DIY TV Antenna for Digital Reception

Thanks. I'll look at this as an alternative in the morning. Wonder how it got missed. . . .

Jim

WHAT IS THE SITE?

Click on the link in the Original post.

experimenters

I don't know what the fuss is about. I am receiving all of the local digital signals just fine on some rabbit ears in my attic. The same rabbit ears that I used for analog signals.

-------------

DTV requires a stronger signal than the old analog method of modulation for proper demodulation (picture processing). There are no weak and fuzzy signals with DTV. You either have enough signal to generate a digital picture, or you get a black screen.

Old antennas that worked fine for analog reception may not provide a strong enough signal for DTV to demodulate.

Someone living in a strong RF field, close proximity to the TV transmitters with no obstacles blocking the signal path, could conceivably pick up adequate RF for successfully demodulating the TV signal with just the transmission line connected. I suspect that this is your situation. Being on a high, clear hill, but being somewhat distant can also lead to success with a minimal antenna setup.

Those in the country/distant from the TV transmission site that watched analog TV satisfactorily, may now find that their sets will not demodulate and display DTV signals at all. That's what the fuss is about.

I can see the Chattanooga, TN transmission sites from my back porch/patio window, even though they are ten to fifteen air miles away, but there are a couple of DTV channels that are iffy even with a two bay UHF antenna connected to my set. Of course, these are the VHF channels, which I can otherwise receive with this antenna - which shouldn't be counted on to work at all on VHF.

All of the UHF DTV channels come in just fine with this antenna, even with the antenna mounted indoors.

I'm thinking of building a fat element dipole (greater bandwidth) for the VHF channels, once I find out if the TV stations currently utilizing the VHF channels are going to remain broadcasting on them. Not all stations will continue utilizing their old VHF channels.

Ed Cregger

try that when the NEAREST station if 50 miles away, behind a ridge of hills and the average distance to a station is around 70 miles according to most sites, you are now in the "deep fringe" zone.

let us know how it works out for you

For us people that are deep fringe have had a bump or two in getting digital to work. The "tech" sources have proven of next to no help to me. But I have learned a fair hunk by trial and error. The first thing you need to know is all preamps are NOT equal. Some of the older antenna mounted preamps that worked great on analog proved 100% worthless for digital. For example my original antenna-preamp system that allowed perfectly viewable analog at a distance of 150 miles to the transmitter. On the odd occasion I got out as far as 300 miles. But when I tried it on digital signals from transmitters 30 miles away zilch. In fact I did better with no preamp at all then that 15 year old preamp.

So if your preamp has any age on it at all it was likely designed for analog and may chop the leading and trailing edges on digital signals all to hell. If you are having problems and have any half decent antenna the first stop should be $60 for a new antenna mounted preamp.

The second thing I have learned is unlike analog digital will stand a LOT more amplification while still providing improved reception. I got a considerable improvement in signal strength as measured by my converter box by using two amps in series. One a top of the line antenna mount and the second an indoor splitter amp just before the converter. In fact I am thinking a second antenna mount just before the set is going to be my next experiment.

I am still not matching the deep fringe distances I got on analog but am coming close.

Just a reminder. Amps are not a solution for a poor antenna system. If you are running rabbit ears or a small roof top unit and need amp you should upgrade the antenna before you upgrade the amp. If you are feeding crap to the first amp you are going to get crap out of it.

Just like computer programs: GIGO: garbage in, garbage out.

Mike

I forgot to mention one of the most critical specs for a digital antenna. Digital turns out to be very sensitive to ghosts. Vastly more sensitive then analog. Ghosts can obliterate the decoders ability to decode even a strong signal at times. So one particularly important criteria for an antenna is it needs to have minimal side lobes that allow ghosts into the signal. Now sometimes, even with side lobes, you can aim the antenna a bit off target and mask side lobes. But not always. From the performance I have seen with a variety of different antenna configurations the flat types have rather bad side lobes compared to the longer boom type antennas. Unfortunately this is a performance character that is usually not listed in any of the specs so you really have to dig to find this kind of information.