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Help Me Make Some Antenna Decisions

gmcjetpilot
08-03-2011, 01:25 PM
I need help picking a miricle multi directional antenna, UHF with one VHF high. There are three directions....

This is my tvfool plot (clearly not a fringe deal but not perfect).
(can't post URL's yet, new member less than 5 post, cut & paste into browser.)

img8.imageshack.us/img8/4980/tvsignals.jpg

The house is wood frame, vynal siding, two story with an attic. The roof is composite shingle and seems to have good signal based on a test I did. There are some HOA rules, but I could put a small outside antenna like a DB2 or RCA ANT751 outside. In keeping in the spirit of the rules, it would not be on the roof, but on the corner of the house under the roof eave. Although legally I could put it on the roof, I don't want them to challenge me and I really don't NEED to do it, for acceptable signals, unless I was doing it as a hobby to DX DTV signals...... The next batch of signals are very weak and out +100 miles. I already get almost 40 channels, so it's not a must have. I guess there are only about 17 stations I will ever watch with any regularity, and I can get those. I love antennas and want to get max signals just for fun but no need to but a 10' Yagi on the roof.

A test I did last night was putting my Terk HDTVa (amplified VHF/UHF indoor antenna) in the attic. This shows that signal is very good there. Also being over 25 feet or more in the air helps. Normally it lives on a shelf about 8 feet up on the first floor. It does well there, but in the attic it does as well or better!

Using a slightly large non amplified antenna in the attic might do the trick. However because most stations are SE, some West and one is NE, it likely will not be that simple. I am thinking DB4, facing SW, to get stations West, strong stations SE off the back corner and the one SE station (47.1) off the back of the antenna. This would be the dream come true. I might have to add a small dipole for the one stronger close VHF Hi station to the SE, channel 11.1. That would be just a UVSJ and one coaxial out the roof eave to the coaxial distrubution box outside on the back of the house. I no longer have cable but have cable internet on just one of the lines. The other coaxial lines are free to connect OTA TV to.

Right now an indoor Terk HDTVa is getting all the channels I can reasonably expect to get (38 channels from 17 networks including duplicate networks). However inside I have to see it and move it at least in two directions to get all the stations. The one odd ball is at 40 miles out, at 63 degrees, NE, ION channel 47.1.

All stations are UHF except for one VHF HIGH.

Most of the stations are SE and can be almost be received (because I tried it) with unamplified rabbit ears. With the TERK HDTVa indoor VHF/UHF antenna it's 100% signal. However I find pointing it South West I get all the stations to the West and the signal still is strong enough off the side back of the Terks "log period" antenna.

The current BASE line is one fixed antenna in the attic.

THE DECISION IS THIS.... If I need to go to multi antennas how to do it. Yes I know there are problems there and you can't just join the signals *usually.

Having only one VHF HI I can put up rabbit ears and us a UHF/VHF signal combiner... That is no problem. So that is two antennas. However to get the stations the NE and may be North I might need a third antenna. I have read about how to do that....

1) Trap
2) A.B switch (I would need to use a IR extender or RF to IR repeater)
3) Rotor

Clearly NOT having to select antennas or rotate the antenna is a BIG PLUS!

The Terk HDTVa is in my attic now. I ran coaxial from the first floor, up the stairs, into the laundry room, up into the fold down attic stairs door. In the attic I faced the antenna facing North (not at any particular direction). There just happen to be some wood between two joist making a nice perch. I was not expecting much. Right now it's almost 100% on all channels. I lost 48.1 and 2.1 is weak. The normally strong stations to the SE are 98% vs 100% signal and 29 dB vs 32 dB SNR. Not a bad compromise. I am not sure how a DB4 will do........

Any ideas and comments?

IDRick
08-04-2011, 12:56 PM
Nice, thorough discussion! You have clearly done your homework! There is one other way of joining antennas that uses a part called "join-tenna". With this device you can use a separate antenna for one channel, say ch 33, and join the signal from another antenna into a single downlead. Jointennas can impact reception for up to 5 channels above and below there target channel number. So there not always useful and getting hard to find. For more info and diagrams, see: http://www.warrenelectronics.com/antennas/Jointennas.htm

Based on your comments, the single location with the Terk HDTVa appears to be a good compromise. To improve ch 48.1 (real ch 33) would require a high gain antenna such as the antenna direct xg-91 aimed at 272 degrees. You could purchase a join-tenna tuned for ch 33 and join with the Terk HDTVa into a single downlead but this approach may reduce reception on WJHP (real ch 35) and/or WUVC (real ch 38). Can you receive WJHP? Is it important to receive WJHP when there is another, easier Fox available (WRAZ)?

teddymines
08-04-2011, 02:08 PM
Just for grins, I'd suggest temporarily putting your terk antenna outdoors on the peak of your roof to see what it can pick up. The point of this would be to estimate how much your roof blocks signal should you decide to keep your antenna(s) in your attic.

JB Antennaman
08-04-2011, 08:25 PM
There is no such thing as a multi directional antenna.
The only thing two antenna's connected together, aimed in two different directions will get you is multipath.

I would compare a Terk antenna in quality to that Ethanol gasoline they keep trying to sell me - not very good.

gmcjetpilot
08-05-2011, 01:52 AM
Just for grins, I'd suggest temporarily putting your terk antenna outdoors on the peak of your roof to see what it can pick up. The point of this would be to estimate how much your roof blocks signal should you decide to keep your antenna(s) in your attic.

Funny you should mention that. I did this with an un-amplified dipole (rabbit ears) a few weeks ago, on a mic stand on the patio and worked for all the local stations VHF and UHF, proving outside is nice. Needless to say the "yellow" stations are a no brainer.

http://img42.imageshack.us/img42/5118/dipoleoutside2.jpg

http://img34.imageshack.us/img34/9036/dipoleoutside3.jpg

Then I put the Terk HDTVa in the ATTIC.... WINNER!

Moved the Terk HDTVa antenna to the attic for an experiment. Running a coxial out the attic through the 2nd floor ceiling access, down the stairs to a first floor TV, the signal is AMAZING! Went from 17 networks, 38 channels, which required aiming it two or three times, to 21 networks to 56 channels in one direction!

I aimed at 220 degrees, splitting the difference between the weak stations (and compensating for limitations in the attic like the AC/heating unit and ducts). Stations at 270 degrees and 60 miles come in. All the strong stations SE (120 degrees) come in, but one or two are no longer strong, still usable but getting near marginal. The one weak station to the NE (60 degrees) at 40 miles that I want does come in. The experiment was a success.

I'm thinking of making this permanent, run coaxial out the attic, via the eave to the coaxial distribution box outside the house (the house is wired for cable TV), then to the TV of choice via coaxial routed in the walls. I only have one TV, so I think the existing Terk HDTVa signal injector (amp) will be fine.

The question, will a dedicated larger attic antenna like a medium sized 4-bay "bowtie", like an Antenna Direct DB4, Channel Master CM4221, Antennacraft U-4000, Wingard PR4400 work? I am worried about directional nature, wanting to avoid a rotor or two antennas and an A/B switch. Also I most likely will need a simple dipole combined with the UHF antenna for my one High VHF station. It is a stronger station so it should not be a big deal. If I was aiming at it with one of these UHF antennas I would get it no doubt, however to get the other two weak directions I need to aim way off the strong stations. That is a simple problem.

gmcjetpilot
08-05-2011, 01:57 AM
There is no such thing as a multi directional antenna.
The only thing two antenna's connected together, aimed in two different directions will get you is multipath.

I would compare a Terk antenna in quality to that Ethanol gasoline they keep trying to sell me - not very good.
That is not true.
There is OMNI directional, mono pole.
There is dipole which is bi-directional.
The "Bow Ties" or cat whiskers with out a reflector are bi directional.

Here is a Winegard PR4400 4-bay that has wide spaced rod reflector verses a mesh.... less gain may be but more off the back. This is the polar plot with my three directions. Theoretically it should work using the two side lobes. One antenna no rotor would be a dream.

http://img12.imageshack.us/img12/2772/pr4400.jpg

gmcjetpilot
08-05-2011, 02:10 AM
Nice, thorough discussion! You have clearly done your homework! There is one other way of joining antennas that uses a part called "join-tenna". With this device you can use a separate antenna for one channel, say ch 33, and join the signal from another antenna into a single downlead. Jointennas can impact reception for up to 5 channels above and below there target channel number. So there not always useful and getting hard to find. For more info and diagrams, see: http://www.warrenelectronics.com/antennas/Jointennas.htm

Based on your comments, the single location with the Terk HDTVa appears to be a good compromise. To improve ch 48.1 (real ch 33) would require a high gain antenna such as the antenna direct xg-91 aimed at 272 degrees. You could purchase a join-tenna tuned for ch 33 and join with the Terk HDTVa into a single downlead but this approach may reduce reception on WJHP (real ch 35) and/or WUVC (real ch 38). Can you receive WJHP? Is it important to receive WJHP when there is another, easier Fox available (WRAZ)?

I am being a CHANNEL HOG. ;) The near stations SE at 20 miles is all you really could want. The one to the NE is a unique station called ION. All the stations to the West are mostly duplicates, but that is nice to have, since programing does vary, especially on the smaller networks, CW, FOX, MyN(orthCarolina) or MyRDU and of course independents, Spanish and religion.

See the post above, the Terk in the ATTIC easily gets all stations for the most part as it did down stairs but the signal is improved making it more multi directional. The two-in-one Terk HDTVa antenna struggles to get all three directions at one time, but performs better than on the first floor of my two story house. Obviously height is always good for signal, but this shows my attic antenna is not a bad option for signals. The HVAC unit up there blocks the signal to the NE right now. If I go to the other end of the attic (kind of hard to get to and my coaxial is not long enough) I should have a good "view" in all three directions. Have not played with it too much, but initial indications are the signal up there, is through the roof (pun intended). :rolleyes:

To my shock doing ADD CHANNEL scan after putting the antenna in the attic last night, I got 11 more channels, including 12.1 which is 94 miles away. I also ended up getting another PBS, so I am encouraged that my attic is a good place for a signal and can get all three directions with out a rotor, I hope. It might take two antennas, one for my one Hi-VHF and one UHF. That is not hard to do. Even a VHF dipole (rabbit ears) should work fine for that one station. However it might take a third antenna & some trap as you mention to get a true multi direction set up for strong signals for all stations. This might mean another antenna, trap and an amplifier to negate all the insertion losses. I'm getting to the point where a rotor makes sense, one big antenna I can aim. Again the goal is to have no need for antenna controls, but a rotor would be fun to "DX" some signals.


This is my plot again now that I can post URL's
http://img838.imageshack.us/img838/4980/tvsignals.jpg

Terk HDTVa in the attic (temporary installation)
http://img196.imageshack.us/img196/7435/terkinattic.jpg

IDRick
08-05-2011, 09:02 AM
gmcjetpilot,

You may want to check out the "stealth hawk" DIY antenna. It is very inexpensive and easy to build. It does not use a reflector and has wide wide band of reception, both front and rear. It is a low gain antenna. However, you are losing on average 13dB plus/minus 7 dB with an attic install. You could easily put one of these up on roof and outperform the Terk HDTVa. Amplification may be needed to cover distribution losses at your location. If so, I would recommend the Winegard HDP 269 preamp.

Computer modeling analysis of the Stealth Hawk is available here: http://imageevent.com/holl_ands/chireix/uhfhivhfstealthhawk

In depth thread with perspectives and various builds by users is available here: http://www.digitalhome.ca/forum/showthread.php?t=123803 This is a very long thread, go to post 304 for current design recommendations.

gmcjetpilot
08-05-2011, 10:27 AM
gmcjetpilot,

You may want to check out the "stealth hawk" DIY antenna. It is very inexpensive and easy to build. It does not use a reflector and has wide wide band of reception, both front and rear. It is a low gain antenna. However, you are losing on average 13dB plus/minus 7 dB with an attic install. You could easily put one of these up on roof and outperform the Terk HDTVa. Amplification may be needed to cover distribution losses at your location. If so, I would recommend the Winegard HDP 269 preamp.

Computer modeling analysis of the Stealth Hawk is available here: http://imageevent.com/holl_ands/chireix/uhfhivhfstealthhawk

In depth thread with perspectives and various builds by users is available here: http://www.digitalhome.ca/forum/showthread.php?t=123803 This is a very long thread, go to post 304 for current design recommendations.


Thanks a million for for the tip.... I don't want to put it on the roof (which you are right would be awesome). This in keeping with the HOA rules, which is min visual impact. I know about the 1996 Fed law, but it's not "necessary" to get acceptable signal. I am sure if the HOA wanted to make a fit they could argue an attic antenna would be good enough.

OUTSIDE was my #1 choice, disregarding the attic before my experiment, but I got such good results in the attic with the TERK HDTVa it seems to be easier with less visual impact. OUTSIDE is not off the table, but I was thinking of something like an RCA ANT751 under the roof eave on the SE corner of the house on a J-pole.... A rotor might be needed with this antenna and installation (but need to experiment). The house would block stations to the N and NW but those are duplicates for the most part I think. I don't need three PBS stations. This would get excellent performance, one antenna and no amplifier, but the is down side is a rotor...... Of course a bigger antenna than the Terk on a rotor in the attic will work as well. The DB4 is the smallest and if it's on a rotor outside I am sure it would be work well.

http://www.dennysantennaservice.com/image/33089250_scaled_384x288.jpghttp://www.dennysantennaservice.com/image/33089317_scaled_129x172.jpg
http://www.dennysantennaservice.com/image/33089286_scaled_242x256.jpg

Turning the RCA ANT751 might be harder with the back radial being 36" wide, needing to be at least 20" from the house. I need to sweep from 70-270 degrees (or less as needed). One of these 4-Bays may be easier and smaller than 39" (1 meter). This would be the ones I would choose for attic.

http://img28.imageshack.us/img28/2149/antennas4bay.png



ROTOR NEEDED
I was asking about the Eagle Aspen ROTR100 in another post. It's a rotor that works through one coaxial with the signal. The antenna goes to the rotor. From the rotor is a combined signal + rotor pwr/control via coaxial to the control box, from the control/power box you feed the TV. Since I want to use the house in the wall cable, not having rotor cable is a big plus. In the attic I can easily put multi antennas facing as needed. The down side of this rotor is it causes signal loss... I think 2 dB or 4 dB. The rotor has power for an amplifier built into it, so I could add an amplifier. However you can run the TV antenna coaxial seperate from the rotor and one coaxial (or any two peices of wire) to the rotor. To get the rotor wire INTO the house with one of the other coaxial feeds into the house. The down side is the control box (which has IR remote) is in a different room and I lose TV to one room (which is no big deal). I could use a IR extender. A standard three wire rotor would work but I would have to route the rotor wire into the house or use a IR extender.


DIY:
Those UHF_HiVHF Stealth Hawk DIY antennas are cool. I have all the parts to make my some antennas, which I have done in the past for SW. The DIY 4 bay antenna with out a reflector might do it. I will use some copper wire and some PVC stand offs.

http://farm4.static.flickr.com/3094/2785701388_54cc8d9e70.jpg

IDRick
08-05-2011, 12:01 PM
A four bay antenna has about 3 dB higher gain than a two bay. The four bays also have a wider beamwidth for the higher channel numbers than the 2 bays. There's a number of different designs out there. The best, IMO, are mclapps designs. I built one of his M4 antennas for use in my attic. In your case, I would recommend a the 9-1/2" by 9" four bay. Plans are available here: http://m4antenna.eastmasonvilleweather.com/Drawings/PDF%20Drawings.html

***Add in, I've attached a picture of a 9-1/2" by 9" M4 that I built using a 2x2, 12 guage copper wire, and 4 carlon 1/2 inch pipe straps (ie, fits over a 1/2" pvc pipe). The straps isolate the wires and you can buy 5 straps for $1.44 at Home Depot in their electrical department. I had a poor performing antenna when I attached the elements directly to the wood (moisture issue?) and now I use the carlon strap exclusively.

gmcjetpilot
08-05-2011, 01:48 PM
A four bay antenna has about 3 dB higher gain than a two bay. The four bays also have a wider beamwidth for the higher channel numbers than the 2 bays. There's a number of different designs out there. The best, IMO, are mclapps designs. I built one of his M4 antennas for use in my attic. In your case, I would recommend a the 9-1/2" by 9" four bay. Plans are available here: http://m4antenna.eastmasonvilleweather.com/Drawings/PDF%20Drawings.html

***Add in, I've attached a picture of a 9-1/2" by 9" M4 that I built using a 2x2, 12 guage copper wire, and 4 carlon 1/2 inch pipe straps (ie, fits over a 1/2" pvc pipe). The straps isolate the wires and you can buy 5 straps for $1.44 at Home Depot in their electrical department. I had a poor performing antenna when I attached the elements directly to the wood (moisture issue?) and now I use the carlon strap exclusively.

Great link and advice. I think that is the next step.... I will make this one this week end. I love the PVC plastic strap spacer. I kind of wish I had a local store to sell me a 4 bay bowtie antenna to try.....

Solid Signal suggest the Winegard MS 2002 omni directional flying saucer. I have my doubts..... It might work of I mount it 3 feet above my +30 foot roof peak.

Right now the Terk HDTVa is doing the job, but not a perminate deal.

IDRick
08-05-2011, 02:00 PM
I've also built M4's using the pvc straps and pvc conduit. The crossover simply goes around the conduit. It is a pretty easy construction technique. Sorry I don't have a picture but I'm sure you get the general idea. The MS 2002 may work up on your roof but probably not well in the attic. It is rare to see positive comments on the omnis in the various antenna forums. The M4 is the better choice, IMO. Good luck, whatever you decide!

Rick

gmcjetpilot
08-05-2011, 02:54 PM
I've also built M4's using the pvc straps and pvc conduit. The crossover simply goes around the conduit. It is a pretty easy construction technique. Sorry I don't have a picture but I'm sure you get the general idea. The MS 2002 may work up on your roof but probably not well in the attic. It is rare to see positive comments on the omnis in the various antenna forums. The M4 is the better choice, IMO. Good luck, whatever you decide!

Rick

I agree. I think the salesman was stuck on looking at the strong signals 20 miles out.... I can get those with unamplified rabbit ears. I do like having multi CW, ION, Fox, Big 3 and others because they do have different programs between affiliates.

I also want a STRONG signal pixelated never, not good enough works most of the the time. That is with in the "technology" if I just engineer it right.....

What do you think of this two antenna combiner? CC7870

IDRick
08-05-2011, 04:03 PM
There's very little difference between the WG CC-7870 and a high quality 2-way splitter. The CC-7870 is power passive on one side while many two way splitters are power passive through all three ports. Power passive is important between the power inserter and the pre-amp but not important (to my knowledge) when joining antennas since they are between antennas and the pre-amp. Joining two identical antennas that are aimed in different directions generally leads to poor results because the signal is out of phase at the respective antennas leading to cancellation of signal.

projectsho89
08-05-2011, 05:27 PM
The four bays also have a wider beamwidth for the higher channel numbers than the 2 bays.

A two bay and a four bay should have the same horizontal patterns. The increased gain of the four bay comes by compressing the lobe in the vertical axis.

What do you thing of this two antenna combiner? CC7870

Not much. It a simple two way broadband ferrite core splitter that's much more lossy than a newer design glass strip design splitter. At 700 MHz, it's down about 4 dB on the power passing port and down almost 5 dB. I've tested glass strip splitters that almost flat as Kansas out to 1 GHz at around 3.5 - 3.7 dB insertion loss.

gmcjetpilot
08-05-2011, 06:05 PM
A four bay antenna has about 3 dB higher gain than a two bay. The four bays also have a wider beamwidth for the higher channel numbers than the 2 bays. There's a number of different designs out there. The best, IMO, are mclapps designs. I built one of his M4 antennas for use in my attic. In your case, I would recommend a the 9-1/2" by 9" four bay. Plans are available here: http://m4antenna.eastmasonvilleweather.com/Drawings/PDF%20Drawings.html

***Add in, I've attached a picture of a 9-1/2" by 9" M4 that I built using a 2x2, 12 gauge copper wire, and 4 carlon 1/2 inch pipe straps (ie, fits over a 1/2" pvc pipe). The straps isolate the wires and you can buy 5 straps for $1.44 at Home Depot in their electrical department. I had a poor performing antenna when I attached the elements directly to the wood (moisture issue?) and now I use the carlon strap exclusively.

I just got back from the home depot with the straps, PVC, some hardware.... I had the copper wire. I am JB welding the straps on. It should but up and running tomorrow, let you know. I went to radio shack for VHF/UHF combiner, $8! Ha ha. I passed on it. I may not need a VHF antenna added to this DIY bow tie, we shall see.

IDRick
08-05-2011, 06:21 PM
A two bay and a four bay should have the same horizontal patterns. The increased gain of the four bay comes by compressing the lobe in the vertical axis.

My field testing does not agree with your statement. Margin to dropout falls much faster when aiming off axis with 2 bays than 4 bays. Holl_ands (a highly respected communications engineer) has modeled 2 and 4 bay antennas and his results agree with my field testing. Beamwidths do vary by frequency and 2 versus 4 bays in Holl_ands modeling (see attachment). Polar plots for 2 and 4 bay antennas are shown in the links below.

http://imageevent.com/holl_ands/multibay/uhf2bays/uhfm2
http://imageevent.com/holl_ands/multibay/4bay/super

IDRick
08-05-2011, 08:49 PM
I just got back form the home depot with the straps, PVC, some hardware.... I had the copper wire. I am JB welding the straps on. It should but up and running tomorrow, let you know. I went to radio shack for VHF/UHF combiner, $8! Ha ha. I passed on it. I may not need a VHF antenna added to this DIY bow tie, we shall see.

M4 has modest positive high vhf gain for real channel 11 and the odds are quite good that you will receive it based on ch 11's high NM. Good luck! I'm interested in reading your results! :)

gmcjetpilot
08-05-2011, 11:42 PM
M4 has modest positive high vhf gain for real channel 11 and the odds are quite good that you will receive it based on ch 11's high NM. Good luck! I'm interested in reading your results! :)

You ARE RIGHT.... Channel 11 is a no problem... no need for a VHF antenna. Built today and just finished it, did not spend time optimizing the whiskers, but I can do that later. They are all a tad long and need their spacing evened out, but they're eye ball close.

http://img196.imageshack.us/img196/6820/diy4baytvantenna4.jpg

http://img684.imageshack.us/img684/7729/diy4baytvantenna2.jpg

I disconnect the Terk and connected my DIY 4 bay'er in the attic. It will work very nicely. I just put it up there in the middle of the attic wedged on-top of a box and roof. I could not locate it well (it's late and had to call it a night). Two station, one East and one NE dropped out. However all the locals and the distant West stations came in very nice. :yippee: (this is what I hoped for)


Big relief, the un-screened 4 bay is doing what I needed (and I hoped for).

Not having the screen did not kill my "front" distant range for the stations West. :yippee:

Not having the screen opened up the back bringing in local station better, including a VHF Hi (Ch 11), thus no second VHF antenna and UVSJ is needed. :yippee:

The stations East and NE should also have come in great, but I lost one independent station East and one NE ION. This I believe is due to blockage of the signal from the furnace and ducts. I have the DIY antenna placed in the middle of the attic initially. Moving the antenna around the attic should solve that problem. Despite that the strong stations SE came in very nicely (better than the Terk which is more directional).

The issue with the attic is it has a MASSIVE HVAC AC condenser and gas furnace smack in the middle. If you get over towards the eave you can get around the HVAC unit, but my "beta" version antenna is still on 5' of PVC. I left extra just in case. I can trim later. Any way I could not get it out into the side wings of the attic due to height. So the furnace and ducts are blocking NE.... The East side of the attic is harder to get at but wide open. The West side is close to the attic stairs and thus used for storage as well. Will have to try it, but right now my $6 antenna is awesome! I need to trim the antennas PVC backbone length, so I can squeeze it further out into the attic wings, away from the HVAC unit to get a better shot east and NE.

I am considering making another identical antenna; have one on the West side of the attic (and HVAC system) and the other on the East side of the attic, East of the HVAC system and ducts. If they are the same antenna and aimed similarly, it might work well. it can't hurt to try

Big success, thanks for the tip. I have been wanting to make a DIY 4 Bay'er for a while. Using PVC clamps and pipe made it easy. I knew bolting to wood was a poor choice. I used JB Weld to bond the clamps to the pipe. Bending the copper wire (liberated from some Romex three conductor house wire I had) was not hard at all. I formed the feed and whiskers while watching TV... how appropriate. I'm still running the little Terk Amplifier, but might not needed. Got to go, but update to come.

PS - I had the 300/75 transformer and some copper wire. If I had to buy bulk large gage copper wire ala cart, from home depot or Ace Hardware, it would have added at least $10.00 to my $6.00 antenna. The transformer should be a buck or two, but local stores want $5 or $7 (radio shack). Give me a break. I better quality one might improve performance. With that said the factory 4 bay antennas that cost $30 or $40 are a bargain, when you consider if you had to buy everything, including wire, transformer, reflector screen, which mind does not have, it would be $25-$30 in materials.

IDRick
08-06-2011, 12:33 AM
Great job and congratulations on your successes to date! You're making great strides and have a good plan for further improvements. :) BTW, in my experience, the spacing of each individual whisker is not particularly important. It's difficult to keep the whiskers pristine in the attic and I've seen little difference when increasing the spread of the whisker from say 2 inches to 5 inches. Leaving the insulation on 6 elements can change the velocity within the copper wire and may reduce performance. It's best to strip away all the insulation. Great progress thus far, congrats and I look forward to your next update!

projectsho89
08-06-2011, 06:08 AM
My field testing does not agree with your statement. Margin to dropout falls much faster when aiming off axis with 2 bays than 4 bays. Holl_ands (a highly respected communications engineer) has modeled 2 and 4 bay antennas and his results agree with my field testing. Beamwidths do vary by frequency and 2 versus 4 bays in Holl_ands modeling (see attachment). Polar plots for 2 and 4 bay antennas are shown in the links below.

http://imageevent.com/holl_ands/multibay/uhf2bays/uhfm2
http://imageevent.com/holl_ands/multibay/4bay/super

Your comparisons are of different element lengths and spacing for the 2 vs 4 bays making such a comparison inaccurate.

My comparison is based on the Antennas Direct DB2 and DB4 as done by their design engineer that was sent to me a while back. The horizontal BW figures are exact for 3 out of 4 data points.

You can also see the simulation at Ken Nist's site for the DB2 and DB4 which show the same relative horizontal BW.
http://www.hdtvprimer.com/ANTENNAS/DB2.html
http://www.hdtvprimer.com/ANTENNAS/DB4.html

IDRick
08-06-2011, 10:29 AM
Your comparisons are of different element lengths and spacing for the 2 vs 4 bays making such a comparison inaccurate.

My comparison is based on the Antennas Direct DB2 and DB4 as done by their design engineer that was sent to me a while back. The horizontal BW figures are exact for 3 out of 4 data points.

You can also see the simulation at Ken Nist's site for the DB2 and DB4 which show the same relative horizontal BW.
http://www.hdtvprimer.com/ANTENNAS/DB2.html
http://www.hdtvprimer.com/ANTENNAS/DB4.html

I've compared 9.5x9 and 10x9.5 four bays and observed no changes in beamwidth or margin to dropout degradation with aiming off axis due to changing dimensions.

I've compared 9.5x9 and 10x9.5 two bays and observed no changes in beamwidth or margin to dropout degradation with aiming off axis due to changing dimensions.

The fact that Holl_ands modeled slightly different sized antennas does not explain the difference in beamwidth. My test data demonstrates changing beamwidth with frequency and number of bays and Holl_ands modeling agrees with my field data. I can post data if you'd like. I could demonstrate that to you in five minutes if you were in the neighborhood. These are M2's and M4's that have longer elements and bay spacings than DB2 and DB4. We can agree to disagree but I'm going with my repeatable data and Holl_ands modeling over Ken Nist.

gmcjetpilot
08-06-2011, 01:35 PM
Great job and congratulations on your successes to date! You're making great strides and have a good plan for further improvements. :) BTW, in my experience, the spacing of each individual whisker is not particularly important. It's difficult to keep the whiskers pristine in the attic and I've seen little difference when increasing the spread of the whisker from say 2 inches to 5 inches. Leaving the insulation on 6 elements can change the velocity within the copper wire and may reduce performance. It's best to strip away all the insulation. Great progress thus far, congrats and I look forward to your next update!

Thanks.... appreciate the congrats....

I forgot to self disclose, I was still using the Terk HDTVa in-line injector near the TV. It is at the wrong end I assume. It should be near the antenna. Also I have a splitter at the TV to drive the TV and a Haggpauge PC TV card. According to the Sony Bravia TV's diagnostic display, the in-line amp increases signal strength about 2%-3% and SNR 1dB-2dB, for one station I looked at. From what I see I don't need it, but I might buy a real, high quality low gain RF amplifier and see what that does. The Terk HDTVa amp is pretty low gain I think. If I do the dual antenna idea, using a "combiner", then an amp might be needed, to compensate for insertion loss. Any way fun with antennas.... ;) I can always use an A/B switch and/or put one outside! See what happens! Heck making antennas for $6 is addictive! Ha ha.

(Any suggestions on what AMP make/model to buy to work with this antenna? I suspect the Terk HDTVa injector is optimized for that antenna and a generic amp might provide better results?)

An amp might make a small difference on the weakest station or may be bring in more stations. As long as SNR is 20 dB and signal strength about 82% (per the Sony diagnostic info) it's a pretty solid signal from experience. However if the conditions are less than optimal I can see these dropping out, but they are secondary stations.... I just notice channel 48.1 (the weakest theoretical station per tvfool.com) dropped out during the day. It was sold last night at 1 AM. I am not going to do anything, right now. I want to see if it comes back tonight as I suspect it will. If I move the antenna in the attic to a more optimal location I think that will solve that problem, as I described before.

For the most part I now have reliable signals up to 16 stations, 41 channels in three directions NE, SE and West with the caveat. I have received and scanned a total of 23 stations and 61 channels at one point or another. I got WLXI 43.1 independent at 64 miles and WCTI 12.1 ABC at 94 miles. That was with the Terk HDTVa in the attic, right conditions and aimed more or less at the station late night. The Terk HDTVa has a tad more front gain but is narrow with much less back side signal, which is what I needed with this DIY antenna, while still giving some gain front. For grins I might just add the Terk HDTVa in parallel with this antenna, see what a mess that becomes? I suspect it might be a bad idea. However I plan on making another one of these antennas, just for fun and to experiment with, whether I combine two antennas or not.

Getting extreme distant stations past 60 miles is not really practical for any indoor/attic set-up I suspect. I might take my new antenna outside, put it on a pole, see what it does. If I paint the PVC same color as the house it might look fine off a J-pole. I'll lose about 6 or 8 feet from the attic elevation above ground level, mounting it below the eave, but the signal not going through roof shingles, tar paper, plywood is a big bonus.

IDRick
08-06-2011, 02:08 PM
You are in area that is subject to tropo effects which means you can have some very distant stations coming in for a period of time and then they're gone. A website that predicts tropo effects can be found here: http://www.dxinfocentre.com/tropo.html For a discussion on tropsheric propagation, see: http://en.wikipedia.org/wiki/Tropospheric_propagation

Which amplifier? You're in a unique situation with several very strong locals and possible reception of distant locals. Tell us more about your distribution system. What is the maximum run of cable to a tv and shortest cable run to a tv? How many splitters in the distribution system and how many tvs and/or tuners? Which cable did you install (rg6? manufacturer and part number?) We need this info to estimate distribution loss.

Putting the antenna outside on a jpole and painting the spine the color of your shingles would make it nearly invisible to your neighbors. In fact, I'm guessing that most would never see your antenna unless pointed out to them. Course, the missus will see it from 10 miles away and want you to do something about that but well that's your battle... ;)

gmcjetpilot
08-06-2011, 02:33 PM
You are in area that is subject to tropo effects which means you can have some very distant stations coming in for a period of time and then they're gone. A website that predicts tropo effects can be found here: http://www.dxinfocentre.com/tropo.html For a discussion on tropsheric propagation, see: http://en.wikipedia.org/wiki/Tropospheric_propagation

Which amplifier? You're in a unique situation with several very strong locals and possible reception of distant locals. Tell us more about your distribution system. What is the maximum run of cable to a tv and shortest cable run to a tv? How many splitters in the distribution system and how many tvs and/or tuners? Which cable did you install (rg6? manufacturer and part number?) We need this info to estimate distribution loss.

Putting the antenna outside on a j pole and painting the spine the color of your shingles would make it nearly invisible to your neighbors. In fact, I'm guessing that most would never see your antenna unless pointed out to them. Course, the missus will see it from 10 miles away and want you to do something about that but well that's your battle... ;)

Right Now:

Ant ---- 300/75 balun transformer ---- ~40 feet of coaxial (low quality consumer china RG59/U) ---- Terk HDTVa amplifier ---- *splitter* ---- 2' of coxial (high quality RG6 and fittings) ---->> one coaxial goes to TV, other to PC TV Card.

* Splitter is high quality, -3.5dB per out, 6-1000 Mhz, model CMC2002H-HEP (a souvenir from time Warner)

What I plan on doing will be similar to the above temp situation, coaxial out the attic direct to the TV. I coaxial will drop outside the house from the roof eave, then go to coxial distribution box on the back of the house. In the box are 4 coaxial lines, one per bedroom and living room. Right now there is a splitter, but I plan on bypassing that and just feeding one line the TV signal. The total coaxial distance will go up about 30 or 40 feet I guess. So the total coaxial run could be 70-100 feet. The room upstairs may be more. I am feeding a down stairs room so the run will be shorter, guessing 70-80 feet. One coaxial line to the upstairs is used exclusively for internet, separated from the "TV" distribution.


Experiment/Test - Winner. I took the splitter out of the picture, with the Terk amp still in the picture, connecting direct to TV, I got channel 48.1 back mid-day. The Sony diagnostic info says 16 dB SNR, 75% signal, that is minimal. We shall see what it does at night, but it came in just fine last night with the splitter? I still saw some pixelation, but no drop out. So that splitter is making the difference. Channel 48.1 is a good bench mark for getting signals to the West. The one that is lower in the same direction is WLXI Chan 43.1 at 56 miles. I have received that in the past, in fact last night. This is why I think the signal is there, it just needs to get a little boost to compensate for losses in coaxial and connections.


If I desire to drive all four lines in the house I would add a distribution amp there at the box where Time Warner had a basic splitter. I makes more sense to put an amplified distribution there. So I might as well buy one of those from the start (like the Motorola below). There is an outside AC power outlet I can access. The weather proof box should have room for the amplifier. If not I can get a bigger one. For now however I am looking for just a SINGLE line amplifier, which Motorola makes as well. I only suggest Motorola because some one else told me they are good low noise units. They cost more but heck Radio Shack sells junk for the same price.

Also I have AC power in the attic as well, so I don't need to put power in the coxial to drive the amp.... In fact I want to avoid that, unless you think that is OK. It seems when you mix DC and RF signals on the same coaxial it's a compromise.

I plan on getting some good RG6. I have high quality RG58 but it's 50 ohms. I hate cheap coaxial, but it's what I had laying around ready to use. I'm guessing just better coaxial will help. Also guessing the Amp should be by the antenna not TV. I can move that in-line injector near the antenna, see what happens. Just for fun I went to radio shack yesterday, just to look. They had an cheap looking amp for $49! Ha ha! I have been told Motorola makes a nice one....
Motorola Signal Booster 4-Port BDA-S4 Cable Modem TV HDTV Amplifier

Link: Motorola Signal Booster 4-Port BDA-S4 Cable Modem TV HDTV Amplifier (http://www.amazon.com/Motorola-Signal-Booster-4-Port-Amplifier/dp/B000WPGRKK)


http://ecx.images-amazon.com/images/I/51t9ExrOWhL._SL500_AA300_.jpg

Or for a single line. Link: Motorola Signal Booster 484095-001-00 Bi-Directional RF Amplifier (http://www.amazon.com/Motorola-Booster-484095-001-00-Bi-Directional-Amplifier/dp/B000066E6Y)

What do you think of Motorola?

IDRick
08-06-2011, 03:45 PM
Nice job! :)

I like the Channel master distribution amps and would recommend the CM 3410 if you have no splitters and the 3414 if you want to send the signal to 4 tvs.

http://www.solidsignal.com/pview.asp?mc=03&p=CM3410&d=Channel-Master-CM3410-Ultra-Mini-Distribution-Amplifier-(CM3410)&c=Amplifiers&sku=
http://www.solidsignal.com/pview.asp?mc=03&p=CM3414&d=Channel-Master-CM3414-Distribution-Amplifier-(CM3414)&c=Amplifiers&sku=

The specs are very similar between the CM3414 and the Motorola amplifier. The 3414 is cheaper at Solid signal. Both are good choices.

gmcjetpilot
08-07-2011, 09:33 AM
WELL NO SHOCK OUTSIDE IS A WINNER! I put it outside and it seems the be a clear winner. Despite being about 20 feet lower, it is getting all the stations, day time WITH the splitter, no amplifier. If I do mount it outside it will go on the corner of the house and higher up near the second floor eave... about 15 feet higher.

I may go back into the attic to make sure that can't be made to work with a single antenna installation. After I put the antenna for the first test in the attic, one of whisker pairs got lose and rotated down into another bay. I am sure that killed some signal. Still the issues in the attic is with the HVAC unit and ducts. I can work around that, and the attic has some advantages... like weather proofing, no ladder climbing. However having the antenna outside, near the cable distribution box, means less coaxial routing and not having to put a hole in the roof eave.

http://img847.imageshack.us/img847/3150/diyantennaoutside.jpg

http://img220.imageshack.us/img220/9481/diyantennaoutside3.jpg

Questions?

1) What color to paint it? Match house color, white, flat black, as is?

2) HOW DO I WEATHER PROOF IT.

I was thinking of dielectric grease to protect each "node" of the antenna, all exposed electrical connections. That would be re-occurring maintenance I guess.

The transformer is not for outdoor use. May me a small electronic project box and silicone might do it. The in-line balun transformers with a short twin lead http://ecx.images-amazon.com/images/I/21kS8zxPj%2BL._SL75_SS50_.jpg might be better than the one I have http://ecx.images-amazon.com/images/I/21R7Y4VTJFL._SL75_SS50_.jpg


3) How to mount?

Light duty metal straps might do it, even PVC would work, however metal brackets could be thin, so it's less of an eye sore. A "L-pole" is over kill and most don't have the reach from what I see. I need about 15 inches from the house. Not sure if the aluminum down spout will affect the signal. Since that downspout will be right off side in the node area it should not hurt it.

IDRick
08-07-2011, 12:06 PM
Good work, glad to hear the M4 works so well outside!

Painting can be used to help disguise an antenna. A black spine works best if one is in an area where leaves come and go. The black blends in well with existing trees with or without leaves. Some have used green camouflage colors, excellent in the summer but more visible in the winter. I would only paint the spine, not the wires. If you choose to paint the wires, make sure you have an excellent electrical contact at each whisker/phase line junction and at the antenna feed point.

Weatherproofing? Hmmm, most DIY'ers just ensure a good tight connections and call it a day. Others may have suggestions.

Mounting? There are several general options for mounting antennas using the following: tripods (roof), chimney mounts, j-mounts (roof or sidewall), eave mounts (at peak of roof), under eave mounts (several used for satellite dishes should work for antennas), tall mast mounted to sidewall of home, and tall telescoping mast mounted in concrete with appropriate mount and guy wires). There's lots of options, just depends on your preferences. An under eave mount may be a good choice for you. There's many undereave mounts on the market, I'll need to do some checking before I can make a recommendation. There is a site called d b s talk dot com that has a Directv satellite installation forum. The installers there can give you good info on which works best. If you search there for undereave mounts, you can see pictures of the various types available.

A reflectorless M4 should be mounted in two locations (1/3 way down and 2/3 way down the spine). You'll need to add a second spine behind the antenna using elbows and other piece of pvc. Attach the antenna to the mount device by attaching to the back spine, not the antenna spine. You can use u-bolts or you can buy Channel master mounts (I like these), see: http://www.solidsignal.com/pview.asp?mc=03&p=CM9017&d=Channel-Master-CM9017-UBolt-and-Nest-Assembly-(CM9017)&c=Mounting%20Supplies&sku=

Balun transformer? Purchase a good outdoor balun such as this one: http://www.solidsignal.com/pview.asp?mc=03&p=CM3075&d=Channel-Master-CM3075-Outdoor-Matching-Transformer-(CM0089)&c=Mounting%20Supplies&sku=

IDRick
08-07-2011, 01:47 PM
gmcjetpilot,

We have not discussed an important aspect, grounding the outdoor antenna. For details see: http://www.hdtvprimer.com/ANTENNAS/basics.html (scroll down to bottom of page)

An excellent discussion on all aspects of antennas, including grounding, can be found here: http://manuals.solidsignal.com/AntInstallGuide.pdf

teddymines
08-08-2011, 11:23 AM
Wow, thanks for posting those pics. I've never heard of a furnace or air conditioner in an attic before...ours are in the basement. Must be a beyotch to service. And what is that yellow piping, gas? Water?

For weatherproofing, I tightened down connections and put some clear silicone on them. My grounding connector has a compound that resists corrosion. Use coaxial boots on the signal lines, with a little silicone to seal the interface.

gmcjetpilot
08-08-2011, 12:05 PM
Wow, thanks for posting those pics. I've never heard of a furnace or air conditioner in an attic before...ours are in the basement. Must be a beyotch to service. And what is that yellow piping, gas? Water?

For weatherproofing, I tightened down connections and put some clear silicone on them. My grounding connector has a compound that resists corrosion. Use coaxial boots on the signal lines, with a little silicone to seal the interface.

Service is easy, pull down ceiling stairs in the upstairs laundry room to the attic takes seconds. It does not need much, just filters every 500 hours. The yellow lines are natural gas lines, teflon with stainless steel case and multi layers of house and outer yellow sheild. Saves on all the fittings and potential leaks with black iron pipes. I guess it will out live me. No basement unfortunately. I suppose if the the HVAC unit needs to be removed completely? Ouch. However they usually are repaired, blower motor, AC evaporator (AC unit outside), gas furnace. It should last for 50 years before it needs major overhaul, new condenser or burners? It is sitting right there with access to work on. I never saw this before either, but it does use space not normally used, and it's convenient for duct work.

For weather proofing I used clamping but I smeared some dielectric grease on it. I found my tube of it. Kind of expensive, but worth it. It stops corrosion. Silicone is good to seal weather boots and housings but not for electrical connections. It has some acids in it that are corrosive. Also moisture can get under it. No antenna last forever.

iLLgRiM
08-08-2011, 12:48 PM
Good Luck!

gmcjetpilot
08-08-2011, 08:26 PM
Well it's done. I gave up on the outside mount and temporary put back in the attic. It is working as hoped. :yippee:

http://img10.imageshack.us/img10/8475/diyfinalantenna2.jpg

I made a small change and put the small Terk HDTVa amplifier with the antenna vs at the TV. This was a BIG gain! It gave several more % of signal and SNR points. By moving the amp close to the antenna in the attic, verses keeping it near the TV I got a nice solid gain across the board. I have to buy a nice amp as discussed.

http://img803.imageshack.us/img803/1176/diyfinalantenna1.jpg

I was looking at routing coaxial out the eave, so I crawled over a sea of insulation, under and over ducts, stepping on rafters to get out there. It's impossible to get at. I have to look for a way to route from the attic to the cable distribution box on the back of the house. It should take less than 40 feet of coaxial if that much.

This is the final count, 45 channels on 17 networks: (edit, day time signal)*
CBS 2.1 57 mi W (87%/23 SNR) (82%/20 SNR) Chan51
PBS 4.1 19mi W (99%/32 SNR)
CBS 5.1 21mi SE (93%/27 SNR)
FOX 8.1 57mi W (86%/29 SNR)
ABC 11.1 21mi SE (100%/32 SNR)
NBC 17.1 21mi SE (95%/29 SNR)
CW 20.1 56mi W (100%/32 SNR) amazing station
CW 22.1 21mi SE (88%/24 SNR)
Span 26.1 17mi NW (92%/27 SNR)
MyR 28.1 21mi SE (96%/30 SNR)
TCT 30.1 38mi E (92%/26 SNR)
Span 40.1 21mi SE (94%/28 SNR)
TCT 43.1 56mi W (86%/ 23 SNR)(80%/19 SNR) Chan61
ABC 45.1 56mi W (90%/26 SNR)
ION 47.1 40mi NE (85%/ 22 SNR)
MyR 48.1 56mi W (89%/25 SNR) (83%/21 SNR) Chan33
Fox 50.1 21mi SE (96%/29 SNR)

* I believe these signals drop during the day vs night.
On my Sony when signal is above 80% and 20 SNR
is good. At 80%/20 it's fair; below this 2 or 3 points
it's marginal. (Confirmed signals drop during day. Ones
noted are the worse hit. Most signals took only a small
hit, 1-2% and 1-2 lower SNR, but all come in, even
channel 2.1. Clearly some troposcatter at night? With
the splitter day time the signal gets marginal on a few
stations during the day. Time for a real amplifer.)

With a real amplifier and better coaxial I should secure
all these channels day or night. I will have to check them
during the day. I might make a second 4 bay and face
it same direction, might bring in a tad more signal.


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