4 - NBC, 9 - CBS, 20, 26, 50 as well. A lot more than what I would have expected...

I suspect multipath. Would a compact antenna mounted outside be an option?

I am lucky enough to be in a SFH with NO HOA! I currently have a Winegard 7084P on the roof. A problem with it is that if we get a strong wind it has moved and goes away from my guess of a decent signal. By decent my Tivo says 30-60% signal strength which I expected better with the antenna.

I also have a channel master pre-amp in the attic but it would be hard to get to since it was put in then I had insulation blown in. I didn't think about it prior to the insulation being added...

Oh, I thought the antenna was in the attic. Is it possible to run a cable straight from the antenna to just one TV for testing purposes? (NO preamp) That antenna should be more than enough for DC if aimed correctly. I have used a much smaller antenna in a low spot west of you (Aldie/Gum Springs) with excellent results.

Also, temporarily disconnect the signal from your TIVO and plug the antenna cable directly into your TV and re-scan. There is much discussion here about the fussy nature of the Tivo tuner. Do this test just to see if that might be part of your problem.

every station is 1 edge or 2 edge, so obviously limited by the terrain there. At what height is your antenna mounted? When you enter the location info on the tvfool website, In the field labelled antenna height AGL you should enter the actual height of your antenna for most accurate results. you may also plug in various heights to see what the impact might be at various heights.

is this an older system that used to work fine for years and is suddenty not working to your satisfaction, or is this a new system you just installed that your not quite happy with??

Also, has reception worsened recently?

We have been in the house about 3.5 years. Once we moved in we purchased the Wingard 7084P after buying a smaller UHF only antenna. It is mounted on the side of the house with a side mount with 10 feet of mast so the Antenna is just above the roof line.

Yea we back right up to hills. I would say from my back patio 20-30 ft and the hill starts going up. The big problem is recently CBS and NBC has gone away for some reason which I don't understand and we watch a lot of shows on CBS anyway.

So I have finally gotten to be proactive and figured I would ask around to figure out what I am doing incorrectly or what I can do to improve things.

Part of me wants to put a rotor up there so when the wind blows it I can re-adjust from the ground as I really hate climbing on the roof.

I would say the roof is in the low 20 foot range so that is where the antenna is mounted. When I am up there I can look into the side of Townhouses that are built on the side of the hill as it goes up. So yea terrain is less that joyous...

Getting the antenna a bit more above the roofline would likley help improve reliability. You shouldn't need a rotor if just the DC stations are important.

I used this small antenna (http://www.winegarddirect.com/viewitem.asp?p=ANWGHST&d=Winegard-HD-7210P-Ghost-Killer-VHFUHF-Yagi-Style-HDTV-Antenna-%28HD7210P%29&post=), 10 feet off the roof, about 10 miles further out from you & the DC stations are solid. (Even Baltimore & Frederick MD are seen, but too un-reliable due to the low flying aircraft from nearby Dulles Airport) This is the TV FOOL report (http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3dec128853f57d0e) for that location off Braddock Road.

I'm not saying you need a new antenna, but start with height experimentation & then bypass the pre amp if the intermittent reception issues still exist. I don't think the pre amp is overloading, but I always like to test without amplification whenever issues arise to develop a baseline.

your worry about the wind blowing makes me wonder if you have a lot of trees nearby around you also? Can you get the antenna as far away from trees as possible? given the terrain your up against, it's likely there may be some multipath going on there. i.e. signals bouncing around off nearby hills, can cause multiple reflected signals from the same transmitter to arrive at the receive antenna out of phase and will degrade the signal quality significantly.

It sounds like you have a suitable antenna, I would consider adding the rotor. If your issues are being caused by multipath, quite often all it takes is a bump of anywhere from a few degrees to tens of degrees in one direction or the other to get out of the degraded area. Or you might just be able relocate the antenna someplace else, a few feet in any direction, horizontally or vertically ya may be able to find a better sweet spot.
You may want to check out this thread which addresses antenna siting.
http://www.digitalhome.ca/forum/showthread.php?t=144400
and this thread which has some thoughts on multipath
http://www.digitalhome.ca/forum/showthread.php?t=136245

If your using a preamp, try taking it out of the picture completely. Sometimes adding a preamp can make your system even more susceptible to multipath by amplifying the reflections more.

What are you using as a receiver BTW. Some newer ATSC receivers behave very well under multipath, while others (mostly older but not necessarily) are pretty bad.

I live in a rural area about 55 miles from stations to the south and 60+ miles from an eastern CBS station, but this is a mountainous region of the U.S. My primary concern is picking up a CBS station, but others would be nice as well.

Here is my tvfool results:
http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d4033417063e955

I have been looking at antennas such as the AntennasDirect DB4e.

Anyone have any idea if I could pickup anything given my location? I am willing to invest in some equipment if needed.

I appreciate any input. Thanks.

Moving a PM from otadtvman to here:

I saw your Fracarro thread and would greatly appreciate your thoughts. I was all set to order a 91xg. Recently, I discovered Fracarro.

UHF = 14-51 since 6/12/09 (470 to 698 Mhz)

GRAPHS COMPARISONS:

http://www.fracarro.com/internationa...s/Sigma9HD.pdf 4.25' L
http://sigma.fracarro.com/download/d...ng_extraUE.pdf 3' L
http://sigma.fracarro.com/download/S...ure_eng_lr.pdf
http://www.fracarro.com/internationa.../BLUSeries.zip (See 920 - most similar to 91XG) 8' L
http://www.antennasdirect.com/cmss_f...f?cjid=4169658 7.75' L

SPECS ONLY:
http://www.antennacraft.net/pdfs/MXU59.pdf 9.5' L
http://www.winegard.com/kbase/upload/HD-9032.pdf 8.3' L


I've read many excellent reports on the tilt-able 91XG: 11.8 dBi (~9.65 dBd) @ 470 Hz

The Fracarro sigma 6 & 9HD look appealing due to their respectable gain and smaller size - Less conspicuous & less wind-load.
Sigma 9HD provides 14 dBi (~11.85 dBd) @ 480 Hz
Sigma 6HD provides 13 dBi (~10.85 dBd) @ 480 Hz

We live about 45 miles from DC & Balt and the majority of our reception is unfortunately 2edge. Additionally, a wall of very tall 30-yr old spruce trees stand between us and DC. When it rains 4.1 (RF 48) is very problematic due to multipath interference caused by the wind blowing the wall of evergreens - our biggest challenge. Harrisburg, Lancaster, & York PA are also possibilities.

Windy ice storms are also a possible in our area.

Which uhf antenna is best suited to our conditions?

Post your TVFool image. Any chance of cutting down or cutting the tops out of those spruce trees to get a clear path thru them ? Spruce trees hold a lot of water, so its almost like having a wire mesh curtain in front of you.

i have the blu 420f, sigma 6 hd and portensigne lambda from france, and i can tell you that they are the Ferrari of the antennas,zinc plated booms(mirror finish)
performance is very good with wide bw.

Post your TVFool image. Any chance of cutting down or cutting the tops out of those spruce trees to get a clear path thru them ? Spruce trees hold a lot of water, so its almost like having a wire mesh curtain in front of you.
300ohm,

Thanks for your reply.

TVFool results (http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d83877d4a4305a6)

Unfortunately, our neighbor planted a continous Norway Spruce evergreen windbreak (http://i496.photobucket.com/albums/rr328/rabbit73_photos/Charlesmap.jpg) the enire perimeter of their backyard more than 25 years ago.

HEIGHT AND GROWTH RATES (http://www.norwayspruce.com/)

The Norway Spruce can grow 2-3+ feet per year their first 25 years under good conditions, in heavy or poor soils they may average 1 foot per year. Soil, moisture, and adequate sunshine is everything to a plant and its growth rate. On a perfect weather year, and no competition from grass or weeds, we have seen over 6 ft of growth in one year! This spruce if given sufficient room to grow will easily grow to over 100 feet tall and be 40 feet wide with spreading branches at the base and will live over 100 years. This is not a tree for a small yard!

Spruce trees hold a lot of water, so its almost like having a wire mesh curtain in front of you. Agreed, during storms our reception of DC becomes very unreliable. Druing good weather, the Spruce are not an issue.

edtrutone,

Thank you for your reply.


How do the Fracarro 420f, Sigma 6 hd, and AD 91XG compare?
Are you also familiar with the Sigma 9HD?
I understand the Fracarro also have a tilt feature as an included accessory. Is it well designed?
Which UHF yagi is best at resolving multipath interference?

Agreed, during storms our reception of DC becomes very unreliable.
What present antenna do you have ?

Is it possible to get the antenna higher, so its near the thinner part of the trees ?

Besides the trees, there are hills between you and Balt and DC. Try tilting the antenna upwards a bit, say 10 or 15 degrees. You should be able to do that with most antennas by adjusting the ubolt and bracket.

My experience with corner reflector yagi (and yagi and lpda) type antennas is that they perform worse for the same gain in a tree blocked environment than broadside type antennas like the GHs and the bowties and hoops.

We're currently using a broadside type antenna, a CM-3021 4-Bay Bowtie with our old CM-0100DSB (http://i496.photobucket.com/albums/rr328/rabbit73_photos/img018_1.jpg) pre-amp inside a South-facing, 2nd-floor, bedroom window w/o a screen. This works well for all of DC (in good weather only) and gives us variable reception from Balt. It also performs much better than our old 2nd-story attic antenna.

The Norway Spruce can grow 2-3+ feet per year their first 25 years ... will easily grow to over 100 feet tall ...
These Spruce are now 25-30 yrs old. See link for picture in post #3. A tower is not in the budget. Max height = 2-story house + mast.

OK, I'll tilt the antenna upwards 10 or 15 degrees.

We have a rotator. Balt. (42 mi.), Harrisburg (65-68 mi.), Lancaster (59 mi.), & York (59 mi.) are the alternatives if DC becomes problematic due to the trees.

That sigma antenna looks just too fancy to work well... but it likely works fine.
I would also expect similar results from a GH antenna, but if you want to impress your neighbors the sigma is the way to go.

In theory the full wave loop element should have more gain than the same 1/2 wave element design, but I have not seen a major advantage using director elements in a full wave loop configuration in the low frequency bands. They are more popular in the 1.2-1.8 and 2.4GHz bands due to broadband nature, which is also advantageous for the TV UHF band. The sigma may have more than one loop in the driven element "assembly" to make it more broad band, and the grid reflector also rather non frequency critical.

Let us know how it works if you order one!
-C.

OK, I'll tilt the antenna upwards 10 or 15 degrees.

I believe youll need a longer bottom ubolt, which is available at Home Depot. I would loosen the top ubolt, then install the longer bottom ubolt with a plastic or durable wood spacer in between the mast and the bracket. That will give you a tilt.

Attaching a wider reflector of say 36" wide by 30" high of 2" X 4" mesh (2" side going up and down, 4" side left and right) to your CM-3021 would dramatically increase your vhf-hi gain and help a bit on uhf gain as well.

See link for picture in post #3.
Well, at least you have about 75 to 100 ft of clear area before the trees. I hope your neighbor realizes its not cheap or easy removing those trees when they get old, heh.

Hello Cham,

I would also expect similar results from a GH antenna, but if you want to impress your neighbors the sigma is the way to go.
We're not looking to impress our neighbors. Every house in our neighborhood lacks a roof-top antenna as they are all connected to Comcast or satellite TV.

The Sigma 6HD (3' L) or 9HD (4.25' L) are appealing due to their respectable gain and shorter length compared to a 91XG (7.75' L), which makes them less conspicuous & less prone to wind &/or ice damage.

They are more popular in the 1.2-1.8 and 2.4GHz bands due to broadband nature, which is also advantageous for the TV UHF band. The sigma may have more than one loop in the driven element "assembly" to make it more broad band, and the grid reflector also rather non frequency critical.


Per Sigma 6HD (6 elements) brochure:
The original design of the new aerials patented by Fracarro, allows a particular directivity (with the maximum reduction in interference) and a maximum gain (17dBi*) and is also high throughout the whole reception band.

The gain achieved is comparable with an aerial twice its length!

*Sigma 9 HD (9 elements) - 18.5dBi
However, the brochure and data sheets don't specify the number of loops in the driven element "assembly"

Can you suggest a basic primer on full wave loop elements? Thanks.