US2751557A - Tau-connected stub filters for use on very high frequencies - Google Patents

Tau-connected stub filters for use on very high frequencies Download PDF

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Publication number
US2751557A
US2751557A US270925A US27092552A US2751557A US 2751557 A US2751557 A US 2751557A US 270925 A US270925 A US 270925A US 27092552 A US27092552 A US 27092552A US 2751557 A US2751557 A US 2751557A
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Prior art keywords
frequency
stub
arms
quarter wave
length
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Expired - Lifetime
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US270925A
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English (en)
Inventor
Sosin Boleslaw Marian
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Marconis Wireless Telegraph Co Ltd
BAE Systems Electronics Ltd
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Marconi 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
    • H01P1/20—Frequency-selective devices, e.g. filters
    • H01P1/201—Filters for transverse electromagnetic waves
    • H01P1/202—Coaxial filters

Definitions

  • This invention relates to filters and other frequency selective arrangements for use on very high frequencies and more particularly to filters of the so-called line or distributed constants type i. e. the type in which, instead of lumped impedances lengths of high frequency line are used.
  • Fig. 1 shows a typical known arrangement
  • Figs. 2, 3, 4 and 5 show embodiments of this invention
  • Figs. 2a and 4a are equivalent block diagrams for purposes of explanation.
  • the longer length is open circuited it is made an odd number of quarter wave lengths long at the stop frequency: if it is short circuited it is made an integral number of half wave lengths long at that frequency.
  • the short length [2 provides, at the pass frequency, a reactance as nearly as possible equal and opposite to that of the long length.
  • a filter or the like of the line type comprises one or more T connected stubs each of which has a connecting arm which is other than a quarter wave length or a multiple thereof long and which meets the other two arms (the cross piece of the T) at their junction, the said arms being either open or short circuited at their far ends.
  • Fig. 2 shows one embodiment of the invention serving the same purpose as the known arrangement of Fig. 1.
  • the main transmission line comprises the conductors M1 and M0.
  • the stub is now a T stub with its inner and outer conductors T1 and T0 in the form of a T with three arms of lengths l1, l2 and Is as 2,751,557 Patented June 19, .1956
  • the length la is any arbitrary length other than a quarter wave length at any frequency within the frequency range having the stop frequency of the filter as one limit and the pass frequency of the filter as the other limit.
  • the significance of making 13 other than a quarter wave length is that it is not required to invert the impedance. It would be practicable if impedance inversion was required to put a quarter wave length at la and then add the stub including an additional element for la designed on the principles outlined in the application. If, in fact, a quarter wave length line was used at [3 the whole benefit of the invention would be lost because the dimensions of the stub would be inconveniently large.
  • What is required at 13 is a means of controlling the impedance level and to do this a length is required which is other than a quarter wave length; as low as 6, 01' it may be very much higher, but the essential feature is that [3 shall not be a quarter wave length.
  • the lengths l1, l2 may be either open circuited or short circuited at their far ends. In this example if 11 is open circuited its length is such that li-I-ls is substantially an odd number of quarter wave lengths long at the required stop frequency-more precisely the length will be slightly modified from the exact odd number of quarter wave lengths owing to the presence of the length [2.
  • the ratio of the lengths of 12 to Z1 is much greater, other things being equal than with the known arrangement of Fig. l and in practice, for the same length of stub, the losses are reduced by about four times or more in an arrangement in accordance with this invention as compared to a known arrangement as in Fig. 1.
  • high currents are kept away from the junction point with the main transmission line and a closer correspondance between practice and theoretical design can be achieved than with known arrangernents.
  • Fig. 3 shows a T-stub arrangement in accordance with the invention inserted in series in the main transmission line instead of, as in Fig. 2, in parallel connection.
  • Fig. 3 shows the same references are used as in Fig. 2 'so'that the said Fig. 3 will be, it is thought, self-explanatory.
  • Fig. 3 shows the series case in which the main'tra'nsrnission line is broken at its outer portion at point P so that the T stub can be connected. The outer portion is then continued as the larger diameter for la, the inner portion of is being a continuation of the outer portion of the main transmission line that is joined to the T stu'b at the opposite end of the stub.
  • the inner portion or 12 is comprised of the outer portiofnof the main transmission line and the inner portion of i1 is connected tb the inner portion of 12 and the inner portion of Is at the point indicated at Q.
  • Figs. 4 and 5 show reciprocal T arrangements connected in parallel to the main line. As shown in Figs. 4 and 5 the ararngemenjts do not look like Ts but in fact they are as will be apparent from Figs. 2a and 4a of which Fig. 2a is the equivalent block diagram of the stub of Figs. 2 and 3 and Fig. 4a hhe equivalent block diagram of the stub of Figs. 4 and 5. Like references are used throughoutgFigs, 2,241.3, 4,
  • the lengths of the various parts are made the same as the corresponding lengths of the straight T-stub but the far end'of the corresponding part of the reciprocal T-stub isshort circuited if that of the straight -T-stub is open circuited and vice versa.
  • a reciprocal T-stub may also be employed in series with the main line but in this case the provision of an isolating stub may be required.
  • the known tapped 'stub arrangements such as that exemplified in Fig. 1 or the reciprocal thereof (which is two stubs in series) present defects as already described.
  • the present invention by adding the interposed length 13 oftransmission line to transform the known type'of arrangement to a T-stub arrangement, avoids these defects modifying the frequency response and enabling the losses to be made very low.
  • 13 may be of any length other than )r/ 4 or a multiple thereof. In all the above cases, by choosing a suitable value for 13 the frequency ii at which substantially zero impedance is presented, may be chosen at will either below or above the frequency fz at which substantially infinite impedance is presented.
  • the lengths 11, la and 13 can be freely chosen in such a way that the bandwidth at f1 can be varied gradually from wide to narrow and the bandwidth at f2 can be varied gradually from narrow to widein other words l1, l2 and 13 can be selected at values which will give a wide band at f1 and a narrow band at is or 'vice versa, or any intermediate condition of bandwidth, widening of the band at f1 being accompanied by narrowing of the band at fz and vice versa.
  • a filter or the like of the line type comprising at least one straigh T-connected stub having a connecting arm which is other than a whole number, including unity, of quarter wave lengths long at any frequency within the frequency range having the stop frequency of the filter as one limit and the pass frequency of the filter as the other limit and two other arms, said connecting arm being parallel connected to the other two arms at their junction, one of said other two arms being open circuited at its far end and being substantially a whole odd number, including unity, of quarter wave lengths long at a frequencywithinsaid range and the other of said other two arms being short circuited at its far end and being short in relation to a quarter wave length at any frequency within said range.
  • a filter or the like of the line type comprising at least one reciprocal T-connected stub having a connecting arm which is other than a whole number, including unity, of quarter wave lengths long at any frequency within the frequency range having the stop frequency of the filter as one limit and the pass frequency of the filter as the other limit and two other arms, said connecting arm being series connected to the other two arms at their junction, one of said other two arms being short circuited at its far end and being substantially a whole odd number, including unity, of quarter wave lengths long at a frequency within said range and the other of said other two arms being short circuited at its far end and being slightly shorter than a quarter wave length long at any frequency within said range.
  • a filter or the like of the line type comprising at least one straight T-connected stub having a connecting arm which is other than a whole number, including unity, of quarter wave lengths long at any frequency within the frequency range having the stop frequency of the filter as one limit and the pass frequency of the filter as the other limit and two other arms, said connecting arm being parallel connected to the other two arms at their junction, one of said other arms being short circuited at its far end and being substantially a whole number, including unity, of half wave lengths long at a frequency within said range and the other of said other two arms being open circuited at its far end and being slightly shorter than a quarter wave length long at any frequency within said range.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)
US270925A 1951-02-26 1952-02-11 Tau-connected stub filters for use on very high frequencies Expired - Lifetime US2751557A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB307769X 1951-02-26
GB281151X 1951-11-28

Publications (1)

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US2751557A true US2751557A (en) 1956-06-19

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US270925A Expired - Lifetime US2751557A (en) 1951-02-26 1952-02-11 Tau-connected stub filters for use on very high frequencies

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US (1) US2751557A (en(2012))
BE (1) BE509377A (en(2012))
CH (1) CH307769A (en(2012))
DE (1) DE1232284B (en(2012))
FR (1) FR1051767A (en(2012))
GB (1) GB698509A (en(2012))

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2861245A (en) * 1952-09-26 1958-11-18 Gen Electric Electrical transmission systems and filters therefor
US2984798A (en) * 1959-08-26 1961-05-16 Harold E Bryan Duplexer
US3181092A (en) * 1960-10-03 1965-04-27 Zh Denryoku Chuo Keukyujo Wave trap by parallel sub-conductors
US3411114A (en) * 1965-04-30 1968-11-12 Allen Bradley Co Microwave transmission-line t-filters
US4670724A (en) * 1985-07-22 1987-06-02 Microwave Development Laboratories, Inc. Stub-supported transmission line device
US4730173A (en) * 1983-06-23 1988-03-08 Murata Manufacturing Co., Ltd. Asymmetrical trap comprising coaxial resonators, reactance elements, and transmission line elements

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2128400A (en) * 1936-06-30 1938-08-30 Rca Corp Transmission line system
US2214041A (en) * 1938-08-31 1940-09-10 Rca Corp Electrical network
US2270416A (en) * 1936-12-23 1942-01-20 Emi Ltd Electrical wave system
US2495589A (en) * 1947-07-21 1950-01-24 Rca Corp Radio frequency transmission network
US2532993A (en) * 1945-06-21 1950-12-05 Rca Corp Band-pass filter
US2540734A (en) * 1946-01-07 1951-02-06 William H Huggins High-frequency filter
US2570579A (en) * 1946-12-06 1951-10-09 Rca Corp Transmission line system

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2238438A (en) * 1935-03-22 1941-04-15 Mackay Radio & Telegraph Co Electrical network
US2321521A (en) * 1941-01-10 1943-06-08 Farnsworth Television & Radio Frequency band filter

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2128400A (en) * 1936-06-30 1938-08-30 Rca Corp Transmission line system
US2270416A (en) * 1936-12-23 1942-01-20 Emi Ltd Electrical wave system
US2214041A (en) * 1938-08-31 1940-09-10 Rca Corp Electrical network
US2532993A (en) * 1945-06-21 1950-12-05 Rca Corp Band-pass filter
US2540734A (en) * 1946-01-07 1951-02-06 William H Huggins High-frequency filter
US2570579A (en) * 1946-12-06 1951-10-09 Rca Corp Transmission line system
US2495589A (en) * 1947-07-21 1950-01-24 Rca Corp Radio frequency transmission network

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2861245A (en) * 1952-09-26 1958-11-18 Gen Electric Electrical transmission systems and filters therefor
US2984798A (en) * 1959-08-26 1961-05-16 Harold E Bryan Duplexer
US3181092A (en) * 1960-10-03 1965-04-27 Zh Denryoku Chuo Keukyujo Wave trap by parallel sub-conductors
US3411114A (en) * 1965-04-30 1968-11-12 Allen Bradley Co Microwave transmission-line t-filters
US4730173A (en) * 1983-06-23 1988-03-08 Murata Manufacturing Co., Ltd. Asymmetrical trap comprising coaxial resonators, reactance elements, and transmission line elements
US4670724A (en) * 1985-07-22 1987-06-02 Microwave Development Laboratories, Inc. Stub-supported transmission line device

Also Published As

Publication number Publication date
CH307769A (fr) 1955-06-15
BE509377A (en(2012))
DE1232284B (de) 1967-01-12
FR1051767A (fr) 1954-01-19
GB698509A (en) 1953-10-14

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