I will be doing detailed analysis with "Splat!" etc. on whether or not I can get OTA signals from 70-80 miles away from my home, with a 20-35' antenna. If so, I will be putting up an antenna and doing lots of upgrades.

One thing that this program will not cover is this: I am about 8' elevation from the top of my hill, and between me and the signal source is another house that is a bit higher than mine. I will get on my roof, calculate how tall this house is, etc (there are trees above the house, but I understand OTA signals will go through them reasonably wel). But, to ensure the house will not block the signals: at 70-80 miles or thereabouts, at about what angle (above horizontal flat) will the signals be coming in to my location at? 1 degree? 5 degrees?

Thanks in advance for any info here.

I will be doing detailed analysis with "Splat!" etc. on whether or not I can get OTA signals from 70-80 miles away from my home, with a 20-35' antenna. If so, I will be putting up an antenna and doing lots of upgrades.

One thing that this program will not cover is this: I am about 8' elevation from the top of my hill, and between me and the signal source is another house that is a bit higher than mine. I will get on my roof, calculate how tall this house is, etc (there are trees above the house, but I understand OTA signals will go through them reasonably wel). But, to ensure the house will not block the signals: at 70-80 miles or thereabouts, at about what angle (above horizontal flat) will the signals be coming in to my location at? 1 degree? 5 degrees?

Thanks in advance for any info here.

Keep it straight at the horizon to start. If you are 8' in elevation from the top of the hill, then an antenna 30' up will overshoot it. And, if your antennas is that high up, you'll overshoot the house. The trees are an entirely different story.

So, I say keep the antenna at 0 degrees (horizontal). If you get adequate reception, you're golden. If not, try a slightly higher tilt, but no more than 5 degrees. You'll need a big, directional antenna (such as the ChannelMaster 4228, Winegard HD8200P, or Antennas Direct XG-91) to get them. Once you reach the limits of Earth's curvature (on flat land, assuming a 1500' tower, it's rooughly 60 miles), anything beyond that is a crapshoot. And that also depends on the power of the stations transmitting.

Thanks, Gilbert, for the info.

I actually wasn't even thinking (or meaning to ask) about the angle of the antenna above horizontal. I just naively assumed you put it level, and if the signal is coming in a few degrees above the horizon (which to this layman who did have geometry seems likely) then the antenna would work.

But I was trying to get a feel for at what angle the signal may be coming in. The house whose elevation is 8' higher is actually taller than my house, but its 50-75 feet away. I was going to do the trig to see if it might block the signal. And from your comments on the antenna angle, it seems that the signal would be coming in somewhere between 0 and 5 degrees above the horizon. Do you (or anyone) know this a little closer, is it say 2 degrees? (I assume its not 0.)

Fortunately, I have checked on my topo program, and as the crow files it is almost exactly 60.0 miles from my house to all but one of the towers (the other one, a local ABC station, is more like 75), and the line of sight looks clear. I will run the Splat! program soon and do a detailed check, but I am somewhat optimistic that this will work out. More questions and observations to follow soon, I hope.

The ABC at 75 miles may be kind of dicey, but the others should be receiveable with a large antenna and a GOOD, low noise , pre-amp (the 28dB UHF kind). DO you have a zip code / Lat ./ Long so we can have a better idea ? One good site for this kind of stuff is www.tvfool.com .

I will be doing detailed analysis with "Splat!" etc. on whether or not I can get OTA signals from 70-80 miles away from my home, with a 20-35' antenna. If so, I will be putting up an antenna and doing lots of upgrades.

Thanks in advance for any info here.

First go to www.tvfool.com; enter your address and the proposed antenna height. DTV stations that are -90 dbm or stronger will be able to be received with normal antennas. Between -90 and -100 might work and might not. Weaker than -100 dbm will require heroic measures.

Also, try this web site. It has option boxes on the bottom to add obstructions.

http://gbppr.dyndns.org/wireless.super.main.cgi

In your situation, a professional installer would say that you should be .6 fresnel zone clearance above your neighbor's house. The height difference changes significantly from low band VHF to UHF and with the distance to the obstruction.

Neither site will tell you everything that you need to know.

Thanks again, Tower Guys and others. OK, here is more info. Its not looking positive from this newbie's vantage point, though YMMV and if so I would love to hear it.

First of all, though, my coordinates are N 46.722922 and W 117.182822, and the local codes allow an antenna up to 35' high. These coordinates should be accurate to within 2-3 meters of where the antenna would be (and the height could of course be exact).

I ran the tvfool site with this, and except for a few local PBS stations, every digital station it thought I could pick up required at least 100' high antenna (most way more). I think, except possibly for the trees (which this site cannot know about) I have a fairly clear shot to the stations (I live in Pullman, WA and they are for Spokane, south of town on a hilll, but they are pointing away from me so most of their ERP does me no good presumably). I also ran it on antennaweb.org with a silly height of 200', and it did not list any digital stations I could pick up (0ther than the 2 local PBS stations, KWSU-DT in Pullman, WA and KUID in Moscow, ID).

I was going to make some sight pins (like my compound bow) on a 48" level to get accurate readings of the tree heights on the path to my stations, take a picture, and then annotate it with where the signal would directly come through. But, given the above, it is not looking too likely I could get anything. But if I am wrong, I will be happy to do this for you all to consider. I did see some info on the FAQs on how many db to compensate for trees at different angles and distances.

FWIW, here are the station I was hoping to catch (if I had a way to make a nice table I would)

Call Sign Net Chan Freq Dist ERP (W)
KREM-DT CBS 2.1 20 60 893
KHQ-DT NBC 6.1 15 60 425
KAYU-DT FOX 28.1 30 60 335
KXLY-DT ABC 4.1 13 ~75 23.3

Again, note that the ERP is from an FCC table, and is pointing in the opposite direction from me. Also, the ABC channel for some reason has a really low ERP so at 75 miles or so even if I could get the rest this one seems quite unlikely.

So is my quixotic quest for long distance free TV over, or should I do a bit more digging (assess the tree obstruction factor as per above)? No matter what, thank you very, very much for all the helpful info provided.

FWIW, here are the station I was hoping to catch (if I had a way to make a nice table I would)

Call Sign Net Chan Freq Dist ERP (W)
KREM-DT CBS 2.1 20 60 893
KHQ-DT NBC 6.1 15 60 425
KAYU-DT FOX 28.1 30 60 335
KXLY-DT ABC 4.1 13 ~75 23.3



Your problem is terrain more than buildings or trees. The four stations listed are all UHF for digital. Your only hope would be a pair of antennas such as the 91 XG or 4228 with a preamp such as the HDP-269 that would not be overloaded by the multitude of PBS stations that are line of sight to you.
http://www.hdtvprimer.com/ANTENNAS/16bay.html
http://www.highdefforum.com/attachment.php?attachmentid=1125&d=1166047876

Fox will be your most challenging station. For CBS KLEW will be much easier than KREM, yet it's in another direction than the others.

Isn't KXLY hi-VHF, not UHF? Looks like its channel 13. The OP would need a VHF antenna as well as the 91 XG won't do VHF and the distance is too great for the 4228 to be effective.

Most yagis have a broad vertical radiation pattern so tilt won't have much effect. TV transmitters on hill tops usualy use down tilt transmitting antennas to get to receivers in shadows from the hill again defeating any tilt.

Once you have line of sight any additional height may have negative effect due to transmission line losses. Be sure to install any pre amp at antenna end of cable. Trees are problem at UHF frequencies as leaves approach 1/4 wave length and absorb the signal.

I'm using a XG-91 mainly because physical size and it works well. I'm only interested in HD (all UHF) and am 30 miles from TXs.

Found this some time ago on AVS: http://69.93.195.178/~electr0/cgi-bin/tilt.main.cgi