One more antenna question: Antenna pitch?

[mm]

One more antenna question: Antenna pitch?

That is, my attic has a pitched roof and the antenna for channels 7 to
60 that I'm thinking of now is almost 13 feet long.

It would fit more easily in the attic if I pointed it down a little
bit just like the roof pitches down from the center. Does the angle
of the axis matter that much if the individual elements are all
horizontal?

After all, if the tranmitter is higher than the antenna, it's as if
even a horizontal antenna is pointed down, from the pov of the
transmitter.

I've been reading but nothing has addressed this. All outdoor
antennas are of course horizontal, and I don't get to see people's
indoor antennas.




BTW, as to loss of signal in an attic,
http://www.dennysantennaservice.com/TV_Antenna_Attic_Installation.html
says: "A plywood roof covered by a single layer of asphalt shingles is
best.", (that is, other roofs are worse) and that's just what I have.
I'm sure it would still work better on the roof, but if I lose one or
two stations, I can accept that.

 

[baron]

Arfa Daily Inscribed thus:

I was actually referring to less-than-ideal reception
circumstances such as those the OP suggests that he may have, which
with an analogue signal, may well give perfectly acceptable results,
but with a digital signal might result in digital cliff pixellation
and freezing. Digital terrestrial TV signals are, in my experience
here in the UK, nothing like as robust, or easily received in many
transmission regions, as the government - whose primary interest lies
in how much money they can make by selling off large chunks of the UHF
TV band to cell phone operators - would have Joe public believe
through their hyped-up and often misleading media campaign directed at
the subject ...

Arfa

Well Said !
Yet another make the people pay Government scheme, among other things.

 

[mm]

Yes, it matters; the main part of that long antenna is 'director'
elements, which create a kind of shadow on the active
dipole. The rays get past if you aren't roughly lined up with
the line-of-sight to the transmitter.

Also, such a long antenna has high 'gain' which means it
MUST be aimed carefully; how can you possibly adjust it
if it's bumping into the roof?

I may be confused about what "gain" is. Why would a high gain antenna
have to be aimed carefully? If it has high gain, it seems like it
would have some gain to spare if it were badly aimed.

If it had low gain, it seems like it would have to be aimed precisely.

 

[Sjouke Burry]

I may be confused about what "gain" is. Why would a high gain antenna
have to be aimed carefully? If it has high gain, it seems like it
would have some gain to spare if it were badly aimed.

If it had low gain, it seems like it would have to be aimed precisely.

High gain means "narrow bundle" , so a high gain antenna needs
careful aiming.

 

[mm]

High gain means "narrow bundle" , so a high gain antenna needs
careful aiming.

So what aobut people on mountains and in valleys, where the
transmitter is lower or higher than they are. Should their antennas
be tipped down or up to aim at the transimitting antenna?

I never hear anyone recommend that, and afaicr (and I don't spend much
time near mountains, but some), every outdoor antenna I've ever seen
has been horizontal.

 

[Sjouke Burry]

So what aobut people on mountains and in valleys, where the
transmitter is lower or higher than they are. Should their antennas
be tipped down or up to aim at the transimitting antenna?

I never hear anyone recommend that, and afaicr (and I don't spend much
time near mountains, but some), every outdoor antenna I've ever seen
has been horizontal.

It turns a little bit into nit picking, but Yes try to aim
as accurately as possible at the transmitter, especially with
multi-element antennas.
And keep in mind,that an antenna cannot look through a big hill
or a mountain. And only with some difficulty through your house/roof
or that of the neighbour.
For the hill/mountain, you might need a repeater on that hill/mountain top.
Or try to find a reliable reflection around those obstacles.
In my country the digital tv is polarized vertically, so although we
can use the same old antennas, they have to be turned on their sides,
and vertical aim is even more important.

 

[mm]

You don't want or need a 13 ft beastly antenna that can get channels
2-6.

I thought this one didn't get 2-6, but I should go check again.

This little guy will be much easier to handle in the attic
(though it's better outside) and has reasonable gain. Don't jet
fighters release 'chaff' to screw up the enemy? Seems a lot like nails
suspended in sheets of plywood. That's one reason to be outside of the
'chaff'.

Good point. Not only that, the roofer used nails that are a lot
longer for the second roof than they had used for the first roof. And
my hair isn't as thick as it used to be if that matters, but I'm more
afraid I'm going to jab my head then I used to be.

http://www.winegard.com/kbase/upload/HD7694P.pdf

BTW there are no channels >51 any more.

Thanks a lot.

 

[mm]

It turns a little bit into nit picking, but Yes try to aim
as accurately as possible at the transmitter, especially with
multi-element antennas.
And keep in mind,that an antenna cannot look through a big hill
or a mountain. And only with some difficulty through your house/roof
or that of the neighbour.
For the hill/mountain, you might need a repeater on that hill/mountain top.
Or try to find a reliable reflection around those obstacles.
In my country the digital tv is polarized vertically, so although we
can use the same old antennas, they have to be turned on their sides,
and vertical aim is even more important.

Very interesting. Really

What about places where there is line of sight between the
transmitting antenna and the home antenna, but the home is a lot lower
or higher than than the T-antenna. Does the home antenna need to be
tipped up to point to a transmitting antenna that's higher? It sounds
like that follows from what was said ealier in this thread, but I've
never seeen it done or recommended.

 

[Sjouke Burry]

Very interesting. Really

What about places where there is line of sight between the
transmitting antenna and the home antenna, but the home is a lot lower
or higher than than the T-antenna. Does the home antenna need to be
tipped up to point to a transmitting antenna that's higher? It sounds
like that follows from what was said ealier in this thread, but I've
never seeen it done or recommended.

Well, you aim carefully at the horizon, and hope that enough radiation
is following the earth surface.
Some bending down always occurs, and hopefully for you it is enough.

 

[GregS]

So what aobut people on mountains and in valleys, where the
transmitter is lower or higher than they are. Should their antennas
be tipped down or up to aim at the transimitting antenna?

I never hear anyone recommend that, and afaicr (and I don't spend much
time near mountains, but some), every outdoor antenna I've ever seen
has been horizontal.

In any situation, if you have done this before, sometimes
it helps and sometimes it doesn't. You are also likely to see
similar results rotating the antenna from horizontal. The transmitted
waves change the plane as it moves over obsticles, so one station
may work better tilted 10 degrees, but it may make the other station worse.

Gain is made by narrowing the beamwidth and providing more front to back ratio.
A NASA 85 foot dish has about a 1 degree beamwidth at 2.3 gHz.

greg

 

[mm]

A small amount of tilt won't make a significant difference. Those that
suggest tilting the antenna will increase the gain are misguided. The
antenna can take advantage of ground reflection up to a theoretical
6db of gain. This gain is seldom reached but the in phase reflected e
field that causes this gain is best achieved when the antenna is
horizontal.

Thanks, and thanks to everyone. in this thread, and if possible,
for any place I haven't thanked people.