Attach,

Your detailed questions are answered and discussed here on the OTA Knowledge Base:

http://www.digitalhome.ca/forum/showthread.php?t=41102

Attach -

I do not understand why your installation of the distribution amp made things worse. That's how I am set up and works fine. Maybe there is something amiss with your installation.

Check angles to the CN Tower and Grand Island (fun with the web) and give extra bias towards Grand Island and away from CN Tower, using the CN sighting as your basis, not your compass.

Those locations are within 2 degrees apart (rats!) at my house 2 miles west of you, but your difference should be more favourable.

Sadly, my three year old large Samsung plasma in the living room is far worse at getting stations than my more recent Vizio small screen in the computer room, when connected to the same piece of cable for comparison. Big difference.

See the business section of the Toronto Star today (Nov 21) for another consumer-oriented OTA article. Seeing more of 'em recently.

Ben

bentoronto: I don't see that you are using your antenna with a Tivo Premiere or are you? My situation only got way worse when I used the pre-amp (and, separately, a distribution amp) with the Tivo Premiere connected to the antenna. If you read my extensive posts you will see that with my antenna directly connected (ie no Tivo Premiere) to my 65" Panasonic Viera Plasma HDTV the picture improved with the pre-amp. In fact I didn't really need the amp when directly connected but was only testing it in the hopes that it would provide me with the stations through the Tivo Premierie that I had through the HDTV.

So, if you are directly connected you likely won't have a problem with a pre-amp or distribution amp.

Also, I tried every aiming of the antenna imaginable to no avail. Read GeorgeMX's post 2056. I think he nailed what my problem is when using the Tivo Premiere, which problems I do not have at all when using the HDTV tuner only, which is likely designed a lot better.

I doubt many in my area (North Rosedale), which is closer in line with both Buffalo and the CN Tower than those areas of Toronto to the east and west of me, are trying to save money and reduce the number of channels they get by putting in an OTA, lol. Certainly when I stand on my roof and look around I don't see a single antenna. Many that's why we haven't seen a lot of my problem on here.

Wondering if anyone has any ideas about how to possibly add a dedicated VHF-hi antenna to my current combo set-up..

Here's the thing, I have a large combo antenna - 7697 pointed more or less directly south that I'm able to recieve the majority of stations without rotating, the thing is, I like and watch CHCH quite often and now that the temperature that I find myself rotating the antenna back and forth between Buffalo/Toronto & Hamilton. Is there any way to add a dedicated VHF-hi to Hamiton (and potentially CTV2 when built).

Thanks for any thoughts!

Wondering if anyone has any ideas about how to possibly add a dedicated VHF-hi antenna to my current combo set-up..

Here's the thing, I have a large combo antenna - 7697 pointed more or less directly south that I'm able to recieve the majority of stations without rotating, the thing is, I like and watch CHCH quite often and now that the temperature that I find myself rotating the antenna back and forth between Buffalo/Toronto & Hamilton. Is there any way to add a dedicated VHF-hi to Hamiton (and potentially CTV2 when built).

Thanks for any thoughts!

If you read my post #2057 above, I was able to get CHCH and CFTO with the addition of a very simple DIY antenna - didn't even have to put it on the mast. Since your combo antenna is pointing south and there aren't any VHF signals in Buffalo you could disconnect the VHF half of your antenna either directly or through a VHF/UHF joiner further down the line. You could then add a custom-length antenna to get 9.1 and 11.1 (9.1 is ~31" and 11.1 is ~28" so it doesn't need to be big). Either mount it on your mast or somewhere lower. Join it back into the line and see what happens. At the very least you could test it by disconnecting your main antenna and hooking up an old set of rabbit ears that you have lying around.

I'd still like to have my combo pointed at Buffalo to receive WBBZ rf7

There's a ton of info on how to combine antennas in this thread:
http://www.digitalhome.ca/forum/showthread.php?t=95148

Short answer is you can do it, but there are bunch of different options and each method has drawbacks. Is your end machine a mythbox or MCE? If so it might be easiest to just add a USB tuner and a pair of rabbit ears - they might even work in the house.

... I will try the 4228HD, but I am unsure what you mean by stacked. Does that mean to get two of them and put one on top of the other on the pole? Would I connect them together using a splitter? Wouldn't that introduce a signal loss? Also, why would one 4228HD not be enough? I wouldn't imagine that two of them would give me double the gain or signal but exactly what do I get by adding the second one? ...

First, I think you were using magnetic bearing for your antenna direction while I was using true North which results in a difference of about 11 degrees. The angle between the CN Tower and your antenna heading is more like 30 degrees which means your antenna has lower gain toward the CN Tower than I originally thought. A look at TVFool suggests you should aim around 148 true or 159 magnetic based on your location. Farther east will reduce the signal level from the CNT. The angular spread of your desired stations is only about 9 degrees from Ch 49 at 143 true N to Ch 38 at 152 N true.

I am backing away from the suggestion of stacked 4228s. I have been looking for a more directional UHF antenna but haven't found a clear answer. Don't worry about CFTO as a very simple VHF antenna combined with the UHF antenna using a UVSJ will do the trick. Check out what 'digitalformguy' did.

With respect to your questions, stacking means connecting two antennas together with a combiner, which in practical terms is a splitter connected 'backwards'. The two antennas go to the output ports (connectors) and the input port feeds to the downlead. There is plenty of good information on this forum about combining antennas.

Two antennas connected together as a stack roughly doubles the received signal power. In terms of dB measurements, the increase is 3dB less some small losses in the combining network. A 3 dB increase is like doubling the transmitter power of the stations you want to receive. Adding a second antenna does not degrade the signal to noise ratio like a preamplifier. All preamplifiers generate some internal noise which adds to all the signals. Stronger signals with a good signal to noise ratio can stand the addition of noise while weaker signals with a poorer signal to noise ratio may drop below the SNR level that the receiver can tolerate.

There is a limit to what can be achieved with broadband antennas and amplifiers when the range of signal levels runs from very weak to very powerful. In commercial installations, the solution is individual processing for each channel. In the simplest form, a single channel antenna and tuned preamplifier are used to receive each channel. The preamplifier amplifies the desired signal up to a standardized level. The individual channels are combined at the same level so the ratio problem goes away. The solution is generally not practical for individual households.

Tuner technology has improved over the past decade since DTV became a commercial reality in 1999. Your Viera may have a newer generation tuner with greater sensitivity and better adjacent channel filtering than the PVR.

Attach,
I finished my research on antennas. I suggest the Antennas Direct 91XG based on very high gain combined with a very directional pattern. Off the side at 40 degrees the gain is down 15 dB from the centerline value. For comparison, my 4 bay antenna is only down about 9 dB at 40 degrees.

The downside of this antenna is the 93 inch length and complex antenna elements that increase wind loading and provide a place for ice to collect in freezing rain conditions. A strong mounting support is required. The narrow beam width will also make aiming a challenge.

If the Tivo problems are caused by desensitization and overload from CNT and FCP, this antenna might help.

Thanks GeorgeMX. I returned my DB4e and the pre-amp and got a full refund, so I have no antenna now, just the mast, the quad-shield RJ6 running to my HDTV and the Tivo Premiere.

I did to a lot of reading on the thread that HWP referred me to about stacking and did a bit of googling. It turns out that Save and Replay does not have the 4228HD in stock and won't until likely January at the earliest. But, I am curious as to why you have backed away from your recommendation of the stacked 4228HD's for me? What is it about my location or the antenna that won't work?

Update: Just saw your post on the 91XG, which was written while I was writing my post. That one is in stock. Still curious though as to why the 4228HD wouldn't work though (just so I can educate myself). Looking at the patterns for both antennas to me the gain seems down the same for both at 40 degrees or maybe I am not reading the pattern right.

Jakeman,

CTV2, I believe, will be a uhf channel when/if approved.

There is a thread dedicated to combining antennas. Also in the OTA Knowledge Base thread there is a whole section on ganging and stacking antennas.

As I understand it, it might be less complicated to combine two identical antennas. But I'm not really sure.

People with rotators like you are, in theory, able to get a really good antenna and then use the rotator to peak for each station if needed.

If you think that you need a ten element vhf-high antenna to get the most VHF-high gain, then you might think about removing the 7697 antenna and instead installing either a Winegard ya1713 or Antennacraft y-10-7-13 vhf high antenna and combining them using either a pre-amp or a UVSJ (UHF - VHF Splitter Joiner) with a really good UHF antenna such as the Antennas Direct 91xg, or Antennas Direct DB4e, or Antennas Direct DB8, or Channel Master 4221hd or 4228hd. Keep on using your rotator.

Update: Just saw your post on the 91XG, which was written while I was writing my post. That one is in stock. Still curious though as to why the 4228HD wouldn't work though (just so I can educate myself). Looking at the patterns for both antennas to me the gain seems down the same for both at 40 degrees or maybe I am not reading the pattern right.
There are several reasons. First, the stack of antennas would increase gain but not improve the horizontal directivity. They would have to be positioned horizontally to change the horizontal pattern. Second, I could not find the UHF polar antenna pattern for the 4228HD. If you have a link please include it in a post. The original 4228 pattern is available and looks good but the 'HD' version uses different construction and has drawn some unfavourable comparisons to the older version. Third, I went through a number of antenna patterns for existing available antennas and the 91XG seemed to have the cleanest directional pattern combined with high gain. The Winegard 9032 is similar but almost 10 feet long. A single antenna solution is less complicated than a stack and doesn't require a phasing harness. One connection from the antenna to downlead beats 5 when it comes to reliability. I think the wind loading on the stack could also have been a problem particularly in freezing rain conditions. Imagine the reflectors filled with ice that increased wind resistance and added weight to the whole assembly. As noted before, the 91XG is a big antenna too.

The antenna research has been useful for my own purposes. I have completely different reception conditions from yours but I think the 91XG may offer some benefits in my situation. Since the analog shutdown and associated power changes, I receive the CN Tower and FCP DTV signals at high levels. Pre-transition, I needed a broader antenna pattern to receive the local low power digital signals but could go to a highly directional, high gain antenna now. I use a high gain preamplifier to overcome low signal levels on US channels resulting from terrain obstacles. I suspect that the local signals are causing some desensitization and possibly overload which might be reduced with a more directional antenna. I don't have the wind loading issues because my antennas are in the attic.

Thanks GeorgeMX. I did a bunch of research myself and even emailed Channel Master for the 4228HD azimuth pattern as I could not find it anywhere and the response I got was that it was exactly the same as the 4228 and that the HD was only added to the product name for marketing purposes. That of course begs the question of why people have reported different results for the HD version.

I did note that the raw gain of the 91XG and the 4228 for WGRZ-DT Ch 33 584-590 MHz (the channel which it is most difficult for me to get) is almost equal at about 14.3dB judging from the comparison charts at http://www.hdtvprimer.com/ANTENNAS/comparing.html which compares closely to the gain vs azimuth angle pattern for the 91XB at http://www.antennasdirect.com/cmss_files/attachmentlibrary/91XG-TDS.pdf. I tried to read the 4228 antenna pattern at http://www.hdtvprimer.com/ANTENNAS/cm4228.html but no matter how much research I did I could not figure out how to interpret it because it starts from 0dB at the outside ring and keeps going up past 40dB inward which makes no sense to me. Maybe someone can show me how to read it because I've spent an hour trying to figure out how to read it by googling various things to no avail.

I understand the very good reasons you posted for picking the 91XG, but have a few more questions about other aspects of the two antennas which I would appreciate the answers to if you have the time:

1. Given the gain appears to be the same for both antennas am I right in concluding that gain has nothing to do with which antenna to pick? Or did I read the gain wrong?

2. The range of the 91XG is 50-70 miles and the 4228 60 miles so given all my stations are within 60 miles so is that also not a reason for picking one over the other?

3. I note that the 91XG is UHF only while the 4228 is both UHF and VHF. I am not worried about that since I'll use another antenna, as you suggested, to get the two VHF stations I want, Ch 5 and Ch 9, but does a UHF antenna generally work better at bringing in UHF stations than a combined UFH and VHF antenna or is there really no hard and fast rule and it depends on that particular antennas being compared?

4. I see reports that the 91XG has a beam width of 25 deg while the 4228 has a beam width of 15 deg (but then I see reports that it's actually 25 deg). In any event it seems to me a narrower beam width would make the 4228 more directional than the 91XG, yet you say it is more directional. What am I missing? Also, what do you mean by 'cleaner'? Do you mean the gain plots for various channels/frequencies are closer together?

5. My tvfool report is at http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d4bbaca4d736b4b. From google earth i find that the CN Tower is 184 degrees true, so about 195 magnetic (adding 11 deg as per the tvfool true and magnetic difference) at my location and WGRZ is 159 magnetic for a 36 deg difference. I do note that the drop-off looks to be about 15dB from maximum at that angle for the 91XG, as you reported, which means I wouldn't have much gain at all from the very strong stations transmitting from the CN Tower and that is good as it will narrow the difference between the strength of adjacent stations. However my tvfool report shows CFTO-DT, which transmits from the CN Tower (albeit on VHF), at 204 degrees magnetic rather than 195 degrees magentic. Why the big difference? Should it be the same?

In short, GeorgeMX, is suggesting the 91xg is the easiest way to get excellent gain in a single antenna -- with the added bonus (that GeoprgeMX suggests you need) of narrow beam width. Aim at Buffalo and with the xg91 you will have a better chance of attenuating the strong Toronto signals.

The 4228 and 4228hd are completely different antennas. Do a Google image search. A lazy employee e-mailed you the 4228 specs and said there is no difference between the antennas.

Size, materials, and build are all completely different. The new one was altered apparently to lighten the weight and to make it foldable for cheaper shipping and packaging. It would appear that some compromises on performance were required in order to increase efficiencies.

The independent third parties that performed the tests and modeling that you can find around Digital Home and the internet are right.

HWP: Yes, that's what GeorgeMX concluded, but that doesn't answer my very specific questions. Hopefully he or someone else knows the answers. I have read through the thread in great detail that you suggested earlier, btw, but still don't have the answers. Thanks.

I have replied to the person at Channel Master again regarding the 4228 vs 4228HD with that new information to get to the bottom of it.

...I tried to read the 4228 antenna pattern at http://www.hdtvprimer.com/ANTENNAS/cm4228.html but no matter how much research I did I could not figure out how to interpret it because it starts from 0dB at the outside ring and keeps going up past 40dB inward which makes no sense to me. Maybe someone can show me how to read it because I've spent an hour trying to figure out how to read it by googling various things to no avail.


Let's start with reading antenna patterns. The pattern is based on subtracting the plotted dB value from the maximum gain to get the actual gain. The maximum gain is set at the 0 degree position on the outer 0 dB ring because you don't need to subtract anything to determine the maximum antenna gain. If you look at the 4228 pattern, you can see that the turquoise line for channel 50 touches the zero ring at 0 degrees. If you follow the turquoise line clockwise you will get to 15 degrees which is marked by a radial line of dots without a legend. On this radial line, each dot represents 1 dB. The channel 50 line crosses the 15 degree line about 5 dots in from the outer ring, so the antenna gain is about 5 dB less than at the 0 degree line. According to a post by stampeder on 09-01-07, the original 4228 has a maximum gain of 15 dB on channel 52 (close enough to channel 50), so the gain at 15 degrees should be 10 dB (15dB - 5 dB). If the CM 4228HD values from the same post are used, the maximum gain is 11.7 dB so the 15 degree gain should be about 6.7 dB assuming the patterns for the two antennas are identical (which doesn't seem to be correct).

If you go back to the 0 degree radial, you see that the plots for other channels do not touch the 0 dB ring. The antenna has less gain on these channels but in the case of the 4228 the variation is less than 1 dB except for channel 20 according to the pattern.

The pattern around the 0 radial is the main lobe of the antenna. If you look around the 30 degree radial, the lines go down just below the -20 dB circle then rise to around -13 dB. The low point is generally called a notch and the second high point is the second lobe. The pattern of notches and minor lobes is repeated around to the back of the antenna at 180 degrees.

If you look at the antenna pattern for the 91XG, you can see the first notch is around 30 degrees like the 4228 but the second lobe peaks closer to -17 dB which is approximately 4 dB lower. The second lobe of the 4228 is also wider in terms of the number of degrees. Overall, the notch and lobe pattern of the 91XG is less pronounced which is the reason for describing it as "cleaner".

Antenna beamwidth is the number of degrees between the points where the plot line drops below -3 dB. For the 4228, depending on the channel chosen, the beamwidth runs between 20 and 30 degrees. The plot lines are more closely grouped for the 91XG and seem to be around 25 degrees. I think the two antennas have effectively the same beamwidth.

The two antennas are different in gain uniformity across the UHF band. The 4228 has gains within 1 dB except for channel 20 which is about 2.5 dB down. The 91XG is less uniform with channel 20 down a little more than 5 dB. While this may seem to be an issue, consider the fact that signal attenuation through the air goes up with increasing frequency so greater gain on higher channels actually makes sense.

Going back to your questions,

1. Given the gain appears to be the same for both antennas am I right in concluding that gain has nothing to do with which antenna to pick? Or did I read the gain wrong?

The stampeder post indicates the gain for the 4228HD is significantly lower than the 4228 with channel 35 at 10.9 dB vs. 15.7 dB. If this is correct, the 91XG appears to have an advantage.

2. The range of the 91XG is 50-70 miles and the 4228 60 miles so given all my stations are within 60 miles so is that also not a reason for picking one over the other?

The term 'range' is about marketing not technical specification. Both antennas are intended for reception of distant signals. Many people use the 4228HD and achieve good results. After all, the antenna is out of stock.

3. I note that the 91XG is UHF only while the 4228 is both UHF and VHF. I am not worried about that since I'll use another antenna, as you suggested, to get the two VHF stations I want, Ch 5 and Ch 9, but does a UHF antenna generally work better at bringing in UHF stations than a combined UFH and VHF antenna or is there really no hard and fast rule and it depends on that particular antennas being compared?

Dual band design involves some compromises so a combined VHF/UHF antenna may not perform as well as separate antennas if a limitation like size or weight is imposed. The classic high gain lo-VHF, hi-VHF and UHF combos are really big antennas. If you don't use a rotator, a combined antenna is useful if all stations are in the same direction. I have a hi-VHF antenna pointed at CHCH while my UHF points toward Buffalo. In the case of the 4228, aiming it toward Buffalo works for channel 9 but is complete wrong for channel 11 unless you live west of Toronto where the CHCH signal is strong enough to come in from the side. WBBZ Buffalo is on channel 7 but the signal is weak and the 4228 has poorer gain below channel 9. You really need a high gain VHF antenna and probably a preamp to get it.

By the way, you don't need to get channel 5 because CBC is actually on UHF channel 20. The station displays 5.1 which is the virtual channel number.

4. I see reports that the 91XG has a beam width of 25 deg while the 4228 has a beam width of 15 deg (but then I see reports that it's actually 25 deg). In any event it seems to me a narrower beam width would make the 4228 more directional than the 91XG, yet you say it is more directional. What am I missing? Also, what do you mean by 'cleaner'? Do you mean the gain plots for various channels/frequencies are closer together?

I think this subject is pretty much covered already.

5. My tvfool report is at http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d4bbaca4d736b4b. From google earth i find that the CN Tower is 184 degrees true, so about 195 magnetic (adding 11 deg as per the tvfool true and magnetic difference) at my location and WGRZ is 159 magnetic for a 36 deg difference. I do note that the drop-off looks to be about 15dB from maximum at that angle for the 91XG, as you reported, which means I wouldn't have much gain at all from the very strong stations transmitting from the CN Tower and that is good as it will narrow the difference between the strength of adjacent stations. However my tvfool report shows CFTO-DT, which transmits from the CN Tower (albeit on VHF), at 204 degrees magnetic rather than 195 degrees magentic. Why the big difference? Should it be the same?

I don't really know. Did you adjust your position using the map marker in TVFool or rely on the address? If the latter, TVFool may have you at the wrong location. You are so close to the CN Tower that the bearing changes very quickly with a relatively small move in position. The variance between magnetic and true has nothing to do with TV. The variance is the result of the magnetic north pole being at a different location than the geographic north pole.

Stick with the true bearing to calculate the antenna angle after you check to see that TV Fool has your location correct. Based on your current TVFool, WGRZ is 45 degrees away from the CN Tower stations where the 91XG is about 25 dB down.

GeorgeMX: Thanks so much for that very detailed and lucid explanation and answers to my questions. I am sure it will also help others understand antenna technology and how to evaluate an antenna.

The discrepancy of CN Tower bearing with respect to my house was indeed because I entered the address and not the exact co-ordinates of my house. I did not realize that entering the former (which tvfool interpreted to be 8 houses to the east of mine) would make it so inaccurate with respect to a location 3 miles away. With the proper co-ordinates I got a bearing of 192 degrees true (203 magnetic) for the CN Tower and 148 degrees true (159 magnetic) for WGRZ, which is the same as what Google Earth reports for true north using the ruler function.

I am going to try the 91XG and report back.

Thanks so much!

I'm at Bathurst and College. I've got a stacked pair of 4221HD's mounted about 35' high with a reverse CM splitter; no pre-amp and about a 75 foot run of RG6 to the tuner in my Panny Plasma. The antennas are pointed 161 degrees (magnetic) as per TVFool.
Reception of NBC,CBS and CW are around 80/100, PBS around 70/100, WUTV around 65/100. However, ABC WKBW 7.1 is consistently down between 0 and 25/100. It is totally pixelated or simply a black screen.

Seems strange that the other Buffalo channels are rock solid and WKBW is so weak. I also have trouble with 49.1 (very intermittent).

Anyone else having trouble with WKBW? Any suggestions?

Nic

Actually Fox and PBS have both faded this afternoon as well as WKBW. I'm sure PBS and Fox will firm up as the day goes by. But I would love to firm all these up, so they don't really ever fade. Is that even something that I can hope to get with Buffalo channels from downtown Toronto.

Someone suggested I think about a CM7778 pre-amp to firm things up. Save and Replay suggested a Winegard HDP-269 as another approach.

Any input here would be great!

Nic

I'm running stacked 4221HDs as well for the same reason. After moving from Woodbine & Danforth to Royal York & Bloor some of the US stations have been sketchy at best.

Solved it for the most part by adding the second 4221 and aiming to maximize ABC's signal quality (ignored the bearing and watched a signal meter instead). With that locked in everything else is good enough.