# US 4,399,406 A · Test head for electron spin resonance and paramagnetic electron resonance measurements

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- Number: US 4,399,406 A
- Document ID: US4399406A
- Status: Granted
- Kind: A
- Application number: 06/271,865
- Filed: 1981-06-09
- Granted: 1983-08-16
- Earliest claimed: 1980-06-14
- Assignees: Bruker Analytische MeBtechnik GmbH
- Inventors: Reinhard Biehl; Dieter Schmalbein
- Web page: https://patentgrep.com/patent/US4399406A

## CPC

- G01R 33/345: of waveguide type (G01R33/343 takes precedence)
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)

## Abstract

A test head for electron spin resonance and paramagnetic electron resonance measurements comprises a resonator of circular cylindrical shape adapted to accommodate a coaxially arranged test tube, and a waveguide arrangement for exciting the H.sub.011 wave in the resonator, said waveguide arrangement comprising one section having its one end arranged adjacent one face of the resonator and communicating with the resonator via an opening provided in the face in eccentrical arrangement relative to the resonator. In order to enable the coupling coefficient to be varied and, thus, the resonator to be adapted to the waveguide section, the waveguide section carrying a H.sub.1n wave communicates with the resonator via a coupling slot the angular position (.phi.) of which can be varied relative to the radial plane of the resonator passing through its center. Preferably, the waveguide section exhibits a circular cross-section and can be rotated about its axis. It guides the H.sub.11 wave, and the coupling slot is provided, symmetrically relative to the axis of the waveguide section, in a wall portion connected to the said waveguide section.

## Claims

### Claim 1

A test head for electron spin resonance and paramagnetic electron resonance measurements comprising a resonator of circular cylindrical shape adapted to accommodate a coaxially arranged test tube, and a waveguide arrangement for exciting the H.sub.011 wave in the resonator, said waveguide arrangement comprising one section having its one end arranged adjacent one face of the resonator and communicating with the resonator via an opening provided in the face in eccentrical arrangement relative to the resonator, characterized in that the waveguide section carrying a H.sub.1n wave communicates with the resonator via a coupling slot the angular position (.phi.) of which can be varied relative to the radial plane of the resonator passing through its centre.

### Claim 2 (depends on 1)

A test head in accordance with claim 1, characterized in that the coupling slot is positioned at a point relative to the resonator where the highest current density is encountered in the face wall of the resonator.

### Claim 3 (depends on 1)

A test head in accordance with claim 1, characterized in that the waveguide section is of circular cross-section and carries the H.sub.11 wave, that the coupling slot is provided, in symmetrical relation to the axis of the waveguide section, in a wall portion connected to the said waveguide section, and that the waveguide section can be rotated about its axis relative to the resonator.

### Claim 4 (depends on 3)

A test head in accordance with claim 3, characterized in that the wall portion forming simultaneously the end portion of the resonator is formed by a dielectric plate with a thin metal coating provided on its side facing the waveguide section.

### Claim 5 (depends on 4)

A test head in accordance with claim 4, characterized in that the plate is made of glass-fibre reinforced polytetrafluor ethylene.

### Claim 6 (depends on 3)

A test head in accordance with claim 3, characterized in that the waveguide section is connected to a coaxially arranged rectangular waveguide via a H.sub.10 -H.sub.11 adaptor.

### Claim 7 (depends on 6)

A test head in accordance with claim 6, characterized in that the broad sides of the rectangular waveguide extend in parallel to the radial plane of the resonator passing through the axis of the rectangular waveguide and of the waveguide section of circular cross-section.

### Claim 8 (depends on 1)

A test head in accordance with claim 1, characterized in that its different components which can be rotated relative to each other are resiliently urged against each other in the axial direction.