal in length to that of said square cross-section, the shorter side of said cross-see tions of said secondary guides having a length substantially equal to half that'of their longer, side.
- a filter as claimed in claim 1 comprising a main guide of square cross-section and four secondary guides of equal rectangular cross-sections, the longer side of latter said cross-section being equal in length to that of said square cross-section, the shorter side of said crosssection of said secondary guides having a length substantially equal to half that of their longer side.
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Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR1110775X | 1956-04-28 |
Publications (1)
Publication Number | Publication Date |
---|---|
US2866595A true US2866595A (en) | 1958-12-30 |
Family
ID=9626389
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US642517A Expired - Lifetime US2866595A (en) | 1956-04-28 | 1957-02-26 | Ultra-high frequency band separating filters |
Country Status (6)
Country | Link |
---|---|
US (1) | US2866595A (de) |
BE (1) | BE554200A (de) |
CH (1) | CH335544A (de) |
DE (1) | DE1110775B (de) |
FR (1) | FR1150118A (de) |
GB (1) | GB820632A (de) |
Cited By (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2961619A (en) * | 1957-06-21 | 1960-11-22 | Sperry Rand Corp | Microwave filter |
US3044026A (en) * | 1958-05-28 | 1962-07-10 | Gen Electric Co Ltd | Transmission line coupling arrangements |
US3237134A (en) * | 1963-03-26 | 1966-02-22 | Gen Electric | Microwave filter |
US3353123A (en) * | 1965-09-01 | 1967-11-14 | Gen Electric | Microwave filter comprising absorbing structures for removing suprious wave energy |
US3451014A (en) * | 1964-12-23 | 1969-06-17 | Microwave Dev Lab Inc | Waveguide filter having branch means to absorb or attenuate frequencies above pass-band |
US3464035A (en) * | 1966-07-25 | 1969-08-26 | Gerald W Van Kol | Filter coupled to microwave guide |
DE1766620B1 (de) * | 1967-06-27 | 1971-06-03 | North American Rockwell | Kopplungsanordnung aus gekreuzten hohlleitern |
US3634788A (en) * | 1967-09-27 | 1972-01-11 | Int Standard Electric Corp | Waveguide filter |
US4520329A (en) * | 1982-02-25 | 1985-05-28 | Italtel Societa Italiana Telecomunicazioni S.P.A. | Circuit component for separating and/or combining two isofrequential but differently polarized pairs of signal waves lying in different high-frequency bands |
US4680558A (en) * | 1983-12-27 | 1987-07-14 | Telecomunicacoes Brasileiras S/A - Telebras | Corrugated transition device for use between a continuous and a corrugated circular waveguide with signal in two different frequency bands |
US4704589A (en) * | 1986-05-27 | 1987-11-03 | The United States Of America As Represented By The United States Department Of Energy | Compact waveguide power divider with multiple isolated outputs |
US4777457A (en) * | 1983-10-25 | 1988-10-11 | Telecomunicacoes Brasileiras S/A - Telebras | Directional coupler for separation of signals in two frequency bands while preserving their polarization characteristics |
US20040000973A1 (en) * | 2002-06-28 | 2004-01-01 | Mccandless Jay | Compact waveguide filter and method |
WO2009121937A1 (fr) * | 2008-04-02 | 2009-10-08 | Centre National D'etudes Spatiales | Coupleur pour systeme radio frequences multibandes |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5105170A (en) * | 1989-07-15 | 1992-04-14 | British Aerospace Public Limited Company | Waveguide coupling networks |
GB2233831B (en) * | 1989-07-15 | 1994-03-23 | British Aerospace | Shared power amplifiers |
GB2237692B (en) * | 1989-11-02 | 1994-02-09 | British Aerospace | Waveguide networks |
Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2129712A (en) * | 1933-12-09 | 1938-09-13 | American Telephone & Telegraph | Transmission of energy effects by guided electric waves in a dielectric medium |
US2558385A (en) * | 1946-01-07 | 1951-06-26 | Edward M Purcell | Branch guide coupler |
US2562281A (en) * | 1944-06-14 | 1951-07-31 | Bell Telephone Labor Inc | Directive pickup for transmission lines |
US2585173A (en) * | 1948-07-01 | 1952-02-12 | Raytheon Mfg Co | Radio-frequency transmission line circuit |
US2626990A (en) * | 1948-05-04 | 1953-01-27 | Bell Telephone Labor Inc | Guided wave frequency range transducer |
US2651759A (en) * | 1946-08-02 | 1953-09-08 | Gen Electric Co Ltd | Wave signal translating and separation system |
US2730677A (en) * | 1952-08-26 | 1956-01-10 | Csf | Ultra-high frequency wave-mode transformers |
US2748350A (en) * | 1951-09-05 | 1956-05-29 | Bell Telephone Labor Inc | Ultra-high frequency selective mode directional coupler |
US2783439A (en) * | 1952-01-03 | 1957-02-26 | Bendix Aviat Corp | Continuously rotatable microwave phase shifter |
-
0
- BE BE554200D patent/BE554200A/xx unknown
-
1956
- 1956-04-28 FR FR1150118D patent/FR1150118A/fr not_active Expired
- 1956-11-14 CH CH335544D patent/CH335544A/fr unknown
- 1956-12-08 DE DEM32589A patent/DE1110775B/de active Pending
-
1957
- 1957-02-26 US US642517A patent/US2866595A/en not_active Expired - Lifetime
- 1957-04-18 GB GB12807/57A patent/GB820632A/en not_active Expired
Patent Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2129712A (en) * | 1933-12-09 | 1938-09-13 | American Telephone & Telegraph | Transmission of energy effects by guided electric waves in a dielectric medium |
US2562281A (en) * | 1944-06-14 | 1951-07-31 | Bell Telephone Labor Inc | Directive pickup for transmission lines |
US2558385A (en) * | 1946-01-07 | 1951-06-26 | Edward M Purcell | Branch guide coupler |
US2651759A (en) * | 1946-08-02 | 1953-09-08 | Gen Electric Co Ltd | Wave signal translating and separation system |
US2626990A (en) * | 1948-05-04 | 1953-01-27 | Bell Telephone Labor Inc | Guided wave frequency range transducer |
US2585173A (en) * | 1948-07-01 | 1952-02-12 | Raytheon Mfg Co | Radio-frequency transmission line circuit |
US2748350A (en) * | 1951-09-05 | 1956-05-29 | Bell Telephone Labor Inc | Ultra-high frequency selective mode directional coupler |
US2783439A (en) * | 1952-01-03 | 1957-02-26 | Bendix Aviat Corp | Continuously rotatable microwave phase shifter |
US2730677A (en) * | 1952-08-26 | 1956-01-10 | Csf | Ultra-high frequency wave-mode transformers |
Cited By (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2961619A (en) * | 1957-06-21 | 1960-11-22 | Sperry Rand Corp | Microwave filter |
US3044026A (en) * | 1958-05-28 | 1962-07-10 | Gen Electric Co Ltd | Transmission line coupling arrangements |
US3237134A (en) * | 1963-03-26 | 1966-02-22 | Gen Electric | Microwave filter |
US3451014A (en) * | 1964-12-23 | 1969-06-17 | Microwave Dev Lab Inc | Waveguide filter having branch means to absorb or attenuate frequencies above pass-band |
US3353123A (en) * | 1965-09-01 | 1967-11-14 | Gen Electric | Microwave filter comprising absorbing structures for removing suprious wave energy |
US3464035A (en) * | 1966-07-25 | 1969-08-26 | Gerald W Van Kol | Filter coupled to microwave guide |
DE1766620B1 (de) * | 1967-06-27 | 1971-06-03 | North American Rockwell | Kopplungsanordnung aus gekreuzten hohlleitern |
US3634788A (en) * | 1967-09-27 | 1972-01-11 | Int Standard Electric Corp | Waveguide filter |
US4520329A (en) * | 1982-02-25 | 1985-05-28 | Italtel Societa Italiana Telecomunicazioni S.P.A. | Circuit component for separating and/or combining two isofrequential but differently polarized pairs of signal waves lying in different high-frequency bands |
US4777457A (en) * | 1983-10-25 | 1988-10-11 | Telecomunicacoes Brasileiras S/A - Telebras | Directional coupler for separation of signals in two frequency bands while preserving their polarization characteristics |
US4680558A (en) * | 1983-12-27 | 1987-07-14 | Telecomunicacoes Brasileiras S/A - Telebras | Corrugated transition device for use between a continuous and a corrugated circular waveguide with signal in two different frequency bands |
US4704589A (en) * | 1986-05-27 | 1987-11-03 | The United States Of America As Represented By The United States Department Of Energy | Compact waveguide power divider with multiple isolated outputs |
US20040000973A1 (en) * | 2002-06-28 | 2004-01-01 | Mccandless Jay | Compact waveguide filter and method |
US7009469B2 (en) * | 2002-06-28 | 2006-03-07 | Harris Corporation | Compact waveguide filter and method |
WO2009121937A1 (fr) * | 2008-04-02 | 2009-10-08 | Centre National D'etudes Spatiales | Coupleur pour systeme radio frequences multibandes |
FR2929796A1 (fr) * | 2008-04-02 | 2009-10-09 | Centre Nat Etd Spatiales | Coupleur pour systeme radio frequences multibandes. |
Also Published As
Publication number | Publication date |
---|---|
FR1150118A (fr) | 1958-01-08 |
DE1110775B (de) | 1961-07-13 |
GB820632A (en) | 1959-09-23 |
BE554200A (de) | |
CH335544A (fr) | 1959-01-15 |
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