US2415141A - Tunable ultra high frequency apparatus - Google Patents

Tunable ultra high frequency apparatus Download PDF

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US2415141A
US2415141A US503766A US50376643A US2415141A US 2415141 A US2415141 A US 2415141A US 503766 A US503766 A US 503766A US 50376643 A US50376643 A US 50376643A US 2415141 A US2415141 A US 2415141A
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line
lines
effective electrical
operating frequencies
electrical length
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US503766A
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Leonard R Malling
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Hazeltine Research Inc
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Hazeltine Research Inc
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Priority to US503766A priority patent/US2415141A/en
Priority to GB15100/44A priority patent/GB586167A/en
Priority to CH257595D priority patent/CH257595A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P7/00—Resonators of the waveguide type
    • H01P7/02—Lecher resonators
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/18—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising distributed inductance and capacitance
    • H03B5/1817—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising distributed inductance and capacitance the frequency-determining element being a cavity resonator
    • H03B5/1835—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising distributed inductance and capacitance the frequency-determining element being a cavity resonator the active element in the amplifier being a vacuum tube
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J3/00—Continuous tuning
    • H03J3/28—Continuous tuning of more than one resonant circuit simultaneously, the tuning frequencies of the circuits having a substantially constant difference throughout the tuning range

Definitions

  • This invention relates to a tunable ultra-highfrequency apparatus including a plurality of effectively resonant transmission lines tunable over given ranges of operating frequencies in manner which maintains a predetermined constant relation between their individual operating frequencies.
  • the invention is subject to a wide range of applications, it is especially suited for use in an ultra-high-frequency oscillation generator of the directly heated cathode type and will be described in such connection.
  • the heater circuit forms part of both the anode-cathode and grid-cathode circuits.
  • the heater circuit For low-frequency operation where the heater circuit is primarily resistive, this arrangement is satisfactory.
  • the distributed inductance and capacitance of the leads which connect a suitable heater voltage to the cathode cause the heater circuit to be reactive at all except its resonant frequency.
  • an undesirable phase shift is introduced into the feed-back circuit of the oscillator, impairing its operating efllciency and in severe cases blocking completely the generation of oscillations.
  • oscillation generators of the type under consideration have a limited operating frequency range unless some provision is made for compensating or avoidin the reactive effects of the heater circuit.
  • a short-circuited ef fectively resonant transmission line is frequently included in the heater circuit to avoid its aforementioned undesirable reactive effects.
  • the line usually is tuned to have an effective electrical length equal to a half wave length corresponding to the oscillator operating frequency and, therefore, is primarily resistive, exhibiting the properties of a series-resonant circuit.
  • the fre truancy-determining circuit of the generator comprises a second short-circuited effectively resonant transmission line, which is the usual case
  • the second line also generally has distributed circuit constants, but has an effective electrical length equal to a quarter wave length corresponding to the operating frequency of the oscillator.
  • It is another object of the invention to provide an improved tunable ultra-high-frequency apparatus comprising a plurality of tunable effectively resonant transmission lines of different effective electrical lengths and having a simplified unicontrol' mechanism for tuning the apparatus over a given range of operating frequencies.
  • a tunable ultra-hlgh-frequency apparatus comprises a first effectively resonant transmission line havin an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency.
  • This first line includes adjustable tuning means for varying its effective electrical length to tune the line over a given range of operating frequencies.
  • the apparatus also comprises a, second efiectively resonant transmission line uniformly loaded throughout at least a portion of its length and having an effective electrical length equal to an integral multiple of a; quarter wave length corresponding to a predetermined operating frequency.
  • the second line also includes adjustable tuning means in the uniformly loaded portion thereof for varying its effectivev electrical length to tune the second line over a given range of operating frequencies and unicontrol means are provided for effecting substantially identical physical adjustments of the tuning means of the first and second lines. Additionally, the loading of the second line is such that a predetermined constant relation is maintained between the operatin fre-- quencies of the first and second lines as these lines are tuned over their ranges of operating frequencies.
  • effectively resonant transmission 'line refers to a transmission line and its terminating impedance which together exhibit certain desirable characteristics at or near its resonant, frequency, which frequency is determined by the distributed parameters of the line and its terminating impedance.
  • Fig. 1 is a perspective view, partially schematic, of a tunable ultra-high-frequency apparatus embodying the present invention in a preferred form
  • Fig. 2 is a schematic circuit diagram which is the electrical equivalent of the circuit of Fig. l
  • Fig. 3 is a fragmentary perspective view of a portion of the apparatus of Fig. 1 in modified form.
  • a tunable ultra-high-frequency apparatus specifically an oscillation generator of the directly heated cathode type, operable over a given range of operating frequencies and embodying the present invention.
  • the apparatus comprises a vacuum-tube oscillator l0, represented schematically, having an anode, a control electrode, and a directly heated cathode, and a frequency-determining circuit provided by a first effectively resonant transmission line H directly connected to the anode and control electrode of the vacuum tube so as to beterminated by their interelectrode capacitance Cg-p.
  • Transmission line H has an effective electrical length equal to an odd integral multiple of a quarter wave length corresponding to a predetermined operating frequency, the integer for the illustrated embodiment preferably being equal to one.
  • the effective electrical length of the line ll equals a quarter wave length corresponding to the operating frequency of the oscillation generator.
  • This transmission line includes a pair of horizontally disposed parallel conductors l2 and I3 of uniformly distributed inductance and capacitance and an adjustable tuning means, comprising a short-circuiting member, for varying their effective electrical length to tune the line over a given range of operating frequencies determined by the desired operating frequency range ofthe apparatus.
  • Conductors I2 and I3 are supported in but insulated from extensions of the end walls of a metal container 30, the line insulators being omitted in order to simplify the drawing.
  • the short-circuiting member for varying their efiective electrical length consists of conductive elements [4 and I5 secured to the horizontal portion of a supporting yoke 16 of suitable insulating material, such as a thermoplastic resin. Elements l4 and [5 are individually apertured to receive and be freely movable along conductors I2 and I3.
  • a mica strip I1 is positioned intermediate the adjacent ends of elements i4 and I5 effectively to constitute the described short-circuiting member a condenser which completes the circuit of line I I for alternating currents.
  • a condenser I8 is bridged across those terminals of conductors l2 and I3 which are remote to tube Ill for the purpose of detuning that portion of line H located between suchremote terminals and short-circuiting member l4l5ll.
  • the cathode of vacuum tube In is heated by means of a suitable battery, indicated A, through a heater circuit that includes a second effectively resonant transmission line 20 uniformly loaded throughout at least a portion of its length and havingan effective electrical length equal to an even integral multiple of a quarter wave length corresponding to a predetermined operating frequency.
  • transmission line 20 is loaded throughout a major portion of its length by dielectric means, in a, manner described more particularly hereinafter, and has an effective electrical length equal to a half wave length corresponding to the operating frequency of the oscillator.
  • This transmission line similarly comprises a.- pair of parallel conductors 2
  • These elements have the same construction as corresponding elements of transmission line H.
  • line 20 is supported in, but insulated from, the end' walls of container 30 through insulating bushings (not shown).
  • Short-circuiting member 23-44-45 is grounded to the metal container 30 through a resilient U-shaped brush 29 which is adapted to engage a side wall of the container and be freely slidable therealong.
  • the. terminating impedance of line 20 provided by the impedance of the cathode of tube In is materially different from the terminating impedance of line H.
  • short-circuiting member 2324-25 of line 20 is adjustably secured to supporting yoke (6 through an insulated U-shaped member 26 having elongated slots 21.
  • Uniform loading of line 20 throughout a major portion of its length is accomplished by immersing that portion thereof in a homogeneous dielectric material. To this end, that portion of line 2
  • a liquid dielectric such as oil
  • the oil utilized is chosen to have such a dielectric constant that equal incremental displacements of shorting bar l4l 5I 1 and 23-2425 along lines II and 20, respectively, cause 'such variations in the operating frequencies of the lines that a predetermined constant relation is maintained between the operating frequencies of the lines as they are tuned over their individual operating frequency ranges.
  • the dielectric is chosen of such value that identical changes are effected in the operating frequencies of lines H and 20 for equal physical adjustments of their individual short-circuiting members.
  • the apparatus further comprises unicontrol means for effecting substantially identical physical adjustments of the tuning mean of lines II and 20.
  • unicontrol means consists of a threaded rod 33 engaging a threaded aperture in yoke I6 and suitably supported in bearings 34' and 35 provided in end walls of container 30.
  • the rod 33 is terminated in a knurled knob 36 which facilitates precise adjustment of yoke l6 and exact tuning of the apparatus.
  • a grid-leak 0 resistor 32 is coupled to the control electrode of vacuum tube l0 through conductor l2 and a .source of space current indicated +B is coupled to the anode thereof through conductor [3.
  • transmission line 20 has an effective electrical length equal to a half wave length corresponding to the instant operating frequency of the oscillation generator. It is well known in transmission network theory that a short-circuited effectively resonant transmission line having such an effective electrical length exhibits impedance characteristics analogous to those of a series-resonant circuit, that is, it has zero series impedance at the resonant frequency.
  • the oscillation generator is of the type represented schematically in Fig. 2, wherein the distributed inductance of conductors l2 and I 3 of transmission line H is represented by the lumped inunicontrol means 33 toeffect such movement of short-circuiting member l4-
  • line 20 is tuned to substantially the same frequency as line I I and, therefore, to the operating frequency of the oscillation generator as the generator is tuned throughout its range of operating frequencies.
  • the circuit diagram of Fig. 2 represents the equivalent circuit of the generator for any tuning condition.
  • the cathode of tube III is effectively maintained at ground potential for all operating conditions, thereby to ensure maximum oscillator efficiency.
  • 'modification includes a pair of effectively resonant transmission lines similar to those of Fig. 1, corresponding components thereof having identical reference numerals primed. For the purpose of simplicity, only a portion of the lines is represented, but it will be understood that their construction and arrangement may be the same as those of Fig. 1.
  • Loading of line 20 is achieved through reactance means comprising a plurality of substantially identical capacitors 40 uniformly spaced along the line. Loading capacitors 40 are selected of such value as to maintain a predetermined constant relation between the operating frequencies of lines H and 20' as the lines are tuned over their ranges of operating frequencies in a manner particularly described with reference to the loading of line 20 in the Fig. 1 arrangement.
  • the tuning arrangement of Fig. 3 may be substituted for that of Fig. 1 in which case condensers 40 are selected to maintain lines II and 20' at the same operating frequencies as the oscillation generator is tuned over its operating frequency range.
  • l and 23- 24-25 are displaced with reference to one another to compensate for the dissimilar terminating impedances of lines II and 20.
  • a compensating impedance may be shunted across the open end of line 20 to cause the line terminations to be substantially identical.
  • the shorting bars l4-l5-Il and 2324-25 may be in. vertical alignment, simplifying the construction of supporting members It and 26.
  • the transmission lines II and 20 may take the form of coaxial lines.
  • uniform loading of one of the lines may be accomplished by filling a portion thereof with a 'liquid dielectric material, such as oil.
  • the invention may be utilized to maintain a predetermined constant frequency difference between the operating frequencies of. two effectively resonant transmission lines.
  • a short-circuited effectively resonant transmission line having an effective electrical length equal to a quarter wave length corresponding to a predetermined operating frequency exhibits the same impedance characteristics as an open-circuited efiectively resonant transmission line having an effective electrical length equal to a half wave length corresponding to such operating frequency.
  • a short-circuited effectively resonant transmission line having an effective electrical length equal to a half wave length of a predetermined operating frequency presents the same impedance characteristics as an open-circuited effectively resonant transmission line having an effective electrical, length equal to a quarter wave length of such operating frequency.
  • Such equivalent lines may be utilized in a tunable ultrahigh-frequency apparatus in accordance with the invention so long as one line is appropriately loaded in the manner hereinbefore described.
  • a tunable ultra-high-frequency apparatus comprising, a first effectively resonant transmis sion line having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said first line including adjustable tuning means for varying its effective electrical length to tune said line over a given range of operating frequencies, a second effectively resonant transmission line uniformly loaded throughout at least a portion of its length and having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said second line including adjustable tuning means in said uniformly loaded portion thereof for varying its effective electrical length to tune said second line over a given range of operating frequencies, and unicontrol means for effecting substantially identical physical adjustments of said tuning means of said first and second lines, said loading of said second line being such that a predetermined constant relation is maintained between the operating frequencies of said first and Second'lines 'as said lines are tuned over said ranges of operating frequencies.
  • a tunable ultra-high-frequency apparatus comprising, a first short-circuited effectively resonant transmission line having an effective electrical length equal to anintegral multiple of a quarter wave length corresponding to a predetermined operating frequency, said first line including adjustable tuning means for varying its effective electrical length to tune said line over a given range of operating frequencies, a second effectively resonant transmission line uniformly loaded throughout at least a portion of its length and having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said second line including adjustable tuning means in said uniformly loaded portion thereof for varying its effective electrical length to tune said second line over a given range of operating frequencies, and unicontrol means for effecting substantially identical physical adjustments of said tuning means of said first and second lines, said loading of said second line being such that a predetermined constant relation is maintained between the operating frequencies of said first and second lines as said lines are tuned over said ranges of operating frequencies.
  • a tunable ultra-high-frequency apparatus comprising, a first effectively resonant transmission line having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said first line including adjustable tuning means for varying its effective electrical length to tune said line over a given range of operating frequencies, a second short-circuited effectively resonant transmission line uniformly loaded throughout at least a portion of its length and having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said second line including adjustable tuning means in said uniformly loaded portion thereof for varying its effective electrical length to tune said second line over a given range of operating frequencies, and unicontrol means for effecting substantially identical physical adjustmerits of said tuning means of said first and second lines, said loading of said second line being such that a predetermined constant relation ismaintained between the operating frequencies of said first and second lines as said lines are tuned over said ranges of operating frequencies.
  • a tunable ultra-high-frequency apparatus comprising, a first effectively resonant transmission line including a pair of parallel'conductors and having an effective electrical length equalto an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said first line including short-circuiting means movable along said conductors for varying the effective electrical length of said line to tune said line over a given range of operating frequencies, a second effectively resonant transmission line including a pair of parallel conductors uniformly loaded throughout at leasta portion of their length and having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said second line including short-circuiting means movable along said loaded portion of said conductors for varying theefiecsion line having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operatingfrequency, said first line including adjustable tuning means for varying its effective electrical length to tune said line over a given range of operating frequencies, a second effectively resonant transmission line uniformly
  • a tunable ultra-high-frequency apparatus comprising, a first effectively resonant transmission line having an effective electrical length equal to a quarter wave length corresponding to a predetermined operating frequency, said first line including adjustable tuning mean-s for varying its effective electrical length to tune said line over a given range of operating frequencies, a second effectively resonant transmission line uniformly loaded throughout at least a portion of its length and having an effective electrical length equal to a half Wave length corresponding to a predetermined operating frequency said second line including adjustable tuning means in said uniformly loaded portion thereof for varying its effective electrical length to tune said second line over a given range of operating frequencies, and
  • unicontrol means for effecting substantially identical physical adjustments of said tuning means of said first and second lines, said loading of said second line being such that a predetermined constant relation is maintained between the operating frequencies of said first and second lines as said lines are tuned over said ranges of operating frequencies.
  • a tunable ultra-high-frequency apparatus comprising, a first effectively resonant, transmission line having an effective electrical length equal to an odd integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said first line including adjustable tuning means for varying its effective electrical length to tune said line over a given range of operating frequencies, a second effectively resonant transmission line uniformly loaded throughout at least a portion of its length and having an effective electrical length equal to an even integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said second line including adjustable tuning means in said uniformly loaded portion thereof for varying its effective electrical length to tune said second line over a given range of operating frequencies, and unicontrol means for effecting substantially identical physical adjustments of said tuning means of said first and second lines, said loading of said second line bein such that a predetermined constant relation is maintained between the operating frequencies of said first and second lines as said lines are tuned over said ranges of operating frequencies.
  • a tunable ultra-high-frequency apparatus comprising, a first effectively resonant transmission line having an effective electrical length.
  • said first line including adjustable tuning means for varying its effective electrical length to tune said line over a given range of operating frequencies, a second effectively resonant transmission line, dielectric means for uniformly loading said second line throughout at least a portion of its length to cause said line to have an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency
  • said second line including adjustable tuning means in said uniformly loaded portion thereof for varying its effective electrical length to tune said second line over a given range of operating frequencies, and unicontrol means for effecting substantially, identical physical adjustments of said tuning means of said first and second lines, said loading of said second line being such that a predetermined constant relation is maintained between the operating frequencies of said first and second lines as said lines are tuned over said ranges of operating frequencies.
  • a tunable ultra-high-frequency apparatus comprising, a first effectively resonant transmission line having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said first line including adjustable tuning means for varying its effective electrical length to tune said line over a given range of operating frequencies, a second effectively resonant transmission line comprising a pair of spaced parallel conductors, a homogeneous dielectric material in the space between said conductors throughout at least a portion of their length for uniformly loading said second line to cause said second line to have an effective electrical length equal to an integral multiple ,of a
  • adjustable tuning means in said uniformly loaded portion thereof for varying its effective electrical length to tune said second line over a given range of operating frequencies, and unicontrol means for effecting substantially identical physical adjustments of said tuning means of said first and second lines, said loading of said second line being such that a predetermined constant relation is maintained between the operating frequencies of said first and second lines as said lines are tuned over said ranges of operating frequencies.
  • a tunable ultra-high-frequency apparatus comprising, a first effectively resonant transmission line having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said first line including adjustable tuning means for varying it effective electrical length to tune said line over a given range of operating frequencies, a second effectively resonant transmission line including reactance means for uniformly loading said line throughout at least a portion of its length and having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said second line including adjustable tuning means in said uniform- 1y loaded portion thereof for varying its effective electrical length to tune said second line over a given range of operating frequencies, and unicontrol means for effecting substantially identical physical adjustments of said tuning means of said first and second lines, said loading of said second line being such that a predetermined constant relation is maintained between the operating frequencies of said first and second lines as said lines are tuned over said ranges of operating frequencies.
  • a tunable ultra-higlr-frequency apparatus comprising, a first effectively resonant transmission line having an effective electrical length equal to an integral multiple of a quarter wave: length corresponding to a predetermined operating frequency, said first line including adjustable tuning means for varying its effective electrical length to tune said line over a given range of operating frequencies, a second effectively resonant transmission line including a plurality of substantially identical and uniformly spaced capacitors for uniformly loading said second line throughout at least a portion of its length and.
  • said second line having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency
  • said second line including adjustable tuning means in said uniformly loaded portion thereof for varying its effective electrical length to tune said second line over a given range of operating frequencies, and unicontrol means for effecting substantially identical physical adjustments of said tuning means of said first and second lines, said loading of said second line being such that a predetermined constant relation is maintained between the operating frequencies of said first and second lines as said lines are tuned over said ranges of operating frequencies.
  • a tunable ultra-"lugh-frequency apparatus comprising, a vacuum tube having an anode, a control electrode and a directly heated cathode, a first effectively resonant transmission line coupled to said anode and control electrode and having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency,
  • said first line including adjustable tuning means for varying its effective electrical length to tune saidline over a given range of operating frequencies, a heater circuit coupled to said cathode including a second effectively resonant transmission'line uniformly loaded throughout at least a portion of its length and having-an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predeterand second lines, said loading of said second line being such that a. predetermined constant rela-- tion is maintained between the operating frequencies of said first and second lines as said lines are tuned over said ranges of operating frequencies.
  • a tunable ultra-high-frequency apparatus comprising, an oscillation generator including a vacuum tube having ananode, a control electrode and a directly heated cathode, a first effectively resonant transmission line coupled to the anode' control electrode for determining the frequency of the generated oscillations and having an efiective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said first line including adjustable tuning'means for varyin its effective electrical length to tune said line over a given range of operating frequencies, a heater circuit coupled to said cathode including a second effectively resonant transmission line uniformly loaded throughout at least a portion of its length and having an effective electrical length equal to a different integral multiple of a quarter wave length corresponding to said predetermined operating frequency, said second line including adjustable tuning means in said uniformly loaded portion thereof for varying its effective electrical length to tune said second line over saidrange of operating frequencies, and unicontrol means for effecting substantially identical physical adlustments of said'tuning means of said first and

Description

Feb. 4, 1947..
L. B. MALLING 'rmiiinm uLm-nmmmqmcr Arrm'ws Filed Se t. 25. 1943 FIG.2
INVENTOR LEONARD R. MALLING A; izR
" Patented Feb. 1947 TUNABLE ULTRA HIGH FREQUENCY APPARATUS Leonard R. Malling, Douglaston, N. Y., assignor, by mesne assignments, to Hazeltine Research, 7 Inc., Chicago, Ill., a corporation of Illinois Application September 25, 1943, Serial No. 503,766
This invention relates to a tunable ultra-highfrequency apparatus including a plurality of effectively resonant transmission lines tunable over given ranges of operating frequencies in manner which maintains a predetermined constant relation between their individual operating frequencies. Although the invention is subject to a wide range of applications, it is especially suited for use in an ultra-high-frequency oscillation generator of the directly heated cathode type and will be described in such connection.
In oscillation generators of the directly heated cathode type, the heater circuit forms part of both the anode-cathode and grid-cathode circuits. For low-frequency operation where the heater circuit is primarily resistive, this arrangement is satisfactory. However, in the ultra-high-frequency range the distributed inductance and capacitance of the leads which connect a suitable heater voltage to the cathode cause the heater circuit to be reactive at all except its resonant frequency. For any operating condition in which the heater circuit is primarily reactive, an undesirable phase shift is introduced into the feed-back circuit of the oscillator, impairing its operating efllciency and in severe cases blocking completely the generation of oscillations. For this reason oscillation generators of the type under consideration have a limited operating frequency range unless some provision is made for compensating or avoidin the reactive effects of the heater circuit.
In prior art arrangements a short-circuited ef fectively resonant transmission line is frequently included in the heater circuit to avoid its aforementioned undesirable reactive effects. The line usually is tuned to have an effective electrical length equal to a half wave length corresponding to the oscillator operating frequency and, therefore, is primarily resistive, exhibiting the properties of a series-resonant circuit. Where the fre truancy-determining circuit of the generator comprises a second short-circuited effectively resonant transmission line, which is the usual case, the second line also generally has distributed circuit constants, but has an effective electrical length equal to a quarter wave length corresponding to the operating frequency of the oscillator. Since the lines have different effective electrical lengths, the movements of their respective short-circuiting elements to effect identical changes in the operating frequencies of the lines are dissimilar. This is an undesirable limitation of such prior art arrangements in that it precludes the use of a simple unicontrol mechanism for tuning the oscillator over its range of operating frequencies.
13 Claims. (Cl. 250-36) It is an object of the invention, therefore, to provide an improved tunable ultra-high-frequency apparatus including a plurality of eifectively resonant transmission lines and which avoids the aforementioned limitations of prior art arrangements.
It is another object of the invention to provide an improved tunable ultra-high-frequency apparatus comprising a plurality of tunable effectively resonant transmission lines of different effective electrical lengths and having a simplified unicontrol' mechanism for tuning the apparatus over a given range of operating frequencies.
In accordance with the invention, a tunable ultra-hlgh-frequency apparatus comprisesa first effectively resonant transmission line havin an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency. This first line includes adjustable tuning means for varying its effective electrical length to tune the line over a given range of operating frequencies. The apparatus also comprises a, second efiectively resonant transmission line uniformly loaded throughout at least a portion of its length and having an effective electrical length equal to an integral multiple of a; quarter wave length corresponding to a predetermined operating frequency. The second line also includes adjustable tuning means in the uniformly loaded portion thereof for varying its effectivev electrical length to tune the second line over a given range of operating frequencies and unicontrol means are provided for effecting substantially identical physical adjustments of the tuning means of the first and second lines. Additionally, the loading of the second line is such that a predetermined constant relation is maintained between the operatin fre-- quencies of the first and second lines as these lines are tuned over their ranges of operating frequencies.
As employed throughout this specification and in the appended claims, the term effectively resonant transmission 'line refers to a transmission line and its terminating impedance which together exhibit certain desirable characteristics at or near its resonant, frequency, which frequency is determined by the distributed parameters of the line and its terminating impedance.
For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.
In the drawing, Fig. 1 is a perspective view, partially schematic, of a tunable ultra-high-frequency apparatus embodying the present invention in a preferred form; Fig. 2 is a schematic circuit diagram which is the electrical equivalent of the circuit of Fig. l; and Fig. 3 is a fragmentary perspective view of a portion of the apparatus of Fig. 1 in modified form.
Referring now more particularly to Fig. 1, there is represented a tunable ultra-high-frequency apparatus, specifically an oscillation generator of the directly heated cathode type, operable over a given range of operating frequencies and embodying the present invention. The apparatus comprises a vacuum-tube oscillator l0, represented schematically, having an anode, a control electrode, and a directly heated cathode, and a frequency-determining circuit provided by a first effectively resonant transmission line H directly connected to the anode and control electrode of the vacuum tube so as to beterminated by their interelectrode capacitance Cg-p. Transmission line H has an effective electrical length equal to an odd integral multiple of a quarter wave length corresponding to a predetermined operating frequency, the integer for the illustrated embodiment preferably being equal to one. Thus, the effective electrical length of the line ll equals a quarter wave length corresponding to the operating frequency of the oscillation generator. This transmission line includes a pair of horizontally disposed parallel conductors l2 and I3 of uniformly distributed inductance and capacitance and an adjustable tuning means, comprising a short-circuiting member, for varying their effective electrical length to tune the line over a given range of operating frequencies determined by the desired operating frequency range ofthe apparatus. Conductors I2 and I3 are supported in but insulated from extensions of the end walls of a metal container 30, the line insulators being omitted in order to simplify the drawing. The short-circuiting member for varying their efiective electrical length consists of conductive elements [4 and I5 secured to the horizontal portion of a supporting yoke 16 of suitable insulating material, such as a thermoplastic resin. Elements l4 and [5 are individually apertured to receive and be freely movable along conductors I2 and I3. A mica strip I1 is positioned intermediate the adjacent ends of elements i4 and I5 effectively to constitute the described short-circuiting member a condenser which completes the circuit of line I I for alternating currents. A condenser I8 is bridged across those terminals of conductors l2 and I3 which are remote to tube Ill for the purpose of detuning that portion of line H located between suchremote terminals and short-circuiting member l4l5ll.
The cathode of vacuum tube In is heated by means of a suitable battery, indicated A, through a heater circuit that includes a second effectively resonant transmission line 20 uniformly loaded throughout at least a portion of its length and havingan effective electrical length equal to an even integral multiple of a quarter wave length corresponding to a predetermined operating frequency. For the embodiment under considera-' tion, transmission line 20 is loaded throughout a major portion of its length by dielectric means, in a, manner described more particularly hereinafter, and has an effective electrical length equal to a half wave length corresponding to the operating frequency of the oscillator. This transmission line similarly comprises a.- pair of parallel conductors 2| and '22, a short-circuiting member including conductive elements 23 and 24, an interposed strip of mica 25, and a detuning condenser 28 connected across the ends of conductors 2| and 22 which are remote to tube l0. These elements have the same construction as corresponding elements of transmission line H. Also, line 20 is supported in, but insulated from, the end' walls of container 30 through insulating bushings (not shown). Short-circuiting member 23-44-45 is grounded to the metal container 30 through a resilient U-shaped brush 29 which is adapted to engage a side wall of the container and be freely slidable therealong.
In general, the. terminating impedance of line 20 provided by the impedance of the cathode of tube In is materially different from the terminating impedance of line H. As a consequence, it is necessary to displace the short-circuiting members of the lines, as indicated by the dimension line d in the drawing, to have the lines tuned to the same operating frequency. For this purpose short-circuiting member 2324-25 of line 20 is adjustably secured to supporting yoke (6 through an insulated U-shaped member 26 having elongated slots 21.
Uniform loading of line 20 throughout a major portion of its length is accomplished by immersing that portion thereof in a homogeneous dielectric material. To this end, that portion of line 2|] is supported within the container 30, the container being filled with a liquid dielectric, such as oil, to such a depth, indicated by broken line 3| in the drawing, that the portion of line 20 contained therein is completely immersed.
The oil utilized is chosen to have such a dielectric constant that equal incremental displacements of shorting bar l4l 5I 1 and 23-2425 along lines II and 20, respectively, cause 'such variations in the operating frequencies of the lines that a predetermined constant relation is maintained between the operating frequencies of the lines as they are tuned over their individual operating frequency ranges. For the described embodiment of the invention, the dielectric is chosen of such value that identical changes are effected in the operating frequencies of lines H and 20 for equal physical adjustments of their individual short-circuiting members.
The apparatus further comprises unicontrol means for effecting substantially identical physical adjustments of the tuning mean of lines II and 20. Such unicontrol means consists of a threaded rod 33 engaging a threaded aperture in yoke I6 and suitably supported in bearings 34' and 35 provided in end walls of container 30. The rod 33 is terminated in a knurled knob 36 which facilitates precise adjustment of yoke l6 and exact tuning of the apparatus. A grid-leak 0 resistor 32 is coupled to the control electrode of vacuum tube l0 through conductor l2 and a .source of space current indicated +B is coupled to the anode thereof through conductor [3.
In considering the operation of the described arrangement, it will be seen that, for a given operating condition, transmission line 20 has an effective electrical length equal to a half wave length corresponding to the instant operating frequency of the oscillation generator. It is well known in transmission network theory that a short-circuited effectively resonant transmission line having such an effective electrical length exhibits impedance characteristics analogous to those of a series-resonant circuit, that is, it has zero series impedance at the resonant frequency.
I Therefore, subject to the usual assumptions that the resistance of the cathode element and transmission line 20 is negligible, the cathode is effectively at ground potential. Accordingly, the oscillation generator is of the type represented schematically in Fig. 2, wherein the distributed inductance of conductors l2 and I 3 of transmission line H is represented by the lumped inunicontrol means 33 toeffect such movement of short-circuiting member l4-|5-l1 produces corresponding and equal displacements of shortcircuiting member 23-24-25. Thus, it will be seen that, by virtue of its selected uniform loading which is difierent from that of line H, line 20 is tuned to substantially the same frequency as line I I and, therefore, to the operating frequency of the oscillation generator as the generator is tuned throughout its range of operating frequencies. In other words, the circuit diagram of Fig. 2 represents the equivalent circuit of the generator for any tuning condition. Hence, the cathode of tube III is effectively maintained at ground potential for all operating conditions, thereby to ensure maximum oscillator efficiency.
While applicant does not intend to limit the invention to any specific circuit constants, the following are given for the purposes of illustration:
Tube Ill Type 368-A Conductors l2, I3, 2!, and
22 rod 6" long separated /4 Condenser C17 and condenser C24 100 micro-microfarads each Condenser C18 and condenser C23 250 micro-microfarads each Distance (2 1 centimeter Loading material and its dielectric constant Castor oil-4.6 Frequency range 500-1500 megacycles Reference is now made to Fig. 3 which illustrates a modified form of the invention. The
'modification includes a pair of effectively resonant transmission lines similar to those of Fig. 1, corresponding components thereof having identical reference numerals primed. For the purpose of simplicity, only a portion of the lines is represented, but it will be understood that their construction and arrangement may be the same as those of Fig. 1. Loading of line 20 is achieved through reactance means comprising a plurality of substantially identical capacitors 40 uniformly spaced along the line. Loading capacitors 40 are selected of such value as to maintain a predetermined constant relation between the operating frequencies of lines H and 20' as the lines are tuned over their ranges of operating frequencies in a manner particularly described with reference to the loading of line 20 in the Fig. 1 arrangement. The tuning arrangement of Fig. 3 may be substituted for that of Fig. 1 in which case condensers 40 are selected to maintain lines II and 20' at the same operating frequencies as the oscillation generator is tuned over its operating frequency range.
In the preferred embodiment of the invention, short-circuiting members M--l5-|l and 23- 24-25 are displaced with reference to one another to compensate for the dissimilar terminating impedances of lines II and 20. However, it will be understood that a compensating impedance may be shunted across the open end of line 20 to cause the line terminations to be substantially identical. In that case, the shorting bars l4-l5-Il and 2324-25 may be in. vertical alignment, simplifying the construction of supporting members It and 26.
It will be understood that the transmission lines II and 20 may take the form of coaxial lines. In this case, uniform loading of one of the lines may be accomplished by filling a portion thereof with a 'liquid dielectric material, such as oil.
While in the described embodiment of the invention, it is desirable so to load one of the transmission lines that the first and second lines have the same operating frequencies, it will be understood that this frequency relationship is an illustrative but not exclusive one. In some applications, for example in the case of an. oscillator-modulator operable over a predetermined range of frequencies in the ultra-high-frequency spectrum, the invention may be utilized to maintain a predetermined constant frequency difference between the operating frequencies of. two effectively resonant transmission lines.
Also, it is well known that a short-circuited effectively resonant transmission line having an effective electrical length equal to a quarter wave length corresponding to a predetermined operating frequency exhibits the same impedance characteristics as an open-circuited efiectively resonant transmission line having an effective electrical length equal to a half wave length corresponding to such operating frequency. Likewise, a short-circuited effectively resonant transmission line having an effective electrical length equal to a half wave length of a predetermined operating frequency presents the same impedance characteristics as an open-circuited effectively resonant transmission line having an effective electrical, length equal to a quarter wave length of such operating frequency. Such equivalent lines may be utilized in a tunable ultrahigh-frequency apparatus in accordance with the invention so long as one line is appropriately loaded in the manner hereinbefore described.
While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fallwithin the true spirit and scope of the invention.
What is claimed is:
1. A tunable ultra-high-frequency apparatus comprising, a first effectively resonant transmis sion line having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said first line including adjustable tuning means for varying its effective electrical length to tune said line over a given range of operating frequencies, a second effectively resonant transmission line uniformly loaded throughout at least a portion of its length and having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said second line including adjustable tuning means in said uniformly loaded portion thereof for varying its effective electrical length to tune said second line over a given range of operating frequencies, and unicontrol means for effecting substantially identical physical adjustments of said tuning means of said first and second lines, said loading of said second line being such that a predetermined constant relation is maintained between the operating frequencies of said first and Second'lines 'as said lines are tuned over said ranges of operating frequencies.
2. A tunable ultra-high-frequency apparatus comprising, a first short-circuited effectively resonant transmission line having an effective electrical length equal to anintegral multiple of a quarter wave length corresponding to a predetermined operating frequency, said first line including adjustable tuning means for varying its effective electrical length to tune said line over a given range of operating frequencies, a second effectively resonant transmission line uniformly loaded throughout at least a portion of its length and having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said second line including adjustable tuning means in said uniformly loaded portion thereof for varying its effective electrical length to tune said second line over a given range of operating frequencies, and unicontrol means for effecting substantially identical physical adjustments of said tuning means of said first and second lines, said loading of said second line being such that a predetermined constant relation is maintained between the operating frequencies of said first and second lines as said lines are tuned over said ranges of operating frequencies.
3. A tunable ultra-high-frequency apparatus comprising, a first effectively resonant transmission line having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said first line including adjustable tuning means for varying its effective electrical length to tune said line over a given range of operating frequencies, a second short-circuited effectively resonant transmission line uniformly loaded throughout at least a portion of its length and having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said second line including adjustable tuning means in said uniformly loaded portion thereof for varying its effective electrical length to tune said second line over a given range of operating frequencies, and unicontrol means for effecting substantially identical physical adjustmerits of said tuning means of said first and second lines, said loading of said second line being such that a predetermined constant relation ismaintained between the operating frequencies of said first and second lines as said lines are tuned over said ranges of operating frequencies.
4. A tunable ultra-high-frequency apparatus comprising, a first effectively resonant transmission line including a pair of parallel'conductors and having an effective electrical length equalto an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said first line including short-circuiting means movable along said conductors for varying the effective electrical length of said line to tune said line over a given range of operating frequencies, a second effectively resonant transmission line including a pair of parallel conductors uniformly loaded throughout at leasta portion of their length and having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said second line including short-circuiting means movable along said loaded portion of said conductors for varying theefiecsion line having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operatingfrequency, said first line including adjustable tuning means for varying its effective electrical length to tune said line over a given range of operating frequencies, a second effectively resonant transmission line uniformly loaded throughout at least a portion of it length and having an effective electrical length equal to an integral multiple of a quarter wave length different from that of the first effectively resonant transmission line corresponding to said predetermined operating frequency, said second line including adjustable tuning means for varying its effectiveelectrical length to tune said second line over said range of operating frequencies, and unicontrol means for effecting substantially identical physical adjustments of said tuning means 'of said first and second lines, said loading'of said second linebeing such that the operating frequencies of said first and second lines are maintained substantially equal as said lines are tuned over said range of operating frequencies.
6. A tunable ultra-high-frequency apparatus comprising, a first effectively resonant transmission line having an effective electrical length equal to a quarter wave length corresponding to a predetermined operating frequency, said first line including adjustable tuning mean-s for varying its effective electrical length to tune said line over a given range of operating frequencies, a second effectively resonant transmission line uniformly loaded throughout at least a portion of its length and having an effective electrical length equal to a half Wave length corresponding to a predetermined operating frequency said second line including adjustable tuning means in said uniformly loaded portion thereof for varying its effective electrical length to tune said second line over a given range of operating frequencies, and
unicontrol means for effecting substantially identical physical adjustments of said tuning means of said first and second lines, said loading of said second line being such that a predetermined constant relation is maintained between the operating frequencies of said first and second lines as said lines are tuned over said ranges of operating frequencies. a
7. A tunable ultra-high-frequency apparatus comprising, a first effectively resonant, transmission line having an effective electrical length equal to an odd integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said first line including adjustable tuning means for varying its effective electrical length to tune said line over a given range of operating frequencies, a second effectively resonant transmission line uniformly loaded throughout at least a portion of its length and having an effective electrical length equal to an even integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said second line including adjustable tuning means in said uniformly loaded portion thereof for varying its effective electrical length to tune said second line over a given range of operating frequencies, and unicontrol means for effecting substantially identical physical adjustments of said tuning means of said first and second lines, said loading of said second line bein such that a predetermined constant relation is maintained between the operating frequencies of said first and second lines as said lines are tuned over said ranges of operating frequencies.
8. A tunable ultra-high-frequency apparatus comprising, a first effectively resonant transmission line having an effective electrical length.
equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said first line including adjustable tuning means for varying its effective electrical length to tune said line over a given range of operating frequencies, a second effectively resonant transmission line, dielectric means for uniformly loading said second line throughout at least a portion of its length to cause said line to have an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said second line including adjustable tuning means in said uniformly loaded portion thereof for varying its effective electrical length to tune said second line over a given range of operating frequencies, and unicontrol means for effecting substantially, identical physical adjustments of said tuning means of said first and second lines, said loading of said second line being such that a predetermined constant relation is maintained between the operating frequencies of said first and second lines as said lines are tuned over said ranges of operating frequencies.
9. A tunable ultra-high-frequency apparatus comprising, a first effectively resonant transmission line having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said first line including adjustable tuning means for varying its effective electrical length to tune said line over a given range of operating frequencies, a second effectively resonant transmission line comprising a pair of spaced parallel conductors, a homogeneous dielectric material in the space between said conductors throughout at least a portion of their length for uniformly loading said second line to cause said second line to have an effective electrical length equal to an integral multiple ,of a
'10 eluding adjustable tuning means in said uniformly loaded portion thereof for varying its effective electrical length to tune said second line over a given range of operating frequencies, and unicontrol means for effecting substantially identical physical adjustments of said tuning means of said first and second lines, said loading of said second line being such that a predetermined constant relation is maintained between the operating frequencies of said first and second lines as said lines are tuned over said ranges of operating frequencies.
10. A tunable ultra-high-frequency apparatus comprising, a first effectively resonant transmission line having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said first line including adjustable tuning means for varying it effective electrical length to tune said line over a given range of operating frequencies, a second effectively resonant transmission line including reactance means for uniformly loading said line throughout at least a portion of its length and having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said second line including adjustable tuning means in said uniform- 1y loaded portion thereof for varying its effective electrical length to tune said second line over a given range of operating frequencies, and unicontrol means for effecting substantially identical physical adjustments of said tuning means of said first and second lines, said loading of said second line being such that a predetermined constant relation is maintained between the operating frequencies of said first and second lines as said lines are tuned over said ranges of operating frequencies.
11. A tunable ultra-higlr-frequency apparatus comprising, a first effectively resonant transmission line having an effective electrical length equal to an integral multiple of a quarter wave: length corresponding to a predetermined operating frequency, said first line including adjustable tuning means for varying its effective electrical length to tune said line over a given range of operating frequencies, a second effectively resonant transmission line including a plurality of substantially identical and uniformly spaced capacitors for uniformly loading said second line throughout at least a portion of its length and. having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said second line including adjustable tuning means in said uniformly loaded portion thereof for varying its effective electrical length to tune said second line over a given range of operating frequencies, and unicontrol means for effecting substantially identical physical adjustments of said tuning means of said first and second lines, said loading of said second line being such that a predetermined constant relation is maintained between the operating frequencies of said first and second lines as said lines are tuned over said ranges of operating frequencies.
l2. A tunable ultra-"lugh-frequency apparatus comprising, a vacuum tube having an anode, a control electrode and a directly heated cathode, a first effectively resonant transmission line coupled to said anode and control electrode and having an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency,
a 11 said first line including adjustable tuning means for varying its effective electrical length to tune saidline over a given range of operating frequencies, a heater circuit coupled to said cathode including a second effectively resonant transmission'line uniformly loaded throughout at least a portion of its length and having-an effective electrical length equal to an integral multiple of a quarter wave length corresponding to a predeterand second lines, said loading of said second line being such that a. predetermined constant rela-- tion is maintained between the operating frequencies of said first and second lines as said lines are tuned over said ranges of operating frequencies.
13. A tunable ultra-high-frequency apparatus comprising, an oscillation generator including a vacuum tube having ananode, a control electrode and a directly heated cathode, a first effectively resonant transmission line coupled to the anode' control electrode for determining the frequency of the generated oscillations and having an efiective electrical length equal to an integral multiple of a quarter wave length corresponding to a predetermined operating frequency, said first line including adjustable tuning'means for varyin its effective electrical length to tune said line over a given range of operating frequencies, a heater circuit coupled to said cathode including a second effectively resonant transmission line uniformly loaded throughout at least a portion of its length and having an effective electrical length equal to a different integral multiple of a quarter wave length corresponding to said predetermined operating frequency, said second line including adjustable tuning means in said uniformly loaded portion thereof for varying its effective electrical length to tune said second line over saidrange of operating frequencies, and unicontrol means for effecting substantially identical physical adlustments of said'tuning means of said first and second lines, said loading of saidsecond line being such that the operating frequencies of said first and second lines are maintained 4 substantially equal as said lines are tuned over said ranges of operating frequencies. v
' LEONARD R. MAILING.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED swims-PATENTS Number Name- Date t 2,233,763 Ayer Mar. 4, 1941 2,192,494 Goddard Mar. 5, 1940
US503766A 1943-09-25 1943-09-25 Tunable ultra high frequency apparatus Expired - Lifetime US2415141A (en)

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BE469787D BE469787A (en) 1943-09-25
US503766A US2415141A (en) 1943-09-25 1943-09-25 Tunable ultra high frequency apparatus
GB15100/44A GB586167A (en) 1943-09-25 1944-08-08 Tunable ultra-high-frequency apparatus
CH257595D CH257595A (en) 1943-09-25 1946-11-12 Tunable ultra-high frequency apparatus.

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2521700A (en) * 1946-03-09 1950-09-12 Standard Telephones Cables Ltd Oscillator control system
US2627579A (en) * 1949-03-08 1953-02-03 Standard Coil Prod Co Inc Tunable amplifier and converter unit for radio apparatus
US2724055A (en) * 1945-09-17 1955-11-15 Bliss William Roderic Coupling system for high frequencies
US2735015A (en) * 1956-02-14 Separator
US2762924A (en) * 1952-04-29 1956-09-11 Du Mont Allen B Lab Inc Tuning system
US2774045A (en) * 1951-10-17 1956-12-11 Gen Electric Ultra-high-frequency tuner

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2192494A (en) * 1936-01-11 1940-03-05 Rca Corp Transmission line transposition
US2233763A (en) * 1939-05-27 1941-03-04 Rca Corp Tuning structure

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2192494A (en) * 1936-01-11 1940-03-05 Rca Corp Transmission line transposition
US2233763A (en) * 1939-05-27 1941-03-04 Rca Corp Tuning structure

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2735015A (en) * 1956-02-14 Separator
US2724055A (en) * 1945-09-17 1955-11-15 Bliss William Roderic Coupling system for high frequencies
US2521700A (en) * 1946-03-09 1950-09-12 Standard Telephones Cables Ltd Oscillator control system
US2627579A (en) * 1949-03-08 1953-02-03 Standard Coil Prod Co Inc Tunable amplifier and converter unit for radio apparatus
US2774045A (en) * 1951-10-17 1956-12-11 Gen Electric Ultra-high-frequency tuner
US2762924A (en) * 1952-04-29 1956-09-11 Du Mont Allen B Lab Inc Tuning system

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BE469787A (en)
CH257595A (en) 1948-10-15

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