Pete, that's a nice image of your vertically stacked HDB8-X antennas.
Quote:
Originally Posted by Pete Higgins
... When I added a second HDB8-X to my TV tower array most channels signal strength improved 1-2 dB...
... but at least one actually appeared to get weaker?
|
Interesting.
There can be certain locations in elevation (height) where an antenna with an aperture that is small in the vertical dimension provides more signal strength than a larger antenna.
Could be that two (not-in-phase) signal fronts simultaneously arrive at different heights within the vertically spaced array (upper and lower portions of the antennas).
Maybe, analogous to the diagram posted earlier under the heading:
Stacked Antennas: Multipath & Diversity Gain?
The post, linked above, contains a drawing of stacked antennas and shows a direct wavefront (D) arriving at the lower antenna with a multipath wavefront (M=-D) arriving at the upper antenna. The signal summation would be less than the direct (D) alone.
A following post will show some measured signal variation versus height, likely the result of multipath.
.