Microwave Resonance Systems Employing A Bimodal Cavity

Patent No. US3581190 (titled "Microwave Resonance Systems Employing A Bimodal Cavity") was filed by Mcdonnell Douglas on Sep 17, 1968. The application was issued on May 25, 1971.

'190 is related to the field of microwave resonance systems, specifically those employing a cavity structure. The background involves the need for accurate measurement of complex substance characteristics by exposing them to microwave energy. Existing methods often require calibrated standards and separate input/output means for each sample, adding complexity and cost.

The underlying idea behind '190 is a bimodal cavity design with two coupled cavity sections. One section holds the sample, while the other is tunable. This allows the sample to interact with multiple resonant modes simultaneously. The key insight is that by adjusting the coupling between the cavities and tuning one of them, a desired frequency separation between the modes can be achieved, enabling more comprehensive sample analysis.

The claims of '190 focus on a microwave cavity structure comprising two communicating cavity portions. One cavity is designed to hold a sample, and the overall structure is resonant in multiple modes. The structure includes an input for microwave energy, a coupling mechanism between the cavities, and a tuning element in one of the cavities to adjust its resonant frequency.

In practice, microwave energy is fed into the dual-cavity structure, and the sample, positioned in one cavity, interacts with the fields of both resonant modes. The frequency separation between the modes is adjusted by modifying the coupling between the cavities using a sliding aperture and by tuning one of the cavities. This allows for the excitation of the sample at one frequency and the monitoring of its magnetic effects at another, providing a more detailed analysis.

This design differs from prior approaches by using a single sample and no standard for comparison. The dual-cavity, dual-mode structure simplifies input and output coupling, and the adjustable coupling and tuning mechanisms provide greater flexibility in achieving desired frequency separations. The device can also operate over a wide temperature range, making it suitable for various applications, including electron paramagnetic resonance spectrometry and even as a two-level maser.

How does this patent fit in bigger picture?

Technical Landscape

In the late 1960s when '190 was filed, microwave resonance systems were used to analyze material properties. At a time when such systems commonly relied on single-mode cavities and external standards for comparison, achieving simultaneous resonance at multiple frequencies within a single cavity presented technical challenges. Furthermore, hardware constraints made it non-trivial to design compact and versatile cavity structures capable of operating across a broad temperature range.

Prosecution Position

The disclosed bimodal cavity structure addresses the need for improved analysis of substance characteristics by enabling simultaneous resonance at multiple modes within a single device. This architectural shift eliminates the need for external standards and separate input/output means, simplifying the measurement process. By exposing a sample to multiple resonant modes, the device enables the extraction of more comprehensive information about the sample's properties, overcoming limitations of single-mode systems and improving accuracy and versatility.

Claims

This patent contains zero claims, therefore there are no independent or dependent claims to analyze.

Key Claim Terms New

Definitions of key terms used in the patent claims.

Term (Source)	Support for Specification	Interpretation
Bimodal microwave cavity structure (Claim 1)	A bimodal microwave cavity structure having separate communicating cavity portions, one of which includes means for positioning a sample or specimen, said cavity structure being able to be resonant in more than one mode such that the sample or specimen when positioned at a suitable location in one of the structure cavities can interact with the fields associated with all modes that are present.	A microwave cavity with two separate communicating cavity portions, designed to resonate in more than one mode.
Interact with the fields (Claim 1)	A bimodal microwave cavity structure having separate communicating cavity portions, one of which includes means for positioning a sample or specimen, said cavity structure being able to be resonant in more than one mode such that the sample or specimen when positioned at a suitable location in one of the structure cavities can interact with the fields associated with all modes that are present.	The sample's properties are influenced or altered by the microwave energy present in the cavity, allowing for measurement or analysis.
Positioning a sample or specimen (Claim 1)	A bimodal microwave cavity structure having separate communicating cavity portions, one of which includes means for positioning a sample or specimen, said cavity structure being able to be resonant in more than one mode such that the sample or specimen when positioned at a suitable location in one of the structure cavities can interact with the fields associated with all modes that are present.	A mechanism or location within one of the cavity portions specifically designed to hold a sample for analysis or interaction with microwave fields.
Separate communicating cavity portions (Claim 1)	The present invention teaches the construction and operation of a novel dual-moded cavity structure having two separate but coupled cavity portions. The present multicavity structure also provides relatively simple means for stimulating samples by exposing them to more than one operating mode in order to obtain data from which to determine information about the sample such as its spin diffusion rates, ascertaining if one or more than one species of the sample substance is giving rise to a complicated electron spin resonance spectrum, distinguishing between different types of paramagnetic substances or species including distinguishing between biradical and monoradical substances, providing means for producing a two level maser and so forth.	Two distinct but connected sections within the cavity structure, allowing energy to flow between them.

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US3581190

MCDONNELL DOUGLAS

Application Number: US3581190D
Filing Date: Sep 17, 1968
Publication Date: May 25, 1971
External Links: Slate, USPTO, Google Patents

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