Title :
Very low loss wideband isolators for mm-wavelengths
Author_Institution :
Dept. of Astron., Massachusetts Univ., Amherst, MA, USA
Abstract :
Isolators based on Faraday rotation in a cylindrical dielectric waveguide have long been used for full waveguide band coverage, but the typical loss has been significantly higher than for Y junction designs. A modification of the Faraday rotation design using better mode conversion and a greatly reduced ferrite length has resulted in much lower loss and better VSWR while maintaining high isolation. The performance is now comparable to the best narrow band Y junction designs but with nearly full waveguide bandwidth, and with even smaller size. The best WR10 units have a loss of 0.5-0.8 dB across the 75-110 GHz band, and a WR5 design has 1.0-1.2 dB loss from 160-180 GHz, increasing to 2 dB at 220 GHz. A further modification to the design using a diamond heat sink to dissipate high power has also been developed. These isolators work at cryogenic temperatures with somewhat lower loss.
Keywords :
Faraday effect; circular waveguides; cryogenic electronics; dielectric waveguides; ferrite isolators; magnetic millimetre wave devices; magneto-optical isolators; 0.5 to 0.8 dB; 1 to 2 dB; 160 to 220 GHz; 75 to 110 GHz; Faraday rotation; VSWR; WR10 units; WR5 design; cryogenic temperatures; cylindrical dielectric waveguide; diamond heat sink; ferrite length; full waveguide bandwidth; high isolation; high power dissipation; mode conversion; very low loss wideband isolators; Bandwidth; Cryogenics; Dielectric losses; Ferrites; Heat sinks; Isolators; Narrowband; Temperature; Waveguide junctions; Wideband;
Conference_Titel :
Microwave Symposium Digest, 2001 IEEE MTT-S International
Conference_Location :
Phoenix, AZ, USA
Print_ISBN :
0-7803-6538-0
DOI :
10.1109/MWSYM.2001.967101