New design methodology for electrically small HF antenna

The design of electrically small HF antennas continues to be a challenging effort, primarily due to the tradeoffs involved in reducing antenna electrical size while attempting to maintain some level of acceptable impedance and bandwidth at lower frequencies. Current doctrine dictates that optimization can only be achieved when the conductive elements are placed on the surface of the sphere enclosing the volume of the antenna. This paper presents an alternative design methodology that actually uses the inner volume to achieve self-resonances at much lower frequencies within a given volume, with performance consistent with the fundamental properties related to antenna height, volume, and wire length. This methodology offers designers an alternative when the design requirements and restrictions on maximum height and volume would otherwise not support self-resonance at a lower required frequency. Four alternative designs have been simulated and performance parameters including radiation resistance, Q, bandwidth, and the minimum operating frequency have been compared. Results from these simulations are presented and tradeoffs discussed.