View Full Version : Pointing the antenna correctly does make a difference


wa2ise
10-11-2013, 04:42 PM
I was upgrading the "MATV" (master antenna TV) network at my mom's. Replacing the RG59 with RG6 for less attenuation. But I was getting erratic reception on some local NYC stations. I went to tvfool.com to find out where the signals of interest would be coming from. So I got the angle from true north, but the house is not orientated directly north-south, but at an angle. So I got a google map to get that angle (house is parallel with the street).
Once I got the above angles, I could point the antenna more accurately (I was off by about 15 degrees). The diagram shows my analysis.
http://videokarma.org/attachment.php?attachmentid=180457&stc=1&d=1381524116
This solved the erratic reception. :banana:
http://www.wa2ise.com/radios/tvantennas.jpg This is that antenna, VHF but I gets enough UHF to work those channels as well.

Username1
10-11-2013, 05:23 PM
Dam, I use to ride my bike along those streets years ago..... Tons of stations there.....
50% Spanish though.... Maybe more...

ISawItOnTV
10-11-2013, 07:32 PM
I was in antenna hell for about 2 months this summer after we got a new Panny plasma 65" ST60. Apparently, it uses up much more signal than our previous TV did. We only have OTA, no cable or satellite. And here's the crazy thing, we were getting around 30+ digital station with the Panasonic sitting on our entertainment center, but once we mounted the TV on the wall, it degraded the signal on many stations. Tried several antennas, preamps, changing wires, FM traps and nothing seemed to help. Since we record on Tivo, we don't use an antenna rotor.

So, as it stands right now, we have one sweet spot for the antenna, and can now get most of all the stations in our area after some tweaking with the antenna, but weather does effect several of them. Still puzzled why wall mounting degrades the signal. :scratch2:

Username1
10-12-2013, 09:09 AM
you have a bad spot in the wire, or noise from some wiring in the wall, and when you bring it closer to the wall, it gets interference. Your new tv does not use more signal, there is either something wrong with it, or it is not as sensitive as your previous setup.

ISawItOnTV
10-12-2013, 02:01 PM
you have a bad spot in the wire, or noise from some wiring in the wall, and when you bring it closer to the wall, it gets interference. Your new tv does not use more signal, there is either something wrong with it, or it is not as sensitive as your previous setup.


I thought about the wall wiring at the time, and cut the power to those wires to see if it made any difference, but no change. The only thing I can figure what may be the cause, is our incoming antenna cable is buried inside the wall just behind the tv, and there could be some interference between it and the tv. I may try some more experimenting when I get the time, but right now we're getting pretty good signal from most of the main channels we watch. We also have a rather powerful tv tower within a few miles of us that could be causing some of this.

Username1
10-12-2013, 05:18 PM
Well if the antenna wire coils past itself, that can increase, or decrease the signal, I have seen that, no matter what the wire. After I pointed my antenna I tweeked it a few degrees left and right to get the sweet spot for a weaker station, the strong one dipped a little, kinda little compromise on the signal.... Its strange doing it with that signal meter, after using it for a day or two, you may have to turn it a little go smooth things out..... Everything effects it, the rain, clouds, farts, wind, seasons, leaves...... Time of day in some cases....

I had trouble with noise, needed to tighten all the connections with a wrench, then also run a extra ground to all the connections on the boosters, and connect it to the ground on the outlet, as well as the ground rod outside.... I think some of it was eddies.... And got end caps for the unused outlets on the signal splitters... Got 1 to 5 splitters in bulk for a good price, then got the end caps while tracing the noise.... I know there is a real name for them, I just don't remember it.... Kinda like the end caps for SCSI boxes years ago, Terminators, I think they were called... A friend of mine called them end caps so the little SCSI's wouldn't get out.... : )

You're lucky you are in such a good signal spot. I'm 70 miles from NYC and when the guy 3 houses away eats kielbasa, and farts outside, there goes channel 2 for the night....

And if I wanna tape something we can't turn on or off any lights in the house or I get drop outs....

DavGoodlin
10-15-2013, 01:10 PM
That VHF antenna in your picture is quite a directional one with a high front-back ratio, so being off by 15 degrees would make a huge difference. Those beasts like yours (looks like an Antennacraft-made, Archer design) must be dead-on, even with strong signals. I have some polar plots from the JFD designs which are similar.

The low-band VHF can tolerate being off beam (no lo-band V in NYC) but by the time you're up to channel 11 and 13, even 10 degrees will result in sufficient multipath (visible only on a spectrum analyzer) to raise the bit-error rate thus disrupting reception.

I found four things that will totally f-up ASTC reception, in order of difficulty to resolve;
1. twin lead or 300 ohm balanced line from the antenna - switch to RG6 coax and matching transformer at the antenna connection
2. switching noise from hi-wattage, multi-lamp electronic lamp ballasts and other noise sources - try a capacitor across/inductor in series with the source of noise or high-pass filter on the antenna, keep electronic-ballasted fluorescent lamps away from the receiver
3. multipath interference (analog "ghosting") due to signal path obstructions, trees moving with the wind, vehicle traffic, aircraft - strengthen primary signal by relocating antenna and/or changing (not necessarily increasing) the mounting height
4. Weather - I am still trying to figure this one out, but clouds, fog and rain are all bad in differing ways - BUT this affects mostly the weaker, non local channels

Username1
10-15-2013, 01:55 PM
Dav; My parents live very near Ridgewood, and they get everything with rabbit ears and a UHF bow-tie attached to one of the rabbit ears... So that antenna on wa2's house, is way overkill for that area. I would say his problem is too much antenna and its picking up lots of multi-path from the buildings... It should be up higher as well, where it is its just getting more multi-path...

And I'm saying this because its ATSC, it may have been great for analog..

wa2ise
10-15-2013, 03:22 PM
... So that antenna on wa2's house, is way overkill for that area. I would say his problem is too much antenna and its picking up lots of multi-path from the buildings... It should be up higher as well, where it is its just getting more multi-path...
...

Lots of signal here, but as I have a 4 way splitter that then feeds 4 rooms around the house, some runs of cable 60 feet. All cable is RG6, used to be RG59. I'm on the top of a hill, and if not for trees I could see the Empire State Building. I figure an oversize antenna is better than amplifiers, in theory no intermod except in TV front ends. Back in the analog days we got 27mV of channel 4. And there is a low VHF station in NYC, WKOB, on RF channel 2, 300 watts. Virtual channel 42. I doubt you could receiver it 75 miles out, though. One of their subchannels is a Jesuscaster, another is a Mohamedcaster. :D

Username1
10-15-2013, 04:03 PM
Actually A distribution amp is better than a giant antenna that can really catch the multi-path....

I see the station you are talking about, not very strong. Rabbitears.info has some guy in Fairfield CT saying he gets it borderline... I don't know what the distance/terrain differences are with you and that guy.... It also seems to indicate your station is on Trump Tower. A Religious station transmitting from atop the devils lair.... How-that-come-about.... Only 973 feet tall.... You might just need to raise that antenna up 10 feet.... They show you well within the coverage map with a good signal...

Well, good luck with how you do it, there is always tuned attenuators for the other stations if they are too strong. Maybe you don't need the dist. amp without getting an attenuator.....

My strongest station is 54 24x7 bible movies, and more on the other subs, I bet you would trade that..... I can get that one in the house with no antenna... They are on a hill, I can see it from some parts of town... I think it gets into my dreams too....

You might get 54 with a good UHF antenna pointed towards poughkipse.

http://www.rabbitears.info/market.php

Ed in Tx
10-16-2013, 11:34 AM
You might do better rejecting multipath WITH a big high gain antenna. Narrower front lobe width, deeper nulls. Adjusting-rotating the antenna to put the reflected signal in a null. That's what I have to do here. Terrible multipath. Last week one of my low power stations got weak, the antenna (old RadioShack-Antennacraft) is in the attic of the garage on a camera tripod. I moved the whole thing over 18" and got my "Retro TV" channel back, from unwatchable, to a 70-75 on the signal display. Just an 18" move made all the difference.

Zenith26kc20
10-20-2013, 03:25 PM
Watch out for balun problems. A lot of the newer ones may look potted (RCA at Lowe's) but they are not. Before you install any balun outside make sure it is well sealed. Also, use a protective grease on the F connector and tape it up to keep moisture out. Don't use the little baluns from the cable company. They are very poor in performance and die quickly outside.
If you use an amplifier, mount it inside. Sometimes I have to take the amplifier (Channel Master 7777, the one with two inputs) out because the weather may cause conditions where you get too much signal for the amplifier.
Plasma TV's are electronic noise makers. If I run mine with anything near the back it upsets it. Mine has no tuner and it will drive the external tuner crazy if it is too close. Ever notice they have metal backs compared to plastic on LCD/LED sets.
Does the Panasonic have a signal strength meter. I know some Sony sets do not. It is very helpful as sometimes the antenna has to be aimed a few degrees off. In actuality (if my memory is right) the signal strength meter really shows decoding quality.

Username1
10-20-2013, 03:45 PM
I wonder what the signal strength meters are actually based on, because I have seen cases where I have no picture, the little blue thing that says "no signal" moving around the screen, and the meter is up to where it normally would be, as if the carrier was there, but no actual digital picture/sound information there..... This is on a insignia/zenith D to A converter....

And I agree with putting pre-amps, and other antenna amps inside.....

boora2
12-26-2013, 02:42 PM
Well if the antenna wire coils past itself, that can increase, or decrease the signal, I have seen that, no matter what the wire. After I pointed my antenna I tweeked it a few degrees left and right to get the sweet spot for a weaker station, the strong one dipped a little, kinda little compromise on the signal.... Its strange doing it with that signal meter, after using it for a day or two, you may have to turn it a little go smooth things out..... Everything effects it, the rain, clouds, farts, wind, seasons, leaves...... Time of day in some cases....

I had trouble with noise, needed to tighten all the connections with a wrench, then also run a extra ground to all the connections on the boosters, and connect it to the ground on the outlet, as well as the ground rod outside.... I think some of it was eddies.... And got end caps for the unused outlets on the signal splitters... Got 1 to 5 splitters in bulk for a good price, then got the end caps while tracing the noise.... I know there is a real name for them, I just don't remember it.... Kinda like the end caps for SCSI boxes years ago, Terminators, I think they were called... A friend of mine called them end caps so the little SCSI's wouldn't get out.... : )

You're lucky you are in such a good signal spot. I'm 70 miles from NYC and when the guy 3 houses away eats kielbasa, and farts outside, there goes channel 2 for the night....

And if I wanna tape something we can't turn on or off any lights in the house or I get drop outs....
When my cat farts,sounds like a shotgun,EVERBODY has to go outside.Have to send him to the gas chamber one day.Wait,when he drops his guts our house IS a gas chamber.