I think the definitive analysis of this antenna has been done by W4RNL: http://www.cebik.com/wbfd.html The analysis shows that on 40 through 10 the gain is about -6 dB compared to the same length doublet fed with lossless feedline. On 75 meters, it's about -9dB on 80 meters, it's about -13 dB Dave Hachadorian, K6LL Yuma, AZ