Abstract-Circularly symmetric patch antennas tuned by transversely magnetized lossy ferrite are studied. The circular and ring patch geometries printed on ferrite substrate or tuned by ferrite post and ferrite toroid are studied. Both saturated and partially magnetized ferrite are considered. Strong effects on the dispersive properties of modes propagating under the patch and in turn on the antenna resonant frequency and input impedance are observed when the ferrite losses are taken into account. The patch antennas resonance at a novel mode propagating in the traditionally assumed switch-off frequency range of negative effective permeability constitutes an essential original contribution of this work. In all cases the dynamic control of the patch resonant frequency through the DC-biasing field is investigated. The "perfect magnetic walls approximation" was employed in the analysis since it offers a valuable physical insight as well as simplified closed form expressions for the resonant conditions. These are used as engineering design formulas for an initial antenna design, which is in turn fine tuned with the aid of a numerical simulation-optimization scheme. The validity of the present method was verified through comparisons with published experimental results and numerical simulations.

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The excitation of a novel single mode in the negative µ eff area is studied for rectangular patch antenna printed on magnetized ferrite substrates or tuned by a ferrite inclusion. In all cases the DC magnetic field is considered perpendicular to the substrate plane. The ferrite inclusion-post shape is considered either cylindrical or rectangular. Numerical simulation results reveal the existence of this novel resonating mode inside the negative µ eff area for both the rectangular microstrip patch printed on ferrite substrate or tuned by a rectangular ferrite post. Also, the input impedance characteristics of these patch antennas are studied.