Pierre Desjardins wrote:

I read somewhere that the dual rhombic could give a gain of almost 27
db using these dimension for 144,2 mHz:

L1- 29.5 ft, L2- 50.67 ft, X- 52.2 degrees, Y- 37.7 degrees, R1/2 660
ohms noninductive, Ht: 12.29 ft, Elevation angle: 7.5 degrees, Vertical
beamwidth: 5.5 degrees and Horizontal beamwidth: 8.5 degrees.

Has anyone ever verified this? Here, using simulation with EZNEC+, I
get about 15 dBi in free space and much lower on real ground. Am I
missing something?

No - it was a complete mistake.

First it was an optimistic estimate from pre-computer days. Then too
many different people each added another 6dB for ground gain.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek