Analysis of a magnetically tunable patch radiator including metallization and ferrite-substrate losses

With the development of ferrite thin-film technology and possible monolithic integration of such substrates, microstrip radiators on ferrite substrates have become increasingly attractive in tunable patch antenna configurations. For the accurate prediction of circuit performance, it is necessary that theoretical models include such material characteristics as substrate losses and anisotropies, finite metallization thickness and finite conductivity of the radiating patch and the ground metallization. While substrate losses are sometimes considered in patch antenna models, the metallizations are still assumed ideal and of vanishing thickness. That this assumption can result in large errors is well known. Therefore, the paper focuses on the incorporation of conductor, bottom metallization and substrate losses in the analysis of magnetically tunable patch radiators on ferrite substrates. A modified spectral-domain immittance approach is used to investigate the influence of different magnitudes and directions of external magnetic bias on the resonant frequency and Q-factor. Pattern calculations demonstrate that the basic shape of radiation characteristics is maintained when applying external magnetic bias.<>