Radiation properties of ring microstrip antenna fed by symmetrical cross slot

Abstract

The microstrip ring antenna (R-MSA) system has been studied by many researchers, because it is possible to reduce the antenna size. However, since the R-MSA has high impedance characteristics at the feeding point, impedance matching is difficult. We investigate the R-MSA element fed by a symmetrical crossed slot (SCS-R-MSA) which easily permits impedance matching. We describe a new type of dual polarized planar antenna with two-port lines coupled to the R-MSA through a symmetrical crossed slot. A circularly polarized planar antenna using this R-MSA as a radiating element and its array are described. In order to evaluate the performance, some planar antennas were tested at C-band. In this experiment, the basic design of both the dual and circularly polarized planar antenna systems were investigated.