Hermetically sealed oscillator with dielectric resonator tuned through dielectric window by adjusting screw

In a microwave resonator apparatus having a dielectric resonator puck for storing microwave energy which is coupled to the puck by a driving circuit and which causes the puck to resonate at a microwave frequency, said puck being associated with a tuning member movable by cooperating mechanical positioning means into and out of positions at which it variously interferes with external field lines of the puck which correspond to a portion of the microwave energy stored in said puck, thereby to alter the microwave resonant frequency of said puck, the improvement wherein said microwave resonator apparatus is provided with a hermetically sealed chamber internally of which said dielectric puck and driving circuit are housed for environmental protection and externally of which said movable tuning member is mounted together with said cooperating mechanical positioning means thereof, said chamber being substantially opaque to microwave fields except at a local wall area thereof which transmits at least a portion of said external field lines of said puck out of said chamber in a path permitting said portion to be interfered with by said tuning member, whereby alterations of the microwave resonant frequency of the dielectric resonator puck caused by positioning the movable tuning member can be made notwithstanding the location of said tuning member outside the hermetically sealed chamber in which said puck is housed.

In a microwave dielectric resonator apparatus of the class comprising a housing containing a negative resistance circuit a dielectric resonator puck for coupling microwave energy from said negative resistance circuit back into the circuit in response to an application of a d.c. voltage to said circuit, said a tuning member mechanically adjustable into different positional states of interference with the microwave field developed around said resonator puck by current circulating therein representative of the microwave energy stored in said resonator puck, thereby to cause respective changes in the resonant frequency of said resonator puck, the improvement wherein:

• said housing is internally provided with a hermetic chamber in which said dielectric resonator puck and negative resistance circuit are disposed for environmental protection and from which said mechanically adjustable tuning member is excluded for preserving the hermetic integrity of said chamber;
• and wherein, in order that said different positional states of interference with said microwave field may be achieved by said mechanically adjustable tuning member notwithstanding its exclusion from said hermetic chamber, a non-hermetic housing region, in which said housing contains said tuning member, interfaces with said hermetic chamber at interface means which are proximate said resonator puck and tuning member, are consonant with the preservation of said hermetic integrity and are transparent to said microwave field.

A microwave oscillator in which a dielectric resonator puck stores microwave energy coupled thereto by a driving circuit which causes said puck to resonate at a microwave frequency to which the output frequency of the oscillator becomes stabilized, said puck being associated with a tuning slug movable into and out of positions at which it variously interferes with external field lines of the puck which correspond to a portion of the microwave energy stored in said puck, thereby to alter the microwave resonant frequency of said puck to which said oscillator output frequency becomes stabilized, wherein the improvement comprises a hermetically sealed chamber internally of which said dielectric puck and driving circuit are housed for environmental protection and externally of which said movable tuning slug is mounted together with cooperating means for mechanically positioning said slug, said chamber being impervious to microwave fields except at a local r-f transparent window thereof which transmits at least a portion of said external field lines of said puck out of said chamber in a path permitting said portion to be interfered with by said tuning slug, whereby mechanical tuning of said oscillator by positioning said movable tuning slug is made possible notwithstanding the location of said movable tuning slug outside the hermetically sealed chamber containing the dielectric resonator puck and driving circuit of said oscillator.

A stable tunable microwave oscillator apparatus comprising:

• (a) a hermetically sealed enclosure confining microwave fields except where a microwave transparent window in a minor portion thereof is provided;
• (b) a microwave oscillator disposed within said enclosure, said oscillator comprising a microwave resonator puck of dielectric material and a solid state driving circuit coupled in driving relation to the puck, said puck being arranged to respond to the output of said driving circuit and to couple energy back to said driving circuit to cause said oscillator to oscillate at the microwave natural frequency of said resonator puck following an application of a d.c. bias to said circuit, said resonator puck being proximate to said window portion so that part of the microwave field created around the puck during oscillation of said oscillator leaves said hermetically sealed enclosure via said window portion;
• and
• (c) a tuning slug adjustably mounted for positioning externally of said enclosure so as selectively to intercept and couple with said leaving microwave field part, thereby to cause said resonator puck to resonate above or below its microwave natural frequency, depending on the selected adjusted position of said slug relative to said field part.

A hermetically sealed mechanically tunable microwave dielectric resonant apparatus in which the precise frequency of resonance is controlled by a solid dielectric resonator excited by an associated microwave circuit, said apparatus comprising:

• a substrate carrying the solid dielectric resonator and the associated microwave circuit;
• a rigid hermetically sealed housing enclosing the solid dielectric resonator and the associated microwave circuit;
• an electrically conducting film forming a ground plane beneath the substrate;
• a microwave field window in the hermetically sealed housing in close proximity to the solid dielectric resonator;
• a metallic tuning slug movably supported adjacent said window outside of the hermetically sealed housing;
• and
• mechanical adjustment means to shift the position of the tuning slug to alter the microwave field in the solid dielectric resonator to change the natural microwave frequency thereof.

A method of obtaining a fine tuning adjustment of the resonant frequency of a dielectric microwave resonator from a location outside of a hermetically sealed chamber which encloses the resonator in common with microwave circuitry energizable to develop fringing fields at microwave frequencies that link with said resonator to excite it into a state of resonance, said method comprising the steps of:

• (a) forming the hermetically sealed chamber with a bounding structure which has the property of confining microwave fields within said chamber except at a window portion thereof transparent to such fields;
• (b) positioning the dielectric microwave resonator relative to said window portion so that part of the field developed about said resonator by the current circulating therein during said state of resonance passes through said window portion;
• (c) movably disposing outside said hermetically sealed chamber proximate said window portion a slug of solid material capable of influencing said field part as a function of the positional relationship of said slug with said field part and of thereby altering the distribution and amount of the energy associated with said resonator current and stored in said field about said resonator, any such alteration being effective to alter the resonant frequency of said resonator;
• and
• (d) adjusting the position of said slug relative to said field part so as to obtain said fine tuning adjustment of the resonant frequency of said resonator.