Hi,

Before investing in a future antenna I have discussed on my site about
antennas designs, quad vs yagi or log.
http://www.astrosurf.com/lombry/antenna4.htm
I would like to get more information from users. If you used both quad and
Yagi, I should be curious to know your opinion about both designs, pro and
cons in various conditions of work (installed on the roof, 10m away fro the
hosue, 2m high only, etc).

I need for example some more information about the noise generated by a yagi
vs a quad or any other relevant information at which I don't think about.
For example, at first "sight" the quad generates 5-10 dB less than a quad.
Have you some similar information or other with all relevant data (nbr of
elements of concerned antennas, wind speed during measurements, location of
antenna, etc).

Also, I am interested in the drawbacks of each model (quad, yagi, log). I
discuss about this problem too, but I 'd like to go further in this matter.
The question is : why did you choose - or didn't choose - this design
(another reason than its price with is of course the main factor).

Thanks in advance

Thierry
ON4SKY

Sorry guys, I mixed 2 problems related to noise.
There are first the noise generated by beam vs quad, but I cannot estimate
the noise level, excepting that the quad is more silent under high wind.

The 5-10 dB less for the quad are related to the white noise. I explain.
According a swedish OM, it appears also some kind of white electrical noise
on a beam compared to a quad. The theory/argument is that the Yagi is more
prone to picking it up due to its high impedance at the dipole ends.

Quoted and translated from Swedish:
"The noise I talk about is on eg. 20 m and 5-10dB above the threshold on a
yagi but barely audible on a quad. It has always the same strength
independent of the time of day, possibly a bit weaker at sunrise. The noise
from static discharges are completely different. The noise I am talking
about is more "white"."
Quoting the list: "I have performed tests between Yagi/quad specailly on 20
meters. I have used a 5 el monoband yagi and a 6 el monoband quad. The
difference is about 5-10dB. The direction seems to be irrelevant, the white
noise is everywhere. "

The origin of noise is unclear but thoughts are (and these are
speculations): Perhaps the first skip of NVIS-noise from a town nearby? Or
that the quad's liftoff angle is different that the yagi's and so picks up
anything from another angle?

Can someone confirm this better performing of the quad ?

Thanks
Thierry
ON4SKY

"Thierry" To answer me in private use
http://www.astrosurf.com/lombry/post.htm wrote in message
...
Hi,

Before investing in a future antenna I have discussed on my site about
antennas designs, quad vs yagi or log.
http://www.astrosurf.com/lombry/antenna4.htm
I would like to get more information from users. If you used both quad and
...

Bill Turner wrote:

SNIP

And finally, don't be persuaded by that old saying about how a two
element quad is equal to a three element yagi. So what? A three
element yagi is FAR easier to build than a two element quad.

The bottom line is this: Once the quad is up in the air, it will
generally outperform a yagi of equivalent cost. The problems lie in
getting it up in the air and keeping it there.

If I had it all to do over again, starting from scratch, I probably
would use a yagi.

--
73, Bill W6WRT
QSLs via LoTW

And, I would use a Log Periodic!! I give up about 1 dB in gain and
acquire a 13.5 MHz to 33 MHz broadband antenna, no traps, full legal
power handling capability and a VSWR 2:1 across the full range. That
means 20, 17, 15, 12 and 10 meters all in ONE Beam.

W1MCE

I have a few thoughts.
I used a 3 / 3 Yagi for 10 years.

I currently have a 5 band 2 element Quad, one feedline to a switch box on
the boom, then series sections to match.

I chose the quad to minimize turning radius. My Yagi hung over the fence
line to the neighbor, the quad does not.

The verticle size is a challenge.

My local tower ordinance is 35 feet to the top of the structure. The top
of the quad is the top of the structure.

I had the tower inspected before I put up the quad.

Standing on my Garage roof I can adjust the 20 meter elements.

An effect that I notice, that I did not have with the Yagi, is that the
tuning changes based on the direction that the
quad is pointed. I attribute this to the proximity to the aluminum sided
garage, and a couple of trees.

Visual impact has not been an issue. It is shorter than the trees, which is
probably why I have not had any city trouble with the
hieght of the top of the quad.


"Thierry" To answer me in private use
http://www.astrosurf.com/lombry/post.htm wrote in message
...
Hi,

Before investing in a future antenna I have discussed on my site about
antennas designs, quad vs yagi or log.
http://www.astrosurf.com/lombry/antenna4.htm
I would like to get more information from users. If you used both quad and
Yagi, I should be curious to know your opinion about both designs, pro and
cons in various conditions of work (installed on the roof, 10m away fro
the
hosue, 2m high only, etc).

I need for example some more information about the noise generated by a
yagi
vs a quad or any other relevant information at which I don't think about.
For example, at first "sight" the quad generates 5-10 dB less than a quad.
Have you some similar information or other with all relevant data (nbr of
elements of concerned antennas, wind speed during measurements, location
of
antenna, etc).

Also, I am interested in the drawbacks of each model (quad, yagi, log). I
discuss about this problem too, but I 'd like to go further in this
matter.
The question is : why did you choose - or didn't choose - this design
(another reason than its price with is of course the main factor).

Thanks in advance

Thierry
ON4SKY

Quad advantages:

1. Simple. Only wires and coax. No baluns, traps, gammas, hairpins,
etc. Full legal power continuously with no problems.

A yagi can be made with a direct dipole feed, which is very simple. BOTH
the quad and yagi need a balun.

2. Broadband. Covers 20/15/10 with less than 2:1 SWR, even on 10.

See Cebik's studies of quads (www.cebik.com). Quads give a very
narrow front/back bandwidth. Not enough even to cover most amateur
bands with = 20 dB F/B.

3. Light. For a given level of performance, a quad should be a bit
lighter than a yagi.

True for a 2 element quad (boomless), but not with more elements. Look
at some of the weights at http://www.mgs4u.com/catalog/.

Torsten
N4OGW

What's a, "narrow front/back bandwidth"?
'Doc

What's a, "narrow front/back bandwidth"?

The pattern (usually quantified by font/back ratio) only remains good over
a narrow frequency range.

Torsten
N4OGW

"KA9CAR" wrote in message
...

....

My local tower ordinance is 35 feet to the top of the structure. The
top
of the quad is the top of the structure.

I had the tower inspected before I put up the quad.

So, your tower is 35 feet tall, right? Good...
__
Steve
KI5YG
..

Hi Bill,

In article ,
says...


On 12 Feb 2004 12:39:06 -0600, (R. Torsten
Clay) wrote:

A yagi can be made with a direct dipole feed, which is very simple.

Please explain how. All the yagis I've heard of have a very low
feedpoint impedance. How do you use 50 ohm coax without a matching
device of some kind?

It all depends how you tune the yagi. For example,
a two-element yagi with about 0.2 wavelength spacing,
with a reflector approximately 5% longer than the
driven element will offer a very good match to
50 ohm coax (according to EZNEC). Costs only a few
tenths of a dB in forward gain to get that match.

73,
Bob
K3PH

--
+----------------------------------------------+
| Bob Schreibmaier K3PH | E-mail: |
| Kresgeville, PA 18333 | http://www.dxis.org |
+----------------------------------------------+

A yagi can be made with a direct dipole feed, which is very simple.

__________________________________________________ _______

Please explain how. All the yagis I've heard of have a very low
feedpoint impedance. How do you use 50 ohm coax without a matching
device of some kind?

See for example

http://www.cebik.com/a10/ant35.html
http://www.naic.edu/~angel/kp4ao/ham/owa.html

just depends on how you tune the yagi. Give up a little (0.5 dB?) gain,
and the impedance can be 50 ohms.

Torsten
N4OGW