Chicago area: Seeking HDTV indoor antenna device 60118 - AVS Forum
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post #1 of 6 Old 09-13-2012, 12:14 PM - Thread Starter
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Hey guys, I've been doing alot of research and came up with my 1st prototype of a DB4? antenna.
I'm doing this for my mother who lives in the St Charles (60174) area and is due south of me but just as
far from the city transmissions. She lives in an Apt building that would require her to have her own indoor
antenna, and she's on the top floor, but the western side of the building.

Here's my front and rear pics of the antenna with my son's TV in the background for tuning with the signal bar.
AntennaRear.jpg
AntennaFrontTV.jpg

I'm living in Sleepy Hollow IL which is past Rt 59 in the NW Suburbs. However, my signal isn't
as well as I expected it to be for some of the channels and I was looking for critique and input.

I've used TV Fool to look up my area , and this is the results.
http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d5ed670a322c81f

I followed the DIY tutorials found in this thread, and every "Whisker" is set correctly 7" in length
and 3" spread at the ends. I did all the measurements to the T, according to the plans.
http://www.tvantennaplans.com/
http://countryplans.com/smf/index.php?topic=7924.0

So here's my questions:


#1. I designed my DB4 side by side, instead of stacked one on top of the other.
Is this affecting performance ?? I angled it due SE from my location which is where Chicago is
with my Digital to Analog converter box signal level on so I could get the best signal possible.

#2. I planned on putting this in my attic, but it's currently sitting in my son's Bedroom by the window
on a kitchen pub chair and I'm getting near 100% on WFLD, but WMAQ.....kinda sucks. I did have
WBBM, WMAQ, WLS, WFLD, WPWR, WGN, etc until I screwed around with it trying to get better
signal now I lost WMAQ into the red. (Red = Bad, Yellow = OK, Green = Great)

#3. If this was put in my attic, which has the same skyward view but it has aluminum siding.....
How much signal loss am I going to sustain ?? Considerable ?? Or minimal ?
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post #2 of 6 Old 09-13-2012, 12:14 PM - Thread Starter
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BTW I did look up a few details on this before posting and read this thread as well.

http://www.avsforum.com/t/815397/chicago-il-ota
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post #3 of 6 Old 09-13-2012, 06:02 PM
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Hello Aceshigh22; welcome to the forum.

Thanks for posting the photos.

Your antenna is a good first effort, but it is not optimum for your location or your mom's.
Quote:
......1st prototype of a DB4? antenna.
Your prototype is two 4-bays side by side, so it should properly be called a DB8.
Quote:
I'm doing this for my mother who lives in the St Charles (60174) area and is due south of me but just as
far from the city transmissions.
Her signals are a little stronger than yours. This is a tvfool report for her zip code:

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d5ed6bbb20d154e
Quote:
......she's on the top floor, but the western side of the building.
That creates a problem because the signals coming from the east will have to go through the building. You will need to try different locations for her indoor antenna even if it means using a coax extension joined with an F81 coupler.
http://www.radioshack.com/product/index.jsp?productId=2103459
http://www.radioshack.com/product/index.jsp?productId=2103648
Quote:
I followed the DIY tutorials found in this thread, and every "Whisker" is set correctly 7" in length
and 3" spread at the ends. I did all the measurements to the T, according to the plans.
Your antenna would work better with 9.5 inch whiskers and 9 inch vertical spacing between the bays. If you look at the links in your country plans link you will see the best plans for a 4-bay UHF antenna are by mclapp. Adding a reflector to your antenna will increase the gain.
Quote:
#1. I designed my DB4 side by side, instead of stacked one on top of the other.
Is this affecting performance ??
Two 4-bays side by side narrows the horizontal beamwidth but leaves the vertical beamwidth unchanged. One over the other narrows the vertical beamwith but leaves the horizontal beamwidth unchanged. Your arrangement requires more careful aim but reduces multipath problems. One over the other is good at reducing reflections from aircraft. I prefer your arrangement. Both give about the same gain.

A well designed 4-bay antenna will have more gain than your less-than-optimum 8-bay and be a lot smaller. Be careful of the ends of the whisker wires; they can easily scratch you. I put plastic caps on the ends of mine, see attachment.

Screwing the whiskers to wood is not ideal. There is loss of signal strength because wood is not a good rf insulator and the attachment point is a high impedance point for the elements where they are most sensitive to loss.
Quote:
#3. If this was put in my attic, which has the same skyward view but it has aluminum siding.....
How much signal loss am I going to sustain ?? Considerable ?? Or minimal ?
Aluminum siding is very effective at blocking the signals; your loss will be considerable.

WBBM-DT is on VHF channel 12. Your antenna is primarily a UHF antenna. You will probably need to add a simple VHF antenna for CH 12 and combine it with your UHF antenna with a UVSJ (UHF VHF splitter joiner) which looks a lot like a conventional 2-way splitter, but is designed to join a UHF antenna with a VHF antenna without each affecting the other. That is what muldoon did in the country plans link, except he used a conventional splitter which is not proper.
http://www.solidsignal.com/pview.asp?p=UVSJ&d=Pico-Macom-UVSJ-UHF-VHF-Band-Separator%2FCombiner-for-Antenna-(UVSJ)
http://www.radioshack.com/product/index.jsp?productId=2103923

He did use a splitter to join the two 4-bay antennas, which is better than the horizontal wires that connect the two 4-bays. When you join two 4-bays together, they must be phased together. Try reversing the leads on one balun to see if you get more or less gain as shown on your signal strength indicator.

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post #4 of 6 Old 09-13-2012, 08:54 PM - Thread Starter
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WOW.....lots of great info, MUCH appreciated.

Is that your antenna you built in that final IMG you uploaded at the end of your response??
If it is, can I see more pics and details of how you built it ?? I'd like to start over and copy your design.

Since I got a wild hair up my arse and waited so long, I ran to Best Buy to grab a Clearstream 4 antenna
and test it out side by side to see my weak points. This antenna grabs almost everything at 100% in my house
in the same position, and I get WBBM on VHF very clearly (High normal range). So obviously mine needs to
be reconfigured or redone.

If I can get more info on your antenna build with specifics on the components and where they can be sourced
I'd be GREATLY appreciative. Also what you used for the catcher, and how you made it all. I don't want to pay
$150 for an antenna , even if it is only $79 on Amazon......so I'd love to get this right.
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post #5 of 6 Old 09-13-2012, 09:20 PM - Thread Starter
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What's your thoughts on a Gray Hoverman design VS the Mclapp 4 Bay design you're recommending I step down to ???
Is it going to have more gain then the McLapp ??? Also where do I acquire #8 Copper wire exactly ?? Yes, I'm a noob to this. LOL

I saw this thread with lots of GH plans and lots of praises.
http://www.dtvusaforum.com/dtv-hdtv-reception-antenna-discussion/30069-gray-hoverman-vs-mclapp.html
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post #6 of 6 Old 09-14-2012, 09:32 PM
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Quote:
WOW.....lots of great info, MUCH appreciated.
Glad to hear that it was helpful.
Quote:
Is that your antenna you built in that final IMG you uploaded at the end of your response??
If it is, can I see more pics and details of how you built it ?? I'd like to start over and copy your design.
That is my antenna, but I didn't build that one. It is an original Channel Master 4221 4-bay bow tie antenna that was designed for the old UHF band that had many channels above the present CH51 upper end. It has 8 inch whisker elements and 8 inch vertical spacing between the bays. The whole antenna is shown in the attachment. I added the wooden frame around the reflector for safer indoor handling. Their new model is the 4221HD.
Quote:
If I can get more info on your antenna build with specifics on the components and where they can be sourced
Mclapp has a website for DIYers:

DIY TV Antennas
http://m4antenna.eastmasonvilleweather.com/index.html

The AVS forum has a thread about DIY UHF antennas:
How to build a UHF antenna...
http://www.avsforum.com/t/798265/how-to-build-a-uhf-antenna

And this forum has threads about antenna design:

Antenna Research & Development
http://www.digitalhome.ca/forum/forumdisplay.php?f=186

Bow Tie TV Antenna Designs (mclapp's M4 featured)
http://www.digitalhome.ca/forum/showthread.php?t=100137
Quote:
What's your thoughts on a Gray Hoverman design VS the Mclapp 4 Bay design you're recommending I step down to ???
I have built 4-bay bowtie UHF antennas, but I haven't built any Gray Hovermans. They both have about the same gain. Some people say that the Gray Hoverman has more gain than the 4-bay, but if you look at the gain curves that compare the SBGH with the CM4221 and imagine that the 4221 elements are made a little longer, and the vertical spacing of the bays is increased to match, to shift the 4221 curve to the left you will see that the gain of the 4221 is at least as good as the SBGH or even better. There are, however, newer Gray Hovermans that have been improved using computer modeling.

Gray-Hoverman Antenna Performance
http://www.digitalhome.ca/ota/superantenna/performance.htm
Look at the chart Single Bay Gray-Hoverman (SBGH)
vs. Channel Master 4221 4-Bay Reflector UHF Antenna:
Quote:
I ran to Best Buy to grab a Clearstream 4 antenna and test it out side by side to see my weak points. This antenna grabs almost everything at 100% in my house in the same position, and I get WBBM on VHF very clearly (High normal range). So obviously mine needs to be reconfigured or redone.
Good job!
Thank you for making a test that confirms my evaluation.

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If you can not measure it, you can not improve it.
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www.megalithia.com/elect/aerialsite/dttpoorman.html
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