EscapeVelocity

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Piggie

Depends on the wall. Just like the difference in high band and UHF.

UHF has the ability to not penetrate walls but sneak in through openings.

So if there is any metal in the walls, UHF will get indoors the best.

But it one lives in a wood framed house with a wood and tile roof low band will go indoor fine.

The kicker is so much foil backed insulation and metal studs in new homes will block most VHF even if it looks like all wood. Some newer roof tiles have enough metal in them to block a lot of signal too.

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Piggie

Note this table is for FM radio and would need to be adjusted to VHF.....

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The more I understand, the less I know.

Piggie

If money and putting up an outdoor antenna is not a problem, I agree with Don, this antenna has a lot of bang for the price and size, in particular on Ch4 where you need it.

If you are pixelating inside in the day, I doubt a lot more of what you could do inside would help. Ch 4 was a huge mistake for CBS to pick, because all the channel 2-6 are not suitable for digital due to noise mainly. Where they put some annoying lines in analog, in digital you get a blank screen with noise.

I would not put up an amp right away if you only have one tv and less than 30 ft of cable from the antenna outside to the TV set.

The fact the old rabbit ears worked better are two fold. One is they are longer and closer to being tuned to ch4, but just as much if not more, they are not amplified.

This is why I suggest you not use an amp or experiment without one first, then if you want to try one do so. The amp on your indoor antenna is probably amplifying the noise as much as the TV signal.

Still be fore warned. Ch4 is a hard signal to pick up. You stand a good chance with them running 24 KW at 22 miles from you with an outside antenna. But there may and probably will be times it just won't come in. More likely during the day when more electrical stuff is running and there is a chance of E-skip.

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Eureka

True. I should've said VHF won't readily penetrate walls roofs or windows that contain certain building materials. The long wavelength VHF signals get mangled, but the shorter wavelength UHF signals can make it through relatively intact.

flcs3

Ooops. Thanks for that catch. I had a misfiled bookmark and only checked it for staleness.

Piggie

If you do any ready and you may have on reflector specifications for screen reflectors be in a yagi, bowtie or even building a dish for VHF, UHF or microwave. Good example of a dish on UHF is the old CM4251.

Remember any mesh screen where the holes (spaces between the metal) are less than 0.1 wavelengths the radio wave sees this as a solid piece of metal. This can be seen in many ways. Simplest might be just the effect of the metal being that close to the wave. It can also be shown considering the radio signal as particles and not waves. This gets bizarre to think about since it doesn't make any sense. It would seem if light photons were very small they would go through anything wider than them. This can be shown with the classic 2 slit experiment where light appears behind the slits in a place where there isn't a slit (same theory as slot antennas). Well they appear in a place between the slits because it is a wave and a particle at the same time. If you think about this, it's really even more bizarre. The particles in the 2 slit experiment not only go through the slit as expected but as above also appear between the slits. This means the particle is in two places at the same time.
Double-slit experiment - Wikipedia, the free encyclopedia
Classic Two-Slit Experiment

So even though can shoot a bullet between the metal in a mess reflector the waves won't penetrate it.

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So what is 1/10 of a wavelength at common TV frequencies? These are approx for example

Lowband 18 inches
Highband 6 inches
UHF 2 inches.

So to block a UHF TV station from entering the house one would have to put a wire or some piece of metal every 2 inches both horizontally and vertically, so that no area of the wall had a gap of more than 2 inches if wishing to reject both horizontal and vertical waves. As you can see houses aren't built that way unless they have solid metal walls or roofs. UHF gets through windows and walls. Even metal studs are not close enough together to stop UHF.

On highband metal studs in the walls spaced on 18 inches would not be a perfect reflector, they are spaces at 3/10 of a wave length, giving a great deal of blockage. As you can then see low band really has a hard time finding a hole large enough to get in, unless the house is soley wooden and little wires in the walls.

There is the large and small of it.

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Piggie

That chart does work extremely well for high band TV antennas, since the entire second harmonic of the FM band is TV high band (yes it was done on purpose). So one only has to divide the high band frequency by 2, then look up that FM frequency, then divide all the dimensions by 2 giving the size and spacing for high band.

To use the table on some of the higher low band channels you need better ratio math skills than just factors of 2.

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The more I understand, the less I know.