Redes de antenas de microfita circularmente polarizadas moldadas sobre superfícies cilíndricas

Kurzfassung

Microstrip antennas are very well suited to conformal array applications. Mounted on cylindrical surfaces, most of the developments emphasize the design of N-element wraparound arrays for omnidirectional radiation in the cylindrical roll plane. The radiation characteristics for linearly and circularly polarized (CP) arrays have been studied and reported by several authors. Recently, the influence of the number of elements on the quality of the circular polarization has been investigated. Following this subject, the present paper discusses the analysis and the design of CP microstrip antenna arrays conformed on cylindrical surfaces. To illustrate the potential of the developed technique, a CP antenna operating at 2.25 GHz was designed using an effective CAD tool (namely Cylindrical), developed by the Antennas and Propagation Laboratory – LAP/ITA. The radius of the cylinder was chosen to comply with SONDA IV, a Brazilian sounding rocket. Using this element, two array topologies were analyzed. The design of the feeding network was performed using a planar simulator as an approximation because the diameter of the second stage of SONDA IV is larger than one guided wavelength. To validate our assumptions and the design procedure, two prototypes of four elements were manufactured, and the tests results for input impedance and radiation pattern show very good agreement with the simulations.