| Communication and radar subsystems contain high-frequency networks in which signals flow in a sequential manner through their components. A sensitive electronic component may be adversely affected by the other components that follow it in such a network. Microwave isolators block signals that are traveling in the wrong direction within a network, thereby providing protection to the sensitive component. This thesis presents the theoretical analysis, fabrication, and measurement of a novel type of microwave isolator. Made from a small substrate (0.6 x 6 x 6 mm) of a magnetic ceramic material known as ferrite, the isolator is compact and can be readily integrated with other planar circuitry. Moreover, the properties of the isolator can be tuned as a function of frequency by the application of an external magnetic field, allowing it to be used in many frequency bands. This new isolator design offers clear performance advantages over other known types of ferrite isolators: it provides very high values of isolation, and it does so over a wider range of frequencies. Measured results indicate that this isolator provides over 30 dB of isolation from 10.3 to 13.3 GHz, with a peak isolation of 57 dB at 11.9 GHz. The peak isolation figure of merit was 48.7 dB at 11.9 GHz.;Keywords. Ferrite, Isolator, Microwave, Anti-Symmetric Bias, Rectangular Waveguide. |
