Abstract
Abstrcat This paper establishes a standard process to design stripline circulator operating at 0.9 GHz for 4G communication. First, the non-reciprocal properties and underlying loss mechanism of EM waves in ferrites was analyzed that helps us to select the proper operating magnetic field. Based on the aforementioned knowledge, we further employed the double-Y-junction theory for designing the shape of stripline as well the dimension of ferrite. Finally, the fine structure of circulator was optimized by using HFSS (High Frequency Structure Simulator). The designed circulator was fabricated and its transmission characteristic was experimentally measured by PNA (performance network analyzer, ) under the magnetic field applied by permanent magnet and electromagnet. The operating band (insertion loss > -0.3 dB) ranging from 872 MHz to 928 MHz (6.22%) was observed, in which the reflection and the isolation are less than -20 dB.