摘要:
A method of producing a microwave resonator comprising a cavity (50) defined, at least in part, by a generally cylindrical wall (64) having an electrically conductive inner surface and containing a generally cylindrical piece of low loss dielectric material (22), characterized by forming a generally cylindrical piece of low loss dielectric material of predetermined size and placing same in a cavity to produce a microwave resonator which operates in a particular mode at a specific frequency at a particular temperature. Microwave radiation corresponding to a further operating mode is then passed into the cavity and then the frequency corresponding to the further operating mode is searched for and measured. A further generally cylindrical piece of dielectric material is produced by scaling from the first piece of dielectric material according to the ratio between the first and second frequencies. Then, the diameter and/or height of the cavity is varied to compensate for manufacturing inaccuracies in the crystal so as to obtain an output frequency close to the desired output frequency.
摘要:
A method of producing a microwave resonator comprising a cavity (50) defined, at least in part, by a generally cylindrical wall (64) having an electrically conductive inner surface and containing a generally cylindrical piece of low loss dielectric material (22), characterised by forming a generally cylindrical piece of low loss dielectric material of predetermined size and placing same in a cavity to produce a microwave resonator which operates in a particular mode at a specific frequency at a particular temperature. Microwave radiation corresponding to a further operating mode is then passed into the cavity and then the frequency corresponding to the further operating mode is searched for and measured. A further generally cylindrical piece of dielectric material is produced by scaling from the first piece of dielectric material according to the ratio between the first and second frequencies. Then, the diameter and/or height of the cavity is varied to compensate for manufacturing inaccuracies in the crystal so as to obtain an output frequency close to the desired output frequency.
摘要:
An interferometric apparatus (10) for producing an output signal characteristic of phase and/or amplitude noise of a device under test (22), an input signal being provided to the interferometric apparatus (10), comprising a signal generation means (36,38) arranged to produce a third signal having a carrier frequency offset from that of the input signal; a first bridge (12) having first (14) and second (16) arms, the first (14) and second (16) arms having input thereto first and second signals, respectively, produced from one of the input signal or the third signal; the device under test (22) being provided in one of the first (14) or second (16) arms of the first bridge (12); a carrier suppression means (24) connected to the first (14) and second (16) arms of the first bridge (12) to produce a carrier suppressed signal; a first amplifier (32) arranged to amplify the carrier suppressed signal; first mixing means (34) responsive to the third signal and to the carrier suppressed signal to produce a signal characteristic of phase and/or amplitude noise of the device under test (22) at an offset frequency.
摘要:
An interferometric signal processing apparatus (10) producing an output signal from a first input signal (34) and a second input signal (34), the input signals (34) having substantially equal carrier frequencies, comprising a bridge (12) having a first arm (26) and a second arm (28), each arm having a first end (30) and a second end (32), the first and second input signals (34) being input to the first end (30) of the first and second arms (26, 28), respectively; a device-under-test (36) provided the first arm (26); a carrier suppressor (14) connected to the second ends (32) of the first and second arms (26, 28) to produce a carrier-suppressed signal at its output (A); an amplifier (16) arranged to amplify said carrier-suppressed signal; and a mixer (22, 24) responsive to the amplified carrier-suppressed signal and a carrier-dominated signal to produce the output signal; wherein the differential group delay between: the first end (30) of the first arm (26) and the output (A) of the carrier suppressor (14); and the first end (30) of the second arm (28) and the output (A) of the carrier suppressor (14) is less than or equal to 1000/fo seconds, where fo is the time-averaged mean value of the carrier frequencies of the input signals (34).
摘要:
An oscillator having a desired output frequency, comprising a cavity resonator 102 loaded with an anisotropic dielectric material and an oscillator circuit 100 including the cavity resonator 102 as a frequency determining element, the oscillator circuit 100 arranged to operate the cavity resonator 102 at a first frequency in a first mode and at a second frequency in a second mode, the first mode and the second mode each being influenced to a different extent by the thermal coefficient of permittivity of at least one crystal axis of the dielectric material, the oscillator circuit arranged to produce the desired operating frequency from the first frequency and the second frequency. The first frequency and the second frequency differ by an amount corresponding to the desired output frequency.
摘要:
A phase detector responsive to a first signal having a carrier frequency and a second signal close to the carrier frequency, including a carrier suppression circuit which produces a carrier suppressed signal from the first and second signals, and a mixer responsive to the carrier suppressed signal and the carrier frequency to produce an output signal corresponding to the phase difference between the first and second signals.