A new two-arm spiral antenna topology named power-spiral with inherently low dispersion is proposed. When compared with conventional Archimedean spirals, up to 40% improved fidelity factor is achieved thus eliminating a need for auxiliary dispersion compensation circuitry. It is, however also shown that the power spiral's axial ratio is noticeably compromised. To enhance the power spiral's frequency domain characteristics, a combined Archimedean/power spiral antenna is developed. Results show that the proposed spiral topology has simultaneously good frequency and time domain performance.