Sal M. Onella wrote:

SNIPPED

I see the gain figures on that beauty and I puzzle over why the dBd and dBi
gain figures are so far apart -- about 7 db. I expect a difference
somewhere in the 2 - 3 dB range. IIRC it's 2.2 dB. What am I missing?

Before I sent this, I did a Google search using some of these terms and
discovered "ground reflection gain," a term I have never seen before, except
in connection with EME with the moon near the horizon. Is this a realizable
gain or damnable inflation of gain numbers?

TKS.



BOTH!!

Ground reflections CAN add to the 'freespace' gain at certain antenna heights
and angles of incidence. The ground reflected wave is is phase with the incident
wave.

'damnable inflation' ... well if one manufacturer uses the term in it's
marketing literature then the competitors will follow. Then 'gain' comparisons
go to H..L!

The best comparison is free space gain [calculated] as dBi or dBd.

I used to mamange a microwave antenna test range. Out antennas were installed
between 20 to 30 wavelengths above ground to reduce 'ground effect confusion'.