Test data are presented on two aluminum-substituted yttrium-iron-garnet (YIG) materials that have low-saturation magnetizations that permit the extension of ferrite devices well into the UHF/VHF region. In particular, one composition has a saturation magnetization of 300 gauss and a line width of 50 oersteds. Measurements are presented that compare the new materials with previously available higher-saturation magnetization materials. A broad-band UHF/L-band four-port circulator that operates over a 2-to-1 frequency band has been developed, using this 300 gauss material. Insertion loss is 1 db or less from 665 to 1320 Mc (with constant magnetic field) and 0.5 db or less from 800 to 1150 Mc. A compact and favorable circulator package design was obtained by using coaxial hybrids and dielectric-loaded strip transmission line. Data on the broad-band magic-tee used in the circulator are included. Isolator measurements down to 200 Mc are reported. Reverse-to-forward magnetic-loss ratios of 36 at 600 Mc and 12 at 300 Mc were obtained.
[1]
L. Young.
Tables for Cascaded Homogeneous Quarter-Wave Transformers
,
1959
.
[2]
B. J. Duncan,et al.
Design Considerations for Broad-Band Ferrite Coaxial Line Isolators
,
1957,
Proceedings of the IRE.
[3]
S. Geller,et al.
Magnetic and Crystallographic Properties of Substituted Yttrium-Iron Garnet, 3 Y 2 O 3 · x M 2 O 3 · ( 5 − x ) Fe 2 O 3
,
1958
.
[4]
Walter V. Tyminski,et al.
A Wide-Band Hybrid Ring for UHF
,
1953,
Proceedings of the IRE.
[5]
E.M.T. Jones,et al.
Coupled-Transmission-Line Directional Couplers
,
1958
.
[6]
G. P. Rodrigue,et al.
Ferromagnetic Resonance in Some Polycrystalline Rare Earth Garnets
,
1958
.
[7]
D. Fleri,et al.
Nonreciprocity in Dielectric Loaded TEM Mode Transmission Lines
,
1959
.
[8]
C. Hogan.
The low-frequency problem in the design of microwave gyrators and associated elements
,
1956
.