Design and Study of a Circular Polarised Conical-Disc-Backed Spiral Antenna for X-Band Applications

Design of a conical-disc-backed circular-polarized Archimedean single-arm spiral antenna is presented in this paper. The antenna operation covers the <inline-formula> <tex-math notation="LaTeX">$X$ </tex-math></inline-formula>-band frequencies ranging from 8 to 12 GHz. The antenna makes use of a very simple structure having the single-arm spiral backed by a cone-shaped metallic disc to achieve high gain, circular polarization, and unidirectional symmetric radiation near the boresight. The diameter of the antenna only measures to 40 mm. The simulated and measured results show that the antenna has a very good impedance matching (better than −10 dB), good right-hand circular polarization (with an axial ratio of ≤3 dB) throughout the frequency range of interest, and offers a maximum peak gain of 11.4 dBiC. The presented <inline-formula> <tex-math notation="LaTeX">$S_{11}$ </tex-math></inline-formula> response and radiation pattern results also show that the antenna offers excellent performance in the <inline-formula> <tex-math notation="LaTeX">$X$ </tex-math></inline-formula>-band with no need of a balun. Antenna usefulness is also established through a detailed parametric study and comparison with a traditional flat disc structure. Compact size, simple design, wide range, and high gain make the proposed antenna design a good choice for radar, terrestrial communications, and satellite/aerospace communications applications.