This post was caught as spam in my comments section, but I thought it was a neat post and the theory behind it looks very plausible. We’ll all be using the new digital broadcasting pretty soon, so I hope you are prepared. I have been using “off-the-air” HDTV for some time now. I am using a Terk antenna (which works just dandy here in Hillsboro on the Portland Oregon towers). The terk cost about $40, it looks like you could build this for the price of the wire and an antenna matching transformer.
I’ll try building on of these. I think I’m going to do mine on a piece of plexiglass instead of using the Radioshack project box. I should just be able to hang it on the wall with a thumbtack.
If you haven’t gotten your coupon for a HDTV converter box. You should quickly sign up for the converter box rebate here.
William Ruckmans Fractal HDTV antenna.
You can look up your local broadcasters and get an idea of what sort of antenna you will need for HDTV and where the towers are here.
I am not really sure about the fractal antenna, because I think it’s possible that a directional yagi antenna might be a better choice. The terk is a yagi.
Here is a yagi design that I found on youtube that looks viable made out of coat hangers.
More Like This one:
Here are a couple of more links that you might find useful regarding DIY HDTV antennas:
http://uhfhdtvantenna.blogspot.com/ has an antenna which pretty much looks like the one in the youtube video you linked, except with a (in my mind dubious) aluminum foil reflector behind it. These aren’t really YAGI antennas: they are just a bunch of stacked bowtie dipoles.
The true “cheap Yagi” antenna design that I’ve seen was published by popular communications, and the PDF is available here. Unlike some of the other designs, this one actually includes some engineering analysis so suggest why it might be better. It’s similar in type to the cheap yagi that I built for goofing around with amateur satellites which worked out very well. One caveat though: the Yagi will be much more directional than the stacked dipoles. If you have more than one tower that you receive stations from, the dipole array might actually work with less fussing.
Here’s a couple of more links:
This slashdot thread talks of the Hoverman antenna which dates back to the 1950s, and which has been revised into a GPL’ed design called the Gray-Hoverman. The same group who designed this is currently experimenting with fractal designs as well.
you said “I am using a Terk antenna (which works just dandy here in Hillsboro…”
I too am in Hillsboro, OR (near Hwy 8 and Cornelius Pass). I’m using a less than stellar flat antenna (cheap-o RCA brand, I think) to my DTV box but have spotty reception with 6.1 and cannot get 2.1 or 32.1 at all. Other channels like 8.1, 12.1 and OBP’s HD 10.1 come in outstanding on my HDTV.
I know the other resources about positioning and such, so not looking for you to solve all my problems
. But was simply wondering if the Terk antenna you have gets some of the channels I cannot… and if so, where/how do you mount yours? I’m missing Lost, need to get my reception fixed!! Thanks.
You are actually a little closer. Aimed toward the tower hill, the terk does the job on all the channels. I’m near the Hillsboro airport, so I get a little jitter when the planes fly over sometimes. All in all, I’d say it works pretty well. Channel 2 is probably the diciest. The aim is touchy, but I get 2, 6, 8, 10, 12, 32 and 49 without having to move the antenna, once it’s aimed…. like I said, a few degrees of aim…. Got to be pointed exactly right. If I move the antenna a little, I can get 24 too. I just set in on the table next to the set.
The terk has an amp, and it definitely needs to be on.
For the rest of you guys out there, the terk seems to work at about 11 miles from the towers, in a very bad, reflective ghosty canyon. Analog TV didn’t work very well here.
Another FYI: The DigitalStream converter box I bought at Radioshaft, seems to recieve better than any of the TV tuners (I have a Visio HDTV and a JVC SDTV bedroom set). I hooked the digitalstream box to an analog capture card in a computer.
This is the Terk I bought
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Thanks! Will give the Terk a try.
btw, I got the Samsung HTDV receiver for my older HD tv that came sans tuner. Has all the outputs you’d want including HDMI. It was kinda pricey at $180, but works great.. better, I’m sure, when I’ve got the right antenna set up.
As an earlier response said, this is a bow tie array, and is undoubtedly good for UHF. However, this will not work very well for VHF, mostly because the wavelength of VHF is much longer than that of UHF. Many TV stations in many areas of the country, will be transmitting DTV on VHF frequencies, if not already, after the transition. There is no such thing, per se, as an HDTV antenna. If you are receiving a good analog signal on your current antenna, on both VHF and UHF channels, you will get a great digital signal. A standard VHF/UHF color television antenna will suffice, be it set top, in the attic or rooftop. In some areas, attenuation may be necessary. Don’t forget to rescan after the transition.
The transformer you installed on the antenna, by the way, is not a UHF to VHF converter. It is called a Balun, for balanced to unbalanced. It converts the 300 Ohm balanced output impedance of the (VHF or UHF) antenna to an unbalanced 75 Ohm impedance.
You must, also, remember that, you cannot display an HDTV picture, in HDTV, on an analog television set. It will display in standard definition.
I like the video. It is well done.
I made one of each, Yagi design first and then the Fractal Antenna on Ruckmans site. The Yagi works great for the UHF bands but needs rabbit ears to pick up VHF band channels. The first Ruckman one I made didn’t do any better than the amplified antenna I already had however I made a second one with a few changes. I doubled the size of the measurements Ruckman used except for the space inbetween the two straight wires. Those changes doubled the reception and I even get a channel from 30miles away and every now and then when the wind blows right I get channels from 50miles away, all without amplification.
It should work, but how is the double sized Ruckman antenna on VHF? I was mistakenly expecting everything to be UHF after the digital change.
I get all the channels Ruckman got with his but with better reception. Two channels are on the VHF band and they come in clear 99% of the time except when the wind is a sustained 30 mph and above. I plan on making a second one for our bedroom tv to replace the Yagi design one since It needs rabbit ears to pick up the two VHF channels. I checked some Antenna calulations site and it told me to go with 16″+ dipoles so thats what I used. I’ve been thinking about tripling Ruckmans measurements to see if the reception would be even better but then I’d need more space to put the antenna and in a small apartment that’s not good.
And be sure to check out antennaweb.org to find where the transmitters are in your area and be sure to put the antenna on pole so you can swivel it to aim at the transmitters.
I’ve been using the Terk, which was perfect until they moved the channels back into the VHF band. All of the stations I am interested are in one place. It’s just the VHF ones that have become a problem. The wakk behind the TV is pretty much perpendicular to the transmitter antennas, so I’m thinking hanging a fractal one on the wall might be a good deal.