Investigations of the Isolators Containing Microstrip FCL Section

This paper describes the design of the isolator containing longitudinally magnetized microstrip ferrite coupled lines (FCL). In the sandwich structure of circuit the ferrite slab was introduced as an overlay. The termination in the isolator circuit was realized in two different ways: as a coaxial load and as a planar microstrip structure with lumped resistor. The results of the simulation were experimentally verified. Between simulations and measurements a good agreement was achieved. Better results was obtained for isolator with the coaxial load. The experiment showed average transmission losses better than -2dB in the band from 10.4 to 15GHz. The average isolation was better than -15dB. The reflection losses in one port were better than in the other one (below -15dB and average -12dB).