Equilateral Delta Loop for 40m with 30ft base height, very good ground
THE DELTA LOOP IS A MONOBAND ANTENNA
Although the vertical-plane delta loop either pointed up or down and fed virtually anywhere will radiate well enough to provide contacts, it is a relatively poor performer in any configuration when stretched to other bands, compared to even the simplest substitute. Modeling of Delta Loops and similar antennas has proven to be a quite reliable indicator of performance, since nothing in the antenna type even approaches, let alone exceeds, the limits of the software for accurate modeling. So the following notes may be useful. These notes apply to vertical-plane equilateral delta triangles, although with some variation, they apply equally well to vertical-plane right angle deltas. Modeling was done on NEC 42.
The antenna should be relatively close to the ground. For a 40 cmeter model, 15 to 30 ft up to the bottom is max, and models suggest that this scales for other bands. If higher at the bottom than about 0.2 wavelength, then a second high angle lobe develops, and stronger, closer in stations can override more distant stations, even if the lobe is not dominant in the pattern.