Take 2 antennas on 6m - one is an inverted V and the
other a 3el quad. Both are mounted at near the same
height and fed with about the same length of coax.

Is it normal for the quad to be quieter?

Signals are louder on the quad - it's just the background
noise is higher on the V.

Just curious.....

--
73's de Ken KG0WX - Kadiddlehopper #11808,
Flying Pigs #-1055, Grid EM17io, FT-857D, AL-84,
Elecraft XG2, 4SQRP Tenna Dipper, Heath GD-1B

Ken Bessler wrote:
Take 2 antennas on 6m - one is an inverted V and the
other a 3el quad. Both are mounted at near the same
height and fed with about the same length of coax.

Is it normal for the quad to be quieter?

Noise almost always arrives from multiple directions and from different
directions than the desired signal.

It is normal for ANY antenna to be quieter when it is more directional.
As a matter of fact, it is expected that S/N ratio is a direct function
of directivity of the antenna as long as the noise and signal are not
coming from the same direction.

To answer your question, it would be very abnormal if your quad (or
Yagi or any other directional antenna) was noisier than a broad pattern
antenna like your Inverted Vee dipole.

By the way, a real Inverted V is a longwire array fed at one end. I'm
assuming you really have an Inverted Vee dipole, and not a true
Inverted V.

73 Tom

Not to mention that noise is normally a phenonmen
of the Vertical Plane (which , depending on how
steep your inverted "vee" is, will contain some
vertical component, while the yagi/quad is
Horizontal to the plane. This has been a factor
on vhf for years, as noise levels tend to peak
at 6 meters (50 MHz). The MAIN reason that F.M.
is Vertical polarized is that for mobiles, it is
easy to construct an omni-directional antenna.
Most vhf manuals detail this effect! Jim NN7K

wrote:
Ken Bessler wrote:

Take 2 antennas on 6m - one is an inverted V and the
other a 3el quad. Both are mounted at near the same
height and fed with about the same length of coax.

Is it normal for the quad to be quieter?


Noise almost always arrives from multiple directions and from different
directions than the desired signal.

It is normal for ANY antenna to be quieter when it is more directional.
As a matter of fact, it is expected that S/N ratio is a direct function
of directivity of the antenna as long as the noise and signal are not
coming from the same direction.

To answer your question, it would be very abnormal if your quad (or
Yagi or any other directional antenna) was noisier than a broad pattern
antenna like your Inverted Vee dipole.


73 Tom

Jim - NN7K wrote:
Not to mention that noise is normally a phenonmen of the Vertical Plane
(which , depending on how steep your inverted "vee" is, will contain some
vertical component, while the yagi/quad is Horizontal to the plane.

Quads are a lot less noisy than Yagis when the wind
is blowing in the Arizona desert. Quads have a DC
short across the feedpoint that reduces noise from
static buildup.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:
Quads are a lot less noisy than Yagis when the wind
is blowing in the Arizona desert. Quads have a DC
short across the feedpoint that reduces noise from
static buildup.

Virtually all Yagi's have dc paths to discharge the elements.

The primary reason a quad is quiter is it has no sharp protruding ends
that are sticking way out in the air.

As a matter of fact if you research the quad, it was initially used to
eliminate corona at radio station HCJB.

Try this test, wire a small 2.5 MHh RF choke across your antenna and
check the before and after noise levels. They will not change.

73 Tom

wrote:
As a matter of fact if you research the quad, it was initially used to
eliminate corona at radio station HCJB.

Yep, designed by my distant cousin, BTW.

Try this test, wire a small 2.5 MHh RF choke across your antenna and
check the before and after noise levels. They will not change.

Obviously a false statement based on limited knowledge and
experience. Any ham living around Phoenix will be glad to
enlighten you.

That's exactly how I eliminated the noise and arcing on my
first bare-wire G5RV installed in Arizona. I didn't measure
the change in noise level but it went from arcing at the coax
connector to not arcing at the coax connector which was
acceptable to me.

If the driven element on a Yagi is an uninsulated dipole, it
is susceptible to wind driven noise on the driven element just
like my G5RV was.

Just because you have never experienced that type of noise in
Georgia doesn't mean it doesn't exist in Arizona. I dare say
you haven't experienced a lot of things that exist in reality.
Mary G. comes to mind. :-)
--
73, Cecil http://www.qsl.net/w5dxp

Jim - NN7K wrote:
Not to mention that noise is normally a phenonmen
of the Vertical Plane (which , depending on how
steep your inverted "vee" is, will contain some
vertical component, while the yagi/quad is
Horizontal to the plane. This has been a factor
on vhf for years, as noise levels tend to peak
at 6 meters (50 MHz). The MAIN reason that F.M.
is Vertical polarized is that for mobiles, it is
easy to construct an omni-directional antenna.
Most vhf manuals detail this effect! Jim NN7K

Dunno...I don't see much difference as far as the polarity
of the antenna. It's more the polarity of the noise source,
and it's radiator. I've got both horizontal and vertical yagi's
on 2m, and I've seen many times when the local line noise
was much worse when horizontal. But I blame that on the
noise being radiated mainly by horizontal power lines.
I see cases of noise with both polarities, or mostly
vertical, or mostly horizontal. Just depends on the source
antenna. You usually see appx 20db attenuation when
cross polarized.
As far as Ken's loop vs inv vee, if the vee is picking up more
noise, that just means the vee is the best antenna at picking
up that particular noise and at that direction and angle.
If he were to transmit on the two antennas, and receive
them from the noise source, using the sources antenna,
the vee would be received the strongest more than likely.
It's all reciprical. Noise is rf just like any other signal, and
obeys the same rules. If a certain antenna picks up more
rf of any type, noise, or desired, it's the best antenna of the
bunch to receive that source of rf. Thats one reason why I
often chuckle about "noise problems".. As long as it's not
local or common mode pickup from the shack, that just means
the antenna is working, and doing what it's supposed to do.
MK