Electrical downtilt is created when the phase of higher elements *leads* the lower elements. An easy way to visualize this is to take a multi-element antenna (a dipole array or whatever is easy to picture in your head) and tilt it to the right. The pattern will have downtilt toward the right because the upper elements are now leading the lower elements referenced to the horizon. Likewise, to the left, the antenna will have uptilt.
As compared to mechanical downtilt in the example above, with electrical downtilt the beamtilt is the same around the 360 degree azimuth.
An end-fed collinear antenna that has phasing sections that are too short will result in upper elements leading in phase. That is, rather than having the nominal 180 degree (half-wave) phase delay between elements for an on-horizon pattern, a shortened phasing element will provide less than 180 degrees of delay, so the further up the antenna you go, the further the radiating elements will be leading in phase. .
Andy was correct in his response - an end-fed collinear antenna like a Stationmaster will have downtilt when operating below its design frequency.
--- Jeff WN3A
