Microstrip antennas are adapted in a number of applications, being their use generally limited 10 the high frequency range [1-2]. However, their versatility has solicited the investigation on the suitability of printed microstrip antemas for low-frequency applicationr, typically requiring other antenna configurations , by v i a e of a considerable reduction on the value of the work frequency attained by means of a double substrate of ferradcchic and ferrimagnetic material, rerpectivsly. In faet, high values of permittivity and permeability allow the usc of the proposed antenna down to the MHz range. Moreover, the possibility of varying the permcability of the femtc through a simple dc bias [4-51 represents a versatile fcahlre in l a " of Nnability ( a d selectivity), e.g. with respect to clas~icall oop antennas. The design of the proposed antenna calls for a careful simulation of both the rubswtes as concems their frequency-dependent behavior and the anisotropy of the ferrite. In particular, a Debye model is adopted for the ferroelcchiic material (barium or strontium titanate), being the relevant values derived from experimental data [6-71, while a c l a ~ ~ i cPaoll der tensor form is considered for the permeability of the ferrite substrate material. The solution of the problem is achievcd by means of an analysis method based on a three-dimensional (3-D) finite-element method (FEM) [X-91, with a nodal-based approach in terms of magnetic vector and electric scalar potentials. In the frequency range of interest, the magnetic field is the quantiry of major interest, and second-order tetrahedral elements are considered. The results, validatcd through a commercial code, demonstrate the feasibility of the antenna as source or receiver of low-frequency EM fields.
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|Titolo:||Analysis and Design of Low Frequency Microstrip Antennas|
|Data di pubblicazione:||2004|
|Appartiene alla tipologia:||04b Atto di convegno in volume|