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Examining the Bandwidth Potential of Volume-Constrained, Electrically-Small, Platform-Based Antennas at the HF Band

In this work, two primary bandwidth considerations for electrically-small, platform based antennas in the HF band are analyzed: coupling element (CE) location and CE design. First, we analyze an all-metallic cuboid platform with dimensions of 3.20×2.76×7.54 m3 at 5 MHz. In this analysis, a variety of electrically-small CE designs, each occupying a fixed hemispherical volume with radius 0.5 m, are considered. The bandwidth potential of each element is examined when mounted at different locations on the platform. This analysis is then extended to a more complex platform: the U.S. Marine Corps Assault Amphibious Vehicle (AAV). The CE type and placement were found to have a significant impact on the impedance bandwidth of the antenna. Though one characteristic mode of the platform is dominant at 5 MHz, contributions of higher-order modes play a significant role in the obtained bandwidth. A scaled model of the cuboid platform and the spherical-cap monopole were fabricated and experimentally characterized. Measurement results were found to be in good agreement with simulations.