Naslov
Conformal patch antennas
(Transmitting phased arrays of phase locked self-oscillating patch antennas)

Autori
Šipuš, Zvonimir

Izvornik
Airforce Research Lab, AFB Hanscom, USA; Program: Window on Science

Vrsta, podvrsta
Ostale vrste radova, ostalo

Godina
1998

Ključne riječi
microstrip antenna; planar antenna; conformal antenna; multilayer structure; cylindrical structure; Green's functions; moment method

Sažetak
When constructing antennas it is popular to use printed metal patterns on multilayer substrates to obtain thin profile, conformability to smooth structures, and low manufacture cost. If the structure is planar or if the curvature of the structure is small, we can analyze the problem by considering a planar structure of infinite extent. For larger curvatures we have to choose a more accurate model, such as a circular cylindrical multilayer structure or a spherical multilayer structure. In order to analyze the antenna by the moment method we have to determine the Green's functions for the chosen multilayer structure. For that purpose we have developed an algorithm for determining Green's functions of planar, circular cylindrical and spherical multilayer structures. The algorithm is based on subdividing the original problem into equivalent subproblems, one for each layer, with the tangential field components at the layer boundaries as unknowns. The algorithm is implemented into three versions of a Fortran routine, one for each geometry. The only difference between them is in two subroutines which calculate the electromagnetic field in homogeneous media due to a current sheet, current tube and current shell for the planar, cylindrical and spherical geometry, respectively. The asymptotic boundary conditions for analyzing strips and corrugations are also implemented in the numerical routine. The routine is used in different moment method programs for calculating characteristics of microstrip antennas and periodic structures. We have calculated input impedance and radiation pattern of both planar and cylindrical patch antennas and arrays. Example of the cylindrical designs is the omnidirectional cylindrical patch antenna for wireless communications, and example of planar designs is the broadband circularly-polarized stacked-patch antenna. Furthermore, we have analyzed spherical lens antennas which have ability to form multipole beams that may point in arbitrary directions. The routine is also implemented into the moment method programs for analyzing planar and cylindrical periodic structures which can be used as frequency or polarization selective surfaces, or as soft and hard surfaces. The latter ones find applications in antenna design to improve symmetry of the radiation pattern, to reduce the sidelobe level, and to reduce scattering from the supporting structure of antennas. Furthermore, we have considered some special topics, like calculations of the absorbed power in a lossy half-plane, cylinder and sphere when there is a source antenna in the vicinity of them, which in usable in designing the handset antennas. We also consider symmetry properties of the Green's functions and of the elements of the moment method matrix.

Izvorni jezik
Engleski

Znanstvena područja
Elektrotehnika

POVEZANOST RADA