US3431485A - Microwave harmonic generator including a waveguide having oppositely extending channels defining a resonant region therein - Google Patents

Microwave harmonic generator including a waveguide having oppositely extending channels defining a resonant region therein Download PDF

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Publication number
US3431485A
US3431485A US622237A US3431485DA US3431485A US 3431485 A US3431485 A US 3431485A US 622237 A US622237 A US 622237A US 3431485D A US3431485D A US 3431485DA US 3431485 A US3431485 A US 3431485A
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waveguide
frequency
harmonic
channels
harmonic generator
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US622237A
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English (en)
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James N Lind
Jerry C Aukland
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Boeing North American Inc
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North American Rockwell Corp
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    • 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
    • H03B19/00—Generation of oscillations by non-regenerative frequency multiplication or division of a signal from a separate source
    • H03B19/16—Generation of oscillations by non-regenerative frequency multiplication or division of a signal from a separate source using uncontrolled rectifying devices, e.g. rectifying diodes or Schottky diodes
    • H03B19/18—Generation of oscillations by non-regenerative frequency multiplication or division of a signal from a separate source using uncontrolled rectifying devices, e.g. rectifying diodes or Schottky diodes and elements comprising distributed inductance and capacitance
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F7/00—Parametric amplifiers
    • H03F7/04—Parametric amplifiers using variable-capacitance element; using variable-permittivity element

Definitions

  • the device comprises a rectangular waveguide capable of supporting the input signal in the lowest order transverse mode and terminating in a second waveguide beyond cutoff.
  • a pair of channels extending oppositely from the top and bottom of the waveguide to a depth of one-quarter guide wavelength at (n1) define a waveguide pseudocavity region resonant at (n1)j
  • Interaction of the input signal with a varactor diode gives rise to energy within the psuedocavity region at harmonically related frequencies; this energy predominantly is at (nl))
  • Parametric interaction occurs between the confined energy (at (n1)f and the signal (at f to produce an output at n which may be extracted via the second waveguide.
  • a second pair of grooves oppositely extending from the top and bottom of the waveguide function as a trap to prevent energy at the output frequency from propagating back down the input waveguide.
  • This invention relates to a microwave harmonic generator and more particularly to a varactor type harmonic generator utilizing a rectangular waveguide having a pseudocavity region therein which is resonant at a harmonic of the input frequency and terminating in an output waveguide whose cutoff frequency lies above the resonant frequency of the pseudocavity region.
  • RF sources such as klystron oscillators
  • klystron oscillators are limited in their very high frequency capabilities and are relatively inefficient at frequencies above about 15 gHz. Above these frequencies, new devices such as Gunn effect oscillators are useful, but these have not yet been developed into operational units except at very low power levels.
  • a more desirable way to provide RF frequenceis above 15 gHZ. is to employ klystron or other oscillator at a frequency within its efficient operating range and to multiply the frequency of the oscillator output using a harmonic generator.
  • the microwave varactor tripler described by C. B. Swan in the Digest of Technical Papers, 1965 International Solid State Circuits Conference (ISSCC), pp. 106407 utilizes a coaxial matching transformer to introduce an input signal to a varactor diode.
  • the varactor diode is disposed within an output waveguide which is tuned to the third harmonic of the input frequency and which also contains a transverse stub resonant at the second harmonic.
  • a requirement of the nited States Patent 0 T 3,431,485 Patented Mar. 4, 1969 Swan device is that the varactor package be resonant at the second harmonic.
  • This harmonic generator employs a snap varactor in which the capacitance is approximately constant over the useful range of reverse bias.
  • the device uses a cavity resonant at the fundamental frequency.
  • a radial-line coupling gap couples the fundamental cavity to a second radial cavity resonant at the desired harmonic.
  • a snap diode is situated within the second cavity.
  • Coupling to an output coaxial line occurs via holes between the harmonic cavity and the coaxial output line.
  • Tenth harmonic output was reported for the Hines and DeKonig device to derive a 16 gHz. output signal using a 1.6 gHz. input. While a radial configuration is useful at these frequencies, it is very difficult to construct such a radial device at much higher frequencies.
  • the present invention provides a harmonic generator of simple mechanical design which is capable of operating with input signals above 50 gHz.
  • the inventive harmonic generator is of rectangular configuration, thereby simplifying its construction, and while utilizing a varactor diode, its proper operation does not depend on the resonant frequency of the diode package.
  • the inventive harmonic generator comprises a rectangular waveguide having a width sufficient to allow propagation of the input signal in the lowest order transverse mode.
  • nf output frequency
  • a pair of channels extending oppositely from the top and bottom of the input waveguide, and having a depth of one-quarter guide wavelength at frequency (n1)f define a pseudocavity region within the input waveguide, which region is resonant at the (n1) harmonic of the input frequency t
  • a varactor diode is disposed within this pseudocavity region.
  • the input signal when impressed across the back-biased varactor diode, gives rise to energy at harmonically related frequencies. This results because of the nonlinear relationship of current to voltage exhibited by such diodes. Because the diode is disposed within a resonant cavity, the interaction energy is concentrated at the resonant frequency (nl) and is constrained to within the pseudocavity region.
  • the output energy which may be extracted via the second waveguide, is prevented from escaping via the input waveguide by means of a trap comprising a second pair of channels oppositely extending from the top and bottom of the input waveguide to a depth of one-quarter guide wavelength at nf
  • the inventive harmonic generator is easy to construct and, in a typical application, may be used as a frequency tripler accepting an input at 60 gHz. and providing an output at gHz.
  • Another object of the invention is to provide a harmonic generator having an input waveguide which terminutes in a second waveguide beyond cutoff and which contains a pseudocavity region resonant at a harmonic of the input frequency.
  • a further object of this invention is to provide a microwave harmonic generator utilizing quarter wave channels to provide containment of various harmonic signals to within various regions of a waveguide.
  • FIG. 1 is an enlarged, perspective view of a preferred embodiment of the inventive microwave harmonic generator.
  • FIG. 2 is a cross sectional view of the harmonic generator as viewed generally along the line 22 of FIG. 1; a possible electric field distribution within the harmonic generator also is illustrated.
  • FIG. 3 is a cross sectional view of the inventive harmonic generator as viewed generally along the line 3-3 of FIG. 1.
  • FIG. 4 is a cross sectional view of the inventive harmonic generator as viewed generally along the lines 44 of FIG. 1.
  • FIG. 5 is another cross sectional view of the inventive harmonic generator as viewed generally along the line 5-5 of FIG. 1; a possible electric field distribution within this region of the harmonic generator also is illustrated.
  • FIG. 1 there is shown a greatly enlargedperspective view of a preferred embodiment of the inventive microwave harmonic generator 10.
  • harmonic generator is illustrated as being of thin walled construction. However, because of the very small dimensions required for operation at high microwave frequencies, the device more easily may be constructed from several solid blocks of metal which are appropriately milled and assembled to form a device having an interior appearance similar to that shown in FIG. 1. In a typical embodiment having an input frequency of about 60 gHz., the overall length of harmonic generator 10 illustrated in FIG. 1 will be less than 0.5 inch.
  • the inventive microwave harmonic generator accepts an input signal at a fundamental or first harmonic frequency f and provides an output signal at a frequency which is an integral multiple of the fundamental.
  • the harmonic generator will provide an output at a frequency nf where 11:3, 4, 5
  • nf where 11:3, 4, 5
  • FIG. 1 will be described in terms of its use as a frequency tripler, providing a third harmonic (11:3) output.
  • the input signal at fundamental frequency f is introduced into harmonic generator 10 via port 12 at one end of rectangular waveguide section 14.
  • the other end of rectangular Waveguide section 14 terminates in shorting plane or wall 16.
  • a second waveguide 40 having a width at and a height b also extends from wall 16 and terminates in port 42.
  • waveguide has a cutoff frequency which lies between the desired output frequency inf and the frequency (n1)f of the next lower harmonic.
  • the cutoff frequency of waveguide 40 preferably is about gHz., midway between the second harmonic frequency (2f :l20 gHz.) and the output frequency.
  • the interior width a (see FIG. 3) of waveguide 14 is selected to be one-half of the free space wavelength at the fundamental frequency f
  • Waveguide section 14 has a height b, measured between waveguide top 17 and bottom 18 (see FIG. 2), which preferably is less than width a. With these dimensions, it is possible for the input signal at frequency f to propagate in waveguide section 14 in the lowest order transverse (TE mode.
  • channels 22 and 22a extend oppositely from top 17 and bottom 18 of waveguide section 14.
  • channels 22 and 22a have a depth d (see FIG. 4) which is one-quarter of the guide wavelength at the frequency (nl)f where the desired output is at the r1 harmonic.
  • the function of channels 22 and 22a is somewhat similar to the U-shaped waveguide channels described in the copending application to J. N. Lind et al., Ser. No. 617,231, filed Feb.
  • channels 24 and 24a are provided to achieve desired propagating modes for the harmonic energy present within regions of harmonic generator 10.
  • Channels 24 and 24a which may extend beyond wall 16, further function to ensure suppression of spurious modes within the harmonic generator.
  • Channels 26 and 260 function as a trap to prevent output energy at the n harmonic from propagating down rectangular waveguide section 14 toward port 12.
  • the depth 1 (see FIG. 3) of channels 26 and 26a is equal to one-quarter of the guide wavelength at output frequency nf Parameters for selection of the distance g between channels 26 and 26a and diode 30 (see FIG. 2) are described hereinbelow.
  • a nonlinear reactance such as varactor diode 30 in a preferred embodiment is mounted within pseudocavity region 20 at a location to be described in detail hereinbelow.
  • Diode 30 may, for example, be of the type described in the copending application to D. B. Anderson et al., Ser. No. 361,069, entitled, High Frequency Diode," and assigned to North American Aviation, Inc., assignee of the present application. Alternately, other varactor diodes may be employed.
  • Diode 30 may be provided with a cone-shaped contact 32, and electrical connections 34 and 36, by means of which an appropriate backward bias voltage may be applied to varactor 30.
  • an input signal at fundamental frequency f is introduced into harmonic generator 10 via input port 12.
  • This input signal, harmonics of which are to be generated, will be present throughout waveguide section 14.
  • an impedance matehing network (not shown in the figures) of a type well known to those skilled in the art may be used to insure that a minimum amount of energy at ,f is reflected back out of port 12 by harmonic generator 10. If the input signal at frequency f is introduced in the lowest order transverse mode (e.g., the TE mode) then the signal will not be propagated beyond wall 16, since f is well below the cutoff frequency of output waveguide section 40.
  • harmonic generator 10 when the input signal is impressed across back-biased varactor diode 30, energy at various harmonics of f will be produced as a result of the nonlinear relation of current to voltage in diode 30. Thus energy will be present in rectangular waveguide section 14 at (among others) the (n1) harmonic (where output is desired at the n harmonic). Since in a preferred embodiment channels 22 and 22a each have a depth of one-quarter guide wavelength at frequency (rt-1H the electric field 50 induced in these channels at this frequency will be a maximum in the planes of the top 17 and bottom 18 of rectangular waveguide 14. Since this energy in effect is being generated at varactor diode 30, it will start to propagate back along waveguide section 14.
  • pseudocavity region 20 of harmonic generator 10 will exhibit a high Q at the frequency (nl)f
  • the harmonic energy generated by interaction with nonlinear reactance 30 will result in a preponderance of energy in the (rt-1) harmonic.
  • the energy will be concentrated in the second harmonic, and may have the standing wave pattern illustrated in FIGS. 2 and 5.
  • nf harmonic generator 10 functions in a manner resembling a parametric up-converter.
  • the signal, at fundamental frequency f, is introduced into waveguide section 14 via port 12 and the pump, at a frequency (n1)f is induced into pseudocavity region 20 as a result of the nonlinear current-voltage characteristics of diode 30, as described hereinabove.
  • varactor diode 30 is situated at the pump voltage maximum midway between channels 24 and 24a (see FIG. 5) and one-half guide wavelength (at (nl)f from wall 16 (see FIG. 2).
  • the energy generated at the n harmonic may be extracted from harmonic generator 10 via waveguide 40, which, as noted above, has a cutoff frequency below nf
  • an impedance matching network (of a type Well known to those skilled in the art), not shown in the figures, may be provided between output port 42 and the load which is to utilize the harmonic generator output signal. This impedance matching network will function to match the impedance of the load to that of harmonic generator 10 and to minimize the amount of energy (at nf reflected back into the generator.
  • Channels 26. and 26a serve as a filter or trap to prevent energy at the output frequency nf from propagating out of harmonic generator 10 via waveguide section 14.
  • channels 26 and 26a have a depth (see FIG. 3) of one-quarter guide wavelength at nf and are located at a distance g (see FIG. 2) which is an integral number of one-half guide wavelengths (at nf from varactor diode 30.
  • channels 26 and 26a preferably should extend from waveguide section 14 at a location between channels 22 and 22a and input port 12, as illustrated in FIGS. 1 and 2.
  • channels 26 and 26a may be placed one wavelength (i.e. two half wavelengths) at 3f from varactor diode 30; in this case, the electric field distribution at the output frequency may have the appearance illustrated by dashed arrows 56 in FIG. 2.
  • the third harmonic (output) energy will see a very high impedance in the area of channels 26 and 26a, caused by the voltage maxima present in channels 26 and 26a in the plane of waveguide top 17 and bottom 18. This will effectively prevent energy at the output frequency from propagating further down waveguide section 14 toward input port 12.
  • the tripler output energy at 3 f will extend into side channels 24 and 24a, and, in a preferred embodiment may be present in harmonic generator 10 in the TE mode.
  • the harmonic generator will produce an output at frequency nf which will propagate down waveguide 40 and be available at output port 42.
  • an additional channel or pair of channels may be added between channels 22 and 22a and the output harmonic trap (channels 26 and 26a) to form a second pseudocavity region, This will provide additional containment of the energy at (n1)f,, and may improve the conversion efficiency of harmonic generator 10.
  • one-quarter guide wavelength deep at the output frequency may be added (between channels 26 and 26a and input port 12) to provide additional attenuation of output energy propagating toward port 12.
  • a harmonic generator comprising:
  • a rectangular waveguide capable of supporting energy at a fundamental frequency and terminating in a shorting plane
  • a varactor diode disposed within said waveguide between said channels and said shorting plane.
  • a harmonic generator as defined in claim 1 further comprising a second pair of channels oppositely extending from the walls of said waveguide, said second pair of channels having a depth of one-quarter guide Wavelength at a second frequency, said second frequency being harmonically related to said fundamental frequency and higher than said first frequency, said second pair of channels extending the entire width of said waveguide and being situated between said first pair of channels and the nonshorted end of said waveguide.
  • a harmonic generator as defined in claim 2 further comprising a second waveguide extending from said shorting plane and having a cutoff frequency between said first and second frequencies.
  • A- harmonic generator as defined in claim 3 wherein said first pair of channels extend the entire width of said waveguide, wherein said waveguide has a width equal to one-half free-space wavelength of said fundamental frequency, and wherein said first pair of channels are situated an odd number of one-quarter guide wavelengths at said first frequency from said shorting plane.
  • a harmonic generator as defined in claim 4 further including means for controlling the mode in which energy is present in regions of said waveguide, said means comprising first and second pairs of side channels extending from said waveguide to a depth of approximately oneeighth free-space Wavelength at said fundamental frequency, said pairs of channels being parallel to the longitudinal axis of said waveguide.
  • a waveguide capable of supporting signal at frequency means comprising at least one channel extending from the wall of said waveguide to a depth of essentially one-quarter guide wavelength at a frequency (rr-1)f for providing a resonant region at frequency (11-1) within said waveguide, and
  • nonlinear reactance means comprising a varactor diode disposed within said region, for producing energy at (n1)1 and to provide an output at nf 7.
  • a harmonic generator as defined in claim 6 further including trap means, comprising at least one channel extending from the wall of said waveguide to a depth of essentially one-quarter guide wavelength at frequency nf for preventing energy at frequency nf from propagating down said waveguide beyond said trap means.
  • a first waveguide capable of supporting a signal at frequency f in the lowest order transverse mode and terminating in a shorting plane
  • means comprising at least one channel extending from said waveguide to a depth of one-quarter guide Wavelength at a frequency (nl)f for providing a psuedocavity region within said first waveguide, said region being resonant at (nl)f a varactor diode disposed within said pseudocavity region, and
  • trap means comprising a second pair of channels oppositely extending from said first waveguide to a depth of one-quarter guide wavelength at a frequency of nf for preventing energy at the output frequency from propagating down said first waveguide beyond said trap means.
  • a microwave frequency tripler comprising, in combination:
  • a first waveguide capable of supporting a signal at a fundamental frequency in the lowest order transverse mode and terminating in a shorting plane
  • a first pair of channels extending from said first waveguide to a depth of one-quarter guide wavelength at said second harmonic, said channels extending the entire width of said waveguide and being located three-quarters of a guide wavelength at said second harmonic from said shorting plane,
  • a varactor diode disposed within said first waveguide at a location equidistant from the sides of said waveguide and one-quarter guide wavelength at said second harmonic from said shorting plane
  • a second pair of channels oppositely extending from said first waveguide to a depth of one-quarter guide wavelength at said third harmonic, said channels extending the entire width of said waveguide and being located one guide wavelength at said third harmonic from said diode.

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  • Power Engineering (AREA)
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US622237A 1967-03-10 1967-03-10 Microwave harmonic generator including a waveguide having oppositely extending channels defining a resonant region therein Expired - Lifetime US3431485A (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
US62223767A 1967-03-10 1967-03-10
GB43285/68A GB1201947A (en) 1967-03-10 1968-09-11 Microwave harmonic generator
NL6813615A NL6813615A (de) 1967-03-10 1968-09-24
FR169868 1968-10-14
DE19681814291 DE1814291A1 (de) 1967-03-10 1968-12-12 Mikrowellen-Oberwellengenerator

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DE (1) DE1814291A1 (de)
FR (1) FR1589309A (de)
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NL (1) NL6813615A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3631331A (en) * 1970-08-10 1971-12-28 Gte Automatic Electric Lab Inc Waveguide frequency multiplier wherein waveguide cutoff frequency is greater than input frequency
US3671848A (en) * 1971-08-27 1972-06-20 Us Navy Frequency conversion with josephson junctions

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3155914A (en) * 1963-04-29 1964-11-03 Northern Electric Co Coaxial reactive tuning stub for tuning a lower frequency signal without affecting a higher frequency signal
US3165690A (en) * 1960-12-12 1965-01-12 Thompson Ramo Wooldridge Inc Harmonic generator utilizing a nonlinear reactance
US3196339A (en) * 1960-06-23 1965-07-20 Microwave Ass Microwave harmonic generator and filter element therefor
US3335357A (en) * 1964-11-23 1967-08-08 Gen Telephone & Elect Harmonic generator employing antiresonant traps in the input and output circuits forfrequency separation
US3369169A (en) * 1964-05-14 1968-02-13 Bell Telephone Labor Inc Microwave frequency multiplier with a plurality of harmonic inhibiting means

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3196339A (en) * 1960-06-23 1965-07-20 Microwave Ass Microwave harmonic generator and filter element therefor
US3165690A (en) * 1960-12-12 1965-01-12 Thompson Ramo Wooldridge Inc Harmonic generator utilizing a nonlinear reactance
US3155914A (en) * 1963-04-29 1964-11-03 Northern Electric Co Coaxial reactive tuning stub for tuning a lower frequency signal without affecting a higher frequency signal
US3369169A (en) * 1964-05-14 1968-02-13 Bell Telephone Labor Inc Microwave frequency multiplier with a plurality of harmonic inhibiting means
US3335357A (en) * 1964-11-23 1967-08-08 Gen Telephone & Elect Harmonic generator employing antiresonant traps in the input and output circuits forfrequency separation

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3631331A (en) * 1970-08-10 1971-12-28 Gte Automatic Electric Lab Inc Waveguide frequency multiplier wherein waveguide cutoff frequency is greater than input frequency
US3671848A (en) * 1971-08-27 1972-06-20 Us Navy Frequency conversion with josephson junctions

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NL6813615A (de) 1970-03-26
FR1589309A (de) 1970-03-23
DE1814291A1 (de) 1970-07-02
GB1201947A (en) 1970-08-12

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