Design of a low-profile compound wideband spiral antenna with embedded chip resistors

This article presents the design and simulation of a low-profile compound spiral antenna with embedded chip resistors and a wideband balun. To obtained low-profile characteristic and solve the problem of bidirectional radiation, a lossy cavity with a horizontal balun is adopted. The simulated and measured results show that the VSWR is less than 2 and the axial ratio is less than 3 dB in the frequency range 1 to 18 GHz (18:1). In the operating band, the antenna presents good circular polarization and wideband properties.