I think Ted is asking if a contour profile has been created for the dorsal vee antenna on the Electra. Bear with me on this for a moment....
Below are two screensnaps of antenna patterns. The first is for a directional AM array. It shows major lobes oriented to the north-east and to the south-west with a minor lobe to the north-west and relatively deep nulls separating the power lobes. Without going into the details of how this array is fed, the orientation and spacing of the towers, the power ratios, and the phase angle, we can see there is pattern where receivers (which are not in the nearfield) distantly to the north-east and south-west would have a better chance of hearing that signal. True, this is not the same as the Electra's setup but again, bear with me for just a little longer....
The second shows a non-directional contour for a low-power FM signal transmitting using a folded dipole antenna. In theory omnidirectional, this signal is shaped by the terrain in the immediate vicinity. This dipole is closer in construction to the Electra's antenna than a simple vertical radiator. (And yes, Niku is essentially flat so there would be no terrain shaping of the signal.)
Though neither of these examples are the same as the dorsal vee antenna on the Electra, I too wonder if the orientation of the aircraft would have any bearing on signal propagation and therefore, signal reception. Given the "donut" in the signal contour which has been previously modeled, was there additionally any phase cancellation due to the off-center feed point of the antenna along with the characteristics of a vee antenna design which could have created a better chance of reception for those listening in certain directions from the aircraft?
Might this have bearing on why the Itasca, though closer (yes - skywave versus ground wave, the harmonics of an unfiltered output circuit, etc.), could only hear a carrier at times while Betty and others heard much more? I'm sure Bob Brandenburg could weigh in on this with much more detail.
(I hope I made sense....)