# US 4,400,669 A · Magnetostatic wave delay line having improved group delay linearity

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- Number: US 4,400,669 A
- Document ID: US4400669A
- Status: Granted
- Kind: A
- Application number: 06/305,667
- Filed: 1981-09-25
- Granted: 1983-08-23
- Earliest claimed: 1981-09-25
- Assignees: The United States of America as represented by the Secretary of the Air Force
- Inventors: Michael R. Daniel; John D. Adam; Robert A. Moore
- Web page: https://patentgrep.com/patent/US4400669A

## CPC

- H03H 2/001: {comprising magnetostatic wave network elements}
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)

## Abstract

The linearity of group delay versus frequency in magnetostatic wave delay lines is improved by a linear variation of one of three discrete parameters in the region between the two delay line transducers. The parameter variation is applied to magnetostatic wave delay lines that have a ground plane, a magnetic garnet crystal film substrate that is spaced from the ground plane and has transmitting and receiving transducers engaged to it, and a magnetic bias field. The discrete parameters varied are the magnetic bias field; the distance of the substrate from the ground plane; and the thickness of the substrate. Appropriate linear variations of any one of the these parameters provides improved linearity of group delay versus frequency.

## Claims

### Claim 1

In a magnetostatic wave delay line having a ground plane member, a magnetostatic substrate member in spaced proximate relationship thereto, transmitting and receiving transducers spaced apart and operably engaged to said substrate member and means for generating a magnetic bias field, the improvement residing in a delay line parameters configuration of discrete parameters for group delay linearity enhancement, said delay line parameters configuration comprising
linear parameter variation with distance, between said transmitting and receiving transducers, said linear parameter variation being implemented by means of a linear variation of the magnetic field bias strength.

### Claim 2 (depends on 1)

A magnetostatic wave delay line as defined in claim 1 wherein the linear parameter variation is implemented by means of a linear variation of the magnetostatic substrate thickness.

### Claim 3 (depends on 1)

A magnetostatic wave delay line as defined in claim 1 wherein the linear parameter variation is implemented by means of a linear variation of magnetostatic substrate member to ground plane member spatial relationship.

### Claim 4 (depends on 1)

A magnetostatic wave delay line as defined in claim 1 wherein said magnetic field bias strength varies from a field strength of 3000 gauss at one transducer to 3200 gauss at the other transducer.

### Claim 5 (depends on 2)

A magnetostatic wave delay line is defined in claim 2 wherein the thickness of said magnetic substrate varies from 10 microns at one transducer to 30 microns at the other transducer.

### Claim 6 (depends on 3)

A magnetostatic wave delay line as defined in claim 3 wherein magnetostatic substrate member to ground plane member spatial relationship varies from 10 microns at one transducer to 30 microns at the other transducer.

### Claim 7 (depends on 1)

A magnetostatic wave delay line as defined in claim 1 wherein said magnetostatic substrate member is comprised of a magnetic crystal garnet film.

### Claim 8 (depends on 7)

A magnetostatic wave delay line as defined in claim 7 wherein said manetic crystal garnet film is Yittmium Iron Garnet.