Need less directional antenna ...



Quote:
Originally Posted by Turbo DV8 /forum/post/12926374


Long story short ... New to OTA HDTV. I have a 140" boom length antenna with a gazillion elements, give or take. Have rotator, will travel. Got good signal until storms a couple weeks ago, then the signal was all over the place. Thought I need some amplification. Weather cleared, then raised mast 7 more feet ... added mast-mount amp. Worked great until next storm, now it dawns on me that likely the wind whips the antenna/rotator gears back and forth a couple degrees and wreaks havoc on my signal. So during storms I have an amplified bad signal ... wonderful. Someone suggested perhaps my long antenna has plenty of gain as-is, but also is too directional, hence slight movement in antenna disrupts signal acquisition. So I am in need of a much less directional antenna, and need suggestions.

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It's highly unlikely your antenna is too directive. As I write this we're in the middle of a storm with gusts to 50 mph and I have a pair of 91XGs which are very directional. The antennas are bouncing around like crazy on top of the tower yet I'm not seeing any dropouts on the digital channels here.


I'm assuming your antenna is a low/high VHF plus UHF antenna. It won't be nearly as directional as my pair of 91XGs. Unless your antenna is poorly mounted, it shouldn't be possible for it to move enough to cause dropouts.


Are your dropouts on all channels at the same time? If yes, then it's probably a connection problem. If no, then it might be trees blowing around somewhere in front of your antenna causing wild swings in signal strength.


I think most people here would say that if your reception is fine without a preamp under normal conditions, then adding one may cause more harm than good.


Bottom line is that your antenna being too directional is probably the last thing I'd look at. I wouldn't be too hasty to get rid of it. Replacing it with some nearly omnidirectional antenna may introduce a whole new set of problems.


Chuck



Quote:
Originally Posted by Calaveras /forum/post/12931853


It's highly unlikely your antenna is too directive. As I write this we're in the middle of a storm with gusts to 50 mph and I have a pair of 91XGs which are very directional. The antennas are bouncing around like crazy on top of the tower yet I'm not seeing any dropouts on the digital channels here. Unless your antenna is poorly mounted, it shouldn't be possible for it to move enough to cause dropouts.


Are your dropouts on all channels at the same time? If yes, then it's probably a connection problem. If no, then it might be trees blowing around somewhere in front of your antenna causing wild swings in signal strength.


I think most people here would say that if your reception is fine without a preamp under normal conditions, then adding one may cause more harm than good.


Bottom line is that your antenna being too directional is probably the last thing I'd look at. I wouldn't be too hasty to get rid of it. Replacing it with some nearly omnidirectional antenna may introduce a whole new set of problems.


Chuck

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Thanks for the thoughts. I can dispense a connection problem right off the bat. The connections and cables from where the matching transformer screws to the boom with wingnuts, clear to the TV are all completely new.


I am tempted to haul the mast down again and bypass the amp, since adding it seemed to have raised the signal numbers, but not necessarily the quality of signal during storms. It is definitely dropouts. The antenna is not wildly swinging about in the wind, but the eye can just discernably see it nudging back and forth a little in the gusts.


No, the dropouts are not on all the channels at the same time, but rather a few of the channels at the same time. There are no trees close by. There is a two-story motel with additional facade directly between the antenna and the transmitters, but I believe the antenna now juyst peeks above that.


Bottom line is before the storm here about three weeks ago, my limited experience with my new TV in good weather was that in general I had "go" reception 99% of the time. Then during the storm, I lost half my stations. I assumed I needed an amp, so added one. The signal meter was stronger and reception was OK until this last storm we are in, and now the reception is better than without the amp, but still a few channels drop out. That's about all I can offer right now for details. When it clears I think I will remove the amp and wait for the next storm to see what happens!



Quote:
Originally Posted by Turbo DV8 /forum/post/12934145


I am tempted to haul the mast down again and bypass the amp, since adding it seemed to have raised the signal numbers, but not necessarily the quality of signal during storms. It is definitely dropouts. The antenna is not wildly swinging about in the wind, but the eye can just discernably see it nudging back and forth a little in the gusts.

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We can rule out directivity then.

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No, the dropouts are not on all the channels at the same time, but rather a few of the channels at the same time. There are no trees close by. There is a two-story motel with additional facade directly between the antenna and the transmitters, but I believe the antenna now juyst peeks above that.

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This is sounding like some sort of multipath problem. How are the analog signals. Any ghosts on any of them, especially UHF?

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Bottom line is before the storm here about three weeks ago, my limited experience with my new TV in good weather was that in general I had "go" reception 99% of the time. Then during the storm, I lost half my stations. I assumed I needed an amp, so added one. The signal meter was stronger and reception was OK until this last storm we are in, and now the reception is better than without the amp, but still a few channels drop out. That's about all I can offer right now for details. When it clears I think I will remove the amp and wait for the next storm to see what happens!

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I should point out that during a storm is the best time to test your reception. There are no inversions or ducts to either enhance or degrade your reception. The perception that bad weather equals bad reception is not true. Bad weather usually equals nominal reception. During storms like now I get long periods of perfect reception of channels 5, 7, and 9 up here in the Sierra foothills and my locals from Walnut Grove are very stable. Once a high pressure returns and the inversions set up I start having problems with the locals, the Bay Area becomes iffy, and Salinas stations bomb in.


BTW, I lived in Sunnyvale in the 70's and 80's and did a lot of experimenting with TV antennas there so I'm very familiar with the area. The farther south you get the more difficult Sutro becomes. It may turn out you need a more directive antenna, not a less directive one.


Chuck



Quote:
Originally Posted by Turbo DV8 /forum/post/12926374


I want to keep the original antenna on the rotator as-is, and add another less directional (omni?) antenna lower on the mast, and be able to select from the two with an indoor switch. I need an antenna that is, 1) omni or at least 180 degrees coverage, and 2) able to cover not just UHF but also VHF, as in my area two stations will still be using VHF in 2009. I purchased a Philips MANT940 to play with, but haven't tried it yet, as my gut says it's likely a waste of time, and also no VHF capability. Suggestions for an antenna that fits the above requirements?

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The signals in the 94085 area are stronger than I would expect. See the attached TV Fool plot.


You may want to consider a bow-tie antenna, such as a Channel Master 4221 or 4228 (at least for UHF) and combine it with the VHF part of your existing antenna. Bow-ties have a wider reception angle (especially the 4221), but if all the stations you want are on Sutro Tower and/or San Bruno, then a more directional antenna would be preferred. Adding a 91XG may be a better option in your case.


Which channels are dropping out? A few specific ones or most of them?



Quote:
Originally Posted by Calaveras /forum/post/12936082


This is sounding like some sort of multipath problem. How are the analog signals. Any ghosts on any of them, especially UHF?

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Well, if I switch to analog channel 36 I see ghosts, but then isn't that south of me, while my antenna is pointed north for Sutro? I would expect ghosts. I will check my other analog channels when I get home tonight.


As far as line of sight ... I raised my antenna so it is now about 30 feet above ground level. But, I do have a motel directly behind us and in the direct path to Sutro. It is two stories with about another 8 feet of upper facade. So that would make it about 28 feet high. I think the antenna can peek over teh top, but I am not sure. I would have raised the mast higher, but I don't think I could raise such a tall mast alone. But I am thinking lose the amp and try for another five feet mast height. That would make the mast 24 feet long with the antenna and heavy rotor up top ... Hope she don't buckle.


As far as which channels drop out ... sometimes it seems KTVU and KRON drop out, but then it can be KICU and KBHK and KTEH. Digital 11 always come in like a bat out of hell, regardless. Mind you, when one or two drop out, I can nudge the antenna just a couple degrees one way or the other and then signals jump up and stabilize, but this is always at the expense of making other channles drop in and out that were not before.


Thanks for the suggestions. keep 'em coming!



Quote:
Originally Posted by Turbo DV8 /forum/post/12939077


As far as which channels drop out ... sometimes it seems KTVU and KRON drop out, but then it can be KICU and KBHK and KTEH. Digital 11 always come in like a bat out of hell, regardless. Mind you, when one or two drop out, I can nudge the antenna just a couple degrees one way or the other and then signals jump up and stabilize, but this is always at the expense of making other channles drop in and out that were not before.

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All of the above listed problems channels are higher up the UHF spectrum. KTVU (56), KRON (57), KBCW (45) and KTEH (50). KNTV 11 broadcasts their DTV signal on VHF-12.


It sounds like your antenna/setup is having problems with the higher frequencies. I would be curious to see how analog KBWB 20 compares with analog KFSF 66.


Your antenna is a VHF/UHF combo, right? The boom length would make it likely, but I have seen some very large VHF only antennas. Can you take a picture of it?


I would expect ghosts from KICU as it will be coming from the side if the antenna is pointed at Sutro Tower.

Thankyou, Calaveras and Falcon_77,


From the TV Fool link, which I find fascinating (does that make me a geek?) and from studying further where my antenna is aimed, I think I may know what is causing this. First, my antenna is generally aimed toward Sutro during my trials, and even aimed in this direction I can often pick up 36.1 and 54.1 over in Fremont with little trouble ... 90 degrees to the east. So much for my antenna being too directional, huh? Today I was contemplating raising the mast another five feet and losing the preamp. I mean, if I get a spotty signal without a preamp, and get a spotty signal with a preamp, I may as well get a spotty signal without the preamp for $60 less, right? Anyway, I went outside and looked where my antenna was aimed.


Recall the motel I mentioned. The back wall of it is on my property line. There are a couple peaks on the roof off to the right which I think/thought were possibly being an impediment to the signal. They were in the general direction of Sutro. Upon closer look today, I arched my head backwards to look up at the antenna and see where it was aimed, slowly followed the invisible line in the sky, and found that it is not aimed at the roof peaks. What I did see for the first time was, about 15 degrees to the left, the top part of a date palm tree just beyond the motel. It's probably about 40 feet tall, with nice fluffy fronds that puff out all around it, and my antenna is aimed smack-dab right at it's core! Ya think maybe a boat-load of palm fronds waving back and forth in the wind across my LOS to Sutro could be causing problems? I notice that 11.1 (Mt. San Bruno) is 5 degrees to the west of Sutro for me, and it comes in like a bat out of hell all the time. Maybe that is enough of an offset to see around the tree, or maybe it is stronger because it is much lower in frequency?


I'm screwed. Raising the mast another five feet isn't going to get it above the date palm, but I'll do it for the hell of it. Even if were inclined to move the antenna horizontally, moving it in one direction would likely put the second floor motel facade direct in the LOS, and moving the antenna the other direction far enough to see around the date palm would put the antenna on top of my neighbor's house. Do you think he would notice? He's going on vacation next week. Hmmm... Well, if raising the mast doesn't improve the signal around the date palm, I can only think of two solutions 1) Listen to the radio more, or, 2) weed killer.

I agree that if you're looking right into a palm tree, that could be a problem. When I lived in Fremont, my neighbor had a palm tree. I had a setup to receive the NOAA low Earth orbiting weather satellites on 1700 MHz. Whenever a satellite went behind the palm tree the signal almost disappeared. It's probably not as bad on UHF TV but I'll bet there's some affect.


I did an OTA setup for my cousin in San Leandro. She's only 17 miles line of site from SF. But she has to look through a line of eucalyptus trees. All the channels are fine except KCSM-DT 43 which is completely destroyed whenever the wind blows and the trees move.


Here's another idea for you. Since you have a rotor, why don't you turn your antenna down to Salinas (about 150 degrees heading) and see if you can receive those stations? The transmitter overlays show some coverage in Sunnyvale and I used to get a pretty good signal from channel 8. The channels of interest would be KSBW 8 (DT 10), KCBA 35 (DT 13) and KION 46 (DT 32).


From experience, the chances of you getting any UHF channels from Sacramento is slim to none. I never had any success with them although VHF was pretty good.


BTW, a 30dB gain preamp where you are is likely far too much and will probably overload. I played with preamps in Sunnyvale and had problems with overload. There are just too many strong signals.


Chuck



Quote:
I did an OTA setup for my cousin in San Leandro. She's only 17 miles line of site from SF. But she has to look through a line of eucalyptus trees. All the channels are fine except KCSM-DT 43 which is completely destroyed whenever the wind blows and the trees move.

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This really sounds more and more like what is happening when it gets stormy then quiets down.

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Here's another idea for you. Since you have a rotor, why don't you turn your antenna down to Salinas (about 150 degrees heading) and see if you can receive those stations?

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My TV has an Achille's Heel that discourages me from doing that. I cannot select a channel manually that has not already been found on a channel scan. And, after the second scan (say, if I wanted to scan in multiple directions) it begins to erase previously saved channels. It really sucks. And it's an $1800 Panasonic, too.

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BTW, a 30dB gain preamp where you are is likely far too much and will probably overload. I played with preamps in Sunnyvale and had problems with overload.

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That is pretty much my conclusion, too, which is why I will lose the amp. When the mast was down and I had the anenna just laying on the rooftop, I hooked up the amp and it seemed to raise the signal strength (as indicated on the TV meter) as I decreased the cut. But once the antenna was back up on the mast, the gain would actually go down as I decreased the attenuation, which someone told me is a sign of overload. Now that I have added one and one together and realize my original problem was wind/weather related (together with tree) rather than signal strength, the amp is coming down. I don't think the TV will miss it.