Many questions
 

http://www.tvfool.com/?option=com_wr...b7c8ab867e5a8f

Ok, I made an antenna out of coat hangers based on some instructions I found on the web (4 bay?). I aimed it in the right direction. Works pretty good (as good as the 2 commercially made antennas I tried - 1 yagi type, 1 omnidir compact type), but periodically the signal fades briefly and gets little frozen pixellated squares. I have tried with an without 2 different amplifiers.

The questions:

1. Lot of trees in the area of my yard, but a somewhat clearer view of the sky can be had from the other end of the house. Is it worth the trade-off to get the clearer view though I'll have to add 50 ft of cable?

2. Is there a significant difference between different antennas. I was thing about trying an Antennacraft® HBU22 or HBU33

3. Is an amplifier an amplifier, or is there considerable variations there, as well?

I care most about WKOP, the local PBS system, which is giving me the most trouble, but not consistently. Some nights it works great...other nights almost unwatchable. I'd really like a few major broadcast networks (I like NBC), but other than that, I don't really care

Thanks in advance.

Greg

First point: many of the bow-tie antenna plans derive from a Youtube video that uses too-small elements. There's a long-running thread on a Canadian site devoted to this design that usually recommends these dimensions.

Use the "start MAPS" option to set your receive location at the different points you're interested in. Zoom in on the Google map (using the satellite option) and move the receive location to each point. You'll see the predictions update below. Be sure to use the correct antenna height, too. Given the noise margin (NM) in your original plot, you've got plenty of signal to work with, so 50 feet should not be a problem.

Antennas of similar construction should perform the same. The only difference between the two Antennacrafts you cite is a trade-off between more sensitivity in the forward direction against sensitivity in other directions. The HBU22 should work for you. However, the bow-tie design that you can make yourself should work just fine, also.

There are differences! The major design factor is noise figure, which subtracts from the noise margin caculation no matter what. Good commercial designs have noise figures of 2 or 3 dB. Cheapies, often buried in indoor amplified antennas, will have 6 to 10 dB noise figures. You should not need an amplifier with the right-sized bow-tie or the Antennacraft you're considering.

WKOP transmits on channel 17, the low end of UHF. If your current antenna has 7" whiskers, then it's too small to perform well on 17. Use the bigger design, or spring for the Antennacraft. You might not have to use all that coax. Good luck!

After posting my reply, I found a site that documents what's wrong with the common coathanger antenna design popularized on Youtube and documented a thousand times over. The biggest problem is the spacing between the whiskers - 5 3/4" is waaayyy too small. Check out the charts here. Important to note that the right-sized bowtie array has actual positive gain in the high-VHF range.

Hello and welcome!

There are many possible explanation as to why you're having difficulty with WKOP. Without knowing what is causing your signal degradation, it's hard to say whether moving the antenna will give you a net improvement or not.

My gut tells me that yes, you will probably see an improvement. Your signals are pretty close, so signal strength should not be a problem. It is more likely that signal quality is your bigger problem.

Sometimes objects in the environment (e.g., walls, trees, neighbors' houses, tall buildings, hillsides, etc.) create extra signal reflections or "echoes" (used to show up as "ghosts" in the days of analog TV) that make their way into your antenna and to your TV. This "multi-path" signal is harder to decode than a clean line-of-sight signal. If the multipath interference gets bad enough, you might see pixellation or drop-outs in your signal.

By trial and error, you might be able to find another spot for your antenna that is picking up less multipath and thus delivering a cleaner signal to your receiver. Open areas that are clear of any obstacles usually work best, but every situation is different. It may take some experimentation to locate the "best" spot for your antenna.



You may also want to double-check your antenna construction. Make sure you've got the right element spacing, angles, connections, etc. Also make sure there are no shorts or open connections that that are not supposed to be there.



The HBU series of antennas are a great choice for your situation because of your channel line-up. The Winegard HD769*P series of antennas are also a good choice for channel 7-69 coverage.

The different sizes of antennas within these families definitely make a difference. Each step up in size usually comes with a couple more dB of gain across most of the spectrum. Your signals are very strong, so gain is not the most critical factor in your setup.

However, gain can help in high multipath situations if that is one of the problems in your environment. Higher gain antennas have tighter beam patterns (gain and "directionality" of an antenna are closely related). Tighter beam patterns can help screen out some of the unwanted extra signal paths (coming from different directions) before allowing them to reach your receiver. If this cleans up the signal, then your receiver should have an easier time decoding channels.

Between Antennacraft and Winegard, it doesn't make that much difference which product you use. Winegard has a slightly better reputation for build quality and design (and they're a little more expensive too), but both companies make pretty high quality antennas, and I don't think you'll have any problems going with either one. The HBU family of antennas starts out smaller (HBU-22) than the smallest Winegard antenna (HD7694P), so just keep that in mind when trying to make apples-to-apples comparisons.



There can be very big differences in amp quality. The most important figure of merit is the Noise Figure of the amp. This is how much noise the amp itself adds to the signal in the process of boosting things to a higher level. Lower Noise Figure is better. "Good" amps from the likes of Channel Master, Winegard, and Antennacraft have a Noise Figure of 3.0 dB or less. There are more expensive and harder to find amps that can have even lower Noise Figures (closer to 1.0 dB), and there are a lot of cheaper amps (or antennas with built-in amps) that have Noise Figures as high as 6-9 dB.

Your signals are so strong that you are probably better off without any kind of amp at all. One problem you might run into with an amp is overload. If the signals going into the amp are too strong, it can cause distortion in the output signal. An overloaded amp can make things worse rather than better.



All of your channels, including WKOP, are considered pretty strong. Hopefully, your difficulty is related to multipath and it can be resolved by simply moving or repointing the antenna.