Analysis of a Rectangular Microstrip Antenna on a Uniaxial Substrate

Over the past years microstrip resonators have been widely used in the range of microwave frequencies. In general these structures are poor radiators, but by proper design the radiation performance can be improved and these structures can be used as antenna elements (Damiano & Papiernik, 1994). In recent years microstrip patch antennas became one of the most popular antenna types for use in aerospace vehicles, telemetry and satellite communication. These antennas consist of a radiating metallic patch on one side of a thin, non conducting, supporting substrate panel with a ground plane on the other side of the panel. For the analysis and the design of microstrip antennas there have been several techniques developed (Damiano & Papiernik, 1994; Mirshekar-Syahkal, 1990). The spectral domain approach is extensively used in microstrip analysis and design (Mirshekar-Syahkal, 1990). In such an approach, the spectral dyadic Green’s function relates the tangential electric fields and currents at various conductor planes. It is found that the substrate permittivity is a very important factor to be determined in microstrip antenna designs. Moreover the study of anisotropic substrates is of interest, many practical substrates have a significant amount of anisotropy that can affect the performance of printed circuits and antennas, and thus accurate characterization and design must account for this effect (Bhartia et al. 1991). It is found that the use of such materials may have a beneficial effect on circuit or antenna (Bhartia et al. 1991; Pozar, 1987). For a rigorous solution to the problem of a rectangular microstrip antenna, which is the most widely used configuration because its shape readily allows theoretical analysis, Galerkin’s method is employed in the spectral domain with two sets of patch current expansions. One set is based on the complete set of orthogonal modes of the magnetic cavity, and the other employs Chebyshev polynomials with the proper edge condition for the patch currents (Tulintsef et al. 1991). This chapter describes spectral domain analyses of a rectangular microstrip patch antenna that contains isotropic or anisotropic substrates in which entire domain basis functions are used to model the patch current, we will present the effect of uniaxial anisotropy on the characterization of a rectangular microstrip patch antenna, also because there has been very little work on the scattering radar cross section of printed antennas in the literature, including the effect of a uniaxial anisotropic substrate, a number of results pertaining to this case will be presented in this chapter.