Yagi Antenna
 

Gents,
Bit of a "ring in" question here but I cant think of
anywhere/anyone else who may know. I,ve put up a yagi TV antenna with from
memory about 19 elements plus reflector. It seems to be too directional so I
can get one signal source perfectly and one poorly because they are in
slightly different directions. Question is, if I remove some of the
elements ( the way the thing is made I can unscrew the front seven or so)
will that make the antenna less directional?. Or if not, is it able to be
done?
Cheers
John

Yagi Antenna
 

John wrote:
Gents,
Bit of a "ring in" question here but I cant think of
anywhere/anyone else who may know. I,ve put up a yagi TV antenna with from
memory about 19 elements plus reflector. It seems to be too directional so I
can get one signal source perfectly and one poorly because they are in
slightly different directions. Question is, if I remove some of the
elements ( the way the thing is made I can unscrew the front seven or so)
will that make the antenna less directional?. Or if not, is it able to be
done?
Cheers
John



If your using the antenna for HDTV, you need only the UHF elements,
which for many TV antennas are the shorter elements at the front end of
the antenna. The VHF elements will not be needed when all OTA TV
stations go to HDTV. If you longer elements at the back end of the
antenna first, you may notice that the antenna is more able to capture
UHF signal sources that are aftward of the antenna structure.

Duane

Yagi Antenna
 

John wrote:
Gents,
Bit of a "ring in" question here but I cant think of
anywhere/anyone else who may know. I,ve put up a yagi TV antenna with from
memory about 19 elements plus reflector. It seems to be too directional so I
can get one signal source perfectly and one poorly because they are in
slightly different directions. Question is, if I remove some of the
elements ( the way the thing is made I can unscrew the front seven or so)
will that make the antenna less directional?. Or if not, is it able to be
done?
Cheers
John



If your using the antenna for HDTV, you need only the UHF elements,
which for many TV antennas are the shorter elements at the front end of
the antenna. The VHF elements will not be needed when all OTA TV
stations go to HDTV. If you remove the longer elements at the back end
of the antenna first, you may notice that the antenna is more able to
capture UHF signal sources that are aftward of the antenna structure.

Duane

Yagi Antenna
 

In article . net,
Duane Allen wrote:

If your using the antenna for HDTV, you need only the UHF elements,
which for many TV antennas are the shorter elements at the front end of
the antenna. The VHF elements will not be needed when all OTA TV
stations go to HDTV.

I believe that this statement is untrue, or is at least of somewhat
limited (regional) truth.

Although most TV stations have chosen to use UHF-band for their
digital signals, that is not universally true. Some stations whose
primary (NTSC analog) transmitters are in the VHF high-band (channels
7 through 13) have decided to use their VHF channels to carry ATSC
digital, after the Big Switchover occurs. In a very few areas of the
country, there's even a station or two which will be using its VHF
low-band frequency slot (channel 2 through 5) for ATSC. The FCC has
recommended against using VHF lowband channel 6 for ATSC, in order to
prevent interference with the bottom of the FM broadcast band.

I believe that these stations are electing VHF for ATSC, rather than
using their "interim" UHF channel assignment, because they'll be able
to get better ATSC signal coverage that way. They can operate at
higher power on the VHF band than they could on UHF (likely because
their interim UHF frequency assignment has co- or adjacent-channel
users not all that far away).

In most areas of the country, a good UHF antenna will suffice for ATSC
digital. In a few (e.g. SF bay area) you'll still need to have an
antenna capable of both UHF, and VHF high-band, to get all of the
local stations... and in one or two areas you'll still need a
full-range VHF-lowband/VHF-highband/UHF antenna such as is used today.
Some people who have bought "digital TV" or "HDTV" antennas (UHF-only)
are likely to be annoyed, when they lose a channel or two on The Big
Day.

A nationwide table of the ATSC frequency assignments can be found at

http://hraunfoss.fcc.gov/edocs_publi...C-06-150A1.pdf

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Yagi Antenna
 

On Thu, 19 Jul 2007 08:25:19 -0700, Dave Platt wrote:

Although most TV stations have chosen to use UHF-band for their
digital signals, that is not universally true. Some stations whose
primary (NTSC analog) transmitters are in the VHF high-band (channels
7 through 13) have decided to use their VHF channels to carry ATSC
digital, after the Big Switchover occurs. In a very few areas of the
country, there's even a station or two which will be using its VHF
low-band frequency slot (channel 2 through 5) for ATSC. The FCC has
recommended against using VHF lowband channel 6 for ATSC, in order to
prevent interference with the bottom of the FM broadcast band.

I believe that these stations are electing VHF for ATSC, rather than
using their "interim" UHF channel assignment, because they'll be able
to get better ATSC signal coverage that way. They can operate at
higher power on the VHF band than they could on UHF (likely because
their interim UHF frequency assignment has co- or adjacent-channel
users not all that far away).

In most areas of the country, a good UHF antenna will suffice for ATSC
digital. In a few (e.g. SF bay area) you'll still need to have an
antenna capable of both UHF, and VHF high-band, to get all of the
local stations... and in one or two areas you'll still need a
full-range VHF-lowband/VHF-highband/UHF antenna such as is used today.
Some people who have bought "digital TV" or "HDTV" antennas (UHF-only)
are likely to be annoyed, when they lose a channel or two on The Big
Day.

A nationwide table of the ATSC frequency assignments can be found at

http://hraunfoss.fcc.gov/edocs_publi...C-06-150A1.pdf

So all this bu$$sh!t about freeing up spectrum, or improving reception,
or yaa-daa yaa-daa yaa-daa is just that - BU$$SH!T!

This is no better than a LandFill Utilization Project.

It is usually a disaster when the government gets involved in promoting
"technology".

I've just about had it, anyway, with the crap being pushed out over the
airwaves. They keep targeting the ever diminishing lowest common
denominator. So, I think when _their_ Big Day comes, it'll be _my_
Last Day.

Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
38.24N 104.55W | @ config.com | Jonesy | OS/2
*** Killfiling google posts: http://jonz.net/ng.htm

Yagi Antenna
 

Thanks Duane/Dave/Marvin,
A lot of help. Enjoyed Marvins spray.
Usually I,m tied up in AirCooled VW newsgroups and you get exasperated souls
there as well.
I have to confess the last time I was that cynical was when Dr Who opened a
sliding door by using as a button a 2N3055 on a heatsink and shot an alien
with a Grid Dip Oscillator.
Probably giving my age away there. I mentioned a 6X4 rectifier to a bloke
at work and he hadn,t heard of it!!!!.
I,ll be more exact next time. I,m down in Australia where we use PAL and
antenna is UHF only, no VHF,no FM.
Cheers
John

"Allodoxaphobia" wrote in message
...
On Thu, 19 Jul 2007 08:25:19 -0700, Dave Platt wrote:

Although most TV stations have chosen to use UHF-band for their
digital signals, that is not universally true. Some stations whose
primary (NTSC analog) transmitters are in the VHF high-band (channels
7 through 13) have decided to use their VHF channels to carry ATSC
digital, after the Big Switchover occurs. In a very few areas of the
country, there's even a station or two which will be using its VHF
low-band frequency slot (channel 2 through 5) for ATSC. The FCC has
recommended against using VHF lowband channel 6 for ATSC, in order to
prevent interference with the bottom of the FM broadcast band.

I believe that these stations are electing VHF for ATSC, rather than
using their "interim" UHF channel assignment, because they'll be able
to get better ATSC signal coverage that way. They can operate at
higher power on the VHF band than they could on UHF (likely because
their interim UHF frequency assignment has co- or adjacent-channel
users not all that far away).

In most areas of the country, a good UHF antenna will suffice for ATSC
digital. In a few (e.g. SF bay area) you'll still need to have an
antenna capable of both UHF, and VHF high-band, to get all of the
local stations... and in one or two areas you'll still need a
full-range VHF-lowband/VHF-highband/UHF antenna such as is used today.
Some people who have bought "digital TV" or "HDTV" antennas (UHF-only)
are likely to be annoyed, when they lose a channel or two on The Big
Day.

A nationwide table of the ATSC frequency assignments can be found at

http://hraunfoss.fcc.gov/edocs_publi...C-06-150A1.pdf

So all this bu$$sh!t about freeing up spectrum, or improving reception,
or yaa-daa yaa-daa yaa-daa is just that - BU$$SH!T!

This is no better than a LandFill Utilization Project.

It is usually a disaster when the government gets involved in promoting
"technology".

I've just about had it, anyway, with the crap being pushed out over the
airwaves. They keep targeting the ever diminishing lowest common
denominator. So, I think when _their_ Big Day comes, it'll be _my_
Last Day.

Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
38.24N 104.55W | @ config.com | Jonesy | OS/2
*** Killfiling google posts: http://jonz.net/ng.htm

Yagi Antenna
 

you have to watch out for those grid dippers, they can be deadly in the
wrong hands!

"John" wrote in message
...
Thanks Duane/Dave/Marvin,
A lot of help. Enjoyed Marvins spray.
Usually I,m tied up in AirCooled VW newsgroups and you get exasperated
souls there as well.
I have to confess the last time I was that cynical was when Dr Who opened
a sliding door by using as a button a 2N3055 on a heatsink and shot an
alien with a Grid Dip Oscillator.
Probably giving my age away there. I mentioned a 6X4 rectifier to a bloke
at work and he hadn,t heard of it!!!!.
I,ll be more exact next time. I,m down in Australia where we use PAL and
antenna is UHF only, no VHF,no FM.
Cheers
John

"Allodoxaphobia" wrote in message
...
On Thu, 19 Jul 2007 08:25:19 -0700, Dave Platt wrote:

Although most TV stations have chosen to use UHF-band for their
digital signals, that is not universally true. Some stations whose
primary (NTSC analog) transmitters are in the VHF high-band (channels
7 through 13) have decided to use their VHF channels to carry ATSC
digital, after the Big Switchover occurs. In a very few areas of the
country, there's even a station or two which will be using its VHF
low-band frequency slot (channel 2 through 5) for ATSC. The FCC has
recommended against using VHF lowband channel 6 for ATSC, in order to
prevent interference with the bottom of the FM broadcast band.

I believe that these stations are electing VHF for ATSC, rather than
using their "interim" UHF channel assignment, because they'll be able
to get better ATSC signal coverage that way. They can operate at
higher power on the VHF band than they could on UHF (likely because
their interim UHF frequency assignment has co- or adjacent-channel
users not all that far away).

In most areas of the country, a good UHF antenna will suffice for ATSC
digital. In a few (e.g. SF bay area) you'll still need to have an
antenna capable of both UHF, and VHF high-band, to get all of the
local stations... and in one or two areas you'll still need a
full-range VHF-lowband/VHF-highband/UHF antenna such as is used today.
Some people who have bought "digital TV" or "HDTV" antennas (UHF-only)
are likely to be annoyed, when they lose a channel or two on The Big
Day.

A nationwide table of the ATSC frequency assignments can be found at

http://hraunfoss.fcc.gov/edocs_publi...C-06-150A1.pdf

So all this bu$$sh!t about freeing up spectrum, or improving reception,
or yaa-daa yaa-daa yaa-daa is just that - BU$$SH!T!

This is no better than a LandFill Utilization Project.

It is usually a disaster when the government gets involved in promoting
"technology".

I've just about had it, anyway, with the crap being pushed out over the
airwaves. They keep targeting the ever diminishing lowest common
denominator. So, I think when _their_ Big Day comes, it'll be _my_
Last Day.

Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
38.24N 104.55W | @ config.com | Jonesy | OS/2
*** Killfiling google posts: http://jonz.net/ng.htm

Yagi Antenna
 

Dave Platt wrote:
In article . net,
Duane Allen wrote:

If your using the antenna for HDTV, you need only the UHF elements,
which for many TV antennas are the shorter elements at the front end of
the antenna. The VHF elements will not be needed when all OTA TV
stations go to HDTV.

I believe that this statement is untrue, or is at least of somewhat
limited (regional) truth.

Although most TV stations have chosen to use UHF-band for their
digital signals, that is not universally true. Some stations whose
primary (NTSC analog) transmitters are in the VHF high-band (channels
7 through 13) have decided to use their VHF channels to carry ATSC
digital, after the Big Switchover occurs. In a very few areas of the
country, there's even a station or two which will be using its VHF
low-band frequency slot (channel 2 through 5) for ATSC. The FCC has
recommended against using VHF lowband channel 6 for ATSC, in order to
prevent interference with the bottom of the FM broadcast band.

I believe that these stations are electing VHF for ATSC, rather than
using their "interim" UHF channel assignment, because they'll be able
to get better ATSC signal coverage that way. They can operate at
higher power on the VHF band than they could on UHF (likely because
their interim UHF frequency assignment has co- or adjacent-channel
users not all that far away).

In most areas of the country, a good UHF antenna will suffice for ATSC
digital. In a few (e.g. SF bay area) you'll still need to have an
antenna capable of both UHF, and VHF high-band, to get all of the
local stations... and in one or two areas you'll still need a
full-range VHF-lowband/VHF-highband/UHF antenna such as is used today.
Some people who have bought "digital TV" or "HDTV" antennas (UHF-only)
are likely to be annoyed, when they lose a channel or two on The Big
Day.

A nationwide table of the ATSC frequency assignments can be found at

http://hraunfoss.fcc.gov/edocs_publi...C-06-150A1.pdf


Thanks for taking the time to correct my error.

Yagi Antenna
 

Just a thought John

Is it a directivity issue or that rotating it places the device in a
null? The way to check is to move the entire antenna some distance in
the horizontal plane, then try the rotation test again. We are talking a
small distance here, no more than a halfwave at the operating frequency
- say 6-12 inches/150-300mm maximum. Leaning on the mast would be good
enough for testing..

Yes chopping the end off the antenna will make it less directive and
lower gain. Will it be enough though? One has to ask how many degrees
"slightly" is. (Decreasing gain means an increase in the half power
beam-width) Simplest answer is to not theorize but try it! If the angle
between stations is too great a second antenna may be the only easy
solution.

Cheers Bob VK2YQA

John wrote:
will that make the antenna less directional?. Or if not, is it able to be
done?

Yagi Antenna
 

In article ,
Allodoxaphobia wrote:

So all this bu$$sh!t about freeing up spectrum, or improving reception,
or yaa-daa yaa-daa yaa-daa is just that - BU$$SH!T!

The transition _does_ free up spectrum. The UHF spectrum between 700
and 800 MHz is being taken back from TV broadcasting, and is being
reallocated for other purposes. Public-safety users get a bunch,
commercial users get a bunch.

As to "improving reception", that's debatable. It's probably a win
for most urban users, and likely a big lose for rural users who are
already in fringe-reception areas (they'll get no picture, rather than
a snowy/ghosty analog picture).

It just turns out to be the case that the FCC is not attempting to
force _all_ stations up into the remaining UHF-band, and reclaim all
of the VHF TV band. Doing so would probably have forced some stations
off of the air or greatly reduced their broadcast coverage area, due
to the fact that some urban areas have so many TV stations that there
wouldn't be good conflict-free UHF channel assignments for all of the
VHF stations. It'd also have cost the existing VHF stations more
money to move, since they'd have been forced to scrap their existing
antenna systems.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!