I'm doing a copy of...

KrissB

DTVUSA Member
#1
dkreichen1968's Antenna Design. I hope it's okay! :\

I did some calculations, and measured once, and may re-cut it later. I added some possible outdoor protection with a good thought/bad idea (once the process was started lol...).

I originally wanted to make the antenna for Ch. 7 174mhz. I think I cut it for 168mhz or lower. As 33" folded dipole was needed for Ch. 7 (if I did it right). My folded dipole is 35-1/2", 6" space at the folds.

**So if anything this thing will also pic up Ch. 6 if I don't need to re-cut it?**


I wanted to add 2" to the connectors to compensate some of the change (not even sure how close 4" was to being correct, I didn't research that part again, but I did remember it could be an issue) going on faith lol... However, it ended up being 5" spacing instead of 6" after mounting.

I then (tried to add) added 3/8" x 1/4" Vinyl Tubing to the 1/4" copper tubing. It was SO soft that covering the 35-1/2" (total of 76") folded dipole was nearly impossible without a lubricant, so I opted to cover the middle *top or maybe it will be bottom on this antenna due to the added weight* of the folded dipole with 30" of 1/2" SCHD 40. The Vinyl tubing goes on with a huge struggle about 26-28". RTV sealant will be added before it goes up to all exposed copper/connections.

I made a 6" loop, as I think that is a common UHF loop?

My only other main concern is, height! I may only barely be able to get this off my room more than 3-5 feet, but the house is a 2 story house. I'm probably able to only use a Satellite mount, that is already installed (looks like a bad spot lol...).

I have some pics below:

The loop
6inch-vinyl-covered-loop.JPG

The folded dipole
35plus-inch-covered-folded-dipole.JPG

Cell phone camera seems to be giving me grief now! Sorry for how blurry it is.


Alright, here is where I leave it to you guys to fill any blanks you may see or want to mention!

Thanks in advance,
KrissB


Latest progress

Nearly finished, but done for the night! Work calls in the morning! lol
35inch-folded-dipole-nearfinished.JPG

Mounted on Camera stand, temporarily!
35inch-folded-dipole-007.JPG

I really had fun building it, fairly simple and straight forward build. Simple, instead of too many layman's terms to understand! lol Currently taking in too much on another project. Not sure where it's going currently, aside from the fact I'm out of Excedrin Migraine!!!
 
Last edited:
#2
Kriss I think going larger is probably a mistake on this one. Keep in mind there will be interaction between the elements. I haven't played with the one I built much. I started out feeding it at the front as in original plans. When I change it to rear feed as in your photo I lost UHF performance. Take a look at dk's indoor photos of it. Fed from the front side worked better on mine. Transformer hanging off the front didn't seem too stable to me but it worked better. I have strong VHF signals here. The UHF signals here are from 300 Watt ERP translators about 30 miles away. Those are 30 watt transmitters when they work right plus 10 db antenna gain. As the owner of the transmitters once told me he is often times getting about 5 to 10 watts to the antenna.
Your photo looks good.
Steve
 

KrissB

DTVUSA Member
#3
For now, it's only inside, so yea, it's still in testing mode, which, really it isn't! I'm pulling a bit better UHF signal than I was however with any of my antenna's so far aside from the bow-tie project. The Bow-tie project is on hold until I take more time to read up on it more, as it is doing worse than this is in signal quality (whatever the TV measures). Again, that could be a matter of being inside still. I'm unsure what my upstairs neighbors have going on, but something up their is causing a near black out at times. The bow-tie brings in Canadian stations at night, about the only difference. This UHF is just a loop, so understandable that it doesn't.

My weak stations are VHF: 7, 10, & 13. Having a real problem getting Ch 14 (29 Fox, although I have a Fox in the opposite direction) as well.

I want to point W/SW and hoping to test up higher (going on a lot of luck) hoping to get 10 and 13 from the E. That would appease my inner TV desires! lol.

Currently sitting on top of a camera stand, that extends to 7 foot, err but already bent the top extension from the weight! lol Shortening each extension a bit seemed to stiffen it up a bit, but if anyone thinks a camera stand might do the trick, if the antenna has much weight, uh, the answer is then no, not idea! lol

Adding a pic of it on the stand though. I used a 5/8 sparkplug socket to cover the camera mount area, then the 1/2" PVC T opening fit right in there (for any light weight antenna's).

I was wondering what size of director to use if I did take off the UHF antenna. Plan on using a 1/2" copper tube, if that could work as a straight dipole director.

I probably could add 3 or so directors. I'm not a fan of the loop, I just feel like I'm losing out hehe, but in fairness in the air (higher than I could achieve) it would do the trick I'm sure!

KrissB
 

dkreichen1968

Moderator
Staff member
#4
With my original build I was theorizing that the dipole was acting as a reflector for the loop antenna. I've also though about adding a low VHF dipole of 83" at 18" behind the high VHF dipole to make a three band antenna, then adding a reflector at the appropriate distance behind the low VHF dipole. I did experiment with a reflector at 18 inches behind the dipole and it added significantly to the signal readings on both my RCA DTA800B1 and my Digital Stream DTX9950. There isn't any low VHF in my area to test with, so that is for another day. ;) For whatever reason the strength/quality readings increased dramatically for VHF signals when I added the UHF loop.
 

KrissB

DTVUSA Member
#5
With my original build I was theorizing that the dipole was acting as a reflector for the loop antenna. I've also though about adding a low VHF dipole of 83" at 18" behind the high VHF dipole to make a three band antenna, then adding a reflector at the appropriate distance behind the low VHF dipole. I did experiment with a reflector at 18 inches behind the dipole and it added significantly to the signal readings on both my RCA DTA800B1 and my Digital Stream DTX9950. There isn't any low VHF in my area to test with, so that is for another day. ;) For whatever reason the strength/quality readings increased dramatically for VHF signals when I added the UHF loop.
I too don't have much Low VHF. Ch: 10 and 13 are my only real concern, I did cut it for Ch 7 as I may get it, but it's only a bonus channel!

Testing inside showed higher signal (but not enough to come in). I was considering adding folded dipoles for 10 and 13, however I think maybe just adding a Ch 10 folded dipole would do the trick maybe with a few directors? Or should I add one for 13 too? thinking I only have enough for Ch 13 folded dipole anyways. :\ I'll have to look tomorrow after work.

I've had luck with UHF, VHF isn't being so friendly at +/-25dB from the towers. lol

KrissB

Side thought (this is how I get sidetracked!!!), could I add a UHF element behind the reflector if I added a reflector for VHF?
I only have UHF <--- | ---> VHF IF that would work, that will be my next step. If the Ch. 7 Folded Dipole will achieve Ch. 10 and 13 I may not change the VHF dipole. Or would I really have better results with Ch. 10 Folded dipole?

(any input is greatly appreciated as VHF seems more touchy),
KrissB :D

Thanks dkreichen1968 for your thoughts, glad to see your post. :D I just wish there was a book to simplify this whole migraine! lol
 

dkreichen1968

Moderator
Staff member
#6
My design works really well for channels 7 and 9. Those are the channels that I'm currently using it for. It also works for channel 8 on the backside, but I watch RMPBS on channel 18 (KRMA 6). Surprisingly the dipole loop antenna worked better for picking up UHF signals from Denver than an Antennacraft U8000 at the same location in the back yard. Ultimately I ended up pulling in the UHF stations using my Gray-Hoverman in the master bedroom.
 

KrissB

DTVUSA Member
#7
My design works really well for channels 7 and 9. Those are the channels that I'm currently using it for. It also works for channel 8 on the backside, but I watch RMPBS on channel 18 (KRMA 6). Surprisingly the dipole loop antenna worked better for picking up UHF signals from Denver than an Antennacraft U8000 at the same location in the back yard. Ultimately I ended up pulling in the UHF stations using my Gray-Hoverman in the master bedroom.
That's kind of the direction I'm going too I think. I haven't made a Gray-Hoverman, but I'm thinking a separate UHF will be slipped into my setup.

I checked online for a Folded Dipole Calc, and it said I needed a 33" Folded Dipole. Maybe the site was goofed (I was lazy, and should have done the math to double check it)! Boy did I pick a bad project to be lazy with, at least I didn't cut it too short! hehe

KrissB
 
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