I see that this is your FIRST post on this forum....congrats, you'll see many other similiar posts.
is the first stop: enter location as accurately as possible
(I use GoogleEarth) into "Online TV Maps" and enable "Show lines pointing to each transmitter"
or enable individual transmitters to see colorized medium-rez RX signal level map.
[High-rez (*.kmz) maps can be (torrent) downloaded for installation into GoogleEarth.]
Enter desired antenna height above ground. Click on RX Icon to reposition.
[Which means you'll want a laptop with some sort of Wireless I-N connection.]
If you don't want to rely on making a Wireless I-N connection in the field, there are some
general purpose Propagation Prediction Programs, such as Radio Mobile
that you can readily find and download for FREE...but requires quite a bit of set-up time....
At top right of chart, you can click on "Radar Plot" to go to the Results page (all text).
You can copy/paste that URL (http://thingy
at top of browser) into a post on this forum.
Net-Margin (NM) indicates how much EXCESS signal strength is predicted if using a 0 dBd
Gain Antenna with zero loss to the Tuner. Adjust NM upwards with the Antenna Gain and
downwards by what we call the "System Noise Factor". You'll see that andy.s.lee colorized
the reception likelihoods, based on a "typical" outdoor antenna implementation....YMMV...
System Noise Factor (using a Preamp) consists of Balun & Antenna-To-Preamp Loss plus
the Noise Figure (NF) of Preamp plus post-Preamp Coax & Tuner NF contribution to
System Noise Figure (which is reduced by Scalar Gain of the Preamp)....
Or if NO Preamp: SystemNoiseFigure = Balun + Coax/Splitter Downlead Loss + Tuner NF:
BTW: "Cascaded Noise Figure" label is incorrect....that would be a DIFFERENT spread sheet,
using a Preamp AND a Distribution Amplifier....NOT recommended unless you really DO HAVE
and USE the correct spread sheet.
Fol. chart is also useful, presuming a (very good) 6 dB NF Tuner (add Balun Loss):
Raw & Net Gain vs Frequency curves for many antennas can be found here (also follow links):
Don't overlook "Files by holl_ands"....lots of useful info....esp. Intermod Distortion, aka "Overload".
NM "should" be positive by 10-20 dB to ensure year-round performance in the presence of
multipath, co-channel & adjacent interference, man-made interference (esp Lo-VHF), etc.
This is frequently called the "Fade Margin" in communication systems....
You also might need to guesstimate additional losses due to trees, surrounding buildings
blocking the signal (good luck!!!!), clutter loss if the signal grazes the rooftops and indoor loss
if located indoors (est 13 dB +/- 7 dB)....or more if Low-E glass & aluminized moisture barrier.
Yes, some people get intermittent reception with slightly negative NM...but troposcatter
propagation (esp across water) can't be relied on.