What are some quantifiable metrics for comparing digital antennae?

Question

I currently have an RCA Indoor digital flat amplified antenna (ANT1450BR), which doesn't work well.

It seems as though the flap of a butterfly's wings in Brazil, causes my television signal in New York to scramble.

Needless to say, I'm ready for a new antenna. I've been looking at outdoor antennas, but I have no qualms about getting another indoor unit (as long as it works). I'm not looking for product recommendations, rather I'm interested in quantifiable metrics that can be used to compare various antennas.

When shopping for a digital television antenna, what should I be looking at, and how should I compare various makes and models?

Answer 1

First things first, there is no such thing as a digital antenna, RF does not care whether the underlying modulation is digital pulse, FM, AM, SSB, Chirp or Spread Spectrum.

Second, if you live any distance away from the transmission antenna, the more aluminum overcast you have, the more signal strength you receive. Whether it's inside or outside, size does matter. VHF/UHF Yagi-Uda or Log-periodic antennas increase gain and narrow the beamwidth as you add elements. UHF Half-wave arrays increase gain and narrow the beamwidth as you add bays to the array.

Third, antenna configuration is dependent on the frequency, so VHF, UHF or both?

Fourth, length of the downlead is important as the longer the run, the more it absorbs the signal, requiring mast amplifiers to strengthen the signal before the SNR destroys it.

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Now for some links to help figure things out. These are long term resources that can't be replicated here, so it will have to do.

From the people who gave us that fine Digital TV that allows you to enjoy Satellite Dish reception. Key in your Address, City, Zipcode and it will tell you High/Low VHF, UHF and best guess at signal strength. "No Signal" sometimes can be taken cum grano salis.

FCC DTV Reception Maps

This site is provided among a consortium that includes CEA and NAB (National Association of Broadcasters) to help figure out signal strength and antenna headings. It gives you a color code that's explained over on their Antenna Info page to help determine what type of antenna will best receive the signal (directional, high gain, general coverage, etc.)

AntennaWeb Antenna Selector

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Directional antennas help cut down on multipath (The old ghosting now is signal jitter, annoying with analog, no signal with digital) but if the beamwidth is too narrow, require a rotator for off-beam signals.

High Gain antennas help improve the received signal strength so it doesn't cut out. Extreme range requires a mast mounted amplifier for yet more signal strength so DTV doesn't drive you insane.

While gain and directional capabilities are directly related (high gain, narrow beam), flat-landers often can get by with less gain and broader beamwidth, tailoring the gain to what's necessary to get a good picture while not having to rotate the antenna if most of the stations are clustered in a certain direction.

Answer 2

There is no such thing as a digital TV antenna

I tend to disagree. I do agree there's no such thing as an HDTV antenna. The analog channels were broadcast on channel frequencies of 2 through 69. The newer digital channels are broadcast on channel frequencies of 2 through 51. A TV antenna properly designed to receive channels 2 through 51 will work better than an antenna properly designed to receive the old analog channels 2 through 69.

Not only will the antenna that has been designed for the new digital frequencies work better when receiving the digital signal it will not work well for the old analog channels of 52 through 69. Since some newer antennas are specifically designed to receive the digital frequency spectrum of 2 through 51 wouldn't that make the antenna a digital antenna?

The thing most confusing is real vs. virtual channel numbers. The channel number displayed on your TV screen may not be the channel in use to broadcast the TV signal. Many of the TV stations moved to a different channel frequency for digital broadcasting. However, they want you to know who they are so they kept the old analog number displayed on the TV screen. For an example channel 5 analog will still display as 5.1 on the TV but may be broadcasting on channel 20. About 1/3 of the TV stations in the U.S. kept the same digital broadcasting channel frequency as they had when broadcasting analog.

Answer 3

There is a science to picking up antennas but for most of us it feels like a little bit of black magic that includes holding the antenna while standing on one leg and strategically placing bits of aluminum foil around.

When shopping for antennas the only quantifiable characteristic you'll find (other than UHF VHF or UHF/VHF) consistently is "gain". Sometimes it may only be interpreted as the distance in miles.

First, go to someplace like tvfool.com enter in your address and see what channels are available to you and which direction they come from. Compare that to the channels you were getting with the 1450R. If there are more channels you want look for an antenna with more gain.

If all the local signals are close enough that the 1450R should pick them up, try and figure out if there is any issues that could be causing your bad reception.

If only some of the channels lose signal look at their strength and position to figure out why the 1450 isn't getting a good signal.

The 1450R claims to be omnidirectional but placement is very important. I found that it worked best when mounted vertically on an exterior wall. It did well when placed on a window but didn't hold up that well. The problem you're having could be due to a defective antenna or amplifier, interference from other buildings or trees. The TVFool info will include a compass direction of the antenna try to determine if there might be any obstructions in the path.

The higher you can get the antenna the better. The less obstructions you can put in front of the antenna the better. Obstructions not only block the signal, depending on their location, could cause reflections which degrade signal quality.

Eventually I got a bigger antenna that worked better. I tested it in the room where the RCA antenna was but eventually it made it's way to the attic. If I had a longer extension ladder it would already be on the roof.

Answer 4

I was also wondering how antennas could be compared when I was shopping. Unfortunately, I couldn't find any real objective way of comparing them. So to directly answer your question I don't think there is a way to objectively compare different antennas by looking at the manufacturers boxes.

All I could do was look at reviews but they were all subjective and while helpful, usually couldn't help me rank one over another. That's when I bought various antennas and tested them myself. I tested them using two methods. One was by using a Winegard Signal Strength Meter (which was about $70) and the other was by using the signal strength meter and actual channels that show up while using a TiVo box. The Winegard was a very objective way of comparing them because you select a frequency (which is often different than the channel number) and it gives you a signal strength.

I figured this information would be useful to others so I made a website at: http://www.ByeByeCableTvBill.com and shared the results there. This way others can see the results and can objectively compare different antenna types. As time progresses, I'll be adding more antenna tests there.

If you're interested in testing your antenna(s) yourself, the Winegard (which I have no affiliation with) is nice to work with. You can hook it up to your antenna, select a frequency and rotate the antenna around and see if you get a signal. If you do get a signal you can adjust the antenna to see exactly where it needs to be positioned to get the max signal. Then you can do a channel scan and see what comes in.