Abstract: A sensing element (10) for an intrinsic gravity gradiometer (IGG) for use in sensing variation in a gravity field at a location. The sensing element (10) is flexible, elongate and has unfixed opposed ends (12, 14) when part of the gravity gradiometer. The sensing element can be a metallic ribbon, and can be mounted by a number e.g. 3 or 5, pivot points or axes 30-40 at each of the opposed sides along the sensing element, with the opposed ends of the sensing element free to move. The pivot points or axes can include pins, preferably cylindrical pins (48) or the sensing element may be etched within the side wall and remain joined to the remainder of the side wall by connections. The sensing element (10) can form part of one or more resonant cavities or wave guide (44, 52-66), such as a side or dividing wall (46) or part thereof. A dual phase bridge (61,612) arrangement can be provided. Electrical current (I) can be injected into the sensing element.

Abstract: A sensing element (10) for an intrinsic gravity gradiometer (IGG) for use in sensing variation in a gravity field at a location. The sensing element (10) is flexible, elongate and has unfixed opposed ends (12, 14) when part of the gravity gradiometer. The sensing element can be a metallic ribbon, and can be mounted by a number e.g. 3 or 5, pivot points or axes 30-40 at each of the opposed sides along the sensing element, with the opposed ends of the sensing element free to move. The pivot points or axes can include pins, preferably cylindrical pins (48) or the sensing element may be etched within the side wall and remain joined to the remainder of the side wall by connections. The sensing element (10) can form part of one or more resonant cavities or wave guide (44, 52-66), such as a side or dividing wall (46) or part thereof. A dual phase bridge (61,612) arrangement can be provided. Electrical current (I) can be injected into the sensing element.

Abstract: A microwave frequency magnetic field manipulation system 10 comprises a re-entrant microwave cavity 12 having a substantially continuous and closed internal surface 14 with at least two opposite sides 16 and 18. Two or more posts, P1, P2, . . . Pn (hereinafter referred to in general as “posts P”) are provided in the cavity 12. The posts P are in physical and more particularly electrical contact with one of the sides 16. Respective gaps G are or can be formed between free ends of the posts P and the side 18. The system 10 also has a signal source 20 coupled to the cavity 12 for supplying microwaves. The source 20 supplies microwave signals at frequencies that facilitate the generation of magnetic fields in opposite directions about at least two mutually adjacent posts P. Accordingly the magnetic field is reinforced in a common region 22 between the mutually adjacent posts P.

Abstract: A microwave frequency magnetic field manipulation system (10) comprises a re-entrant microwave cavity (12) having a substantially continuous and closed internal surface (14) with at least two opposite sides (16 and 18). Two or more posts, P1, P2, . . . Pn (hereinafter referred to in general as “posts P”) are provided in the cavity (12). The posts P are in physical and more particularly electrical contact with one of the sides 16. Respective gaps G atre or can be formed between free ends of the posts P and the side (18). The system (10) also has a signal source (20) coupled to the cavity (12) for supplying microwaves. The source (20) supplies microwave signals at frequencies that facilitate the generation of magnetic fields in opposite directions about at least two mutually adjacent posts P. Accordingly the magnetic field is reinforced in a common region (22) between the mutually adjacent posts P.

Abstract: 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 charac

Abstract: 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.

Abstract: A multi-layer microwave resonator (10) comprises a cavity (12) having an inner surface formed from an electrically conductive material. Pieces (16a-16e) of dielectric materials stacked on top of each other form a conriguous body (14) that is provided in the cavity (12). The dielectric materials of the pieces (16a-16e) are chosen such that the dielectric constant of the pieces (16a-16e) alternate between a relatively high dielectric constant and a relatively low dielectric constant.

Abstract: 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.

Abstract: 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); an

Abstract: An interferometric signal processing apparatus (10) producing an output signal from a first input signal (34) and a second input signal (34), said input signals (34) having substantially equal carrier frequencies, comprising:

Abstract: 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.

Abstract: 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.

Abstract: 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.