Improved lumped-element two-port isolator

In a lumped-element two-port isolator, the relationship between the angle across two central conductors and electric characteristics is revealed using circuit analysis. At /spl phi/=90 degree, high isolation loss is achieved. At /spl phi/=60 degree, the bandwidth of insertion loss becomes maximum. This theoretical prediction at /spl phi/=60 degree was confirmed qualitatively by 360 MHz band experiments. Furthermore, we obtained the interesting result that the perfect isolation conditions at /spl phi/=60 degree is quite similar to three-port circulator conditions.