I have a question about how the ANC-4 works. Specifically, it's about
the antennas that you connect to the ANC-4 in order to cancel noise or
make a 'phased array'.

In some contexts, when noise is a problem, people will say that you
want to keep the "noise antenna" that you use with the ANC-4 as small
as possible. This is because you want the noise antenna to hear *only*
the noise, which will be phased out, and not the target signal, which
you don't want to be phased out. The suggestion here is clearly that,
if your noise antenna *does* hear the target signal, you're going lose
signal along with noise.

However, when people use the ANC-4 to establish phased arrays of two or
more antennas, this is usually with a couple of serious antennas,
widely separated, *both* of which can hear the target signal. Hence my
question: When the ANC-4 is connected to two largish antennas, both of
which are capable of hearing the target signal, what prevents the
desired signal from simply being phased out? Is determining what gets
phased out just a matter of carefully adjusting the controls on the
ANC-4?

Thanks!

Steve

In article .com,
Steve wrote:
In some contexts, when noise is a problem, people will say that you
want to keep the "noise antenna" that you use with the ANC-4 as small
as possible. This is because you want the noise antenna to hear *only*
the noise, which will be phased out, and not the target signal, which
you don't want to be phased out. The suggestion here is clearly that,
if your noise antenna *does* hear the target signal, you're going lose
signal along with noise.

However, when people use the ANC-4 to establish phased arrays of two or
more antennas, this is usually with a couple of serious antennas,
widely separated, *both* of which can hear the target signal. Hence my
question: When the ANC-4 is connected to two largish antennas, both of
which are capable of hearing the target signal, what prevents the
desired signal from simply being phased out? Is determining what gets
phased out just a matter of carefully adjusting the controls on the
ANC-4?

A noise bridge works by subtracting the noise from the signal. (The
adjustments work by making the time delay, the polarity, and the amplitude
of the noise antenna signal to be the same as the noise coming in on the
main antenna so it can be subtracted). Thus forming an antenna that,
electrically, looks like the difference between the two antennas. So,
to work, you need two antennas that receive the noise and desired signals
in different ratios.

Say, you have a main antenna that picks up signal and noise, and you
have a noise antenna that picks up 10 times as much noise as the
signal. After you adjust your noise bridge to match the amplitude,
the desired signal on the noise channel is only one tenth that on the
main antenna, and that's all you'll lose.

You can get this different noise-to-desired ratio by either putting the
noise antenna as close as possible to the source, or using a directional
antenna. As I remember another poster there, (Ron Hardin?), it often
works better to use a loop to null out the desired signal and just get
the noise and then use the ANC-4 to combine that with another antenna.

Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)

Steve wrote:
I have a question about how the ANC-4 works. Specifically, it's about
the antennas that you connect to the ANC-4 in order to cancel noise or
make a 'phased array'.

In some contexts, when noise is a problem, people will say that you
want to keep the "noise antenna" that you use with the ANC-4 as small
as possible. This is because you want the noise antenna to hear *only*
the noise, which will be phased out, and not the target signal, which
you don't want to be phased out. The suggestion here is clearly that,
if your noise antenna *does* hear the target signal, you're going lose
signal along with noise.

However, when people use the ANC-4 to establish phased arrays of two or
more antennas, this is usually with a couple of serious antennas,
widely separated, *both* of which can hear the target signal. Hence my
question: When the ANC-4 is connected to two largish antennas, both of
which are capable of hearing the target signal, what prevents the
desired signal from simply being phased out? Is determining what gets
phased out just a matter of carefully adjusting the controls on the
ANC-4?

Thanks!

Steve


Hi Steve,

You might get a better response from the folks over at
rec.radio.amateur.antenna

I have eight antennas combined in 7 ANC-4's.

If you use the two serious antenna approach, you simply steer a null
onto the noise source. Unless the desired signal is in the same
direction, it's not cancelled.

Depending on the separation and orientation of the array, it may even
be enhanced (in a peak of the pattern of the phased pair) while the
noise is eliminated (in a null of the pattern of the phased pair).

Generally a quarter wave of separation is good, giving you a peak
at one endfire while you have a null at the other endfire. In general
the null will be a V pattern that you sweep from one endfire, opening
up at broadside to a line, and closing at the other endfire, as you
tune the phasing and gain.

And more generally than noise sources, you can cancel out a local
broadcaster and listen to what's under it, by steering your null onto
him, though it can be a tricky adjustment, since you need an insanely
deep null, so you're dealing in fractions of a degree.

--
Ron Hardin


On the internet, nobody knows you're a jerk.

On Thu, 31 Aug 2006 01:32:40 GMT, Ron Hardin
wrote:

I have eight antennas combined in 7 ANC-4's.

If you use the two serious antenna approach, you simply steer a null
onto the noise source. Unless the desired signal is in the same
direction, it's not cancelled.

Depending on the separation and orientation of the array, it may even
be enhanced (in a peak of the pattern of the phased pair) while the
noise is eliminated (in a null of the pattern of the phased pair).

Generally a quarter wave of separation is good, giving you a peak
at one endfire while you have a null at the other endfire. In general
the null will be a V pattern that you sweep from one endfire, opening
up at broadside to a line, and closing at the other endfire, as you
tune the phasing and gain.

And more generally than noise sources, you can cancel out a local
broadcaster and listen to what's under it, by steering your null onto
him, though it can be a tricky adjustment, since you need an insanely
deep null, so you're dealing in fractions of a degree.


You should point out your antennas are active verticals of the Dymek
DA-100E type. It's not possible to steer an array of random wires
with any precision.

http://www.universal-radio.com/CATALOG/sw_ant/0328.html

In article ,
"A. Pismo Clam" wrote:

Steve wrote:
I have a question about how the ANC-4 works. Specifically, it's about
the antennas that you connect to the ANC-4 in order to cancel noise or
make a 'phased array'.

In some contexts, when noise is a problem, people will say that you
want to keep the "noise antenna" that you use with the ANC-4 as small
as possible. This is because you want the noise antenna to hear *only*
the noise, which will be phased out, and not the target signal, which
you don't want to be phased out. The suggestion here is clearly that,
if your noise antenna *does* hear the target signal, you're going lose
signal along with noise.

However, when people use the ANC-4 to establish phased arrays of two or
more antennas, this is usually with a couple of serious antennas,
widely separated, *both* of which can hear the target signal. Hence my
question: When the ANC-4 is connected to two largish antennas, both of
which are capable of hearing the target signal, what prevents the
desired signal from simply being phased out? Is determining what gets
phased out just a matter of carefully adjusting the controls on the
ANC-4?

Thanks!

Steve


Hi Steve,

You might get a better response from the folks over at
rec.radio.amateur.antenna

I would not recommend rec.radio.amateur.antenna to anybody for any
reason.

--
Telamon
Ventura, California

David wrote:
You should point out your antennas are active verticals of the Dymek
DA-100E type. It's not possible to steer an array of random wires
with any precision.

http://www.universal-radio.com/CATALOG/sw_ant/0328.html

It doesn't matter. Precision doesn't come into it any more or less
with random wires.
--
Ron Hardin


On the internet, nobody knows you're a jerk.

On Thu, 31 Aug 2006 08:27:40 GMT, Ron Hardin
wrote:



It doesn't matter. Precision doesn't come into it any more or less
with random wires.

A random wire is already full of nulls and nodes. Much easier to
phase vertical omnis.

David wrote:

On Thu, 31 Aug 2006 08:27:40 GMT, Ron Hardin
wrote:


It doesn't matter. Precision doesn't come into it any more or less
with random wires.

A random wire is already full of nulls and nodes. Much easier to
phase vertical omnis.

No, if one antenna isn't hearing the signal you want to eliminate, the
job is done for you. If it is hearing it, you phase it away with the
other antenna.

Nothing in the operation changes. You diddle the knobs the same way
in either case, and respond the same way.

The ANC-4 doesn't care where the signal comes from, just that it's
present.

--
Ron Hardin


On the internet, nobody knows you're a jerk.

On Thu, 31 Aug 2006 15:02:46 GMT, Ron Hardin
wrote:

David wrote:

On Thu, 31 Aug 2006 08:27:40 GMT, Ron Hardin
wrote:


It doesn't matter. Precision doesn't come into it any more or less
with random wires.

A random wire is already full of nulls and nodes. Much easier to
phase vertical omnis.

No, if one antenna isn't hearing the signal you want to eliminate, the
job is done for you. If it is hearing it, you phase it away with the
other antenna.

Nothing in the operation changes. You diddle the knobs the same way
in either case, and respond the same way.

The ANC-4 doesn't care where the signal comes from, just that it's
present.

Very imprecise and technically minimalist.