With all the hoopla going on for this antenna I was surprised that no
one reported any calculated antenna efficiencies. So I modeled the
antenna in free space - to remove environmental influences other than
those contained within the antenna itself (terminating resistor and
wire loss) - NEC reported the following:

Freq. MHz. Efficiency Average Gain Peak Gain
MHz % DBi DBi

3.5 9.6 -10.43 -8.49
7.15 41.24 -3.85 -1.33
14.2 23.21 -6.36 -1.59
21.2 30.01 -5.23 -1.36
29 53.81 -2.69 2.17

73
Danny, K6MHE