David F Trowbridge

US Patent:

40558100, Oct 25, 1977

Filed:

Jul 26, 1976

Appl. No.:

5/708796

Inventors:

James C. Administrator of the National Aeronautics and Space Fletcher
David L. Trowbridge - Sunland CA

International Classification:

H01S 102

US Classification:

330 4

Abstract:

An X-band traveling wave maser of the folded-comb type is provided with two figure-eight coils for gain and bandwidth control. One figure-eight coil covers the full length of the comb structure for bandwidth adjustment of an external magnetic field. The other figure-eight coil covers a central half of the comb structure for independent gain adjustment of the external magnetic field. The half of each figure-eight coil at the turn around end of the comb structure is oriented to aid the external magnetic field, and the half of each figure-eight coil at the input-output end of the comb structure is oriented to buck the external magnetic field. The maser is pumped in the push-push mode with two different frequencies.

US Patent:

40841324, Apr 11, 1978

Filed:

Nov 24, 1976

Appl. No.:

5/744477

Inventors:

James C. Administrator of the National Aeronautics and Space Fletcher
David L. Trowbridge - Sunland CA

International Classification:

G01R 2700

US Classification:

324 57DE

Abstract:

A method and apparatus for recording directly group delay measurement of a system under temperature and stress tests employing a modulated carrier frequency swept over an S or X-band of interest and applied through a reference path and a test path to separate detectors for group delay measurement using a power divider, e. g. , a directional coupler or a hybrid-T junction. A phase comparator is initially balanced, and then the modulated carrier is swept in frequency over the band of interest for different conditions of temperature and/or mechanical stress to obtain a family of characteristic group-delay curves for the system under test.