Abstract : One of the most useful microwave ferrite components is the isolator, which is a two-port device having unidirectional transmission characteristics. A common application uses an isolator between a high-power source and a load to prevent possible reflections from damaging the source. The most popular type of microwave isolator is the resonance isolator. A single tone resonance isolator with resonance frequency of 10 GHz, and a broad band resonance isolator have been designed and optimized. The attenuations for the forward and reverse directions have been calculated for both the single tone and the broadband isolators, and they were 30 dB for the reverse direction of the 10 GHz single tone isolator and 0.629 dB for the forward direction. The total reverse attenuation was 52.104 dB, 55.549 dB and 55.922 dB for the 9 GHz, 10 GHz, and 11 GHz isolators respectively. The forward attenuation was 10.897 dB for the 9 GHz, 9.337 dB for the 10 GHz, 11.192 dB for the 11 GHz .