I received this very nice and thorough response from nitewatchman and am posting it here for you to enjoy. It's not too often we here get such a thorough response to a question.
Saw your post asking about the parabolic UHF Dish antenna, and thought I'd reply via PM, as I'm not in your area -- Channel Master used to make these in I believe 6' and 7' diameter versions, but they have been discontinued for quite a while. Certianly, a fine antenna(Considered the best UHF antenna "ever" by some), but, due to it's size and shape, it also requires a lot of "mounting support" due to wind/ice loading. There's a nice pic of one on a 85' tower in the pics near bottom of this page(7' Channel master dish photo -- You'll probably need to right click and choose "show picture" to see the pic):http://www.oldtvguides.com/DXPhotos/
Concerning WCBS-DT 56, along the lines of what you mentioned on the thread, it is certianly the case that becasue of the shorter wavelength's involved, much more power is necessary for a station operating on Hi-UHF channels than is the case on lower frequenices in order to cover the same area, and also, these high frequencies are also more "sensitive" "signal propagation wise" to terrain and other "environmental factors" ...
For example, RF absorbtion by leaves would be much more of a problem on 56 than on lower UHF channels or, even moreso for the much longer wavelengths of VHF. Rain and wind can also be a factor on these high frequencies --- Now, these "environmental factors" aren't really a BIG issue(although terrain/building blockage of signal is a big issue), but if you're dealing with a weak signal coming from your antenna to begin with, a little issue can appear like a big issue. (keep in mind, in nearly all cases, the "signal meters" on our receivers don't measure "signal strength" , it's a sort of "signal quality" meter, which is implemented on the "digital datastream" "side" of the receiver, not the "RF Signal" portion of the receiver ... For this reason, a actual, fairly weak signal, just over the "threshold" needed for good DTV reception can produce High readings on our receiver's meters.
It's also the case that some receving antennas don't do as good of a job on the higher UHF channels. VHF/UHF combo antennas, typcially don't do well on Hi-UHF, for example, although I have had good luck with hi-UHF local DT's here with the RS VU210 antenna, a a LARGE VHF/UHF Combo - which has also been discontinued. Also, Feedline incurs more signal loss the higher the frequency.
Really though, more "reasonably sized", and conventional UHF antennas such as the CM4248 Yagi, CM4228 Bowtie, and some of the European hi-gain antennas from Blake, Televes and Triax are pretty close to the performance wise to the "big dish", and one of these, outside up nice and high with a hi-gain/low noise preamp such as the CM7777 would come very close, if not exceeding the "Big dish's" performance.
Follows is info WCBS-DT's technical parameters from FCC CDBS database, concerning their currently licensed facilities. :
I pulled up WCBS-DT's current Technical paramenters, and given their TX antenna height on ESB(1345FT Above Sea Level), Non-directional antenna, and 349KW ERP power level for their licensed facility(According to FCC data, this is what they should be operating with unless their having Temporary technical problems that don't require issuance of a STA by FCC, or, to meet RF exposure regulations if anyone working on the ESB antennas). You might want to check with them to make sure, on the power, though. One of their Engineer's did start/post a thread recently in local AVS area, asking for reception reports.
If this is the power/antenna height they are operating with however, I'd think they should do a decent job getting out to as far away as around 50 Miles or so, although, the "fringe area guy" at 50 Miles+ from the ESB would likely want a very good antenna setup for UHF, as high as possible, with no terrain/signal blockage issues invloved....
As a bit of a comparision, In our area, for instance, we have a DT on 58 running 290KW ERP, which is being received well on a attic antenna from almost 60 miles distant! Their antenna height, while only about 1000 feet above average terrain, is over 2000FT above sea level.(Most of the terrain in this area, however, is between 600-1100 Feet above sea level).
WCBS-TV NY NEW YORK USA (Digital)
Licensee: CBS BROADCASTING INC.
Service Designation: DT "Full Service" TV Station or Application (digital)
Channel 56 (722-728 MHz) Licensed
File No.: BLCDT -19981026KG Facility ID No: 9610
CDBS Application ID No.: 276124
Antenna Structure Registration Number (ASRN): 1007048
40 ° 44' 54.00" Latitude Zone: 1
73 ° 59' 10.00" Longitude (NAD27) Frequency Offset: None
Polarization: Horizontally Polarized (H)
Effective Radiated Power (ERP): 349. kW ERP
Ant. Height Above Average Terrain (HAAT): 397.0 meters HAAT
Ant. Radiation Center Above Mean Sea Level: 410.0 meters RCAMSL
Ant. Radiation Center Above Ground Level: 395. meters RCAGL
Not in a Border Zone
Anyhow, hope some of this helps, I enjoy looking at the NYC OTA thread, and I hope NYC can get the OTA situation back to "normal" as soon as possible. I know the NYC broadcasters are doing the best they can, but I can't help but think how much different things might be if we were in the 1960's or 70's, before cableTV ... Still, though, I may have missed it, but I'm surprised I haven't seen a Major News story concerning the loss of the WTC OTA transmitters.
Anyhow, take it easy,
Jeff in Middletown, Ohio