(06-21-2020, 09:03 AM)TDKPE Wrote: Grounding is only for static reduction and lightning “protection” and has nothing to do with reception.  

Www.tvfool.com has the best locator function I know of.  Use the >>Start Maps<<  button on the right side of the screen, put in your zip code, and drag the little icon to your chimney using satellite view.  Set your antenna height to 25 ft.  If you click the “Show lines pointing to each transmitter” button under the map, you’ll see traces to each tower from your location.  

Click the “Make Radar Plot” button at the top-right to generate a radar plot with a more complete listing of stations and signal characteristics.  The higher the noise margin (NM), the better the signal, as it’s a composite of signal strength and the negative effects that can reduce the ability of the receiver to lock on.  Clicking on any station line will give you an elevation with exaggerated ground features that highlight how your signal from that particular tower is shielded and deteriorated, or not (line of sight).

There’s a ton of useful stuff in there.  The radar plot page even includes a URL to your plot, but it hides your actual location so you can post it online without revealing where you are to any but the crudest degree.  Here’s mine - Lat/Lon are truncated to a generic area.  

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d90384d8cf5f38a

What’s most useful about the radar plot is in helping you determine how much antenna gain you really need, what bands you need to receive (high-VHF plus UHF, or just UHF), and if you need more than one antenna with transmitters in different locations, at angles that preclude reception with a single directional antenna (that’s where Omni-directional antennas come in, though they have essentially no gain by definition).

Oh, and there’s no such thing as a “digital antenna”.  If it’s designed for high-VHF and UHF*, it’ll receive what they’re broadcasting, in full high-def glory.  I’m using a 1950’s rabbit ears with UHF loop for my office TV.  That ‘high def’ and/or ‘digital’ antenna stuff is just marketing, and if one does it, they all have to do it or they’ll lose sales.

*There is essentially nothing broadcast on low-VHF (2-6) any more, except I think in Alaska, since longer wavelengths travel further, more or less.  High-VHF (7-12) and a greatly reduced UHF band (now only 14-51, used to go up to 69, and before that up to 83) are what’s used, so antennas are smaller since you don’t need the giant long elements for low-VHF any more.  But each channel still has the same 6 MHz bandwidth - they just impress a different signal onto the carrier than in the analog days.  Sort of like phone lines for voice that were then also used for fax and computer digital information.

(06-21-2020, 09:21 AM)WxMan Wrote: http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d90384d8cf5f38a

Yep, that's the site I used; thanks for posting that.  I liked the map.  It showed that the strongest stations for our house were along two radials:  about 250 degrees and 60 degrees.  I oriented the antenna to maximize those directions; easy to do since they're nearly 180 degrees apart.

(06-19-2020, 04:58 PM)Scouter Wrote: I have a question about grounding television antennas.

Decades ago we trashed our outdoor antennas in favor of the brand new phenomena of cable TV. Now we are going back (cutting the cord as it's called) and I installed a new digital antenna, a plastic box containing who-knows-what inside.

Right now it's mounted on the chimney with a simple bracket drilled into the chimney. I am still missing a few channels, so I am planning on trying to add a 5' mast that the antenna will sit on, if successful then that is how it will be, otherwise I will go back to the current configuration.

Question: does this type of antenna require grounding? Nothing is mentioned in the installation guide, I've tried reaching out to the company, but turns out they are in China and don't answer emails (wish I had know that before purchasing, thanks Home Depot).

Thoughts?

(06-21-2020, 10:10 AM)Scouter Wrote: As for low-VHF, that's not true. The FCC has been reassigning stations over the last few years to make room for other types of signals. We lost one of our TV stations because it went from UHF to low-VHF and, as you said, it doesn't travel far enough for us to pick it up anymore.

(06-22-2020, 11:02 AM)TDKPE Wrote: Wow, you're right!  I did some sniffing around, and in a nutshell, they're bringing back low-band VHF.  Voluntarily, it seems, with potentially large payouts to vacate UHF channels.  Way lower operating costs, too, since they use much lower power, in part due to the potential to travel too far and interfere with other signals, and that doesn't count the noise problems down at the bottom from almost everything electrical (remember when a passing car's crappy spark wires would mess up the picture?).  But weaker signal strength isn't always such a good thing, either, and without the long elements, folks may not get those channels.  And unless you live right next door to the transmitter, those little flat wall or window 'placemat'  antennas aren't going to work, either.

And now I'm seeing what used to be relatively small 'digital tv' antennas, like the classic Winegard YA7000 (channels 7-51) being sold with extended rear elements as the YA7000C, for channels 3-51.  Saw that today for the first time ever.  It's just an old-time full band Yag, and looks just like the old one except for the extra elements. 

https://www.amazon.com/Winegard-YA7000C-Antenna-Mount-VHF-Low/dp/B07Y2MN2QX

https://www.amazon.com/dp/B07YMG5SPW/ref=emc_b_5_t

The old "batwing" Winegard Sensar antennas which were on just about every RV has a single long element, and was being eclipsed by newer designs with shorter element(s) plus UHF director elements like the Rayzar (looks like a horseshoe crab), or all in a nice plastic case that looks like an arrow head (King Jack), but may be eclipsed back again by the old original design but with the UHF directors.  

https://www.amazon.com/Winegard-8551203-400S-RVW-395-Sensar-Antenna/dp/B003VAZ6OG/ref=sr_1_8?dchild=1&keywords=rv+tv+antenna&qid=1592841518&sr=8-8

https://www.amazon.com/Winegard-RZ-6035-Rayzar-Antenna-Digital/dp/B01B9K5UGS/ref=sr_1_9?dchild=1&keywords=rv+tv+antenna&qid=1592841249&sr=8-9

https://www.amazon.com/KING-OA8500-Directional-Antenna-Signal/dp/B01N1MLFGK/ref=sr_1_3?dchild=1&keywords=rv+tv+antenna&qid=1592841498&sr=8-3

What's old is new again.  I need to keep up better.  

(06-22-2020, 05:25 PM)Scouter Wrote: I don't know how "voluntarily" it is, talking with the local PBS channel, it wasn't their decision to change frequencies.

(06-20-2020, 05:29 AM)Ohio Mike Wrote: The professional installations I've had done over the years all ran the coax through a grounding block on the outside of the home.  Then they ran a bare copper ground wire from the block to the existing electrical ground rod near the foundation.

(06-20-2020, 06:31 PM)chrisntam Wrote: I moved mine from the attic to the roof after I installed radiant barrier.  I grounded it, thinking the grounding is only for lightning.  No strikes so far (about 10 years), but if I get a direct strike, I think the antenna will be the least of my worries.

(06-29-2020, 05:22 PM)Scouter Wrote: Okay, if you're still around I have a question, ready to do this. The electrical ground is on the other side of the house, so running that long of a wire isn't feasible. How would I ground the antenna/coax on the side of the house where I have to install it?