US2985851A - Unidirectional waveguide attenuator - Google Patents

Unidirectional waveguide attenuator Download PDF

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Publication number
US2985851A
US2985851A US683076A US68307657A US2985851A US 2985851 A US2985851 A US 2985851A US 683076 A US683076 A US 683076A US 68307657 A US68307657 A US 68307657A US 2985851 A US2985851 A US 2985851A
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United States
Prior art keywords
waveguide
strip
stub
line
conductor
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Expired - Lifetime
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US683076A
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English (en)
Inventor
Lewin Leonard
Thompson George Horace Brooke
Sagnard Francois
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International Standard Electric Corp
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International Standard Electric Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/32—Non-reciprocal transmission devices
    • H01P1/36—Isolators
    • H01P1/365—Resonance absorption isolators

Definitions

  • a uni-directional waveguide attenuator owes its nonreciprocal property to the fact that it operates on an aspect of an electromagnetic field which depends on the direction of propagation, namely, a condition of circular polarization of the magnetic field vector. If a region of pure circular polarisation exists, a theoretically perfect operation can be obtained.
  • a unidirectional attenuator arrangement comprising a main waveguide along which electromagnetic energy is normally propagated in a mode approximating the T.E.M. mode, a waveguide stub coupled to the main waveguide for developing a circularly polarised magnetic field, ferromagnetic ceramic material located within said circularly polarised magnetic field, and means for applying a static magnetic field to condition said ceramic material for gyromagnetic resonance.
  • Example of waveguides along which electromagnetic energy is normally propagated in a mode approximating the T.E.M. mode are strip line waveguides and co-axial line waveguides.
  • Fig. 1 is a cross-sectional view of a unidirectional attenuator arrangement
  • Fig. 2 is a plan view of part of the arrangement shown in Fig. 1 along AA.
  • a strip line Waveguide is meant a waveguide (transmission line) which includes strip-line conductors disposed in a spaced parallel relation, and in which electromagnetic energy is normally propagated in a mode approximating the T.E.M. mode.
  • An example of a strip-line waveguide is a waveguide including two striplike conductors disposed in dielectrically spaced parallel relation a small fraction of a quarter wavelength apart with one of the strip conductors wider than the other ice to present thereto a planar conducting surface.
  • Another example is a waveguide having three strip-like conductors disposed in dielectrically spaced parallel relation a small fraction of a quarter wavelength apart with two of the strips wider than the third, and on opposite sides thereof, such a strip-line being known as sandwich form.
  • the dielectric materials may be polyethylene, polystyrene, fibreglass, or other suitable material of dielectric quality, or if the waveguide structure permits, the dielectric may be a gas such as air or nitrogen.
  • Fig. 1 is a cross-sectional view through a main stripline waveguide having a strip-like conductor 1, 1 on one surface of a dielectric 3 and having a ground plane 4 on the other surface of the dielectric.
  • the dielectric 3 and the ground plane 4 are considerably wider than the strip-like conductor 1, 1' as shown in Fig. 2.
  • Electromagnetic energy is propagated along the stripline waveguide in a mode. approximating the T.E.M. mode, the magnetic vectors being transverse of the strip conductor 1, 1.
  • a strip-line stub 5 (Fig. 2) extends at from, and is integral and co-planar with the strip-line waveguide.
  • the strip-line stub 5 is a striplike conductor co-planar with the strip-like conductor 1, 1, the same dielectric 3 and the same ground plane 4 as the strip-line waveguide the width of the strip-like conductor 5 being preferably narrower than the conductor 1, 1'.
  • the current at the stub base and the transmitted current in the main strip-line waveguide past the stub are substantially equal in magnitude and are in phase quadrature.
  • the magnetic vectors are substantially equal in magnitude and are in phase quadrature, thereby resulting in a region of circular polarisation of the magnetic vector.
  • a piece of ferromagnetic ceramic material such as a cylinder 6 of nickel-zinc ferrite having a low Curie point, is positioned within the region of the circularly polarised magnetic field, namely, between the strip-like conductor 1, 1 and the ground plane 4 as shown in Fig. l.
  • the diameter of the cylindrical ferrite part 6 is 0.13 cm. and the length is equal to the thickness of the dielectric of the strip line.
  • the ferrite part may conveniently be positioned by drilling a hole through the ground plane, di-
  • auxiliary strip-line stub 9 may be provided to improve the matching in the main strip-line waveguide. This auxiliary stub 9 is positioned symmetrically opposite to the stub 5 and utilises the dielectric 3 and the ground plane 4 as shown in Fig. 2.
  • the stub 5 may, for example, be of a length equal to of the operating wavelength and the auxiliary stub 9 may be equal to A; of the operating wavelength.
  • a magnet is disposed with its pole-pieces 7 and 8 on opposite sides of the ferrite part 6, the pole-pieces 7 and 8 being north and south respectively.
  • the magnetic field across the ferrite part 6 is of a definite sense according to the desired direction of attenuation, and of field strength to condition the ferrite for gyromagnetic resonance. In the present embodiment the field strength is equal to 500 oersteds, for a wave frequency of 4000 mc./s.
  • a wave at a particular frequency and travelling from the part 1 of the strip-like conductor 1, 1' to the other part 1 will be practically unattenuated as it passes the ferrite part 6, whereas the same wave, travelling in the reverse direction along the waveguide, will produce a substantially circularly polarised magnetic field of such sense that the wave will be substantially attenuated.
  • a ratio in attenuation of 30 to 1 in the different directions has been obtained at the frequency 4000 mc./s.
  • the ferrite is inserted, within the region of circular polarisation, on both sides of the central strip conductor. This may be effected in the manner previously described, namely by drilling a hole through the waveguide, inserting the ferrite part so as to be flush with the internal surfaces of the outer ground planes, and soldering the holes in these ground planes. If a co-axial line is used it will be appreciated that in the region of the stub, where the side arms in the outer casing extend from the main line, the field distribution is similar to that of the sandwich form strip line waveguide.
  • a uni-directional attenuator arrangement comprising a main waveguide adapted for the propagation of energy therealong in a mode approximating the T.E.M. mode, a waveguide stub coupled in shunt with said main waveguide at an intermediate junction point whereby there is developed at said junction a transition region of circular polarization of the magnetic field, said main waveguide and said stub waveguide being disposed with their respective axes of wave propagation in mutually perpendicular relationship at said junction point, a ferrite located within said region of circular polarization, and means for applying a static magnetic field transverse to 4 the plane of said circular polarization to condition said ferrite for gyromagnetic resonance.
  • main waveguide is a strip-line waveguide and the waveguide stub is a strip-line stub, each strip-like conductor of the main strip-line waveguide being co-planar with and integral with each associated strip-like conductor of the strip-line stub.

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  • Variable-Direction Aerials And Aerial Arrays (AREA)
US683076A 1956-09-24 1957-09-10 Unidirectional waveguide attenuator Expired - Lifetime US2985851A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB351310X 1956-09-24

Publications (1)

Publication Number Publication Date
US2985851A true US2985851A (en) 1961-05-23

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US683076A Expired - Lifetime US2985851A (en) 1956-09-24 1957-09-10 Unidirectional waveguide attenuator

Country Status (6)

Country Link
US (1) US2985851A (enrdf_load_stackoverflow)
BE (1) BE561047A (enrdf_load_stackoverflow)
CH (1) CH351310A (enrdf_load_stackoverflow)
DE (1) DE1038138B (enrdf_load_stackoverflow)
FR (1) FR75174E (enrdf_load_stackoverflow)
GB (1) GB799172A (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3680006A (en) * 1970-08-21 1972-07-25 Addington Lab Inc Microwave isolator
US4568945A (en) * 1984-06-15 1986-02-04 Winegard Company Satellite dish antenna apparatus
US4766443A (en) * 1984-06-15 1988-08-23 Winegard Company Satellite dish antenna apparatus

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3835420A (en) * 1972-07-26 1974-09-10 Mitsubishi Electric Corp Isolator

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2755447A (en) * 1954-10-29 1956-07-17 Itt Radio frequency coupling devices
US2767379A (en) * 1954-04-14 1956-10-16 Bell Telephone Labor Inc Electromagnetic wave equalization
US2892161A (en) * 1955-01-31 1959-06-23 Bell Telephone Labor Inc Nonreciprocal circuit element
US2922125A (en) * 1954-10-20 1960-01-19 Bell Telephone Labor Inc Nonreciprocal single crystal ferrite devices

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2767379A (en) * 1954-04-14 1956-10-16 Bell Telephone Labor Inc Electromagnetic wave equalization
US2922125A (en) * 1954-10-20 1960-01-19 Bell Telephone Labor Inc Nonreciprocal single crystal ferrite devices
US2755447A (en) * 1954-10-29 1956-07-17 Itt Radio frequency coupling devices
US2892161A (en) * 1955-01-31 1959-06-23 Bell Telephone Labor Inc Nonreciprocal circuit element

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3680006A (en) * 1970-08-21 1972-07-25 Addington Lab Inc Microwave isolator
US4568945A (en) * 1984-06-15 1986-02-04 Winegard Company Satellite dish antenna apparatus
US4766443A (en) * 1984-06-15 1988-08-23 Winegard Company Satellite dish antenna apparatus

Also Published As

Publication number Publication date
GB799172A (en) 1958-08-06
BE561047A (enrdf_load_stackoverflow)
DE1038138B (de) 1958-09-04
FR75174E (enrdf_load_stackoverflow) 1961-09-08
CH351310A (de) 1961-01-15

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