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I don't see a significant difference if 2dbd is measured in free space or over real earth. Once the antenna is over real earth there is added gain from the ground reflections. So long as the Sigma is compared to the dipole at the same height above real earth, the Sigma should still come out close to 2 db over the dipole. Because the phase of the cone on the Sigma is in phase with the top 1/2 wave, this also means any currents descending on the mast will also be in phase up to a 1/2 wavelength down from the connector feedpoint. Contrary to what W8JI says, the performance of this antenna improves with mast and coax as a result of this.

[QUOTE="Shockwave, post: 414671, member: 10882"] I don't see a significant difference if 2dbd is measured in free space or over real earth. Once the antenna is over real earth there is added gain from the ground reflections. So long as the Sigma is compared to the dipole at the same height above real earth, the Sigma should still come out close to 2 db over the dipole. Because the phase of the cone on the Sigma is in phase with the top 1/2 wave, this also means any currents descending on the mast will also be in phase up to a 1/2 wavelength down from the connector feedpoint. Contrary to what W8JI says, the performance of this antenna improves with mast and coax as a result of this. [/QUOTE]

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