TV reception

[Andy K]

I use an RCA HDTV antenna.

Sometimes I get electronic static.

It is usually with stations just outside of the range of the station.

But it also occurs with stations which are withing range.

Would it helped if I got an external outdoor antenna, one with the folding aluminum arms ?

Thanks.

 

[Andy K]

On Friday, May 30, 2014 5:45:10 PM UTC-5, Andy K wrote:

I use an RCA HDTV antenna.



Sometimes I get electronic static.



It is usually with stations just outside of the range of the station.



But it also occurs with stations which are withing range.



Would it helped if I got an external outdoor antenna, one with the folding aluminum arms ?



Thanks.

I found this.

It looks promising.

I found a cheaper alternative here.

http://www.tvantennaplans.com/

 

[David Platt]

I use an RCA HDTV antenna.

Sometimes I get electronic static.

It is usually with stations just outside of the range of the station.

But it also occurs with stations which are withing range.

Would it helped if I got an external outdoor antenna, one with the folding aluminum arms ?

Quite possibly.

In my experience, the best / most stable TV picture, and the best FM
reception, require having:

- A directional outdoor antenna

- Mounted on a mast above the roof, as high as is reasonally
practical given the situation

- Aimed properly for each station you want to receive

Even a modest roof antenna is likely to give you better results than
almost any indoor antenna (amplified or not).

In some cases, you may get away with an omnidirectional roof
antenna... but having a directional (and properly aimed) antenna often
gives better results.

The antenna's directional pattern gives you two advantages - you get a
stronger signal from the transmitter you point it towards, and it also
"rejects" signals coming from other directions (other stations,
interference, and "multipath" delayed reflections of the signal you
want which have bounced off of buildings, trees, mountains, etc.).

The specific type of directional antenna you would want, depends to
some extent on the TV stations in your area. If all of the stations
are on UHF frequencies, a "flat panel" antenna such as a bowtie with
reflector or a Gray-Hoverman may do very well, as might a "corner
reflector" UHF antenna. If you've got stations which are still on
VHF, and/or if you want FM reception as well, you'll probably need a
larger "log-periodic" antenna.

 

[RobertMacy]

On Fri, 30 May 2014 15:45:10 -0700, Andy K <andrewkennedy775@gmail.com>
wrote:

I use an RCA HDTV antenna.

Sometimes I get electronic static.

It is usually with stations just outside of the range of the station.

But it also occurs with stations which are withing range.

Would it helped if I got an external outdoor antenna, one with the
folding aluminum arms ?

Thanks.

You MUST try each in your actual location any of those active antennas,
most are useless, even depends on the model. I found TERK TV5 indoor
version received quite a few stations when all went digital. Radio Shack
was worse than a pair of rabbit ears! Also, bad weather usually reduced
most of ours to the point of pure frustration. At least with analog you
could 'kind of see' between bad spots, but with digital...

You didn't say where you were, how far to stations, nor if all same
location or spread around the clock so to speak. Makes a big difference.
There are websites that will tell you exactly where, and how far, each
station is and sometimes even signal strength you should expect.

Historically nothing beats a giant, fringe antenna mounted on a two story
roof top about another 15 feet up with NOTHING between you and
transmitters. I had to use 2 antennas, VHF = huge and UHF strange shape.
But I used to receive 66 channels free.

Well, except for cable or dish types.

 

[rickman]

On 5/30/2014 7:50 PM, David Platt wrote:

The antenna's directional pattern gives you two advantages - you get a
stronger signal from the transmitter you point it towards, and it also
"rejects" signals coming from other directions (other stations,
interference, and "multipath" delayed reflections of the signal you
want which have bounced off of buildings, trees, mountains, etc.).

I've always wondered if various antennas of the same size actually
produce a stronger signal or if they are just more directional and so
reject the unwanted signals better which improves the SNR.. which is
almost as important as a stronger signal depending on your first
amplifier stage.

The specific type of directional antenna you would want, depends to
some extent on the TV stations in your area. If all of the stations
are on UHF frequencies, a "flat panel" antenna such as a bowtie with
reflector or a Gray-Hoverman may do very well, as might a "corner
reflector" UHF antenna. If you've got stations which are still on
VHF, and/or if you want FM reception as well, you'll probably need a
larger "log-periodic" antenna.

I was not aware that the VHF frequencies were being vacated. But I have
seen "digital" antennas which don't look like they would receive a VHF
signal well, just not very large. Is there a way to build a good VHF
antenna without making the elements several feet long like the antennas
I remember from my youth?

--

Rick

 

[David Platt]

I've always wondered if various antennas of the same size actually
produce a stronger signal or if they are just more directional and so
reject the unwanted signals better which improves the SNR.. which is
almost as important as a stronger signal depending on your first
amplifier stage.

Some of both, actually.

If we neglect losses in the antenna itself, then a more highly
directional antenna does provide a stronger signal into the receiver
than a less directional antenna having a similar pattern shape
(assuming both are pointed towards the transmitter). A single-channel
TV Yagi might give you 10 times the power (10 dB of gain) compared
with a simple dipole, and might give you 20-30 dB of "front to back"
ratio as well (where a dipole has 0 dB of F/B).

In some situations, it's that extra signal - the antenna's pattern
gain - that you want. These might be situations where the signal is
weak, and there aren't any strong reflections or interfering signals,
and what you need to do is overcome losses and noise in the coax and
receiver.

In other situations (interference and multipath) the fact that the
highly-directional antenna is rejecting signals from other directions
is the more important factor.

In amateur radio HF operations this is not infrequently the case -
it's more important to "null out" an interfering station so you can
hear the one you want, than to get the maximum signal strength from
the desired station. You end up pointing your antenna somewhat
"away" from the guy you're talking to, so as to put Noisy George in a
null in the antenna pattern.

As to comparing different TV antennas of the same size - a 6'-long TV
log-periodic antenna can cover the whole VHF/UHF band, but its gain
(in the desired direction) and front-to-back ratios aren't going to be
super-high. A Yagi-Uda antenna of the same length could be designed
for a single station's frequencies - it would have significantly
higher gain and F/B numbers for that one station, but would have
mediocre (or horrid) performance on other stations.

>I was not aware that the VHF frequencies were being vacated.

This happened several years ago. In most areas of the country, there
are few or no TV stations still using the "VHF low" sub-band (band I,
RF channels 2 through 6 - the ones "below" the FM broadcast band).

There are still a significant number of stations using the "VHF high"
sub-band (band III, RF channels 7 through 13, "above" FM broadcast).

Most stations which were previously on VHF, moved up to UHF during the
switchover to digital.

The stations numbers that they transmit in their HDTV signals don't
necessarily have any relationship to the frequencies they use.
Historical "Channel 4" might still be on VHF-low channel 4 (66-72
MHz), or might have moved up to VHF-high, or might be UHF. The TV
finds the signals by scanning the band, and then extracts the "channel
number" to display.

But I have
seen "digital" antennas which don't look like they would receive a VHF
signal well, just not very large. Is there a way to build a good VHF
antenna without making the elements several feet long like the antennas
I remember from my youth?

No really good way, especially if you want multi-station coverage or
any sort of directionality or both. Shortening the elements and still
getting good efficiency requires some form of reactive loading (coils
near the base of the element, or "capacity hats" at the ends), and
these tend to create rather narrow-band antennas. The VHF channels
are pretty wide (channel 2's width of 6 MHz is a full 10% of its
upper-edge frequency) and so narrow-band antennas aren't a great
solution.

Efficiency, size, broad bandwidth - pick the two you want, and accept
that you must compromise on the third factor.

If all the TV stations lie in the same direction, and if you've got a
decent-sized roof to play with, you could install a terminated wire
rhombic antenna pointed in that direction. They're big but can be
made fairly inconspicuous because they're just a big diamond-shaped
pattern of wire. Remove the termination resistor and you'd have a
narrow bidirectional pattern - might be good if you're right in
between two big cities.

 

[David Platt]

I found this.

It looks promising.

I found a cheaper alternative here.

http://www.tvantennaplans.com/

These sorts of home-build antennas can work quite nicely.

You'll still get better results if you can figure out how to mount it
outdoors and rotate it to point in the right direction. Build it out
of sturdy weatherproof material - varnish or paint the wood before
construction, use heavy wire, screw the reflectors onto the wood with
multiple sturdy screws, etc.

Getting it outside of the building walls, and up into "clear air"
makes a huge difference. TV signals travel almost entirely by "line
of sight".