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Jeff Thies Jeff Thies is offline
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Default Old antenna for new tv

On 9/2/2010 2:59 AM, mm wrote:
On Wed, 1 Sep 2010 20:05:02 -0700 (PDT),
wrote:

I have an old antenna in the attic. When i moved into my house i
hooked it up to the tv. It works ok. Some channels dont come in
perfect some of the time. I've tried adjusting it w/ no luck. I see
these new style antennas for sale on line.

Are they better then the old style?
Has anyone tried both?


I just noticed the dimensions.

Dimensions: 22.8" x 17.7" x 25.8"

I'm not sure which dimension refers to what, but all but one of the
elements are smaller than the maximum in the same direction. They
are folded over, but I'm not sure that's good. Let's assume it's not
bad. It still leaves those elements at about 3/2 the dimension, ad
most 38", and 5 of the 6 of them are the same size. (or 7. One or
two things are reflectors)

The antennas they have been selling for 60 years have elements of
different lengths because there are channels o

f different wavelengths.

That's a LPDA (log periodic dipole array).

A popular choice for UHF are bow tie.

This antenna has large diameter closed loop elements which leads to a
wide frequency range.

That won't work well on VHF as the elements, particularly in the low
range are small compared with the wavelength. Ditto on the reflector
which becomes smaller than a wavelength.

http://www.hdtvprimer.com/ANTENNAS/types.html

I'd probably choose a different antenna, although if the OP know what
stations and where this may work well. Most stations are now UHF but
there are a few VHF.


The better antenanas have more elements, each of a different length.

Let's assume it could be bad to have the element folded over. It
could be because the same tv signal will induce a current in one
direction in one half of the element and in the opposite direction in
the ohter half of the element. Or maybe not, but it seems that way to
me.

Ah, but it probably has an amplifier. It's much better to have a
strong signal from the antenna, than a weak signal that is amplified.
Amplifiers are recommended when there is a long distance from the
antenna to the tv. Of course maybe that used to be more true, because
the antenna would amplify the "noise" too. Now most noise is filtered
out in the process of digital detection. Maybe. I'm no techie.



That is my take also.

Note if you take the number of elements and do a rough gain
calculation, the numbers don't add up to all antenna gain. My rough
guess is about 8 dB or so.

That said, I'm dissatisfied with my big antenna and I'm going to buy
an amplifier on the hopesw that it will help.

The first week the antenna was in the attic, I got channel 26, and
channels 30.1 to 30.5. Teh channels 30 are even farther from me than
DC, but I hven't gotten them again except in the middle of the night.
So I do have a signal but maybe it is too weak.


Might need to get it out of the attic.

Jeff
(used to hold a ham license, still remember something.... or part of
something!)