Broadband, Frequency Selective Limiters in the 4-16 GHz Range

Passive single crystal, ferrite limiters have been developed in several frequency ranges with instantaneous bandwidths of better than 20%, limiting thresholds of less than +20 dbm, and dynamic ranges of more than 20 db. A compact, traveling-wave structure comprised of an array of high-Q dielectric resonators yields a low level insertion loss of less than 1 db at all frequencies. Low linewidth spheres of yttrium-iron-garnet (YIG) or lithium ferrite are placed in a region of high r.f. magnetic field of each dielectric resonator, and a permanent magnet serves to bias the ferrites to the non-linear region of subsidiary-resonance absorption. Structures of this type have been built for the ranges of 4.4 to 5.0 GHz, 8 to 10 GHz, 10 to 12 GHz, 12 to 14 GHz and 14 to 16 GHz. All limiters exhibit the excellent frequency selectivity characteristics of YIG devices.