Does it matter if the tv antenna points one way, or 180^ the other?
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From: Jeff Liebermann on 2 Dec 2009 02:25 On Tue, 1 Dec 2009 13:48:07 -0800, dplatt(a)radagast.org (Dave Platt) wrote: >Let me toss out another idea for you. If you've got attic space which >runs long-wise towards, and away from the TV towers, you could install >a rhombic antenna. Been there, tried that. It works well but is rather sensitive to nearby metal objects. It will probably work in the attic. <http://www.tvtechnology.com/article/11412> The problem is that it's rather big. -- Jeff Liebermann jeffl(a)cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
From: baron on 2 Dec 2009 11:21 PlainBill47(a)yahoo.com Inscribed thus: > On Tue, 01 Dec 2009 00:29:31 -0500, mm <NOPSAMmm2005(a)bigfoot.com> > wrote: > >>Does it matter if the tv antenna points one way, or 180^ the other? >> >>You guys, especially Dave, have convinced me that I need a better (and >>thus bigger) antenna more than I need an amplified antenna. Does it >>matter if I point an antenna with several elements of different >>lengths to the station, or if I point it the exact opposite direction? >>In my attic, it would be more convenient to do the latter. (I'm too >>old and at least now, too fat to go on the roof.) >> >> >>Also, I thought 50 miles was the longest range on level ground for a >>transmitting tower of typical height and an antenna on the roof of a >>two-story house. >> >>So what about a claim that a Wineguard antenna has a range of 75 to 80 >>miles???? >>http://estore.websitepros.com/1129733/-strse-159/Winegard-HD-8200U/Detail.bok >>This antenna is rated for low-band VHF and I don't need that, I've >>learned, but it's the mileage claim I am asking about. >> >>Even this one says: Up to 60 mile VHF range; 45 mile UHF range Don't >>they get that by mounting it on a 100 foot tower or something? >>http://www.radioshack.com/product/index.jsp?productId=3739594 >>And isn't the info obsolete because digital transmitters are working >>at lower power than analog did? >> >>Thanks a lot. > I have to say you are going about this the wrong way. You are > choosing to mount the antenna in the attic because it's easier. An > indoor mount also has the advantage of reducing exposure to the > weather. While this is easier, it has several major disadvantages. > You have already mentioned one - difficulty in orienting it properly. > There is another - signal attenuation, particularly at higher > frequencies. > > Have you considered the possibility you are focusing on convenience > and ignoring performance? > > As far as antenna range, my parents lived over 60 miles from the > transmitter and received good signal levels with an antenna that was > mounted less than 15 feet above ground level. > > PlainBill With all due respect to Bill, what works in one place doesn't always work in another. An example, Rhonda Valley. Two identical Tv's antenna and cables but a common chimney stack. Really good signal reception on one side of the stack and next to none on the other. Antenna less than 6 ot 7 feet apart at the same hight. Solution split the feed from the high signal antenna and feed both sets from the single antenna. Which also had the effect of reducing the signal improving the picture on both Tv's. -- Best Regards: Baron.
From: GregS on 2 Dec 2009 12:05 In article <fd99h51ouj0q2isbuujf2k1qbrkggjip72(a)4ax.com>, mm <NOPSAMmm2005(a)bigfoot.com> wrote: >Does it matter if the tv antenna points one way, or 180^ the other? > >You guys, especially Dave, have convinced me that I need a better (and >thus bigger) antenna more than I need an amplified antenna. Does it >matter if I point an antenna with several elements of different >lengths to the station, or if I point it the exact opposite direction? >In my attic, it would be more convenient to do the latter. (I'm too >old and at least now, too fat to go on the roof.) > > >Also, I thought 50 miles was the longest range on level ground for a >transmitting tower of typical height and an antenna on the roof of a >two-story house. > >So what about a claim that a Wineguard antenna has a range of 75 to 80 >miles???? >http://estore.websitepros.com/1129733/-strse-159/Winegard-HD-8200U/Detail.bok >This antenna is rated for low-band VHF and I don't need that, I've >learned, but it's the mileage claim I am asking about. > >Even this one says: Up to 60 mile VHF range; 45 mile UHF range Don't >they get that by mounting it on a 100 foot tower or something? >http://www.radioshack.com/product/index.jsp?productId=3739594 >And isn't the info obsolete because digital transmitters are working >at lower power than analog did? > You certainly don't need VHF low, but do you really need VHF high ? I only have one station here on ch 13. You could also use two separate antennas with a combiner. Concentrate on the UHF. Milages is highly dependant on height and terrain. Height means nothing if there is a mountain in between. Its surprsing though, there are some big hills around here, and people got by from 30 mi away with hilly terrain on the old TV's. Getting rid of shadows on the old TV was the main problem. Digital has no shadows but must have a minimum signal to decode. greg
From: Arfa Daily on 5 Dec 2009 06:45
"baron" <baron.nospam(a)linuxmaniac.nospam.net> wrote in message news:hf6450$8pv$2(a)news.eternal-september.org... > PlainBill47(a)yahoo.com Inscribed thus: > >> On Tue, 01 Dec 2009 00:29:31 -0500, mm <NOPSAMmm2005(a)bigfoot.com> >> wrote: >> >>>Does it matter if the tv antenna points one way, or 180^ the other? >>> >>>You guys, especially Dave, have convinced me that I need a better (and >>>thus bigger) antenna more than I need an amplified antenna. Does it >>>matter if I point an antenna with several elements of different >>>lengths to the station, or if I point it the exact opposite direction? >>>In my attic, it would be more convenient to do the latter. (I'm too >>>old and at least now, too fat to go on the roof.) >>> >>> >>>Also, I thought 50 miles was the longest range on level ground for a >>>transmitting tower of typical height and an antenna on the roof of a >>>two-story house. >>> >>>So what about a claim that a Wineguard antenna has a range of 75 to 80 >>>miles???? >>>http://estore.websitepros.com/1129733/-strse-159/Winegard-HD-8200U/Detail.bok >>>This antenna is rated for low-band VHF and I don't need that, I've >>>learned, but it's the mileage claim I am asking about. >>> >>>Even this one says: Up to 60 mile VHF range; 45 mile UHF range Don't >>>they get that by mounting it on a 100 foot tower or something? >>>http://www.radioshack.com/product/index.jsp?productId=3739594 >>>And isn't the info obsolete because digital transmitters are working >>>at lower power than analog did? >>> >>>Thanks a lot. >> I have to say you are going about this the wrong way. You are >> choosing to mount the antenna in the attic because it's easier. An >> indoor mount also has the advantage of reducing exposure to the >> weather. While this is easier, it has several major disadvantages. >> You have already mentioned one - difficulty in orienting it properly. >> There is another - signal attenuation, particularly at higher >> frequencies. >> >> Have you considered the possibility you are focusing on convenience >> and ignoring performance? >> >> As far as antenna range, my parents lived over 60 miles from the >> transmitter and received good signal levels with an antenna that was >> mounted less than 15 feet above ground level. >> >> PlainBill > > With all due respect to Bill, what works in one place doesn't always > work in another. > > An example, Rhonda Valley. Two identical Tv's antenna and cables but a > common chimney stack. Really good signal reception on one side of the > stack and next to none on the other. Antenna less than 6 ot 7 feet > apart at the same hight. > > Solution split the feed from the high signal antenna and feed both sets > from the single antenna. Which also had the effect of reducing the > signal improving the picture on both Tv's. > > -- > Best Regards: > Baron. I too have seen this. I clearly remember installing an early CTV in a village that had generally poor UHF reception. Several members of the same family all lived in this tiny village, and all rented CTVs from the company that I worked for. One of the sons moved into a cottage in the same row as one of his brothers, who had good enough signals to receive colour without any preamping. We turned up at the same time as the antenna rigger, and then spent most of the rest of the day there, trying to get useable signals, just 100 feet from his brother. I remember watching the rigger (with my heart in my mouth - winter, frosty, slippy!) walking back and forth along the roof ridge, holding a bloody great pole with a phased pair of long Yagis on the top, trying to see if there was any point where we could get an acceptable signal from any transmitter, with a view to then moving back to the chimney, to see if we could figure a way to get the same signal from there. As I recall, we ended up with something like a 15ft pole, with a double chimney lashing kit, and a phased pair of long Yagis *and* a preamp. House same height as his brother's one, no visible obstructions or hills as far as the eye could see across open countryside. Sometimes, there's just no rhyme or reason to TV reception. As to receivable distance for an antenna, this depends a lot on the frequency involved. At UHF, there is little 'bending' effect of the basic radiated signal, so reception can be considered as pretty much 'line of sight'. There are effects that can extend this, but nothing that you could rely on. However, at VHF, wavefront tilt becomes more significant, and the signal will try to follow the curvature of the earth more or less, due to the wavefront 'digging in' and being 'pulled over'. This can give a significantly greater 'range' to a signal. When I was a kid, we used to watch really strong TV signals from a transmitter some sixty miles away. The antenna was a double 4 ele with a shared loop 'dipole' and delta match. This was a very common antenna type in my neck of the woods, at the time Arfa |