The antenna appears to be a shortened vertical dipole, using a tuner to enable feeding it. It will work, not as well as a good 1/4 wave vertical with a decent radial field, but it will work. I used a vertical dipole for years, and was happy with it. If it is in fact a vertical dipole, it is not dependant on radials. 20 feet is not long enough to be resonant on 40, so it will probably work best on bands above 40. These are my general feelings about vertical dipoles, not specific to this brand. They work, but my 6BTV with 40 radials works far better than my old ground mounted vertical dipole did. The old ground mounted dipole was almost 40 feet tall.