Low-profile mounting-tolerant folded-out annular slot antenna for VHF applications

The goal of this investigation is to obtain mount-independent low profile, tunable antenna operation over VHF and UHF with an omni-directional azimuth radiation pattern for both line-of-sight (LoS) and SATCOM functions thus replacing multiple antennas (including an 8 foot long whip) on current Marine Corps vehicles. The baseline form-factor was an annular slot antenna (ASA) 24" times24" times2.5" with the UHF antenna integrated into the center disk of the ASA. The VHF antenna was to be tunable across two bands of operation, 30 - 88 MHz and 136 - 174 MHz. Thus, at the low end of the band the antenna is extremely small electrically: lambda/14 in diameter and lambda/143 in depth.