The Official AVS Antenna and Related Hardware Topic! - Page 486 - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #14551 of 16266 Old 03-02-2012, 02:45 PM
AVS Addicted Member
 
arxaw's Avatar
 
Join Date: May 2002
Posts: 10,909
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by bcg123 View Post

My TVFool report is at:
http://www.tvfool.com/?option=com_wr...0b86d8bee756e7

Well, you definitely don't need an amplified antenna, because signals are very strong at your location, and the amp would likely overload. If you have no outdoor options, what you need is trial and error and a lot of patience to find an indoor reception hot spot. The most likely spot would be near a South-facing wall or window. If you still have the rabbit ear/loop antenna, that's all you need, although the RCA one is not very good. This similar looking one from RS (model 15-1874) nearly always works better than the RCA. The loop is bigger and the cable is larger gauge.

To find a reception hot spot, connect a longer piece of RG6 coax to it (no more than ~50' longer), using a barrel splice, also available at RS.

If your building has metal siding, metal roof, stucco, or foil-backed insulation, you will very likely need to put the antenna in or near a window.

If you can do outdoor or attic, the RCA ANT751 (made by Winegard) would be a very good choice at your location.
arxaw is offline  
Sponsored Links
Advertisement
 
post #14552 of 16266 Old 03-03-2012, 10:26 AM
Newbie
 
bcg123's Avatar
 
Join Date: Mar 2012
Posts: 10
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by arxaw View Post

Well, you definitely don't need an amplified antenna, because signals are very strong at your location, and the amp would likely overload. If you have no outdoor options, what you need is trial and error and a lot of patience to find an indoor reception hot spot. The most likely spot would be near a South-facing wall or window. If you still have the rabbit ear/loop antenna, that's all you need, although the RCA one is not very good. This similar looking one from RS (model 15-1874) nearly always works better than the RCA. The loop is bigger and the cable is larger gauge.

I don't have a long coax yet, but I tried this: I moved my TV into the bedroom, plugged in the current antenna, and set the current antenna on my bedroom windowsill. That window is south-facing, and I tried to tilt the antenna a little southwest, too (since the antenna farm is southwest of me). It worked better and I got 50-odd channels (mostly in the 20s and above), but, of the four I care about (2.1-NBC, 11.1-CBS, 13.1-ABC, 26-FOX), the only one I got was 26 (FOX). So, no NBC, CBS, or ABC. I'm a little surprised, but I have a few theories about why it's still so bad:

1) My antenna's bad, and I need a better one. Solution: get a better antenna. Any suggestions? Any thoughts on whether just a different model, same design is fine, or whether a different design might be helpful? (I know you recommended the Radio Shack Basic Antenna--should I start there, or is my situation bad enough that a better, non-amplified antenna is necessary?)

2) Tall office buildings are blocking the signal (I'm a few blocks north of a bunch of them). Solution: I'm not really sure. Any ideas?

I'm planning to get the coax cable anyway, and just test it, both on the balcony and in the bedroom, but given my earlier experiment, I'm not hopeful, at least not without doing something else different (maybe a better antenna?).

Quote:
Originally Posted by arxaw View Post

If you can do outdoor or attic, the RCA ANT751 (made by Winegard) would be a very good choice at your location.

Unfortunately, I don't have an attic, and I can't put anything on my roof. I do have an outdoor balcony, but it's facing away from the antenna farm. So I'm not sure this is an improvement over having it indoors.
bcg123 is offline  
post #14553 of 16266 Old 03-03-2012, 10:37 AM
AVS Addicted Member
 
arxaw's Avatar
 
Join Date: May 2002
Posts: 10,909
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by bcg123 View Post

...1) My antenna's bad, and I need a better one. Solution: get a better antenna. Any suggestions? Any thoughts on whether just a different model, same design is fine, or whether a different design might be helpful? (I know you recommended the Radio Shack Basic Antenna--should I start there...

Uh, yes. That's why I posted a link to it.

Quote:


2) Tall office buildings are blocking the signal (I'm a few blocks north of a bunch of them). Solution: I'm not really sure. Any ideas?

If you have other buildings to the north of you, you might try aiming at them, to see if you can get a bounced signal. Your outdoor balcony would be the best place to try that. And out there, the ANT751 would be a better choice because it's more directional, plus suitable for outdoor use.

With buildings in the way, a lot of trial and error is your best option. Unfortunately, there is no magic antenna, contrary to many ads you see online. A better TV tuner often helps in your situation. LG and Sony are two that work better in difficult reception environments.
arxaw is offline  
post #14554 of 16266 Old 03-03-2012, 12:00 PM
Newbie
 
bcg123's Avatar
 
Join Date: Mar 2012
Posts: 10
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by arxaw View Post

If you have other buildings to the north of you, you might try aiming at them, to see if you can get a bounced signal. Your outdoor balcony would be the best place to try that. And out there, the ANT751 would be a better choice because it's more directional, plus suitable for outdoor use.

With buildings in the way, a lot of trial and error is your best option. Unfortunately, there is no magic antenna, contrary to many ads you see online. A better TV tuner often helps in your situation. LG and Sony are two that work better in difficult reception environments.

Well, I will start with the better antenna then, and I'll see if that helps, and then I'll see if I can get a bounced signal. Unfortunately, my TV tuner is in the TV, which is brand-new (not a separate box), but I'll see about changing that if nothing else works. Thanks for your help!
bcg123 is offline  
post #14555 of 16266 Old 03-03-2012, 12:14 PM
AVS Special Member
 
ctdish's Avatar
 
Join Date: Dec 2000
Location: Mystic,CT,USA
Posts: 1,338
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Liked: 21
CBS, ABC and PBS are all on VHF channels so an indoor antenna that includes rabbitears will work best for those channels. Getting the long coax is also likely to be needed to find a good indoor spot. I would not exclude the putting the antenna outside on the balcony. A bounced or refracted signal might be stronger there because it does not have to pass through the attenuation in the wall.
John
ctdish is offline  
post #14556 of 16266 Old 03-04-2012, 08:22 AM
AVS Addicted Member
 
arxaw's Avatar
 
Join Date: May 2002
Posts: 10,909
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
bcg123,
Your dipole rods (for VHF channels PBS, ABC, & CBS) should be extended in a "V" shape and no longer than about half length, to best tune them to the frequencies your VHF channels (PBS, ABC, & CBS) are on. All your other channels are UHF and received by the "loop" on your indoor antenna.
arxaw is offline  
post #14557 of 16266 Old 03-05-2012, 12:14 PM
Member
 
DTVintermods's Avatar
 
Join Date: May 2009
Posts: 175
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by AcuraCL View Post

I think I know the answer but I'll just put the question out there ....

what is the best solution to a bad multipath problem?

Space diversity, polarization diversity and angular diversity. One or all of the above. In space diversity the antennas should be spaced about 1/2 wavelength apart. For space diversity, add vertical polarization (or horizontal polarization turned 90 deg). Use lossless (reactive) combiner with the shortest and equal length feedlines to the two antennas. Then rotate/change height for maximum attenuation of the strongest echo
DTVintermods is offline  
post #14558 of 16266 Old 03-05-2012, 04:00 PM
AVS Special Member
 
Calaveras's Avatar
 
Join Date: Jan 2007
Location: Mountain Ranch
Posts: 2,882
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 74 Post(s)
Liked: 80
Quote:
Originally Posted by DTVintermods View Post

Space diversity, polarization diversity and angular diversity. One or all of the above. In space diversity the antennas should be spaced about 1/2 wavelength apart. For space diversity, add vertical polarization (or horizontal polarization turned 90 deg). Use lossless (reactive) combiner with the shortest and equal length feedlines to the two antennas. Then rotate/change height for maximum attenuation of the strongest echo

Just curious..... Why are you responding now to a post made almost 8 years ago?

Chuck
Calaveras is offline  
post #14559 of 16266 Old 03-05-2012, 09:05 PM
Newbie
 
bcg123's Avatar
 
Join Date: Mar 2012
Posts: 10
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I really appreciate all the feedback and advice I've received. I am happy to report that it's paid off--I decided to test one thing at a time, beginning with a long coax cable so I could put my antenna in the window facing the antenna farm. To my surprise (given my test run the day before), I am now getting all five channels I wanted (plus 58 others, if I ever get bored). Success! Thanks to everyone who helped, and now if I ever move into a place with even more difficult-to-get reception than here I have lots of ideas about what to do!
bcg123 is offline  
post #14560 of 16266 Old 03-06-2012, 06:00 AM
AVS Addicted Member
 
arxaw's Avatar
 
Join Date: May 2002
Posts: 10,909
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
bcg123,
With your strong signals on your TVFool report, I figured that with trial and error, you could eventually find a good spot for your antenna. Indoors, it's all about location and patience. Which antenna did you use?
arxaw is offline  
post #14561 of 16266 Old 03-06-2012, 07:17 AM
AVS Special Member
 
holl_ands's Avatar
 
Join Date: Jun 2004
Location: San Diego, CA
Posts: 3,616
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Liked: 57
OAM, "Orbital Angular Momentum" is the formal physics name for a basic E&M Theory
property for the OTHER component of Angular Momentum carried by light. OAM permits
transmitting MULTIPLE (2, 3, 4, 5, 6, etc) signals on the same frequency at the same time.

The primary component is "Spin Angular Momentum", better known as Linear or
Circular Polarization. By transmitting OAM on BOTH Horizontal & Vertical Polarization
(or Right Hand & Left Hand Circular Polarization), the number of simultaneous
transmissions can be DOUBLED even more....or TRIPLED using a Tripole Antenna:
http://www.nature.com/nature/journal...9316a0_ft.html
Note this article only addressed Linear Polarization, i.e. Spin Angular Momentum (SAM).

The ultimate solution to spectrum shortage??? Perhaps for point-to-point links,
but I doubt it will work for broadcast in it's current form....unless there is yet
another leap forward....

=======================================================
"The FCC Broadcast and Spectrum" thread (10Oct2011) seems to be ONLY mention of
"Twisting Radio Waves" aka "Radio Vorticity aka OAM" on this forum:
http://www.avsforum.com/avs-vb/showt...php?p=21062403
http://discovermagazine.com/2011/oct...less-bandwidth

On 1 May 2012 (just a few days ago), a public demonstration was conducted on
a point-to-point link across the lagoon in Venice, demonstrating:
http://www.bbc.co.uk/news/science-environment-17221490

More on this demo, including various references explaining OAM:
http://www.digitalhome.ca/forum/show....php?p=1393415

Note that a minimalist receive antenna is described as an array of 3 or 4 antennas,
each capable of sensing the 3D nature of the E&M field, such as a Tripole or a
Cubical Antenna. Since each Tripole would require THREE Receivers, the total
number of receivers would be either 9 or 12. For the Cubical Antenna, there
are twice as many sensor locations and hence a minimum of 18 or 24 Receivers.

PS: An orthogonal Triple Loop antenna could also be used:
http://www2.rohde-schwarz.com/file_2...020_dat_en.pdf
http://www.autex.spb.ru/download/wav...ensor/CH47.PDF
http://dspace.dsto.defence.gov.au/ds...-2321%20PR.pdf

Although my D-Link Wi-Fi Router has THREE antennas...and hence three receivers,
building an OAM receive/antenna system would be fairly expensive....plus what
appears to be direct RF (or IF?) Sampling (with ZERO phase error) feeding a
very high speed signal processor.

It is important to observe that the Venice Experiment used an Interferometer
with a SINGLE Receiver....and very careful alignment of a pair of Yagi Antennas....
holl_ands is offline  
post #14562 of 16266 Old 03-06-2012, 07:44 AM
Senior Member
 
Dave Loudin's Avatar
 
Join Date: Nov 2007
Location: King George, VA
Posts: 410
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
I would have to think that multipath and edge-diffraction would do OAM in, thereby severely limiting this technique for broadcasting.
Dave Loudin is offline  
post #14563 of 16266 Old 03-06-2012, 06:59 PM
AVS Special Member
 
300ohm's Avatar
 
Join Date: May 2008
Location: Somewhere in Delaware
Posts: 1,823
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Plus it would require a separate antenna for each channel on the same frequency.

Quote:


On 1 May 2012 (just a few days ago)

Heh, its not going to feel like May until Thursday around here.
300ohm is offline  
post #14564 of 16266 Old 03-06-2012, 07:30 PM
Member
 
MaxFly's Avatar
 
Join Date: Jan 2009
Posts: 20
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I have an interesting problem with multipath and am hoping that someone will be able to help. I live 18 miles southwest of my desired TV transmitters. I live in a valley and a wooded hill is between my house and the transmitters-close to my house. I have an old (probably >50 years old) butterfly UHF antenna extended above my 48ft tower. (Pictured here: http://i284.photobucket.com/albums/l...N/P3062435.jpg ) It has a preamp that is also extremely old. The indoor part says Galaxy III series. I think the outdoor part is older.

My biggest problem is that there is a train track that runs from southeast to southwest of my house about 1/4 mile away. When trains go by, my picture on several channels pixellates and stops. Audio completely cuts out for 30 seconds to a minute. It naturally depends on how long and fast the train is. The channel signal strength according to my Samsung HDTV or my OTA DishDTVPal DVR is in the mid to upper 80%s for my worst channels. My 95%+ channels don't cut out much. I theorize that the signal is bouncing off the moving train cars into the back of my antenna. This is worse in Winter when there are no leaves on the trees to block the bounced signal. The funny thing is, the area where the train begins to interfere is directly behind the antenna, but the faces of the cars are at an oblique angle. That doesn't make much sense to me.
Does anyone have advice for me? I installed a rotator but I can't find a position that fixes it. My thinking is that I might need to get a new antenna that is more directional and/or rejects signal better from behind. I don't have any specs. on my old antenna to compare to new ones. What should I be looking for in beam width or front-to-back ratio. Or any other advice would be appreciated.

Thanks!
MaxFly is offline  
post #14565 of 16266 Old 03-06-2012, 07:46 PM
Member
 
Ben98gs's Avatar
 
Join Date: Mar 2005
Location: Mooresville, IN
Posts: 70
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Just purchased a new house and was hoping to mount an antenna (or two) in the attic. I am thinking that I probably will need a UHF and VHF-Hi, but do not know what might be best.

I have attached the TVFool. We will only have 2 TV's hooked up, but might be adding a third in the near future if that matters.

What are your recommendations?

Thanks in advance.
LL
Ben98gs is offline  
post #14566 of 16266 Old 03-07-2012, 03:43 AM
AVS Special Member
 
ProjectSHO89's Avatar
 
Join Date: Feb 2009
Posts: 2,588
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 42 Post(s)
Liked: 65
MaxFly,

Looks like a bidirectional G-V variant from years past. It doesn't have any front to back ratio.

In order to know what stations are being affected, we need to know what's around you. Please post a TVFool report and let us know which particular stations are being most affected.

You might be encountering either electrical interference (diesel locomotives use electrical drive motors) or dynamic multi-path.
ProjectSHO89 is online now  
post #14567 of 16266 Old 03-07-2012, 05:16 AM
AVS Addicted Member
 
arxaw's Avatar
 
Join Date: May 2002
Posts: 10,909
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by Ben98gs View Post

Just purchased a new house and was hoping to mount an antenna (or two) in the attic. I am thinking that I probably will need a UHF and VHF-Hi, but do not know what might be best.

I have attached the TVFool. We will only have 2 TV's hooked up, but might be adding a third in the near future if that matters.

What are your recommendations?

Thanks in advance.

You do need a VHF-HI + UHF antenna. An RCA ANT751 (made by winegard) should get at least all your major channels of interest in green on your TVFool. That's assuming you don't have foil radiant barrier roof decking or foil backed insulation in the attic.

If coax runs are long, you may need a distribution amp, but don't add one unless you're experiencing dropouts.
arxaw is offline  
post #14568 of 16266 Old 03-07-2012, 06:45 AM
Member
 
DTVintermods's Avatar
 
Join Date: May 2009
Posts: 175
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Calaveras
It was my first time here and I didn't realize that I was on the wrong page...
DTVintermods is offline  
post #14569 of 16266 Old 03-07-2012, 09:15 AM
AVS Special Member
 
holl_ands's Avatar
 
Join Date: Jun 2004
Location: San Diego, CA
Posts: 3,616
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Liked: 57
Quote:
Originally Posted by 300ohm View Post

Plus it would require a separate antenna for each channel on the same frequency.

For an OAM Multi-Antenna Receive Array, I'm not sure that would be true.

If the modes are truly "orthogonal", as is claimed, then the Receiver IF
outputs could be processed digitally with the requisite phase shifts and
amplitude weightings to form each of the say l=4 configurations. This
process would need to be done in PARALLEL, using the SAME IF digital
samples (hey, that's what super-fast signal processors are for). And by
reciprocity, the same process could be performed in REVERSE for an
OAM Transmit Array. [I'll keep reading to see if this a viable alternative....]

However, since the Helicoidal Parabola used a PHYSICAL structure to generate
the increasing phase offsets around the circumference, there would need
to be separate Transmit antennas for each of the eigenvalues, and DOUBLE
that if H/V or RHCP/LHCP Polarization for an additional DOUBLING of capacity.

================================================
BTW: If used for Broadcast coverage, a set of (say) EIGHT OAM Transmit
Antenna Arrays (probably not FOUR, depending on beamwidth) would need
to encircle the Broadcast tower, resulting in EIGHT sweet-spots and EIGHT
self-interference zones as the LEFT side of the pattern overlaps the RIGHT
side of the adjacent pattern.

Suppose antenna eigenvalue patterns ALTERNATE, so l = positive integers
alternate with l = negative integers for the same eigenvalues. In the case of
Helicoidal Parabolic Antennas, the phase step at the Gap would alternate
between positive and negative X-Axis offsets, so that in the self-interference
regions, the receive array would see an increasing (or decreasing) phase
shift from BOTH antennas.

If [and that's a very BIG IF] it is possible to construct the arrays so that
these L/R patterns result in the SAME E&M Field orientations in the
self-interference zones, i.e. are mirror images of each other, then the
self-interference MIGHT not be all that bad [Thesis project anyone????].....
holl_ands is offline  
post #14570 of 16266 Old 03-07-2012, 01:25 PM
Member
 
MaxFly's Avatar
 
Join Date: Jan 2009
Posts: 20
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by ProjectSHO89 View Post

MaxFly,

Looks like a bidirectional G-V variant from years past. It doesn't have any front to back ratio.

In order to know what stations are being affected, we need to know what's around you. Please post a TVFool report and let us know which particular stations are being most affected.

You might be encountering either electrical interference (diesel locomotives use electrical drive motors) or dynamic multi-path.

Thanks,
Here is my tvfool report:
http://i284.photobucket.com/albums/l...foolreport.png
Just to refresh memories, my issue is that I lose TV signal whenever a train runs past my property. The track is basically runs basically ENE to WSW and it is south of my property. It is NOT between the transmitters and my house. My TV stations I am interested in all are in the same direction: NorthEast. We watch the top 5 stations on the list. The worst one affected is ABC, then PBS. NBC is sometimes affected, but CBS doesn't cut out at all. I am shooting over a wooded hill from a valley to the Fort Wayne stations.

Here is my old antenna: http://i284.photobucket.com/albums/l...N/P3062435.jpg
Again, I wonder if I need to get a new antenna that is more directional and/or rejects signal better from behind. What should I be looking for in beam width or front-to-back ratio.
Thanks!
MaxFly is offline  
post #14571 of 16266 Old 03-07-2012, 01:32 PM
Member
 
Ben98gs's Avatar
 
Join Date: Mar 2005
Location: Mooresville, IN
Posts: 70
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by arxaw View Post

You do need a VHF-HI + UHF antenna. An RCA ANT751 (made by winegard) should get at least all your major channels of interest in green on your TVFool. That's assuming you don't have foil radiant barrier roof decking or foil backed insulation in the attic.

If coax runs are long, you may need a distribution amp, but don't add one unless you're experiencing dropouts.

Will that be fine for an attic mount (mentions outdoor). I do not know if I have a foil radiant barrier or insulation, might try and check. If I do have that, is there another choice for attic mount or is my only option an outside mount?

It appears that the antenna you posted gets both the VHF and UHF in one, correct? I believe my last setup used a CM 4221 and Antennas Direct Y5-7-13 at my previous house (but it was a 2 story vinyl siding house, while this is a single story brick house with many energy efficient items so possibly has radiant foil???).

I dont mind doing 2 separate antenns or a single that does the same job, I just know currently I really only get WTTV (4.1), WRTV (6.1), and WXIN (59.1) that have anything worth watching and want to be sure to get WISH (8.1), WTHR (13.1), and WFYI (20.1).
Ben98gs is offline  
post #14572 of 16266 Old 03-07-2012, 01:39 PM
AVS Addicted Member
 
arxaw's Avatar
 
Join Date: May 2002
Posts: 10,909
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
MaxFly,
You may be getting bounced signals from the train as it goes behind the house. I would try a directional antenna with better f/b ratio. Since your channels of interest are all UHF, a 91XG is very directional and might help. Precise aiming is often critical with a directional antenna. Fortunately, you have a rotor to fine tune your aim. Your best aim is likely magnetic compass direction 47° NE.

You could also try an inline attenuator to reduce your signal.
arxaw is offline  
post #14573 of 16266 Old 03-07-2012, 01:46 PM
AVS Addicted Member
 
arxaw's Avatar
 
Join Date: May 2002
Posts: 10,909
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by Ben98gs View Post

Will that be fine for an attic mount (mentions outdoor). I do not know if I have a foil radiant barrier or insulation, might try and check. If I do have that, is there another choice for attic mount or is my only option an outside mount?...

New construction homes often have the foil radiant barrier on the roof decking underside (facing downward into the attic), to block 90% of the sun's radiant heat from the attic. It also effectively blocks radio frequency waves. Same for foil backed wallboard insulation and stucco-on-screen exteriors. If you have these, an attic is an unlikely place for reliable reception, as any signals that manage to get in there are bouncing around like crazy.

The ANT751 is small and very well built. It is designed for outdoor installation and is tuned for VHF-HI and UHF bands.
arxaw is offline  
post #14574 of 16266 Old 03-07-2012, 01:46 PM
AVS Special Member
 
300ohm's Avatar
 
Join Date: May 2008
Location: Somewhere in Delaware
Posts: 1,823
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:


I have an old (probably >50 years old) butterfly UHF antenna extended above my 48ft tower.

Not quite that old. Its a double bay Hoverman variant sold by Radio Shack (and I think others) from the 70's to the early 90's.
Page 9 of the 1972 Radio Shack catalog has it : http://www.radioshackcatalogs.com/catalogs/1972-b/

While it has a gain of about 14.5 dbi on some channels, its the worst design variant of the Hoverman type antennas, as the gain curve severly dips around channel 30 and then recovering.
Much better optimized single bay GH designs are here : http://clients.teksavvy.com/~nickm/gh_n3_uV.html

You could try putting some mesh on the reflector rods to see if that will help your multipath problems when trains go by.
300ohm is offline  
post #14575 of 16266 Old 03-07-2012, 06:14 PM
Member
 
Ben98gs's Avatar
 
Join Date: Mar 2005
Location: Mooresville, IN
Posts: 70
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by arxaw View Post

New construction homes often have the foil radiant barrier on the roof decking underside (facing downward into the attic), to block 90% of the sun's radiant heat from the attic. It also effectively blocks radio frequency waves. Same for foil backed wallboard insulation and stucco-on-screen exteriors. If you have these, an attic is an unlikely place for reliable reception, as any signals that manage to get in there are bouncing around like crazy.

The ANT751 is small and very well built. It is designed for outdoor installation and is tuned for VHF-HI and UHF bands.

I was looking at other houses on the street and see satellite dishes mounted to the roof and my high speed internet (wireless) antenna is mounted outside, so a small outdoor antenna should not be an issue.
Ben98gs is offline  
post #14576 of 16266 Old 03-07-2012, 06:40 PM
AVS Addicted Member
 
arxaw's Avatar
 
Join Date: May 2002
Posts: 10,909
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
If you have an HOA and are concerned about rules, they cannot legally prevent you from putting up an antenna for OTA TV reception. They can't even require a permit. See:
http://www.fcc.gov/guides/over-air-r...evices-rule#QA

The ANT751 is much less obtrusive than a satellite dish. You can also spray paint it to blend in with background, when viewed from the street.
arxaw is offline  
post #14577 of 16266 Old 03-08-2012, 11:44 AM
Advanced Member
 
Konrad2's Avatar
 
Join Date: Apr 2006
Posts: 542
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 10
Since you have the source of the problem identified, you can
work to minimise reception from that direction.

Step one, get a highly directional antenna with a very good
front to back ratio.

The 91XG is one of the best. Specs:
http://www.antennasdirect.com/cmss_f...y/91XG-TDS.pdf

Step two, experiment with aim, both horizontal and tilt.

If you still have problems, step three consider improving the reflector,

or shielding the antenna from the rear.
http://www.prism.gatech.edu/%7Ewn17/

or try the "two antenna trick" and aim a null at the train.
http://www.hdtvprimer.com/ANTENNAS/ganging.html#TAT

Be sure to consider the wind load, Indiana gets a bit windy this time of year.

>> This is worse in Winter when there are no leaves on the trees to block
>> the bounced signal.

Plant some evergreens? Locate the antenna north-east of a house/barn/silo/...?

>> What should I be looking for in beam width or front-to-back ratio.

Your five stations are all within 5 degrees, so go for the smallest
beam width you can find. Given the location of the train, go for the
highest front-to-back ratio you can find. In your case, front-to-back
ratio is probably more important than beam width.

> You could also try an inline attenuator to reduce your signal.

An attenuator is useful if you get overload, and it reduces
reflections in the coax, but it isn't going to help with external
multipath.
Konrad2 is offline  
post #14578 of 16266 Old 03-08-2012, 09:14 PM
Member
 
MaxFly's Avatar
 
Join Date: Jan 2009
Posts: 20
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
[quote=arxaw;21748176]MaxFly,
You may be getting bounced signals from the train as it goes behind the house. I would try a directional antenna with better f/b ratio. Since your channels of interest are all UHF, a 91XG is very directional and might help. Precise aiming is often critical with a directional antenna. Fortunately, you have a rotor to fine tune your aim. Your best aim is likely magnetic compass direction 47° NE.
ProjectSHO89
Looks like a bidirectional G-V variant from years past. It doesn't have any front to back ratio.

You might be encountering either electrical interference (diesel locomotives use electrical drive motors) or dynamic multi-path.

300ohm:
Not quite that old. Its a double bay Hoverman variant sold by Radio Shack (and I think others) from the 70's to the early 90's.
Page 9 of the 1972 Radio Shack catalog has it : http://www.radioshackcatalogs.com/catalogs/1972-b/

While it has a gain of about 14.5 dbi on some channels, its the worst design variant of the Hoverman type antennas, as the gain curve severly dips around channel 30 and then recovering.
Much better optimized single bay GH designs are here : http://clients.teksavvy.com/~nickm/gh_n3_uV.html

You could try putting some mesh on the reflector rods to see if that will help your multipath problems when trains go by.


Thanks to you guys for your thoughts. That 91XG has some impressive specs with regard to beam width and front-to-back ratio. I was toying with finding a hiVHS/UHS antenna so that I could swing it south to get channel 13 in Indianapolis. None of those units that I have seen has anywhere close to the same f-to-b ration as 91XG (or do you know of any?). I probably wouldn't really do that often anyway.

I am running about 80 feet of RG59 to a 4 way splitter then a few more feet to my DVR and TV. (Plus 15 more feet to another room.) Do you have any advise about preamps in my application? I have a Galaxy III series preamp. The outdoor portion looks pretty gnarly. Some of the terminals are badly corroded. I wonder if I should replace it while I'm at it. I have to hire the climber and I'd like to do it right the first or second time...
Thanks a lot!
MaxFly is offline  
post #14579 of 16266 Old 03-08-2012, 11:22 PM
AVS Special Member
 
300ohm's Avatar
 
Join Date: May 2008
Location: Somewhere in Delaware
Posts: 1,823
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:


I was toying with finding a hiVHS/UHS antenna so that I could swing it south to get channel 13 in Indianapolis.

I would probably forget about that being its -4.3 NM, 2 edge. You probably wont get it with any antenna CONSISTANTLY unless TVFool is drastically wrong.

Quote:


I am running about 80 feet of RG59 to a 4 way splitter then a few more feet to my DVR and TV. (Plus 15 more feet to another room.) Do you have any advise about preamps in my application? I have a Galaxy III series preamp. The outdoor portion looks pretty gnarly. Some of the terminals are badly corroded. I wonder if I should replace it while I'm at it. I have to hire the climber and I'd like to do it right the first or second time...

Yep, that cable is pining for the fiords. http://www.mtholyoke.edu/~ebarnes/py...ead-parrot.htm

Replace it with new RG-6. Unless youre running very close to power lines, you don't need the pricey RG-6 Quad sheild.

As far as the preamp goes, they are pretty simple one transistor devices with no electrolytic caps. As such, in a properly designed circuit, it could last for another 50 years. However, it probably has more noise than more modern preamps from Channel Master or Winegard. Avoid preamps from the Rat Shack.
300ohm is offline  
post #14580 of 16266 Old 03-09-2012, 12:33 AM
AVS Special Member
 
Larry Kenney's Avatar
 
Join Date: Nov 2001
Location: San Francisco, CA
Posts: 2,607
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 40 Post(s)
Liked: 29
A neighbor asked me about getting an antenna for OTA. He's got a Dish Network 722 and wants to record using the OTA input. The problem is, he wants to be able to record stations that are 3/4 mile away to the west on Sutro Tower, 5 miles away to the south on Mt. San Bruno, 35 miles away to the southeast in the South Bay and a station that's 45 miles to the north and not have to worry about where the antenna is pointing.

I didn't have a good answer. I told him that with a fixed antenna pointed to the south he would get most of the stations, but probably not all of them. The ones 3/4 mile away would be strong enough to come in off the side and the ones 5 miles away to the south would be good and strong, but the stations 35 and 45 miles away would maybe come in, maybe not.

I set my 10-7-13 - 4228 combo pointed south and we took a look at what we actually received. What I told him was pretty close to being right. All Sutro and Mt. San Bruno stations were solid, although one of the Sutro stations was only at 70%. Three out of the five from the southeast were pretty strong. The other two and the station to the north that's 45 miles out were "No Signal".

I was wondering... do any of you know if there is an omni-directional antenna that will receive stations up to 45 miles away that could be used for instances like this? Multipath, I guess, could be a big problem with such an antenna but is there one that's available to try?

Thanks for your input.

Larry
San Francisco

My complete SF Bay Area DTV Station Lists: http://www.choisser.com/sfonair.html
Lots of Broadcasting links and information: http://www.choisser.com/broadcast.html

Check out photos and info on my antennas: http://www. larrykenney.com/tvantennas.html

Larry Kenney is offline  
Reply HDTV Technical

Tags
Channel Master Cm 4228 8 Bay Hdtv Uhf Antenna Cm4228hd
Gear in this thread - Cm4228hd by PriceGrabber.com

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off