Tilting Antenna for Better Reception
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Antenna Tilting Theory and Practice
If I, in the Vancouver area, am aiming for SeaTac stations, I need to bear in mind that 110 miles away a TV signal emanating horizontally from there is not arriving here horizontally, but rather with a slight upwards angle, so it is therefore theoretically most efficient to aim my antenna slightly downwards
to match the angle. Having said that, in real-life practical terms pointing the antenna downward usually means worse reception! The usual method of tilting is to aim the antenna at the tops of the local trees and then testing, re-tilting, testing, repeating, etc. etc. to see if any improvement in signal strength is found.
Antennas on rotors are not good candidates for tilting. The tilt might be be efficient for one group of stations in one direction but not for others at a different bearing. For that reason tilting should rarely be used on rotor-mounted antennas.
Another situation that might call for tilting is if your antenna is statically mounted in line of sight to a broadcast tower, in which case you would tilt the antenna to point right at the top of that tower and run your signal strength tests. If you're using line of sight, a yagi is simple since you can aim it like a rifle. For a bowtie reflector, use a carpenter's square with the long section heading straight out from the centre so you can aim it like a rifle.
I hope this helps, and if I find any of those tilt calculators I'll post it in this thread. Is there a particular aiming scenario you are thinking about, bsr2002?
Some people who are far away from desired stations get an improvement using slight tilting, and I've seen charts of recommended tilt based on distance to the transmission antenna. This has to do with the curvature of the earth and any obstructions in the way between the transmitter and the receiving antenna. Antenna tilting can work well for some people, but might have no effect at all for others. Tilting an antenna is a time consuming process since we're talking about a very small degree of arc to be adjusted each time you test.bsr2002 said:
If I, in the Vancouver area, am aiming for SeaTac stations, I need to bear in mind that 110 miles away a TV signal emanating horizontally from there is not arriving here horizontally, but rather with a slight upwards angle, so it is therefore theoretically most efficient to aim my antenna slightly downwards
to match the angle. Having said that, in real-life practical terms pointing the antenna downward usually means worse reception! The usual method of tilting is to aim the antenna at the tops of the local trees and then testing, re-tilting, testing, repeating, etc. etc. to see if any improvement in signal strength is found.Antennas on rotors are not good candidates for tilting. The tilt might be be efficient for one group of stations in one direction but not for others at a different bearing. For that reason tilting should rarely be used on rotor-mounted antennas.
Another situation that might call for tilting is if your antenna is statically mounted in line of sight to a broadcast tower, in which case you would tilt the antenna to point right at the top of that tower and run your signal strength tests. If you're using line of sight, a yagi is simple since you can aim it like a rifle. For a bowtie reflector, use a carpenter's square with the long section heading straight out from the centre so you can aim it like a rifle.
I hope this helps, and if I find any of those tilt calculators I'll post it in this thread. Is there a particular aiming scenario you are thinking about, bsr2002?
Tilting Antenna for Better Reception?
Hi there.Thanks for all your answers guys. Here is another one. I just read article about reception of distant TV stations and they say that when you have TV tower out of site, signal is coming not just from that direction, where transmitter is, but is coming from about. Anywhere from 4° to 20°. Depending on terrain on the way from transmitter. So antennas type 4B should have array elements facing signal. If antenna is out by apr. 2° lets say top element gets it first, then signal is transmitted out by bottom element, so you get nothing. That is some kind of " gimmick" of stacked antennas. Also they recommend 4B antenna to be placed on face of building ,or in middle of roof, where homogeneity of signal is better. On top of building is better antenna type yagi. According to that article So I guess I'm going to try tilt my antenna. I hope that, what I wrote is making sence.
Hi there.Thanks for all your answers guys. Here is another one. I just read article about reception of distant TV stations and they say that when you have TV tower out of site, signal is coming not just from that direction, where transmitter is, but is coming from about. Anywhere from 4° to 20°. Depending on terrain on the way from transmitter. So antennas type 4B should have array elements facing signal. If antenna is out by apr. 2° lets say top element gets it first, then signal is transmitted out by bottom element, so you get nothing. That is some kind of " gimmick" of stacked antennas. Also they recommend 4B antenna to be placed on face of building ,or in middle of roof, where homogeneity of signal is better. On top of building is better antenna type yagi. According to that article
So I guess I'm going to try tilt my antenna. I hope that, what I wrote is making sence.Hi kgb, this is from Post #21 in the OTA FAQ:
WIth a GH, 4 Bay, or 8 Bay antenna there's an easy way to change the tilt: just loosen the upper U-bolt nuts and then remove the lower U-bolt nuts, then insert several plate washers to force the lower part of the antenna to stick out a bit more, which increases the upwards tilt with each washer. Tighten them up and test.
For most people the idea of antenna tilt doesn't have much importance, but If you are in a deep to deepest fringe area and are able to change the angle of tilt then go ahead and do some tests and see which angle works best for you.
WIth a GH, 4 Bay, or 8 Bay antenna there's an easy way to change the tilt: just loosen the upper U-bolt nuts and then remove the lower U-bolt nuts, then insert several plate washers to force the lower part of the antenna to stick out a bit more, which increases the upwards tilt with each washer. Tighten them up and test.
My main UHF rig is on a manual tilt mount, and I have it leaning back somewhere around 5-9 degrees, which gave the best signal when I originally lined it up for analog UHF-18 -- a very deep/far fringe signal. Here, at least, the tilt made a noticeable difference.
Now that UHF-18 is off-the-air for good, I should really recalibrate the tilt for its digital replacement channel on UHF-23.
On the workbench, is a small clockwork-style geared motor assembly, about the size of a person's hand. I plan to use it as the basis for a simple shop-built tilt motor for remote control/adjustment. Someday.
Now that UHF-18 is off-the-air for good, I should really recalibrate the tilt for its digital replacement channel on UHF-23.
On the workbench, is a small clockwork-style geared motor assembly, about the size of a person's hand. I plan to use it as the basis for a simple shop-built tilt motor for remote control/adjustment. Someday.
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Stamp,
I do have excellent results from my 4221 HD clone. As you know living here in London, On; I am like 95 to 110 miles to Americian DTV signals. My newest setup has two connected together with one towards Detroit and the other at Cleveland. They are connected together by two 30 inch identical RG6 cable to a splitter (3.5 dB per side) used backwards as a combiner. I have spaced them about 29 inches apart. With the one pointed towards Cleveland, I do not use the built in tilt feature (it's crap) but I tilt it about 10 degrees back from 90 degree position. This produces nice results but not for reliable everyday watching, as you my already know.
Currently I live in an apartment in Kansas City and I've been using a CM 4228 (older model not new HD) mounted a couple of feet off the floor facing a sliding glass door. I have found that some signals will improve if I do tilt the antenna forward about 45 degrees. I lean the antenna against the sliding glass door to accomplish this. I am guessing that it cuts down on the multipath that affects most of the signals I watch.
My guess is that each environment is a bit different and in some cases tilting the antenna will work and in others it will not. Also, it probably depends upon the kind of antenna you are using as well.
My guess is that each environment is a bit different and in some cases tilting the antenna will work and in others it will not. Also, it probably depends upon the kind of antenna you are using as well.
Breakups / Interference: WNLO & WNYO
I have noticed that I have breakups/interference quite often for US channels, especially on channels 23-1 WNLO-HD and 49-1 WNYO-HD. I can be watching 23-1 WNLO-HD or 49-1 WNYO-HD at 60% to 70% signal strength and then it is just frozen (or, it's showing "no signal" or "signal cannot be decoded") for one or more seconds. One thing that I noticed is that when I had the breakouts/interference, in most cases, I heard airplane.
So I was wondering if airplane is the cause of the breakouts / interference (However, for ABC (7.1), so far I haven't seen any noticeable breakouts). Or, is it something else (e.g my TV)? Or, may be it's normal?
PS: I angled the antenna (4221HD) a little bit (may be about 10 degree) toward the horizon. I am not sure if this may cause the breakups.
Thanks.
I have noticed that I have breakups/interference quite often for US channels, especially on channels 23-1 WNLO-HD and 49-1 WNYO-HD. I can be watching 23-1 WNLO-HD or 49-1 WNYO-HD at 60% to 70% signal strength and then it is just frozen (or, it's showing "no signal" or "signal cannot be decoded") for one or more seconds. One thing that I noticed is that when I had the breakouts/interference, in most cases, I heard airplane.
So I was wondering if airplane is the cause of the breakouts / interference (However, for ABC (7.1), so far I haven't seen any noticeable breakouts). Or, is it something else (e.g my TV)? Or, may be it's normal?
PS: I angled the antenna (4221HD) a little bit (may be about 10 degree) toward the horizon. I am not sure if this may cause the breakups.
Thanks.
What you're experiencing is a phenomenon known as "Airplane Flutter"
Since you live near the Airport the jets are coming in low over your home and they are reflecting the signal causing a multipath
Airplane flutter is a very important problem. It
causes the receiving antenna to receive both direct
signal by the Tx (Transmitter antenna) and reflected
signal scattered by the airplane with phase delay. The
sum of two signals results in fading, sometime collapse
and distortion of picture on TV screen.
http://2003.iccas.org/Full_Paper/airp_ICCAS2003_5(19).pdf
This document on the subject deals with the phenomenon on VHF and analog TV signals… however Digital TV on UHF is affected too in the exact same way.
A well known solution to this problem is to stack 2 identical antennas vertically connected together in phase.
Where I live in Mississauga I get jets flying in right overhead doing their approach to YYZ. When I was using a Wingard 9032 I use to experience the Airplane flutter problem on WUTV digital 14. But for the last 2 years I switched from using the Wingard 9032 to a more sophisticated antenna the DAT-75. The DAT-75 uses 3 vertically stacked beams at different vectors. I just wanted to point this out… since this antenna seems to have solved the Airplane flutter problem I was experiencing.
Wingard 9032
DAT-75
If its aircraft flutter it can also be stopped by adding shielding above the antenna: http://www.digitalhome.ca/forum/showpost.php?p=927222&postcount=52
Stampeder/HDTV101,
I tried restoring the mast and I lost some channels. So, I put it angled just a little bit and they are back. I still notice the interference, and again, I heard airplane when it happened. I guess it is airplane flutter as HDTV101 said. I guess the simplest way to fix this would be to put the shielding (rather than to stack identical antennas). I'll try this first and see what happens.
Stampeder, I looked at the link you gave me. Is there more detailed explanation as to how big the shielding is, how to attach it to the antenna etc.?
HDTV101, rather than stacking 2 antennas, would it be helpful if I replace my CM4221HD with CM4228HD?
Thanks.
I tried restoring the mast and I lost some channels. So, I put it angled just a little bit and they are back. I still notice the interference, and again, I heard airplane when it happened. I guess it is airplane flutter as HDTV101 said. I guess the simplest way to fix this would be to put the shielding (rather than to stack identical antennas). I'll try this first and see what happens.
Stampeder, I looked at the link you gave me. Is there more detailed explanation as to how big the shielding is, how to attach it to the antenna etc.?
HDTV101, rather than stacking 2 antennas, would it be helpful if I replace my CM4221HD with CM4228HD?
Thanks.
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