US3274504A - Micro-wave detector - Google Patents

Micro-wave detector Download PDF

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Publication number
US3274504A
US3274504A US349407A US34940764A US3274504A US 3274504 A US3274504 A US 3274504A US 349407 A US349407 A US 349407A US 34940764 A US34940764 A US 34940764A US 3274504 A US3274504 A US 3274504A
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US
United States
Prior art keywords
waveguide
aperture
wall
rectifier
terminal
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
Application number
US349407A
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English (en)
Inventor
Ronde Frans Christiaan De
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.)
US Philips Corp
North American Philips Co Inc
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US Philips Corp
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Filing date
Publication date
Application filed by US Philips Corp filed Critical US Philips Corp
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Publication of US3274504A publication Critical patent/US3274504A/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D9/00—Demodulation or transference of modulation of modulated electromagnetic waves
    • H03D9/02—Demodulation using distributed inductance and capacitance, e.g. in feeder lines
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R21/00—Arrangements for measuring electric power or power factor

Definitions

  • This invention relates to detector devices for microwaves.
  • a microwave detector in which a rectifier is connected, in series with a capacitance forming substantially a short circuit with respect to microwaves, between opposite points of a circular aperture provided in a side wall of a wave guide.
  • the rectifier is arranged outside the waveguide proper and also outside the wall thereof.
  • Said device may be made suitable for a broad range of frequencies by placing the rectifier in a suitably chosen cavity resonator outside the wave guide.
  • the present invention provides a very efficacious solution of the problem whereby the reflection coefficient of the detector may be lower than that of the known device.
  • a detector according to the invention employs a rectifier of a kind known per se.
  • the rectifier is arranged inside a cylindrical shielding sleeve and has one pole connected to the shielding sleeve and its other pole connected to a concentric connecting pin.
  • Such so-called coaxial rectifiers are sold commercially.
  • a detector according to the invention has an aperture provided at a corner in the wall of the wave guide.
  • the rectifier is arranged so that the connecting pin extends in a longitudinal bore in the adjacent wall of the wave guide and at right angles to the edge of the corner.
  • a series capacitance is formed by a narrow gap between the said shielding sleeve and further parts of the wall.
  • FIGURE 1 is a cross-sectional view of a waveguide of rectangular section in which a detector is housed.
  • FIGURE 2 shows a longitudinal section of the waveguide of FIGURE 1, taken along the plane II-II.
  • a conductive stub 2 for accommodating a detector 3 is provided at the left-hand upper corner of a wave guide 1.
  • the stub 2 surrounds an aperture 20 in a waveguide wall 21 at the longitudinally extending junction between the wall 21 and the adjoining wall 10. Said stub may be omitted if the wall of the waveguide 1 itself is of sutficient thickness.
  • the rectifier 3 may be of a kind known per se and FIGURE 1 shows diagrammatically a cross-section thereof.
  • the detector 3 includes a crystal diode 4, secured to the upper end of a connecting pin 6 which is held in a circular conductive shielding sleeve 8 by means of an insulating ring 7.
  • a connecting spring is connected to the sleeve 8 so that the terminals of the detector are formed by the pin 6 and the sleeve 8.
  • the pin 6 extends into a vertical bore 9 provided in the middle of the left-hand side wall 10 of the wave guide 1.
  • the bore 9 extends in a transverse plane of the waveguide which passes through the aperture 20.
  • the shielding sleeve 8 is situated in a circular aperture in the "ice stub 2 so that a narrow gap 11 exists between the sleeve 8 and the stub 2.
  • This gap has a comparatively high capacity and substantially forms a short-circuit for microwaves.
  • the gap preferably has a height equal to one quarter of the operational wavelength.
  • the direct out put voltage may be applied to an output circuit 22 connected between the sleeve 8 and the stub 2.
  • an aperture 12 is provided in the left-hand side wall having a re-entrant portion 13 which serves as a stop for the ring 7 so that the position of the rectifier is fixed.
  • the reentrant portion 13 of the aperture 12 is aligned with the aperture 20, so that the aperture 12 effectively consists of two apertures in the wall 10 on opposite sides of the aperture 20 with respect to the longitudinal direction of the waveguide.
  • the direct output voltage of the detector may be made substantially constant through a broad range of frequencies.
  • the sensitivity of the detector usually decreases with increasing frequency, whereas just the reverse is the case if the aperture is comparatively long, so that the sensitivity is constant for a given intermediate length.
  • the impedance of the rectifier is substantially determined by the capacitance between the connecting pin 6 and the shielding sleeve 8.
  • the impedance of this capacitance is comparatively low with respect to the impedance of the crystal diode 4 itself.
  • the latter impedance exhibits comparatively great differences from rectifier to rectifier because of structural differences.
  • the capacitance between the connecting pin 6 and the shielding sleeve 8 is comparatively constant the rectifier may be replaced by another in a simple manner without the frequency response curve substantially varying.
  • two different detectors also exhibit substantially the same frequency response curve.
  • This property may be employed by controlling the strength of a high-frequency oscillator by means of an output voltage from a first detector device and using a second detector device for measuring purposes.
  • the output voltage of the second detector device may then be constant throughout the X band (8.2 to 12.4 Gc./s.) with a deviation less than 0.3 decibel.
  • the alternating voltage set up across the crystal will usually be comparatively low so that the rectifier operates in the quadratic portion of its characteristic and the direct out- .put voltage is proportional to the square of the field strength in the waveguide, that is to say proportional to the energy of the waves.
  • the sensitivity is, for example, 10 mv./mw.
  • the detector according to the invention affords the considerable advantage that it does not substantially bring about reflection of the waves in the wave guide, for example at a standing wave ratio (V.S.W.R.) better than 1.01.
  • the supply conductors to the crystal are very short and hence have little impedance.
  • the impedance of the detector is also comparatively low so that only a comparatively low voltage is set up across the aperture in the side wall and the configuration of the lines of force in the waveguide is also deformed but slightly.
  • the detector may alternatively be arranged in a partition between the waveguides, the wall parts 16 shown in broken line having to be regarded as belonging to a waveguide placed to the left of the waveguide 1.
  • the direct output voltage will be proportional to the sum of the wall currents in the two guides.
  • the coupling between the two conductors is comparatively low (for example from 40 to 60 decibels) despite the aperture in the common side wall.
  • the longitudinal bore 9 need not fundamentally be formed in a short side of the wave guide and may alternatively be provided in a long side, and the detector device may alternatively be arranged at the corner of a ridge in a ridge waveguide.
  • Means for detecting high frequency oscillations in a waveguide comprising a waveguide for conveying high frequency oscillations, said waveguide having a rectangular cross-section with first and second adjacent side walls, said first side wall having a first aperture at the junction of said first and second side walls, unidirectional current means having first and second terminals, means connecting said first terminal to said second side wall in the transverse plane of said waveguide which extends through said first aperture, capacitor means for coupling said second terminal to said first side wall in said plane, said second side wall having second and third apertures on opposite sides of said first aperture with respect to the longitudinal direction of said waveguide, whereby wall currents in said waveguide flow through said unidirectional current means, and output circuit means connected between said second terminal and said first side wall.
  • Means for detecting high frequency oscillations in a waveguide comprising a waveguide for conveying high frequency oscillations, said waveguide having first and second longitudinally extending adjoining walls, a cylindrical rectifier device of the type having a first cylindrical end portion comprising a first terminal and joined to a second cylindrical end portion of larger diameter, the second terminal of said rectifier device being on said second end portion, said waveguide having an aperture in said first wall adjacent the junction of said first and second walls, said second wall having a bore at said junction in the transverse plane of said waveguide passing through said aperture, said bore extending within said second wall substantially normal to the plane of said first wall, said first end portion being inserted within said bore, a conductive sleeve surrounding said second end portion 'and contacting said second terminal, means providing a capacitance between said sleeve and said first wall at said aperture, and output circuit means connected between 'said second terminal and said first Wall.
  • Means for detecting high frequency oscillations in a waveguide comprising a waveguide for conveying high frequency oscillations, said waveguide having a rectangular cross-section with first and second adjoining walls, said first wall having a first aperture adjacent the junction of said first and second walls, said second wall having second and third apertures adjacent said junction and overlapping said first aperture on opposite sides, rectifier means having first and second terminals, said first terminal being in contact with said second wall at said junction and between said second and third apertures, capacitor means connected between said second terminal and the edges of said first aperture, and output circuit means connected between said second terminal and said first wall.
  • said capacitor means comprises a conductive sleeve surrounding said rectifier means and spaced from said first aperture, said sleeve being connected to said second terminal.
  • Means for detecting high frequency oscillations in a waveguide comprising a waveguide for conveying high frequency oscillations, said waveguide having a rectangular cross-section with first and second adjoining walls, said first wall having a first aperture adjacent the junction of said first and second walls, said second wall having apertures adjacent said junction and overlapping said first aperture on opposite sides, a stub extending from the edges of said first aperture normal to said first wall, said second wall having a bore between said second and third apertures and normal to said first wall, a coaxial diode having a pin comprising one terminal thereof inserted Within said bore, a conductive sleeve surrounding said diode and being electrically connected to the other terminal thereof, said sleeve being within said stub and forming a capacitor between said stub and other terminal, and an output circuit connected between said other terminal and said stub.
  • a detecting means of claim 5, comprising a second waveguide, wherein said second wall is a common wall between said first-mentioned waveguide and said second waveguide, said first aperture extending through a wall of said second waveguide.
  • Means for detecting high frequency oscillations in a waveguide comprising a waveguide for conveying high frequency oscillations, said waveguide having first and second longitudinally extending adjoining walls, .a coaxial rectifier device having first and second terminals on opposite ends of a cylindrical body, said first wall having an aperture extending therethrough at the junction of said first and second walls, said second wall having a bore extending from said junction at said aperture, said bore extending into said second wall substantially normal to said junction, said first terminal of said rectifier device being within said here in contact with said second wall, said second terminal extending externally of said waveguide, capacitive means coupling said second terminal to said first wall externally of said Waveguide, whereby wall currents in said waveguide flow through said rectifier device, output circuit means, and means connecting said output circuit means between said second terminal and said waveguide.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Waveguide Connection Structure (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
US349407A 1963-03-21 1964-03-04 Micro-wave detector Expired - Lifetime US3274504A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL290518 1963-03-21

Publications (1)

Publication Number Publication Date
US3274504A true US3274504A (en) 1966-09-20

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Application Number Title Priority Date Filing Date
US349407A Expired - Lifetime US3274504A (en) 1963-03-21 1964-03-04 Micro-wave detector

Country Status (5)

Country Link
US (1) US3274504A (enrdf_load_stackoverflow)
DE (1) DE1198871B (enrdf_load_stackoverflow)
GB (1) GB1015733A (enrdf_load_stackoverflow)
NL (1) NL290518A (enrdf_load_stackoverflow)
SE (1) SE318629B (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5398858A (en) * 1991-08-23 1995-03-21 Dugan; Tracy P. Whisker-reinforced ceramic roller guides

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2642494A (en) * 1948-05-26 1953-06-16 Sperry Corp Mode suppressing coupling for cavity wavemeters
US2956160A (en) * 1957-12-18 1960-10-11 Bell Telephone Labor Inc Millimeter wave crystal rectifier
US3028560A (en) * 1955-01-28 1962-04-03 Sylvania Electric Prod Electrical crystal unit

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2642494A (en) * 1948-05-26 1953-06-16 Sperry Corp Mode suppressing coupling for cavity wavemeters
US3028560A (en) * 1955-01-28 1962-04-03 Sylvania Electric Prod Electrical crystal unit
US2956160A (en) * 1957-12-18 1960-10-11 Bell Telephone Labor Inc Millimeter wave crystal rectifier

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5398858A (en) * 1991-08-23 1995-03-21 Dugan; Tracy P. Whisker-reinforced ceramic roller guides

Also Published As

Publication number Publication date
NL290518A (enrdf_load_stackoverflow)
GB1015733A (en) 1966-01-05
SE318629B (enrdf_load_stackoverflow) 1969-12-15
DE1198871B (de) 1965-08-19

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