Spiral antennas are broadband antennae which are extensively used for applications like direction finding radars, radar warning systems, electronic warfare (EW) systems, etc. because of their low profile (planar) structure, wideband characteristics, and circular polarization. However, the practical implementation of spiral antenna is not simple due to its high input characteristic impedance, the requirement for a balanced feed, and to achieve a good axial ratio (<3 dB) for a wide frequency range. For direction-finding radar applications, spiral antennas are usually used in the form of small interferometric arrays. Interferometer arrays in general employ an amplitude and phase-matched set of a few (typically four) spiral antennas and are used to estimate the received signals. This paper presents the electromagnetic (EM) design of a right-handed circularly polarized (RHCP) cavity-backed Archimedean spiral (CBAS) antenna with VSWR <2.2, AR<3 dB, and +ve gain over the frequency range of 2 GHz to 18 GHz. Using the designed CBAS antenna, linear (4-element) and planar (4 × 4) configurations of spiral antenna array are simulated and the corresponding EM performance is evaluated in terms of axial ratio, gain, and radiation pattern. It is shown that non-uniform spacing in the spiral antenna array demonstrates better radiation performance with lower side lobe levels.