If this is more appropriate for the engineering board, please move this post there:
When the Freedom Tower is completed (1,776') will that structure create any type of "null" to the Southwest for stations that continue to broadcast from the ESB? I know that mountains (e.g, West of Denver and East of Seattle) create a barrier for FM& TV signals, but wasn't sure about the impact that a building would have. Thanks in advance. Tom S
I can answer that.
Since there are a couple of miles separating ESB and WTC, the reflection is minimal and not worth the hassle of moving the antennas. Short-spacing will make that even harder.
The master antenna is about the 1,360 ft level. The overall height of WTC will be a "symbolic" 1,776 ft., but that is to the tip of the "antenna". If that is a permanent mast, then it will be included in the overall height, but the reflective material will end at a somewhat shorter height and therefore be invisible to multipath at the street level.
In the case of Empire, the official height is 1,250 to the base of the antenna. Even though it is permanent to us, because it can be removed, the antenna is not included in the overall height by the people who determine these things.
1WTC had a reflective problem and in fact, a radiation problem, with the UHFs radiating into the top floors of Tower 2. From what I was told, they corrected it with a film coating on the windows in the direction facing the antenna. There was an outdoor observation deck on the roof of Tower 2, just as they have on ESB. The difference is, the long term, constant, exposure for workers inside the building. Visitors would be exposed for only a short period of time.
For a period of time, the 102 inside observation deck was closed due to stricter radiation protocols. Empire is unique in sooo many ways. One of which is the only place I know where the average person can stand in the middle of a full power FM signal. The spikes you see around the top and bottom of the windows at "102" are the old Alford master antenna. They consider that a 2 bay antenna. I've always questioned if that might actually be higher ERP than was claimed. After a redesigned master and at a higher level, they don't use ol' Alford anymore, but because it's there, Empire people have to include it in their reports. The windows at 102 have that same film.
Pretty cool, eh?
Jeff in Sa-ra-so-ta!