Low-Dispersion Spiral Antennas

A two-arm power spiral antenna with inherently low dispersion is proposed. Analytical, computational, and experimental steps are taken to demonstrate its superior time domain performance. When compared with conventional Archimedean and equiangular spirals, up to 40% improved fidelity factor and pulse compression are achieved. It is, however also shown that the power spiral's mid and high band axial ratio is compromised. To enhance the power spiral's frequency domain characteristics, a combined Archimedean/power spiral is developed. VSWR below 2:1, clean patterns with wobble on the wave (WoW) and axial ratio < 3 dB over multi-octave wide bandwidth, all similar to those of well-performed frequency domain spirals, and more than 34% fidelity factor improvement over the wide-field of view are achieved. Herein presented results show that the proposed spiral topology can have simultaneously good frequency and time domain characteristics and no additional hardware or software is needed to enhance either.