Devices and methods for below-resonance radio-frequency applications

Abstract

Devices and methods for below-resonance radio-frequency applications. In some embodiments, a ferrite device can include a modified yttrium iron garnet material in which bismuth occupies at least some of dodecahedral sites, and aluminum occupies at least some of tetrahedral sites.

What is claimed is: 
     
         1 . A ferrite device comprising a modified yttrium iron garnet material in which bismuth occupies at least some of dodecahedral sites, and aluminum occupies at least some of tetrahedral sites. 
     
     
         2 . The ferrite device of  claim 1  wherein the octahedral sites are substantially free of aluminum. 
     
     
         3 . The ferrite device of  claim 1  wherein the material has a dielectric constant value that is at least 25. 
     
     
         4 . The ferrite device of  claim 1  wherein the material has a 3-db ferrimagnetic resonance linewidth value that is less than 50 Oersted. 
     
     
         5 . The ferrite device of  claim 1  wherein the material has a saturation magnetization value in a range of 400 to 1000 Gauss. 
     
     
         6 . The ferrite device of  claim 1  wherein the modified yttrium iron garnet material is represented by the formula Y 3-x-2y-z Bi x Ca 2y+z Fe 5-y-z-a V y Zr z Al a O 12 . 
     
     
         7 . The ferrite device of  claim 6  wherein bismuth occupies x formula units of dodecahedral sites, zirconium occupies z formula units of octahedral sites, vanadium occupies y formula units of tetrahedral sites, calcium occupies 2y+z formula units of the dodecahedral sites to compensate for a valency imbalance resulting from the presence of zirconium and vanadium, aluminum occupies a formula units of the tetrahedral sites while having the octahedral sites substantially free of aluminum. 
     
     
         8 . The ferrite device of  claim 7  wherein the quantity a is greater than zero such that saturation magnetization of the modified yttrium iron garnet material decreases in a substantially linear manner as the quantity a increases to an upper limit value of at least 0.6. 
     
     
         9 . The ferrite device of  claim 8  wherein the upper limit of the quantity a is less than or equal to 0.75. 
     
     
         10 . The ferrite device of  claim 7  wherein the quantity x is greater than zero and less than or equal to 1.4. 
     
     
         11 . The ferrite device of  claim 7  wherein the quantity y is greater than zero and less than or equal to 0.7. 
     
     
         12 . The ferrite device of  claim 7  wherein the quantity z is greater than zero and less than or equal to 0.7. 
     
     
         13 . A circulator comprising:
 a conductor having a plurality of signal ports;   one or more magnets configured to provide a magnetic field; and   one or more ferrite disks implemented relative to the conductor and the one or more magnets so that a radio-frequency signal is routed selectively among the signal ports due to the magnetic field, each of the one or more ferrite disks including a modified yttrium iron garnet material in which bismuth occupies at least some of dodecahedral sites, and aluminum occupies at least some of tetrahedral sites.   
     
     
         14 . The circulator of  claim 13  wherein the conductor includes a plurality of impedance transformers corresponding to the plurality of signal ports, each impedance transformer including a stripline transmission line. 
     
     
         15 . The circulator of  claim 13  wherein each ferrite disk has a dielectric constant value that is at least 25. 
     
     
         16 . The circulator of  claim 15  wherein each ferrite disk has a 3-db ferrimagnetic resonance linewidth value that is less than 50 Oersted. 
     
     
         17 . The circulator of  claim 16  wherein each ferrite disk has a saturation magnetization value in a range of 400 to 1000 Gauss. 
     
     
         18 . The circulator of  claim 17  wherein the circulator is a below-resonance device. 
     
     
         19 . The circulator of  claim 18  wherein the circulator is an octave bandwidth device. 
     
     
         20 . A wireless system comprising:
 a transceiver configured to process signals;   an antenna in communication with the transceiver; and   a signal routing circuit implemented between the transceiver and the antenna, the signal routing circuit having a circulator that includes a conductor having a plurality of signal ports, one or more magnets configured to provide a magnetic field, the circulator further including one or more ferrite disks implemented relative to the conductor and the one or more magnets so that a signal is routed selectively among the signal ports due to the magnetic field, each of the one or more ferrite disks including a modified yttrium iron garnet material in which bismuth occupies at least some of dodecahedral sites, and aluminum occupies at least some of tetrahedral sites.