US2399779A - Inductive coupling arrangement - Google Patents

Inductive coupling arrangement Download PDF

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Publication number
US2399779A
US2399779A US440292A US44029242A US2399779A US 2399779 A US2399779 A US 2399779A US 440292 A US440292 A US 440292A US 44029242 A US44029242 A US 44029242A US 2399779 A US2399779 A US 2399779A
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Prior art keywords
coupling
coil
circuit
tuning
inductance
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Expired - Lifetime
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US440292A
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English (en)
Inventor
Willoughby Eric Osborne
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International Standard Electric Corp
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International Standard Electric Corp
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Publication date
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Publication of US2399779A publication Critical patent/US2399779A/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H2/00—Networks using elements or techniques not provided for in groups H03H3/00 - H03H21/00
    • H03H2/005—Coupling circuits between transmission lines or antennas and transmitters, receivers or amplifiers
    • H03H2/006—Transmitter or amplifier output circuits
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H2/00—Networks using elements or techniques not provided for in groups H03H3/00 - H03H21/00
    • H03H2/005—Coupling circuits between transmission lines or antennas and transmitters, receivers or amplifiers
    • H03H2/008—Receiver or amplifier input circuits

Definitions

  • the present invention relates to inductive coupling arrangements betweena tunable feed circuit having a' variable inductance ganged to the tuning element of a related tunable circuit and a-condenser of constant capacity and a tunable load circuit having a coupling inductance coupled to the inductance of the feed circuit.
  • variable inductance in the feed circuit comprises two helical coils connected in series and coaxially disposed and one of which at least has a variable number of turns adjusted so that the feed circuit is purely resistive at the operating frequency and the said coupling inductance comprises one or more coupling coils connected in series, one or more of the factors on which the mutual inductance of the two coupled coils depends, viz.
  • variable inductance size, shape, disposition and number of turns of the coupling coil or coils and the disposition of said coupling coil or coils with respect to the said variable inductance being so chosen that for variations in the'said variable induct-' ance for diiferent frequencies the mutual inductance between the feed and load circuits is substantially at the appropriate value for constant power in the load circuit throughout the operating frequency range.
  • an inductance coupling arrangement of the type hereinbefore specified is characterised in this that the variable inductance in the feed circuit comprises two helical coils connected in series and coaxially disposed and one at least of which has a variable number of turns and the coupling inductance comprises one or more coupling coils connected in series, the said coupling coil or one or more of the coupling coils being over-coupled as determined by the load resistance to the part of the said variable inductance effective to tune the feed circuit at the shorter wave end of the operating wave range, this over-coupling in the feed circuit being compensated by adjustment of the constant capacity of saidfeed circuit so that on tuning the load circuitfor maximum power the coupling is at the appropriate value for constant power output for all frequencies within the operating range.
  • FIG. 2 shows an alternative arrangement of the coupling coils.
  • the most important field of application of the invention is to aircraft transmitter antennae, operating at wavelengths such that the antenna circuit electrical length is less than a quarter wavelength throughout the working frequency range of the transmitter.
  • the object of the present invention is to ellmimate the coupling adjustment.
  • the output circuit of the last stage amplifier V comprises a tunable circuit consisting of and of the operating range, whilst the coil LF is assumed to have a constant number of turns and is approximately the correct tuning inductance at the shorter wave end of the operating range.
  • LF also has a high "Q factor, 1. e. ratio of inductive impedance to resistance.
  • the antenna circuit AE comprises a variable inductance LA for tuning the antenna circuit, and a coupling coil LC of a constant number of turns disposed between the two coaxial helical coils LF, LV so as to be inductively coupled thereto.
  • the active portion X of the output stage tuning coil automatically varies the mutual inductance between the output tuning inductance coil LV, LF and the coupling coil LC, and one or more of the factors controlling the mutual inductance, namely the size, number of turns, shape and position of the coupling coil LC with respect to the tuning coil LV, LF is/are so chosen that the mutual inductance between the tuning and coupling coil varies with change of position of the adjustable tuning member so that the mutual inductance is automatically maintained substantially at the correct value to give constant power output throughout the operating frequency range.
  • each tuning coil With ganged tuning inductances covering a frequency range, the operation of the transmitter at the shorter wave end of its range is considerably improved by dividing each tuning coil into two units, a coil LF of constant inductance equal to that necessary to tune the fixed capacity at the shorter wave end of the operating range, and a variable coil LV over which the adjustable tuning contact R moves to cover the frequency variation.
  • the Q (i. e. ratio of inductive impedance to resistance) of the tuning coil is thereby maintained at a high value at the shorter wave end of the operating range, and effects due to high tank circuit losses at the shorter wave end of the operating range are minimised.
  • This'type of construction lends itself readily to automatic coupling adjustment as it is relatively easy to place a coupling coil LC between the constant coil LF and vaiiable coil LV of the tuning inductance and the coupling is adjusted to the correctvalue at the highest and lowest irequencies, for instance, by adjusting the position and number of turns on the coupling coil LC.
  • the radio' frequency current through a fixed load resistance was maintained constant over a 22:1 frequency range to "within when both output tank circuit and antenna circuit were tuned to be purely resistive.
  • the power output is then checked at the longer wave end of the tuning range with this adjustment and the trimmer condenser and coupling are manipulated until the conditions are adjusted for the correct power output at the two ends of the tuning range.
  • the size of the coupling coil is determined almost entirely by practical considerations and the number of turns is obtained in early approximate adjustments, and once the coil size and turns have been determined, the coupling and tuning condensers are adjusted as explained above.
  • the coupling is adjusted by positioning LC relative to LV and LF and the number of turns on LC, and the condenser C by adjustment of the tuning condenser CT.
  • the coupling coil LC can be made up of two separate coupling coils in series as shown in Fig. 2 if greater control over the said relation is required.
  • An inductive coupling arrangement comprising a tunable feed circuit having a condenser of constant capacity when the frequency of the current passing through said arrangement lies between predetermined limits, and an inductance comprising first and second coaxially disposed longitudinally spaced helical coils connected in series and with the first coil having one end-open and thus inactive, means associated with said first coil for varying'the number of turns of said coil included in said feed circuit, and a tunable load circuit having at least one inductance coil coupled to said first-mentioned inductance and positioned adjacent the inactiveend of said first so coil.
  • An inductive coupling arrangement compris- 5 ing a tunable feed circuit having a condenser of constant capacity when the frequency of the current passing through the arrangement lies between predetermined limits and first and second coaxially-dispo'sed helical coils, longitudinally displaced with respect to one another, a connection between the inner end of said first coil and the outer end of said second coil, a variable tapping on said second coil, and a coupling coil disposed between and coaxial with said first and second coils.
  • An inductive coupling arrangement comprising a tunable feed circuit having a condenser of constant capacity when the frequency of the cur- I rent passing through the arrangement lies bepositioned adjacent the outer end of a respective tween predetermined limits and first and second coaxially-disposed helical coils, longitudinally displaced with respect to one another, a connection between the inner ends of said coils, a variable tapping on one of said coils, and two series-connected coupling coils each of which is one of said first and second coils and is coaxial therewith.

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US440292A 1941-05-27 1942-04-24 Inductive coupling arrangement Expired - Lifetime US2399779A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2399779X 1941-05-27

Publications (1)

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US2399779A true US2399779A (en) 1946-05-07

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Application Number Title Priority Date Filing Date
US440292A Expired - Lifetime US2399779A (en) 1941-05-27 1942-04-24 Inductive coupling arrangement

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US (1) US2399779A (en, 2012)
BE (1) BE469707A (en, 2012)
FR (1) FR929103A (en, 2012)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2637809A (en) * 1947-11-01 1953-05-05 Rauland Corp Coupling for frequency modulation discriminators

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2637809A (en) * 1947-11-01 1953-05-05 Rauland Corp Coupling for frequency modulation discriminators

Also Published As

Publication number Publication date
BE469707A (en, 2012)
FR929103A (fr) 1947-12-17

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