The 21-20-21 is a lightweight, top loaded small VHF blade suitable for helicopters and fixed wing aircraft operating up to Mach 0.85. Use of loss less matching enables this antenna to significantly exceed the minimum operation performance standards (MOPS) for gain defined in DO-186B as required by TSO C38d. Design uses a glass loaded, thermoplastic, one-piece moulded blade with internal radiating and matching elements, fully sealed and filled with closed cell foam. A short, lightweight aluminum alloy top loading bar and leading edge protector combine to provide a highly efficient antenna with a very small profile.